[PATCH v3 0/5] google firmware support

[PATCH v3 0/5] google firmware support

[Mike Waychison]

This patchset applies to v2.6.38-rc8 with the efivars patches (1-7) from
v2 of this series already applied.  It also applies cleanly to gregkh's
driver-core-next branch.

The following series implements some support for interfaces exposed by
google's servers' firmware.  As in the previous send-out, only the gsmi
and memconsole driver are present.  I've dropped the efivars changes as
Greg has already queued them.

In order to address various concerns had with the previous patchset,
I've re-worked the drivers to declare (an admittedly simple)
dmi_device_id structure that only matches "Google, Inc." board vendor id
strings.

As well, I've fixed the gsmi driver up to be able to be built as a
module.  Both drivers also now are disabled by default in the Kconfigs.

I'd like to have these small drivers included as they are required for
proper use of the kernel in our infrastructure.  They may not seem like
much, but a lot of our health automation as well as our human debugging
efforts are dependent on the functionality herein.  Getting these in the
public Linux tree would bring us closer to being able to easily test
kernels as they are released.

Thanks,

Patchset summary
================

Patches [1] and [2] add sanity checking for accessing the EBDA.

Patch [3] introduces CONFIG_GOOGLE_FIRMWARE that is disabled by
default and which gates Google-specific drivers.

Patch [4] adds the "gsmi" driver that we use to make calls into our
firmware.

Patch [5] adds the "memconsole" driver that finds the firmware's logs
and exposes them on /sys/firmware/log.

Diffstat
========
 Documentation/ABI/testing/sysfs-firmware-gsmi |   58 +
 Documentation/ABI/testing/sysfs-firmware-log  |    7 
 arch/x86/include/asm/bios_ebda.h              |   28 
 drivers/firmware/Kconfig                      |    2 
 drivers/firmware/Makefile                     |    2 
 drivers/firmware/google/Kconfig               |   31 
 drivers/firmware/google/Makefile              |    3 
 drivers/firmware/google/gsmi.c                |  941 ++++++++++++++++++++++++++
 drivers/firmware/google/memconsole.c          |  166 ++++
 9 files changed, 1236 insertions(+), 2 deletions(-)

ChangeLog:
==========
- v3
   - Drivers now use dmi_system_id structures to identify matching DMI
     strings, and export these tables via MODULE_DEVICE_TABLE to aid
     autoloading.
   - gsmi can now be compiled as a module.
   - memconsole fixed to require matching DMI strings.
   - efivars patchset dropped from this series as it is now an assumed
     pre-requisite.
- v2
   - Efivars can now be used by other drivers.
   - Documentation added for /sys/firmware/efi/vars
   - Memory console no longer touches log_buf ring buffer.
   - The firmware log is exported to userland as /sys/firmware/log
   - Ioctls for accessing nvram variables in gsmi driver replaced with
     efivars at /sys/firmware/gsmi/vars.
   - die_notifier is used instead of adding new notifer_lists.
   - EBDA scrubbing for memconsole now checks that we aren't walking
     into 0xA0000.
   - Documentation added for /sys/firmware/log
   - Documentation added for /sys/firmware/gsmi
   - Use kernel fixed width types instead of C99 types.
- v1
   - Initial public send-out.

[PATCH v3 1/5] x86: get_bios_ebda_length()

[Mike Waychison]

Add a wrapper routine that tells us the length of the EBDA if it is
present.  This guy also ensures that the returned length doesn't let the
EBDA run past the 640KiB mark.

Signed-off-by: Mike Waychison <mikew@google.com>
---
 arch/x86/include/asm/bios_ebda.h |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/bios_ebda.h b/arch/x86/include/asm/bios_ebda.h
index 3c75210..5174cf0 100644
--- a/arch/x86/include/asm/bios_ebda.h
+++ b/arch/x86/include/asm/bios_ebda.h
@@ -14,6 +14,27 @@ static inline unsigned int get_bios_ebda(void)
 	return address;	/* 0 means none */
 }
 
+/*
+ * Return the sanitized length of the EBDA in bytes, if it exists.
+ */
+static inline unsigned int get_bios_ebda_length(void)
+{
+	unsigned int address;
+	unsigned int length;
+
+	address = get_bios_ebda();
+	if (!address)
+		return 0;
+
+	/* EBDA length is byte 0 of the EBDA (stored in KiB) */
+	length = *(unsigned char *)phys_to_virt(address);
+	length <<= 10;
+
+	/* Trim the length if it extends beyond 640KiB */
+	length = min_t(unsigned int, (640 * 1024) - address, length);
+	return length;
+}
+
 void reserve_ebda_region(void);
 
 #ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION

Re: [PATCH v3 1/5] x86: get_bios_ebda_length()

[Greg KH]

On Mon, Mar 14, 2011 at 11:58:45PM -0700, Mike Waychison wrote:
> Add a wrapper routine that tells us the length of the EBDA if it is
> present.  This guy also ensures that the returned length doesn't let the
> EBDA run past the 640KiB mark.
> 
> Signed-off-by: Mike Waychison <mikew@google.com>
> ---
>  arch/x86/include/asm/bios_ebda.h |   21 +++++++++++++++++++++
>  1 files changed, 21 insertions(+), 0 deletions(-)

Again, x86 maintainers, any ack/nak for this and the second patch in
this series?  Any objection for me queueing this up through the
driver-core tree so I can take the follow-on patches in this series?

thanks,

greg k-h

Re: [PATCH v3 1/5] x86: get_bios_ebda_length()

[Greg KH]

On Mon, Mar 14, 2011 at 11:58:45PM -0700, Mike Waychison wrote:
> Add a wrapper routine that tells us the length of the EBDA if it is
> present.  This guy also ensures that the returned length doesn't let the
> EBDA run past the 640KiB mark.
> 
> Signed-off-by: Mike Waychison <mikew@google.com>
> ---
>  arch/x86/include/asm/bios_ebda.h |   21 +++++++++++++++++++++
>  1 files changed, 21 insertions(+), 0 deletions(-)

Ok, due to a total lack of response from the x86 maintainers, I'm going
to take this through my driver-core tree as I have no objection to it
and Mike's been very patient for a while now...

thanks,

greg k-h

[PATCH v3 2/5] x86: Better comments for get_bios_ebda()

[Mike Waychison]

Make the comments a bit clearer for get_bios_ebda so that it actually
tells us what it is returning.

Signed-off-by: Mike Waychison <mikew@google.com>
---
 arch/x86/include/asm/bios_ebda.h |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/bios_ebda.h b/arch/x86/include/asm/bios_ebda.h
index 5174cf0..aa6a317 100644
--- a/arch/x86/include/asm/bios_ebda.h
+++ b/arch/x86/include/asm/bios_ebda.h
@@ -4,11 +4,14 @@
 #include <asm/io.h>
 
 /*
- * there is a real-mode segmented pointer pointing to the
- * 4K EBDA area at 0x40E.
+ * Returns physical address of EBDA.  Returns 0 if there is no EBDA.
  */
 static inline unsigned int get_bios_ebda(void)
 {
+	/*
+	 * There is a real-mode segmented pointer pointing to the
+	 * 4K EBDA area at 0x40E.
+	 */
 	unsigned int address = *(unsigned short *)phys_to_virt(0x40E);
 	address <<= 4;
 	return address;	/* 0 means none */

[PATCH v3 3/5] Introduce CONFIG_GOOGLE_FIRMWARE

[Mike Waychison]

In order to keep Google's firmware drivers organized amongst themselves,
create a new directory for them to live in.  As well, all Google
firmware drivers are gated on CONFIG_GOOGLE_FIRMWARE=y, which defaults
to 'n' in the kernel build.

Signed-off-by: Mike Waychison <mikew@google.com>

---
Changelog:
v3:
   - Removed comment about 'other implementations' in Kconfig message as
     per gregkh.
---
 drivers/firmware/Kconfig         |    2 ++
 drivers/firmware/Makefile        |    2 ++
 drivers/firmware/google/Kconfig  |   13 +++++++++++++
 drivers/firmware/google/Makefile |    1 +
 4 files changed, 18 insertions(+), 0 deletions(-)
 create mode 100644 drivers/firmware/google/Kconfig
 create mode 100644 drivers/firmware/google/Makefile

diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 3c56afc..9b00072 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -145,4 +145,6 @@ config ISCSI_IBFT
 	  detect iSCSI boot parameters dynamically during system boot, say Y.
 	  Otherwise, say N.
 
+source "drivers/firmware/google/Kconfig"
+
 endmenu
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 20c17fc..5a7e273 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -12,3 +12,5 @@ obj-$(CONFIG_DMIID)		+= dmi-id.o
 obj-$(CONFIG_ISCSI_IBFT_FIND)	+= iscsi_ibft_find.o
 obj-$(CONFIG_ISCSI_IBFT)	+= iscsi_ibft.o
 obj-$(CONFIG_FIRMWARE_MEMMAP)	+= memmap.o
+
+obj-$(CONFIG_GOOGLE_FIRMWARE)	+= google/
diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig
new file mode 100644
index 0000000..02a7366
--- /dev/null
+++ b/drivers/firmware/google/Kconfig
@@ -0,0 +1,13 @@
+config GOOGLE_FIRMWARE
+	bool "Google Firmware Drivers"
+	depends on X86
+	default n
+	help
+	  These firmware drivers are used by Google's servers.  They are
+	  only useful if you are working directly on one of their
+	  proprietary servers.  If in doubt, say "N".
+
+menu "Google Firmware Drivers"
+	depends on GOOGLE_FIRMWARE
+
+endmenu
diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/drivers/firmware/google/Makefile
@@ -0,0 +1 @@
+

Re: [PATCH v3 3/5] Introduce CONFIG_GOOGLE_FIRMWARE

[Greg KH]

On Mon, Mar 14, 2011 at 11:58:55PM -0700, Mike Waychison wrote:
> In order to keep Google's firmware drivers organized amongst themselves,
> create a new directory for them to live in.  As well, all Google
> firmware drivers are gated on CONFIG_GOOGLE_FIRMWARE=y, which defaults
> to 'n' in the kernel build.
> 
> Signed-off-by: Mike Waychison <mikew@google.com>

This patch breaks the build:

ld: cannot find drivers/firmware/google/built-in.o: No such file or directory

Care to reoder this to be the last patch in the series?

I've applied the first two, so just send the last 3, with this one being
the last one, and it should be fine.

thanks,

greg k-h

[PATCH v4 1/3] driver: Google EFI SMI

[Mike Waychison]

The "gsmi" driver bridges userland with firmware specific routines for
accessing hardware.

Currently, this driver only supports NVRAM and eventlog information.
Deprecated functions have been removed from the driver, though their
op-codes are left in place so that they are not re-used.

This driver works by trampolining into the firmware via the smi_command
outlined in the FADT table.  Three protocols are used due to various
limitations over time, but all are included herein.

This driver should only ever load on Google boards, identified by either
a "Google, Inc." board vendor string in DMI, or "GOOGLE" in the OEM
strings of the FADT ACPI table.  This logic happens in
gsmi_system_valid().

Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Aaron Durbin <adurbin@google.com>
Signed-off-by: Mike Waychison <mikew@google.com>
---
Changelog:
v4:
   - Re-ordered to be before the introduction of CONFIG_GOOGLE_FIRMWARE
v3:
   - Require a match on a dmi_system_id, and export table via
     MODULE_DEVICE_TABLE.
   - Mark gsmi_system_valid as __init.
   - Allow driver to be compiled as a removable module.
   - Default to 'n' in Kconfig.
v2:
   - Use ARRAY_SIZE() rather than open coded construct.
   - Fix off-by-one in array lookup.
   - Removed superfluous memset.
   - Removed superfluous variable clear.
   - switch from posix integer types to linux kernel integer types.
   - Replaced use of dropped oops_notifier_list with die_notifier_list.
   - Added dependency on CONFIG_DMI.
   - Fixed a bug which crashed the kernel if no DMI tables were found.
   - Replace nvram ioctls with efivars interface at
     /sys/firmware/gsmi/vars.
   - Removed NOOP command that is unused.
   - Change gsmi_dev to not be statically allocated.
   - Removed ioctl interface
   - Removed chardev interface
   - Removed header as user ABI is all done via sysfs.
   - Fix output clobber for firmware call so that we don't clobber the
     compiler-cached value for 'cmd'.
   - Added docs to Documentation/ABI for exposed system call interface.
---
 Documentation/ABI/testing/sysfs-firmware-gsmi |   58 ++
 drivers/firmware/Kconfig                      |    2 
 drivers/firmware/Makefile                     |    2 
 drivers/firmware/google/Kconfig               |    9 
 drivers/firmware/google/Makefile              |    2 
 drivers/firmware/google/gsmi.c                |  941 +++++++++++++++++++++++++
 6 files changed, 1014 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-firmware-gsmi
 create mode 100644 drivers/firmware/google/Kconfig
 create mode 100644 drivers/firmware/google/Makefile
 create mode 100644 drivers/firmware/google/gsmi.c

diff --git a/Documentation/ABI/testing/sysfs-firmware-gsmi b/Documentation/ABI/testing/sysfs-firmware-gsmi
new file mode 100644
index 0000000..0faa0aa
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-gsmi
@@ -0,0 +1,58 @@
+What:		/sys/firmware/gsmi
+Date:		March 2011
+Contact:	Mike Waychison <mikew@google.com>
+Description:
+		Some servers used internally at Google have firmware
+		that provides callback functionality via explicit SMI
+		triggers.  Some of the callbacks are similar to those
+		provided by the EFI runtime services page, but due to
+		historical reasons this different entry-point has been
+		used.
+
+		The gsmi driver implements the kernel's abstraction for
+		these firmware callbacks.  Currently, this functionality
+		is limited to handling the system event log and getting
+		access to EFI-style variables stored in nvram.
+
+		Layout:
+
+		/sys/firmware/gsmi/vars:
+
+			This directory has the same layout (and
+			underlying implementation as /sys/firmware/efi/vars.
+			See Documentation/ABI/*/sysfs-firmware-efi-vars
+			for more information on how to interact with
+			this structure.
+
+		/sys/firmware/gsmi/append_to_eventlog - write-only:
+
+			This file takes a binary blob and passes it onto
+			the firmware to be timestamped and appended to
+			the system eventlog.  The binary format is
+			interpreted by the firmware and may change from
+			platform to platform.  The only kernel-enforced
+			requirement is that the blob be prefixed with a
+			32bit host-endian type used as part of the
+			firmware call.
+
+		/sys/firmware/gsmi/clear_config - write-only:
+
+			Writing any value to this file will cause the
+			entire firmware configuration to be reset to
+			"factory defaults".  Callers should assume that
+			a reboot is required for the configuration to be
+			cleared.
+
+		/sys/firmware/gsmi/clear_eventlog - write-only:
+
+			This file is used to clear out a portion/the
+			whole of the system event log.  Values written
+			should be values between 1 and 100 inclusive (in
+			ASCII) representing the fraction of the log to
+			clear.  Not all platforms support fractional
+			clearing though, and this writes to this file
+			will error out if the firmware doesn't like your
+			submitted fraction.
+
+			Callers should assume that a reboot is needed
+			for this operation to complete.
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 3c56afc..9b00072 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -145,4 +145,6 @@ config ISCSI_IBFT
 	  detect iSCSI boot parameters dynamically during system boot, say Y.
 	  Otherwise, say N.
 
+source "drivers/firmware/google/Kconfig"
+
 endmenu
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 20c17fc..9fcf3b2 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -12,3 +12,5 @@ obj-$(CONFIG_DMIID)		+= dmi-id.o
 obj-$(CONFIG_ISCSI_IBFT_FIND)	+= iscsi_ibft_find.o
 obj-$(CONFIG_ISCSI_IBFT)	+= iscsi_ibft.o
 obj-$(CONFIG_FIRMWARE_MEMMAP)	+= memmap.o
+
+obj-y  += google/
diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig
new file mode 100644
index 0000000..4a03835
--- /dev/null
+++ b/drivers/firmware/google/Kconfig
@@ -0,0 +1,9 @@
+config GOOGLE_SMI
+	tristate "SMI interface for Google platforms"
+	depends on ACPI && DMI
+	select EFI_VARS
+	help
+	  Say Y here if you want to enable SMI callbacks for Google
+	  platforms.  This provides an interface for writing to and
+	  clearing the EFI event log and reading and writing NVRAM
+	  variables.
diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile
new file mode 100644
index 0000000..fb127d7
--- /dev/null
+++ b/drivers/firmware/google/Makefile
@@ -0,0 +1,2 @@
+
+obj-$(CONFIG_GOOGLE_SMI)		+= gsmi.o
diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c
new file mode 100644
index 0000000..34b1ffa
--- /dev/null
+++ b/drivers/firmware/google/gsmi.c
@@ -0,0 +1,941 @@
+/*
+ * Copyright 2010 Google Inc. All Rights Reserved.
+ * Author: dlaurie@google.com (Duncan Laurie)
+ *
+ * Re-worked to expose sysfs APIs by mikew@google.com (Mike Waychison)
+ *
+ * EFI SMI interface for Google platforms
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/spinlock.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/ioctl.h>
+#include <linux/acpi.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <linux/dmi.h>
+#include <linux/kdebug.h>
+#include <linux/reboot.h>
+#include <linux/efi.h>
+
+#define GSMI_SHUTDOWN_CLEAN	0	/* Clean Shutdown */
+#define GSMI_SHUTDOWN_NMIWDT	1	/* NMI Watchdog */
+#define GSMI_SHUTDOWN_PANIC	2	/* Panic */
+#define GSMI_SHUTDOWN_OOPS	3	/* Oops */
+#define GSMI_SHUTDOWN_DIE	4	/* Die -- No longer meaningful */
+#define GSMI_SHUTDOWN_MCE	5	/* Machine Check */
+#define GSMI_SHUTDOWN_SOFTWDT	6	/* Software Watchdog */
+#define GSMI_SHUTDOWN_MBE	7	/* Uncorrected ECC */
+#define GSMI_SHUTDOWN_TRIPLE	8	/* Triple Fault */
+
+#define DRIVER_VERSION		"1.0"
+#define GSMI_GUID_SIZE		16
+#define GSMI_BUF_SIZE		1024
+#define GSMI_BUF_ALIGN		sizeof(u64)
+#define GSMI_CALLBACK		0xef
+
+/* SMI return codes */
+#define GSMI_SUCCESS		0x00
+#define GSMI_UNSUPPORTED2	0x03
+#define GSMI_LOG_FULL		0x0b
+#define GSMI_VAR_NOT_FOUND	0x0e
+#define GSMI_HANDSHAKE_SPIN	0x7d
+#define GSMI_HANDSHAKE_CF	0x7e
+#define GSMI_HANDSHAKE_NONE	0x7f
+#define GSMI_INVALID_PARAMETER	0x82
+#define GSMI_UNSUPPORTED	0x83
+#define GSMI_BUFFER_TOO_SMALL	0x85
+#define GSMI_NOT_READY		0x86
+#define GSMI_DEVICE_ERROR	0x87
+#define GSMI_NOT_FOUND		0x8e
+
+#define QUIRKY_BOARD_HASH 0x78a30a50
+
+/* Internally used commands passed to the firmware */
+#define GSMI_CMD_GET_NVRAM_VAR		0x01
+#define GSMI_CMD_GET_NEXT_VAR		0x02
+#define GSMI_CMD_SET_NVRAM_VAR		0x03
+#define GSMI_CMD_SET_EVENT_LOG		0x08
+#define GSMI_CMD_CLEAR_EVENT_LOG	0x09
+#define GSMI_CMD_CLEAR_CONFIG		0x20
+#define GSMI_CMD_HANDSHAKE_TYPE		0xC1
+
+/* Magic entry type for kernel events */
+#define GSMI_LOG_ENTRY_TYPE_KERNEL     0xDEAD
+
+/* SMI buffers must be in 32bit physical address space */
+struct gsmi_buf {
+	u8 *start;			/* start of buffer */
+	size_t length;			/* length of buffer */
+	dma_addr_t handle;		/* dma allocation handle */
+	u32 address;			/* physical address of buffer */
+};
+
+struct gsmi_device {
+	struct platform_device *pdev;	/* platform device */
+	struct gsmi_buf *name_buf;	/* variable name buffer */
+	struct gsmi_buf *data_buf;	/* generic data buffer */
+	struct gsmi_buf *param_buf;	/* parameter buffer */
+	spinlock_t lock;		/* serialize access to SMIs */
+	u16 smi_cmd;			/* SMI command port */
+	int handshake_type;		/* firmware handler interlock type */
+	struct dma_pool *dma_pool;	/* DMA buffer pool */
+} gsmi_dev;
+
+/* Packed structures for communicating with the firmware */
+struct gsmi_nvram_var_param {
+	efi_guid_t	guid;
+	u32		name_ptr;
+	u32		attributes;
+	u32		data_len;
+	u32		data_ptr;
+} __packed;
+
+struct gsmi_get_next_var_param {
+	u8	guid[GSMI_GUID_SIZE];
+	u32	name_ptr;
+	u32	name_len;
+} __packed;
+
+struct gsmi_set_eventlog_param {
+	u32	data_ptr;
+	u32	data_len;
+	u32	type;
+} __packed;
+
+/* Event log formats */
+struct gsmi_log_entry_type_1 {
+	u16	type;
+	u32	instance;
+} __packed;
+
+
+/*
+ * Some platforms don't have explicit SMI handshake
+ * and need to wait for SMI to complete.
+ */
+#define GSMI_DEFAULT_SPINCOUNT	0x10000
+static unsigned int spincount = GSMI_DEFAULT_SPINCOUNT;
+module_param(spincount, uint, 0600);
+MODULE_PARM_DESC(spincount,
+	"The number of loop iterations to use when using the spin handshake.");
+
+static struct gsmi_buf *gsmi_buf_alloc(void)
+{
+	struct gsmi_buf *smibuf;
+
+	smibuf = kzalloc(sizeof(*smibuf), GFP_KERNEL);
+	if (!smibuf) {
+		printk(KERN_ERR "gsmi: out of memory\n");
+		return NULL;
+	}
+
+	/* allocate buffer in 32bit address space */
+	smibuf->start = dma_pool_alloc(gsmi_dev.dma_pool, GFP_KERNEL,
+				       &smibuf->handle);
+	if (!smibuf->start) {
+		printk(KERN_ERR "gsmi: failed to allocate name buffer\n");
+		kfree(smibuf);
+		return NULL;
+	}
+
+	/* fill in the buffer handle */
+	smibuf->length = GSMI_BUF_SIZE;
+	smibuf->address = (u32)virt_to_phys(smibuf->start);
+
+	return smibuf;
+}
+
+static void gsmi_buf_free(struct gsmi_buf *smibuf)
+{
+	if (smibuf) {
+		if (smibuf->start)
+			dma_pool_free(gsmi_dev.dma_pool, smibuf->start,
+				      smibuf->handle);
+		kfree(smibuf);
+	}
+}
+
+/*
+ * Make a call to gsmi func(sub).  GSMI error codes are translated to
+ * in-kernel errnos (0 on success, -ERRNO on error).
+ */
+static int gsmi_exec(u8 func, u8 sub)
+{
+	u16 cmd = (sub << 8) | func;
+	u16 result = 0;
+	int rc = 0;
+
+	/*
+	 * AH  : Subfunction number
+	 * AL  : Function number
+	 * EBX : Parameter block address
+	 * DX  : SMI command port
+	 *
+	 * Three protocols here. See also the comment in gsmi_init().
+	 */
+	if (gsmi_dev.handshake_type == GSMI_HANDSHAKE_CF) {
+		/*
+		 * If handshake_type == HANDSHAKE_CF then set CF on the
+		 * way in and wait for the handler to clear it; this avoids
+		 * corrupting register state on those chipsets which have
+		 * a delay between writing the SMI trigger register and
+		 * entering SMM.
+		 */
+		asm volatile (
+			"stc\n"
+			"outb %%al, %%dx\n"
+		"1:      jc 1b\n"
+			: "=a" (result)
+			: "0" (cmd),
+			  "d" (gsmi_dev.smi_cmd),
+			  "b" (gsmi_dev.param_buf->address)
+			: "memory", "cc"
+		);
+	} else if (gsmi_dev.handshake_type == GSMI_HANDSHAKE_SPIN) {
+		/*
+		 * If handshake_type == HANDSHAKE_SPIN we spin a
+		 * hundred-ish usecs to ensure the SMI has triggered.
+		 */
+		asm volatile (
+			"outb %%al, %%dx\n"
+		"1:      loop 1b\n"
+			: "=a" (result)
+			: "0" (cmd),
+			  "d" (gsmi_dev.smi_cmd),
+			  "b" (gsmi_dev.param_buf->address),
+			  "c" (spincount)
+			: "memory", "cc"
+		);
+	} else {
+		/*
+		 * If handshake_type == HANDSHAKE_NONE we do nothing;
+		 * either we don't need to or it's legacy firmware that
+		 * doesn't understand the CF protocol.
+		 */
+		asm volatile (
+			"outb %%al, %%dx\n\t"
+			: "=a" (result)
+			: "0" (cmd),
+			  "d" (gsmi_dev.smi_cmd),
+			  "b" (gsmi_dev.param_buf->address)
+			: "memory", "cc"
+		);
+	}
+
+	/* check return code from SMI handler */
+	switch (result) {
+	case GSMI_SUCCESS:
+		break;
+	case GSMI_VAR_NOT_FOUND:
+		/* not really an error, but let the caller know */
+		rc = 1;
+		break;
+	case GSMI_INVALID_PARAMETER:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Invalid parameter\n", cmd);
+		rc = -EINVAL;
+		break;
+	case GSMI_BUFFER_TOO_SMALL:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Buffer too small\n", cmd);
+		rc = -ENOMEM;
+		break;
+	case GSMI_UNSUPPORTED:
+	case GSMI_UNSUPPORTED2:
+		if (sub != GSMI_CMD_HANDSHAKE_TYPE)
+			printk(KERN_ERR "gsmi: exec 0x%04x: Not supported\n",
+			       cmd);
+		rc = -ENOSYS;
+		break;
+	case GSMI_NOT_READY:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Not ready\n", cmd);
+		rc = -EBUSY;
+		break;
+	case GSMI_DEVICE_ERROR:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Device error\n", cmd);
+		rc = -EFAULT;
+		break;
+	case GSMI_NOT_FOUND:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Data not found\n", cmd);
+		rc = -ENOENT;
+		break;
+	case GSMI_LOG_FULL:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Log full\n", cmd);
+		rc = -ENOSPC;
+		break;
+	case GSMI_HANDSHAKE_CF:
+	case GSMI_HANDSHAKE_SPIN:
+	case GSMI_HANDSHAKE_NONE:
+		rc = result;
+		break;
+	default:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Unknown error 0x%04x\n",
+		       cmd, result);
+		rc = -ENXIO;
+	}
+
+	return rc;
+}
+
+/* Return the number of unicode characters in data */
+static size_t
+utf16_strlen(efi_char16_t *data, unsigned long maxlength)
+{
+	unsigned long length = 0;
+
+	while (*data++ != 0 && length < maxlength)
+		length++;
+	return length;
+}
+
+static efi_status_t gsmi_get_variable(efi_char16_t *name,
+				      efi_guid_t *vendor, u32 *attr,
+				      unsigned long *data_size,
+				      void *data)
+{
+	struct gsmi_nvram_var_param param = {
+		.name_ptr = gsmi_dev.name_buf->address,
+		.data_ptr = gsmi_dev.data_buf->address,
+		.data_len = (u32)*data_size,
+	};
+	efi_status_t ret = EFI_SUCCESS;
+	unsigned long flags;
+	size_t name_len = utf16_strlen(name, GSMI_BUF_SIZE / 2);
+	int rc;
+
+	if (name_len >= GSMI_BUF_SIZE / 2)
+		return EFI_BAD_BUFFER_SIZE;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* Vendor guid */
+	memcpy(&param.guid, vendor, sizeof(param.guid));
+
+	/* variable name, already in UTF-16 */
+	memset(gsmi_dev.name_buf->start, 0, gsmi_dev.name_buf->length);
+	memcpy(gsmi_dev.name_buf->start, name, name_len * 2);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_GET_NVRAM_VAR);
+	if (rc < 0) {
+		printk(KERN_ERR "gsmi: Get Variable failed\n");
+		ret = EFI_LOAD_ERROR;
+	} else if (rc == 1) {
+		/* variable was not found */
+		ret = EFI_NOT_FOUND;
+	} else {
+		/* Get the arguments back */
+		memcpy(&param, gsmi_dev.param_buf->start, sizeof(param));
+
+		/* The size reported is the min of all of our buffers */
+		*data_size = min(*data_size, gsmi_dev.data_buf->length);
+		*data_size = min_t(unsigned long, *data_size, param.data_len);
+
+		/* Copy data back to return buffer. */
+		memcpy(data, gsmi_dev.data_buf->start, *data_size);
+
+		/* All variables are have the following attributes */
+		*attr = EFI_VARIABLE_NON_VOLATILE |
+			EFI_VARIABLE_BOOTSERVICE_ACCESS |
+			EFI_VARIABLE_RUNTIME_ACCESS;
+	}
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return ret;
+}
+
+static efi_status_t gsmi_get_next_variable(unsigned long *name_size,
+					   efi_char16_t *name,
+					   efi_guid_t *vendor)
+{
+	struct gsmi_get_next_var_param param = {
+		.name_ptr = gsmi_dev.name_buf->address,
+		.name_len = gsmi_dev.name_buf->length,
+	};
+	efi_status_t ret = EFI_SUCCESS;
+	int rc;
+	unsigned long flags;
+
+	/* For the moment, only support buffers that exactly match in size */
+	if (*name_size != GSMI_BUF_SIZE)
+		return EFI_BAD_BUFFER_SIZE;
+
+	/* Let's make sure the thing is at least null-terminated */
+	if (utf16_strlen(name, GSMI_BUF_SIZE / 2) == GSMI_BUF_SIZE / 2)
+		return EFI_INVALID_PARAMETER;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* guid */
+	memcpy(&param.guid, vendor, sizeof(param.guid));
+
+	/* variable name, already in UTF-16 */
+	memcpy(gsmi_dev.name_buf->start, name, *name_size);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_GET_NEXT_VAR);
+	if (rc < 0) {
+		printk(KERN_ERR "gsmi: Get Next Variable Name failed\n");
+		ret = EFI_LOAD_ERROR;
+	} else if (rc == 1) {
+		/* variable not found -- end of list */
+		ret = EFI_NOT_FOUND;
+	} else {
+		/* copy variable data back to return buffer */
+		memcpy(&param, gsmi_dev.param_buf->start, sizeof(param));
+
+		/* Copy the name back */
+		memcpy(name, gsmi_dev.name_buf->start, GSMI_BUF_SIZE);
+		*name_size = utf16_strlen(name, GSMI_BUF_SIZE / 2) * 2;
+
+		/* copy guid to return buffer */
+		memcpy(vendor, &param.guid, sizeof(param.guid));
+		ret = EFI_SUCCESS;
+	}
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return ret;
+}
+
+static efi_status_t gsmi_set_variable(efi_char16_t *name,
+				      efi_guid_t *vendor,
+				      unsigned long attr,
+				      unsigned long data_size,
+				      void *data)
+{
+	struct gsmi_nvram_var_param param = {
+		.name_ptr = gsmi_dev.name_buf->address,
+		.data_ptr = gsmi_dev.data_buf->address,
+		.data_len = (u32)data_size,
+		.attributes = EFI_VARIABLE_NON_VOLATILE |
+			      EFI_VARIABLE_BOOTSERVICE_ACCESS |
+			      EFI_VARIABLE_RUNTIME_ACCESS,
+	};
+	size_t name_len = utf16_strlen(name, GSMI_BUF_SIZE / 2);
+	efi_status_t ret = EFI_SUCCESS;
+	int rc;
+	unsigned long flags;
+
+	if (name_len >= GSMI_BUF_SIZE / 2)
+		return EFI_BAD_BUFFER_SIZE;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* guid */
+	memcpy(&param.guid, vendor, sizeof(param.guid));
+
+	/* variable name, already in UTF-16 */
+	memset(gsmi_dev.name_buf->start, 0, gsmi_dev.name_buf->length);
+	memcpy(gsmi_dev.name_buf->start, name, name_len * 2);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+	memcpy(gsmi_dev.data_buf->start, data, data_size);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_NVRAM_VAR);
+	if (rc < 0) {
+		printk(KERN_ERR "gsmi: Set Variable failed\n");
+		ret = EFI_INVALID_PARAMETER;
+	}
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return ret;
+}
+
+static const struct efivar_operations efivar_ops = {
+	.get_variable = gsmi_get_variable,
+	.set_variable = gsmi_set_variable,
+	.get_next_variable = gsmi_get_next_variable,
+};
+
+static ssize_t eventlog_write(struct file *filp, struct kobject *kobj,
+			       struct bin_attribute *bin_attr,
+			       char *buf, loff_t pos, size_t count)
+{
+	struct gsmi_set_eventlog_param param = {
+		.data_ptr = gsmi_dev.data_buf->address,
+	};
+	int rc = 0;
+	unsigned long flags;
+
+	/* Pull the type out */
+	if (count < sizeof(u32))
+		return -EINVAL;
+	param.type = *(u32 *)buf;
+	count -= sizeof(u32);
+	buf += sizeof(u32);
+
+	/* The remaining buffer is the data payload */
+	if (count > gsmi_dev.data_buf->length)
+		return -EINVAL;
+	param.data_len = count - sizeof(u32);
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+	memcpy(gsmi_dev.data_buf->start, buf, param.data_len);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_EVENT_LOG);
+	if (rc < 0)
+		printk(KERN_ERR "gsmi: Set Event Log failed\n");
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return rc;
+
+}
+
+static struct bin_attribute eventlog_bin_attr = {
+	.attr = {.name = "append_to_eventlog", .mode = 0200},
+	.write = eventlog_write,
+};
+
+static ssize_t gsmi_clear_eventlog_store(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 const char *buf, size_t count)
+{
+	int rc;
+	unsigned long flags;
+	unsigned long val;
+	struct {
+		u32 percentage;
+		u32 data_type;
+	} param;
+
+	rc = strict_strtoul(buf, 0, &val);
+	if (rc)
+		return rc;
+
+	/*
+	 * Value entered is a percentage, 0 through 100, anything else
+	 * is invalid.
+	 */
+	if (val > 100)
+		return -EINVAL;
+
+	/* data_type here selects the smbios event log. */
+	param.percentage = val;
+	param.data_type = 0;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_CLEAR_EVENT_LOG);
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	if (rc)
+		return rc;
+	return count;
+}
+
+static struct kobj_attribute gsmi_clear_eventlog_attr = {
+	.attr = {.name = "clear_eventlog", .mode = 0200},
+	.store = gsmi_clear_eventlog_store,
+};
+
+static ssize_t gsmi_clear_config_store(struct kobject *kobj,
+				       struct kobj_attribute *attr,
+				       const char *buf, size_t count)
+{
+	int rc;
+	unsigned long flags;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* clear parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_CLEAR_CONFIG);
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	if (rc)
+		return rc;
+	return count;
+}
+
+static struct kobj_attribute gsmi_clear_config_attr = {
+	.attr = {.name = "clear_config", .mode = 0200},
+	.store = gsmi_clear_config_store,
+};
+
+static const struct attribute *gsmi_attrs[] = {
+	&gsmi_clear_config_attr.attr,
+	&gsmi_clear_eventlog_attr.attr,
+	NULL,
+};
+
+static int gsmi_shutdown_reason(int reason)
+{
+	struct gsmi_log_entry_type_1 entry = {
+		.type     = GSMI_LOG_ENTRY_TYPE_KERNEL,
+		.instance = reason,
+	};
+	struct gsmi_set_eventlog_param param = {
+		.data_len = sizeof(entry),
+		.type     = 1,
+	};
+	static int saved_reason;
+	int rc = 0;
+	unsigned long flags;
+
+	/* avoid duplicate entries in the log */
+	if (saved_reason & (1 << reason))
+		return 0;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	saved_reason |= (1 << reason);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+	memcpy(gsmi_dev.data_buf->start, &entry, sizeof(entry));
+
+	/* parameter buffer */
+	param.data_ptr = gsmi_dev.data_buf->address;
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_EVENT_LOG);
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	if (rc < 0)
+		printk(KERN_ERR "gsmi: Log Shutdown Reason failed\n");
+	else
+		printk(KERN_EMERG "gsmi: Log Shutdown Reason 0x%02x\n",
+		       reason);
+
+	return rc;
+}
+
+static int gsmi_reboot_callback(struct notifier_block *nb,
+				unsigned long reason, void *arg)
+{
+	gsmi_shutdown_reason(GSMI_SHUTDOWN_CLEAN);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block gsmi_reboot_notifier = {
+	.notifier_call = gsmi_reboot_callback
+};
+
+static int gsmi_die_callback(struct notifier_block *nb,
+			     unsigned long reason, void *arg)
+{
+	if (reason == DIE_NMIWATCHDOG)
+		gsmi_shutdown_reason(GSMI_SHUTDOWN_NMIWDT);
+	else if (reason == DIE_OOPS)
+		gsmi_shutdown_reason(GSMI_SHUTDOWN_OOPS);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block gsmi_die_notifier = {
+	.notifier_call = gsmi_die_callback
+};
+
+static int gsmi_panic_callback(struct notifier_block *nb,
+			       unsigned long reason, void *arg)
+{
+	gsmi_shutdown_reason(GSMI_SHUTDOWN_PANIC);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block gsmi_panic_notifier = {
+	.notifier_call = gsmi_panic_callback,
+};
+
+/*
+ * This hash function was blatantly copied from include/linux/hash.h.
+ * It is used by this driver to obfuscate a board name that requires a
+ * quirk within this driver.
+ *
+ * Please do not remove this copy of the function as any changes to the
+ * global utility hash_64() function would break this driver's ability
+ * to identify a board and provide the appropriate quirk -- mikew@google.com
+ */
+static u64 __init local_hash_64(u64 val, unsigned bits)
+{
+	u64 hash = val;
+
+	/*  Sigh, gcc can't optimise this alone like it does for 32 bits. */
+	u64 n = hash;
+	n <<= 18;
+	hash -= n;
+	n <<= 33;
+	hash -= n;
+	n <<= 3;
+	hash += n;
+	n <<= 3;
+	hash -= n;
+	n <<= 4;
+	hash += n;
+	n <<= 2;
+	hash += n;
+
+	/* High bits are more random, so use them. */
+	return hash >> (64 - bits);
+}
+
+static u32 __init hash_oem_table_id(char s[8])
+{
+	u64 input;
+	memcpy(&input, s, 8);
+	return local_hash_64(input, 32);
+}
+
+static struct dmi_system_id gsmi_dmi_table[] __initdata = {
+	{
+		.ident = "Google Board",
+		.matches = {
+			DMI_MATCH(DMI_BOARD_VENDOR, "Google, Inc."),
+		},
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(dmi, gsmi_dmi_table);
+
+static __init int gsmi_system_valid(void)
+{
+	u32 hash;
+
+	if (!dmi_check_system(gsmi_dmi_table))
+		return -ENODEV;
+
+	/*
+	 * Only newer firmware supports the gsmi interface.  All older
+	 * firmware that didn't support this interface used to plug the
+	 * table name in the first four bytes of the oem_table_id field.
+	 * Newer firmware doesn't do that though, so use that as the
+	 * discriminant factor.  We have to do this in order to
+	 * whitewash our board names out of the public driver.
+	 */
+	if (!strncmp(acpi_gbl_FADT.header.oem_table_id, "FACP", 4)) {
+		printk(KERN_INFO "gsmi: Board is too old\n");
+		return -ENODEV;
+	}
+
+	/* Disable on board with 1.0 BIOS due to Google bug 2602657 */
+	hash = hash_oem_table_id(acpi_gbl_FADT.header.oem_table_id);
+	if (hash == QUIRKY_BOARD_HASH) {
+		const char *bios_ver = dmi_get_system_info(DMI_BIOS_VERSION);
+		if (strncmp(bios_ver, "1.0", 3) == 0) {
+			pr_info("gsmi: disabled on this board's BIOS %s\n",
+				bios_ver);
+			return -ENODEV;
+		}
+	}
+
+	/* check for valid SMI command port in ACPI FADT */
+	if (acpi_gbl_FADT.smi_command == 0) {
+		pr_info("gsmi: missing smi_command\n");
+		return -ENODEV;
+	}
+
+	/* Found */
+	return 0;
+}
+
+static struct kobject *gsmi_kobj;
+static struct efivars efivars;
+
+static __init int gsmi_init(void)
+{
+	unsigned long flags;
+	int ret;
+
+	ret = gsmi_system_valid();
+	if (ret)
+		return ret;
+
+	gsmi_dev.smi_cmd = acpi_gbl_FADT.smi_command;
+
+	/* register device */
+	gsmi_dev.pdev = platform_device_register_simple("gsmi", -1, NULL, 0);
+	if (IS_ERR(gsmi_dev.pdev)) {
+		printk(KERN_ERR "gsmi: unable to register platform device\n");
+		return PTR_ERR(gsmi_dev.pdev);
+	}
+
+	/* SMI access needs to be serialized */
+	spin_lock_init(&gsmi_dev.lock);
+
+	/* SMI callbacks require 32bit addresses */
+	gsmi_dev.pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
+	gsmi_dev.pdev->dev.dma_mask =
+		&gsmi_dev.pdev->dev.coherent_dma_mask;
+	ret = -ENOMEM;
+	gsmi_dev.dma_pool = dma_pool_create("gsmi", &gsmi_dev.pdev->dev,
+					     GSMI_BUF_SIZE, GSMI_BUF_ALIGN, 0);
+	if (!gsmi_dev.dma_pool)
+		goto out_err;
+
+	/*
+	 * pre-allocate buffers because sometimes we are called when
+	 * this is not feasible: oops, panic, die, mce, etc
+	 */
+	gsmi_dev.name_buf = gsmi_buf_alloc();
+	if (!gsmi_dev.name_buf) {
+		printk(KERN_ERR "gsmi: failed to allocate name buffer\n");
+		goto out_err;
+	}
+
+	gsmi_dev.data_buf = gsmi_buf_alloc();
+	if (!gsmi_dev.data_buf) {
+		printk(KERN_ERR "gsmi: failed to allocate data buffer\n");
+		goto out_err;
+	}
+
+	gsmi_dev.param_buf = gsmi_buf_alloc();
+	if (!gsmi_dev.param_buf) {
+		printk(KERN_ERR "gsmi: failed to allocate param buffer\n");
+		goto out_err;
+	}
+
+	/*
+	 * Determine type of handshake used to serialize the SMI
+	 * entry. See also gsmi_exec().
+	 *
+	 * There's a "behavior" present on some chipsets where writing the
+	 * SMI trigger register in the southbridge doesn't result in an
+	 * immediate SMI. Rather, the processor can execute "a few" more
+	 * instructions before the SMI takes effect. To ensure synchronous
+	 * behavior, implement a handshake between the kernel driver and the
+	 * firmware handler to spin until released. This ioctl determines
+	 * the type of handshake.
+	 *
+	 * NONE: The firmware handler does not implement any
+	 * handshake. Either it doesn't need to, or it's legacy firmware
+	 * that doesn't know it needs to and never will.
+	 *
+	 * CF: The firmware handler will clear the CF in the saved
+	 * state before returning. The driver may set the CF and test for
+	 * it to clear before proceeding.
+	 *
+	 * SPIN: The firmware handler does not implement any handshake
+	 * but the driver should spin for a hundred or so microseconds
+	 * to ensure the SMI has triggered.
+	 *
+	 * Finally, the handler will return -ENOSYS if
+	 * GSMI_CMD_HANDSHAKE_TYPE is unimplemented, which implies
+	 * HANDSHAKE_NONE.
+	 */
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+	gsmi_dev.handshake_type = GSMI_HANDSHAKE_SPIN;
+	gsmi_dev.handshake_type =
+	    gsmi_exec(GSMI_CALLBACK, GSMI_CMD_HANDSHAKE_TYPE);
+	if (gsmi_dev.handshake_type == -ENOSYS)
+		gsmi_dev.handshake_type = GSMI_HANDSHAKE_NONE;
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	/* Remove and clean up gsmi if the handshake could not complete. */
+	if (gsmi_dev.handshake_type == -ENXIO) {
+		printk(KERN_INFO "gsmi version " DRIVER_VERSION
+		       " failed to load\n");
+		ret = -ENODEV;
+		goto out_err;
+	}
+
+	printk(KERN_INFO "gsmi version " DRIVER_VERSION " loaded\n");
+
+	/* Register in the firmware directory */
+	ret = -ENOMEM;
+	gsmi_kobj = kobject_create_and_add("gsmi", firmware_kobj);
+	if (!gsmi_kobj) {
+		printk(KERN_INFO "gsmi: Failed to create firmware kobj\n");
+		goto out_err;
+	}
+
+	/* Setup eventlog access */
+	ret = sysfs_create_bin_file(gsmi_kobj, &eventlog_bin_attr);
+	if (ret) {
+		printk(KERN_INFO "gsmi: Failed to setup eventlog");
+		goto out_err;
+	}
+
+	/* Other attributes */
+	ret = sysfs_create_files(gsmi_kobj, gsmi_attrs);
+	if (ret) {
+		printk(KERN_INFO "gsmi: Failed to add attrs");
+		goto out_err;
+	}
+
+	if (register_efivars(&efivars, &efivar_ops, gsmi_kobj)) {
+		printk(KERN_INFO "gsmi: Failed to register efivars\n");
+		goto out_err;
+	}
+
+	register_reboot_notifier(&gsmi_reboot_notifier);
+	register_die_notifier(&gsmi_die_notifier);
+	atomic_notifier_chain_register(&panic_notifier_list,
+				       &gsmi_panic_notifier);
+
+	return 0;
+
+ out_err:
+	kobject_put(gsmi_kobj);
+	gsmi_buf_free(gsmi_dev.param_buf);
+	gsmi_buf_free(gsmi_dev.data_buf);
+	gsmi_buf_free(gsmi_dev.name_buf);
+	if (gsmi_dev.dma_pool)
+		dma_pool_destroy(gsmi_dev.dma_pool);
+	platform_device_unregister(gsmi_dev.pdev);
+	pr_info("gsmi: failed to load: %d\n", ret);
+	return ret;
+}
+
+static void __exit gsmi_exit(void)
+{
+	unregister_reboot_notifier(&gsmi_reboot_notifier);
+	unregister_die_notifier(&gsmi_die_notifier);
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &gsmi_panic_notifier);
+	unregister_efivars(&efivars);
+
+	kobject_put(gsmi_kobj);
+	gsmi_buf_free(gsmi_dev.param_buf);
+	gsmi_buf_free(gsmi_dev.data_buf);
+	gsmi_buf_free(gsmi_dev.name_buf);
+	dma_pool_destroy(gsmi_dev.dma_pool);
+	platform_device_unregister(gsmi_dev.pdev);
+}
+
+module_init(gsmi_init);
+module_exit(gsmi_exit);
+
+MODULE_AUTHOR("Google, Inc.");
+MODULE_LICENSE("GPL");

Re: [PATCH v4 1/3] driver: Google EFI SMI

[Greg KH]

On Fri, Apr 29, 2011 at 03:55:51PM -0700, Mike Waychison wrote:
> The "gsmi" driver bridges userland with firmware specific routines for
> accessing hardware.
> 
> Currently, this driver only supports NVRAM and eventlog information.
> Deprecated functions have been removed from the driver, though their
> op-codes are left in place so that they are not re-used.
> 
> This driver works by trampolining into the firmware via the smi_command
> outlined in the FADT table.  Three protocols are used due to various
> limitations over time, but all are included herein.
> 
> This driver should only ever load on Google boards, identified by either
> a "Google, Inc." board vendor string in DMI, or "GOOGLE" in the OEM
> strings of the FADT ACPI table.  This logic happens in
> gsmi_system_valid().
> 
> Signed-off-by: Duncan Laurie <dlaurie@google.com>
> Signed-off-by: Aaron Durbin <adurbin@google.com>
> Signed-off-by: Mike Waychison <mikew@google.com>

{sigh}

I now get this build error with this patch applied:

 CC [M]  drivers/firmware/google/gsmi.o
drivers/firmware/google/gsmi.c: In function ‘gsmi_die_callback’:
drivers/firmware/google/gsmi.c:660:16: error: ‘DIE_NMIWATCHDOG’ undeclared (first use in this function)
drivers/firmware/google/gsmi.c:660:16: note: each undeclared identifier is reported only once for each function it appears in
make[3]: *** [drivers/firmware/google/gsmi.o] Error 1


Also, I had to hand edit the drivers/firmware/Makefile and Kconfig parts
of this patch to get it to apply, care to respin it against the
linux-next tree so I don't have to do that next time around?

thanks,

greg k-h

Re: [PATCH v4 1/3] driver: Google EFI SMI

[Mike Waychison]

On Fri, Apr 29, 2011 at 4:40 PM, Greg KH <greg@kroah.com> wrote:
> On Fri, Apr 29, 2011 at 03:55:51PM -0700, Mike Waychison wrote:
>> The "gsmi" driver bridges userland with firmware specific routines for
>> accessing hardware.
>>
>> Currently, this driver only supports NVRAM and eventlog information.
>> Deprecated functions have been removed from the driver, though their
>> op-codes are left in place so that they are not re-used.
>>
>> This driver works by trampolining into the firmware via the smi_command
>> outlined in the FADT table.  Three protocols are used due to various
>> limitations over time, but all are included herein.
>>
>> This driver should only ever load on Google boards, identified by either
>> a "Google, Inc." board vendor string in DMI, or "GOOGLE" in the OEM
>> strings of the FADT ACPI table.  This logic happens in
>> gsmi_system_valid().
>>
>> Signed-off-by: Duncan Laurie <dlaurie@google.com>
>> Signed-off-by: Aaron Durbin <adurbin@google.com>
>> Signed-off-by: Mike Waychison <mikew@google.com>
>
> {sigh}
>
> I now get this build error with this patch applied:
>
>  CC [M]  drivers/firmware/google/gsmi.o
> drivers/firmware/google/gsmi.c: In function ‘gsmi_die_callback’:
> drivers/firmware/google/gsmi.c:660:16: error: ‘DIE_NMIWATCHDOG’ undeclared (first use in this function)
> drivers/firmware/google/gsmi.c:660:16: note: each undeclared identifier is reported only once for each function it appears in
> make[3]: *** [drivers/firmware/google/gsmi.o] Error 1
>
>
> Also, I had to hand edit the drivers/firmware/Makefile and Kconfig parts
> of this patch to get it to apply, care to respin it against the
> linux-next tree so I don't have to do that next time around?
>

Ya, I'm looking at these now.

Hmm :(  It seems the nmi watchdog got renamed to the 'hard lockup'
detector, and we lost the DIE callback in the meantime.

I think for the moment, I'm going to respin and drop the NMI bits for
now.  We can revisit actually calling notify_die() when we panic in
watchdog_overflow_callback() as a follow on.

[PATCH v5 1/3] driver: Google EFI SMI

[Mike Waychison]

The "gsmi" driver bridges userland with firmware specific routines for
accessing hardware.

Currently, this driver only supports NVRAM and eventlog information.
Deprecated functions have been removed from the driver, though their
op-codes are left in place so that they are not re-used.

This driver works by trampolining into the firmware via the smi_command
outlined in the FADT table.  Three protocols are used due to various
limitations over time, but all are included herein.

This driver should only ever load on Google boards, identified by either
a "Google, Inc." board vendor string in DMI, or "GOOGLE" in the OEM
strings of the FADT ACPI table.  This logic happens in
gsmi_system_valid().

Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Aaron Durbin <adurbin@google.com>
Signed-off-by: Mike Waychison <mikew@google.com>
---
Changelog:
v5:
   - refreshed to next-20110429
   - Dropped handling of DIE_NMIWATCHDOG as it was dropped in the 2.6.39
     cycle.
v4:
   - Re-ordered to be before the introduction of CONFIG_GOOGLE_FIRMWARE
v3:
   - Require a match on a dmi_system_id, and export table via
     MODULE_DEVICE_TABLE.
   - Mark gsmi_system_valid as __init.
   - Allow driver to be compiled as a removable module.
   - Default to 'n' in Kconfig.
v2:
   - Use ARRAY_SIZE() rather than open coded construct.
   - Fix off-by-one in array lookup.
   - Removed superfluous memset.
   - Removed superfluous variable clear.
   - switch from posix integer types to linux kernel integer types.
   - Replaced use of dropped oops_notifier_list with die_notifier_list.
   - Added dependency on CONFIG_DMI.
   - Fixed a bug which crashed the kernel if no DMI tables were found.
   - Replace nvram ioctls with efivars interface at
     /sys/firmware/gsmi/vars.
   - Removed NOOP command that is unused.
   - Change gsmi_dev to not be statically allocated.
   - Removed ioctl interface
   - Removed chardev interface
   - Removed header as user ABI is all done via sysfs.
   - Fix output clobber for firmware call so that we don't clobber the
     compiler-cached value for 'cmd'.
   - Added docs to Documentation/ABI for exposed system call interface.
---
 Documentation/ABI/testing/sysfs-firmware-gsmi |   58 ++
 drivers/firmware/Kconfig                      |    2 
 drivers/firmware/Makefile                     |    2 
 drivers/firmware/google/Kconfig               |    9 
 drivers/firmware/google/Makefile              |    2 
 drivers/firmware/google/gsmi.c                |  940 +++++++++++++++++++++++++
 6 files changed, 1013 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-firmware-gsmi
 create mode 100644 drivers/firmware/google/Kconfig
 create mode 100644 drivers/firmware/google/Makefile
 create mode 100644 drivers/firmware/google/gsmi.c

diff --git a/Documentation/ABI/testing/sysfs-firmware-gsmi b/Documentation/ABI/testing/sysfs-firmware-gsmi
new file mode 100644
index 0000000..0faa0aa
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-gsmi
@@ -0,0 +1,58 @@
+What:		/sys/firmware/gsmi
+Date:		March 2011
+Contact:	Mike Waychison <mikew@google.com>
+Description:
+		Some servers used internally at Google have firmware
+		that provides callback functionality via explicit SMI
+		triggers.  Some of the callbacks are similar to those
+		provided by the EFI runtime services page, but due to
+		historical reasons this different entry-point has been
+		used.
+
+		The gsmi driver implements the kernel's abstraction for
+		these firmware callbacks.  Currently, this functionality
+		is limited to handling the system event log and getting
+		access to EFI-style variables stored in nvram.
+
+		Layout:
+
+		/sys/firmware/gsmi/vars:
+
+			This directory has the same layout (and
+			underlying implementation as /sys/firmware/efi/vars.
+			See Documentation/ABI/*/sysfs-firmware-efi-vars
+			for more information on how to interact with
+			this structure.
+
+		/sys/firmware/gsmi/append_to_eventlog - write-only:
+
+			This file takes a binary blob and passes it onto
+			the firmware to be timestamped and appended to
+			the system eventlog.  The binary format is
+			interpreted by the firmware and may change from
+			platform to platform.  The only kernel-enforced
+			requirement is that the blob be prefixed with a
+			32bit host-endian type used as part of the
+			firmware call.
+
+		/sys/firmware/gsmi/clear_config - write-only:
+
+			Writing any value to this file will cause the
+			entire firmware configuration to be reset to
+			"factory defaults".  Callers should assume that
+			a reboot is required for the configuration to be
+			cleared.
+
+		/sys/firmware/gsmi/clear_eventlog - write-only:
+
+			This file is used to clear out a portion/the
+			whole of the system event log.  Values written
+			should be values between 1 and 100 inclusive (in
+			ASCII) representing the fraction of the log to
+			clear.  Not all platforms support fractional
+			clearing though, and this writes to this file
+			will error out if the firmware doesn't like your
+			submitted fraction.
+
+			Callers should assume that a reboot is needed
+			for this operation to complete.
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index b3a25a5..efba163 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -157,4 +157,6 @@ config SIGMA
 	  If unsure, say N here.  Drivers that need these helpers will select
 	  this option automatically.
 
+source "drivers/firmware/google/Kconfig"
+
 endmenu
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 00bb0b8..d7d6009 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -13,3 +13,5 @@ obj-$(CONFIG_ISCSI_IBFT_FIND)	+= iscsi_ibft_find.o
 obj-$(CONFIG_ISCSI_IBFT)	+= iscsi_ibft.o
 obj-$(CONFIG_FIRMWARE_MEMMAP)	+= memmap.o
 obj-$(CONFIG_SIGMA)		+= sigma.o
+
+obj-y  += google/
diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig
new file mode 100644
index 0000000..4a03835
--- /dev/null
+++ b/drivers/firmware/google/Kconfig
@@ -0,0 +1,9 @@
+config GOOGLE_SMI
+	tristate "SMI interface for Google platforms"
+	depends on ACPI && DMI
+	select EFI_VARS
+	help
+	  Say Y here if you want to enable SMI callbacks for Google
+	  platforms.  This provides an interface for writing to and
+	  clearing the EFI event log and reading and writing NVRAM
+	  variables.
diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile
new file mode 100644
index 0000000..fb127d7
--- /dev/null
+++ b/drivers/firmware/google/Makefile
@@ -0,0 +1,2 @@
+
+obj-$(CONFIG_GOOGLE_SMI)		+= gsmi.o
diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c
new file mode 100644
index 0000000..fa7f0b3
--- /dev/null
+++ b/drivers/firmware/google/gsmi.c
@@ -0,0 +1,940 @@
+/*
+ * Copyright 2010 Google Inc. All Rights Reserved.
+ * Author: dlaurie@google.com (Duncan Laurie)
+ *
+ * Re-worked to expose sysfs APIs by mikew@google.com (Mike Waychison)
+ *
+ * EFI SMI interface for Google platforms
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/spinlock.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/ioctl.h>
+#include <linux/acpi.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <linux/dmi.h>
+#include <linux/kdebug.h>
+#include <linux/reboot.h>
+#include <linux/efi.h>
+
+#define GSMI_SHUTDOWN_CLEAN	0	/* Clean Shutdown */
+/* TODO(mikew@google.com): Tie in HARDLOCKUP_DETECTOR with NMIWDT */
+#define GSMI_SHUTDOWN_NMIWDT	1	/* NMI Watchdog */
+#define GSMI_SHUTDOWN_PANIC	2	/* Panic */
+#define GSMI_SHUTDOWN_OOPS	3	/* Oops */
+#define GSMI_SHUTDOWN_DIE	4	/* Die -- No longer meaningful */
+#define GSMI_SHUTDOWN_MCE	5	/* Machine Check */
+#define GSMI_SHUTDOWN_SOFTWDT	6	/* Software Watchdog */
+#define GSMI_SHUTDOWN_MBE	7	/* Uncorrected ECC */
+#define GSMI_SHUTDOWN_TRIPLE	8	/* Triple Fault */
+
+#define DRIVER_VERSION		"1.0"
+#define GSMI_GUID_SIZE		16
+#define GSMI_BUF_SIZE		1024
+#define GSMI_BUF_ALIGN		sizeof(u64)
+#define GSMI_CALLBACK		0xef
+
+/* SMI return codes */
+#define GSMI_SUCCESS		0x00
+#define GSMI_UNSUPPORTED2	0x03
+#define GSMI_LOG_FULL		0x0b
+#define GSMI_VAR_NOT_FOUND	0x0e
+#define GSMI_HANDSHAKE_SPIN	0x7d
+#define GSMI_HANDSHAKE_CF	0x7e
+#define GSMI_HANDSHAKE_NONE	0x7f
+#define GSMI_INVALID_PARAMETER	0x82
+#define GSMI_UNSUPPORTED	0x83
+#define GSMI_BUFFER_TOO_SMALL	0x85
+#define GSMI_NOT_READY		0x86
+#define GSMI_DEVICE_ERROR	0x87
+#define GSMI_NOT_FOUND		0x8e
+
+#define QUIRKY_BOARD_HASH 0x78a30a50
+
+/* Internally used commands passed to the firmware */
+#define GSMI_CMD_GET_NVRAM_VAR		0x01
+#define GSMI_CMD_GET_NEXT_VAR		0x02
+#define GSMI_CMD_SET_NVRAM_VAR		0x03
+#define GSMI_CMD_SET_EVENT_LOG		0x08
+#define GSMI_CMD_CLEAR_EVENT_LOG	0x09
+#define GSMI_CMD_CLEAR_CONFIG		0x20
+#define GSMI_CMD_HANDSHAKE_TYPE		0xC1
+
+/* Magic entry type for kernel events */
+#define GSMI_LOG_ENTRY_TYPE_KERNEL     0xDEAD
+
+/* SMI buffers must be in 32bit physical address space */
+struct gsmi_buf {
+	u8 *start;			/* start of buffer */
+	size_t length;			/* length of buffer */
+	dma_addr_t handle;		/* dma allocation handle */
+	u32 address;			/* physical address of buffer */
+};
+
+struct gsmi_device {
+	struct platform_device *pdev;	/* platform device */
+	struct gsmi_buf *name_buf;	/* variable name buffer */
+	struct gsmi_buf *data_buf;	/* generic data buffer */
+	struct gsmi_buf *param_buf;	/* parameter buffer */
+	spinlock_t lock;		/* serialize access to SMIs */
+	u16 smi_cmd;			/* SMI command port */
+	int handshake_type;		/* firmware handler interlock type */
+	struct dma_pool *dma_pool;	/* DMA buffer pool */
+} gsmi_dev;
+
+/* Packed structures for communicating with the firmware */
+struct gsmi_nvram_var_param {
+	efi_guid_t	guid;
+	u32		name_ptr;
+	u32		attributes;
+	u32		data_len;
+	u32		data_ptr;
+} __packed;
+
+struct gsmi_get_next_var_param {
+	u8	guid[GSMI_GUID_SIZE];
+	u32	name_ptr;
+	u32	name_len;
+} __packed;
+
+struct gsmi_set_eventlog_param {
+	u32	data_ptr;
+	u32	data_len;
+	u32	type;
+} __packed;
+
+/* Event log formats */
+struct gsmi_log_entry_type_1 {
+	u16	type;
+	u32	instance;
+} __packed;
+
+
+/*
+ * Some platforms don't have explicit SMI handshake
+ * and need to wait for SMI to complete.
+ */
+#define GSMI_DEFAULT_SPINCOUNT	0x10000
+static unsigned int spincount = GSMI_DEFAULT_SPINCOUNT;
+module_param(spincount, uint, 0600);
+MODULE_PARM_DESC(spincount,
+	"The number of loop iterations to use when using the spin handshake.");
+
+static struct gsmi_buf *gsmi_buf_alloc(void)
+{
+	struct gsmi_buf *smibuf;
+
+	smibuf = kzalloc(sizeof(*smibuf), GFP_KERNEL);
+	if (!smibuf) {
+		printk(KERN_ERR "gsmi: out of memory\n");
+		return NULL;
+	}
+
+	/* allocate buffer in 32bit address space */
+	smibuf->start = dma_pool_alloc(gsmi_dev.dma_pool, GFP_KERNEL,
+				       &smibuf->handle);
+	if (!smibuf->start) {
+		printk(KERN_ERR "gsmi: failed to allocate name buffer\n");
+		kfree(smibuf);
+		return NULL;
+	}
+
+	/* fill in the buffer handle */
+	smibuf->length = GSMI_BUF_SIZE;
+	smibuf->address = (u32)virt_to_phys(smibuf->start);
+
+	return smibuf;
+}
+
+static void gsmi_buf_free(struct gsmi_buf *smibuf)
+{
+	if (smibuf) {
+		if (smibuf->start)
+			dma_pool_free(gsmi_dev.dma_pool, smibuf->start,
+				      smibuf->handle);
+		kfree(smibuf);
+	}
+}
+
+/*
+ * Make a call to gsmi func(sub).  GSMI error codes are translated to
+ * in-kernel errnos (0 on success, -ERRNO on error).
+ */
+static int gsmi_exec(u8 func, u8 sub)
+{
+	u16 cmd = (sub << 8) | func;
+	u16 result = 0;
+	int rc = 0;
+
+	/*
+	 * AH  : Subfunction number
+	 * AL  : Function number
+	 * EBX : Parameter block address
+	 * DX  : SMI command port
+	 *
+	 * Three protocols here. See also the comment in gsmi_init().
+	 */
+	if (gsmi_dev.handshake_type == GSMI_HANDSHAKE_CF) {
+		/*
+		 * If handshake_type == HANDSHAKE_CF then set CF on the
+		 * way in and wait for the handler to clear it; this avoids
+		 * corrupting register state on those chipsets which have
+		 * a delay between writing the SMI trigger register and
+		 * entering SMM.
+		 */
+		asm volatile (
+			"stc\n"
+			"outb %%al, %%dx\n"
+		"1:      jc 1b\n"
+			: "=a" (result)
+			: "0" (cmd),
+			  "d" (gsmi_dev.smi_cmd),
+			  "b" (gsmi_dev.param_buf->address)
+			: "memory", "cc"
+		);
+	} else if (gsmi_dev.handshake_type == GSMI_HANDSHAKE_SPIN) {
+		/*
+		 * If handshake_type == HANDSHAKE_SPIN we spin a
+		 * hundred-ish usecs to ensure the SMI has triggered.
+		 */
+		asm volatile (
+			"outb %%al, %%dx\n"
+		"1:      loop 1b\n"
+			: "=a" (result)
+			: "0" (cmd),
+			  "d" (gsmi_dev.smi_cmd),
+			  "b" (gsmi_dev.param_buf->address),
+			  "c" (spincount)
+			: "memory", "cc"
+		);
+	} else {
+		/*
+		 * If handshake_type == HANDSHAKE_NONE we do nothing;
+		 * either we don't need to or it's legacy firmware that
+		 * doesn't understand the CF protocol.
+		 */
+		asm volatile (
+			"outb %%al, %%dx\n\t"
+			: "=a" (result)
+			: "0" (cmd),
+			  "d" (gsmi_dev.smi_cmd),
+			  "b" (gsmi_dev.param_buf->address)
+			: "memory", "cc"
+		);
+	}
+
+	/* check return code from SMI handler */
+	switch (result) {
+	case GSMI_SUCCESS:
+		break;
+	case GSMI_VAR_NOT_FOUND:
+		/* not really an error, but let the caller know */
+		rc = 1;
+		break;
+	case GSMI_INVALID_PARAMETER:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Invalid parameter\n", cmd);
+		rc = -EINVAL;
+		break;
+	case GSMI_BUFFER_TOO_SMALL:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Buffer too small\n", cmd);
+		rc = -ENOMEM;
+		break;
+	case GSMI_UNSUPPORTED:
+	case GSMI_UNSUPPORTED2:
+		if (sub != GSMI_CMD_HANDSHAKE_TYPE)
+			printk(KERN_ERR "gsmi: exec 0x%04x: Not supported\n",
+			       cmd);
+		rc = -ENOSYS;
+		break;
+	case GSMI_NOT_READY:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Not ready\n", cmd);
+		rc = -EBUSY;
+		break;
+	case GSMI_DEVICE_ERROR:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Device error\n", cmd);
+		rc = -EFAULT;
+		break;
+	case GSMI_NOT_FOUND:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Data not found\n", cmd);
+		rc = -ENOENT;
+		break;
+	case GSMI_LOG_FULL:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Log full\n", cmd);
+		rc = -ENOSPC;
+		break;
+	case GSMI_HANDSHAKE_CF:
+	case GSMI_HANDSHAKE_SPIN:
+	case GSMI_HANDSHAKE_NONE:
+		rc = result;
+		break;
+	default:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Unknown error 0x%04x\n",
+		       cmd, result);
+		rc = -ENXIO;
+	}
+
+	return rc;
+}
+
+/* Return the number of unicode characters in data */
+static size_t
+utf16_strlen(efi_char16_t *data, unsigned long maxlength)
+{
+	unsigned long length = 0;
+
+	while (*data++ != 0 && length < maxlength)
+		length++;
+	return length;
+}
+
+static efi_status_t gsmi_get_variable(efi_char16_t *name,
+				      efi_guid_t *vendor, u32 *attr,
+				      unsigned long *data_size,
+				      void *data)
+{
+	struct gsmi_nvram_var_param param = {
+		.name_ptr = gsmi_dev.name_buf->address,
+		.data_ptr = gsmi_dev.data_buf->address,
+		.data_len = (u32)*data_size,
+	};
+	efi_status_t ret = EFI_SUCCESS;
+	unsigned long flags;
+	size_t name_len = utf16_strlen(name, GSMI_BUF_SIZE / 2);
+	int rc;
+
+	if (name_len >= GSMI_BUF_SIZE / 2)
+		return EFI_BAD_BUFFER_SIZE;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* Vendor guid */
+	memcpy(&param.guid, vendor, sizeof(param.guid));
+
+	/* variable name, already in UTF-16 */
+	memset(gsmi_dev.name_buf->start, 0, gsmi_dev.name_buf->length);
+	memcpy(gsmi_dev.name_buf->start, name, name_len * 2);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_GET_NVRAM_VAR);
+	if (rc < 0) {
+		printk(KERN_ERR "gsmi: Get Variable failed\n");
+		ret = EFI_LOAD_ERROR;
+	} else if (rc == 1) {
+		/* variable was not found */
+		ret = EFI_NOT_FOUND;
+	} else {
+		/* Get the arguments back */
+		memcpy(&param, gsmi_dev.param_buf->start, sizeof(param));
+
+		/* The size reported is the min of all of our buffers */
+		*data_size = min(*data_size, gsmi_dev.data_buf->length);
+		*data_size = min_t(unsigned long, *data_size, param.data_len);
+
+		/* Copy data back to return buffer. */
+		memcpy(data, gsmi_dev.data_buf->start, *data_size);
+
+		/* All variables are have the following attributes */
+		*attr = EFI_VARIABLE_NON_VOLATILE |
+			EFI_VARIABLE_BOOTSERVICE_ACCESS |
+			EFI_VARIABLE_RUNTIME_ACCESS;
+	}
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return ret;
+}
+
+static efi_status_t gsmi_get_next_variable(unsigned long *name_size,
+					   efi_char16_t *name,
+					   efi_guid_t *vendor)
+{
+	struct gsmi_get_next_var_param param = {
+		.name_ptr = gsmi_dev.name_buf->address,
+		.name_len = gsmi_dev.name_buf->length,
+	};
+	efi_status_t ret = EFI_SUCCESS;
+	int rc;
+	unsigned long flags;
+
+	/* For the moment, only support buffers that exactly match in size */
+	if (*name_size != GSMI_BUF_SIZE)
+		return EFI_BAD_BUFFER_SIZE;
+
+	/* Let's make sure the thing is at least null-terminated */
+	if (utf16_strlen(name, GSMI_BUF_SIZE / 2) == GSMI_BUF_SIZE / 2)
+		return EFI_INVALID_PARAMETER;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* guid */
+	memcpy(&param.guid, vendor, sizeof(param.guid));
+
+	/* variable name, already in UTF-16 */
+	memcpy(gsmi_dev.name_buf->start, name, *name_size);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_GET_NEXT_VAR);
+	if (rc < 0) {
+		printk(KERN_ERR "gsmi: Get Next Variable Name failed\n");
+		ret = EFI_LOAD_ERROR;
+	} else if (rc == 1) {
+		/* variable not found -- end of list */
+		ret = EFI_NOT_FOUND;
+	} else {
+		/* copy variable data back to return buffer */
+		memcpy(&param, gsmi_dev.param_buf->start, sizeof(param));
+
+		/* Copy the name back */
+		memcpy(name, gsmi_dev.name_buf->start, GSMI_BUF_SIZE);
+		*name_size = utf16_strlen(name, GSMI_BUF_SIZE / 2) * 2;
+
+		/* copy guid to return buffer */
+		memcpy(vendor, &param.guid, sizeof(param.guid));
+		ret = EFI_SUCCESS;
+	}
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return ret;
+}
+
+static efi_status_t gsmi_set_variable(efi_char16_t *name,
+				      efi_guid_t *vendor,
+				      unsigned long attr,
+				      unsigned long data_size,
+				      void *data)
+{
+	struct gsmi_nvram_var_param param = {
+		.name_ptr = gsmi_dev.name_buf->address,
+		.data_ptr = gsmi_dev.data_buf->address,
+		.data_len = (u32)data_size,
+		.attributes = EFI_VARIABLE_NON_VOLATILE |
+			      EFI_VARIABLE_BOOTSERVICE_ACCESS |
+			      EFI_VARIABLE_RUNTIME_ACCESS,
+	};
+	size_t name_len = utf16_strlen(name, GSMI_BUF_SIZE / 2);
+	efi_status_t ret = EFI_SUCCESS;
+	int rc;
+	unsigned long flags;
+
+	if (name_len >= GSMI_BUF_SIZE / 2)
+		return EFI_BAD_BUFFER_SIZE;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* guid */
+	memcpy(&param.guid, vendor, sizeof(param.guid));
+
+	/* variable name, already in UTF-16 */
+	memset(gsmi_dev.name_buf->start, 0, gsmi_dev.name_buf->length);
+	memcpy(gsmi_dev.name_buf->start, name, name_len * 2);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+	memcpy(gsmi_dev.data_buf->start, data, data_size);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_NVRAM_VAR);
+	if (rc < 0) {
+		printk(KERN_ERR "gsmi: Set Variable failed\n");
+		ret = EFI_INVALID_PARAMETER;
+	}
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return ret;
+}
+
+static const struct efivar_operations efivar_ops = {
+	.get_variable = gsmi_get_variable,
+	.set_variable = gsmi_set_variable,
+	.get_next_variable = gsmi_get_next_variable,
+};
+
+static ssize_t eventlog_write(struct file *filp, struct kobject *kobj,
+			       struct bin_attribute *bin_attr,
+			       char *buf, loff_t pos, size_t count)
+{
+	struct gsmi_set_eventlog_param param = {
+		.data_ptr = gsmi_dev.data_buf->address,
+	};
+	int rc = 0;
+	unsigned long flags;
+
+	/* Pull the type out */
+	if (count < sizeof(u32))
+		return -EINVAL;
+	param.type = *(u32 *)buf;
+	count -= sizeof(u32);
+	buf += sizeof(u32);
+
+	/* The remaining buffer is the data payload */
+	if (count > gsmi_dev.data_buf->length)
+		return -EINVAL;
+	param.data_len = count - sizeof(u32);
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+	memcpy(gsmi_dev.data_buf->start, buf, param.data_len);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_EVENT_LOG);
+	if (rc < 0)
+		printk(KERN_ERR "gsmi: Set Event Log failed\n");
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return rc;
+
+}
+
+static struct bin_attribute eventlog_bin_attr = {
+	.attr = {.name = "append_to_eventlog", .mode = 0200},
+	.write = eventlog_write,
+};
+
+static ssize_t gsmi_clear_eventlog_store(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 const char *buf, size_t count)
+{
+	int rc;
+	unsigned long flags;
+	unsigned long val;
+	struct {
+		u32 percentage;
+		u32 data_type;
+	} param;
+
+	rc = strict_strtoul(buf, 0, &val);
+	if (rc)
+		return rc;
+
+	/*
+	 * Value entered is a percentage, 0 through 100, anything else
+	 * is invalid.
+	 */
+	if (val > 100)
+		return -EINVAL;
+
+	/* data_type here selects the smbios event log. */
+	param.percentage = val;
+	param.data_type = 0;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_CLEAR_EVENT_LOG);
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	if (rc)
+		return rc;
+	return count;
+}
+
+static struct kobj_attribute gsmi_clear_eventlog_attr = {
+	.attr = {.name = "clear_eventlog", .mode = 0200},
+	.store = gsmi_clear_eventlog_store,
+};
+
+static ssize_t gsmi_clear_config_store(struct kobject *kobj,
+				       struct kobj_attribute *attr,
+				       const char *buf, size_t count)
+{
+	int rc;
+	unsigned long flags;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* clear parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_CLEAR_CONFIG);
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	if (rc)
+		return rc;
+	return count;
+}
+
+static struct kobj_attribute gsmi_clear_config_attr = {
+	.attr = {.name = "clear_config", .mode = 0200},
+	.store = gsmi_clear_config_store,
+};
+
+static const struct attribute *gsmi_attrs[] = {
+	&gsmi_clear_config_attr.attr,
+	&gsmi_clear_eventlog_attr.attr,
+	NULL,
+};
+
+static int gsmi_shutdown_reason(int reason)
+{
+	struct gsmi_log_entry_type_1 entry = {
+		.type     = GSMI_LOG_ENTRY_TYPE_KERNEL,
+		.instance = reason,
+	};
+	struct gsmi_set_eventlog_param param = {
+		.data_len = sizeof(entry),
+		.type     = 1,
+	};
+	static int saved_reason;
+	int rc = 0;
+	unsigned long flags;
+
+	/* avoid duplicate entries in the log */
+	if (saved_reason & (1 << reason))
+		return 0;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	saved_reason |= (1 << reason);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+	memcpy(gsmi_dev.data_buf->start, &entry, sizeof(entry));
+
+	/* parameter buffer */
+	param.data_ptr = gsmi_dev.data_buf->address;
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_EVENT_LOG);
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	if (rc < 0)
+		printk(KERN_ERR "gsmi: Log Shutdown Reason failed\n");
+	else
+		printk(KERN_EMERG "gsmi: Log Shutdown Reason 0x%02x\n",
+		       reason);
+
+	return rc;
+}
+
+static int gsmi_reboot_callback(struct notifier_block *nb,
+				unsigned long reason, void *arg)
+{
+	gsmi_shutdown_reason(GSMI_SHUTDOWN_CLEAN);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block gsmi_reboot_notifier = {
+	.notifier_call = gsmi_reboot_callback
+};
+
+static int gsmi_die_callback(struct notifier_block *nb,
+			     unsigned long reason, void *arg)
+{
+	if (reason == DIE_OOPS)
+		gsmi_shutdown_reason(GSMI_SHUTDOWN_OOPS);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block gsmi_die_notifier = {
+	.notifier_call = gsmi_die_callback
+};
+
+static int gsmi_panic_callback(struct notifier_block *nb,
+			       unsigned long reason, void *arg)
+{
+	gsmi_shutdown_reason(GSMI_SHUTDOWN_PANIC);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block gsmi_panic_notifier = {
+	.notifier_call = gsmi_panic_callback,
+};
+
+/*
+ * This hash function was blatantly copied from include/linux/hash.h.
+ * It is used by this driver to obfuscate a board name that requires a
+ * quirk within this driver.
+ *
+ * Please do not remove this copy of the function as any changes to the
+ * global utility hash_64() function would break this driver's ability
+ * to identify a board and provide the appropriate quirk -- mikew@google.com
+ */
+static u64 __init local_hash_64(u64 val, unsigned bits)
+{
+	u64 hash = val;
+
+	/*  Sigh, gcc can't optimise this alone like it does for 32 bits. */
+	u64 n = hash;
+	n <<= 18;
+	hash -= n;
+	n <<= 33;
+	hash -= n;
+	n <<= 3;
+	hash += n;
+	n <<= 3;
+	hash -= n;
+	n <<= 4;
+	hash += n;
+	n <<= 2;
+	hash += n;
+
+	/* High bits are more random, so use them. */
+	return hash >> (64 - bits);
+}
+
+static u32 __init hash_oem_table_id(char s[8])
+{
+	u64 input;
+	memcpy(&input, s, 8);
+	return local_hash_64(input, 32);
+}
+
+static struct dmi_system_id gsmi_dmi_table[] __initdata = {
+	{
+		.ident = "Google Board",
+		.matches = {
+			DMI_MATCH(DMI_BOARD_VENDOR, "Google, Inc."),
+		},
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(dmi, gsmi_dmi_table);
+
+static __init int gsmi_system_valid(void)
+{
+	u32 hash;
+
+	if (!dmi_check_system(gsmi_dmi_table))
+		return -ENODEV;
+
+	/*
+	 * Only newer firmware supports the gsmi interface.  All older
+	 * firmware that didn't support this interface used to plug the
+	 * table name in the first four bytes of the oem_table_id field.
+	 * Newer firmware doesn't do that though, so use that as the
+	 * discriminant factor.  We have to do this in order to
+	 * whitewash our board names out of the public driver.
+	 */
+	if (!strncmp(acpi_gbl_FADT.header.oem_table_id, "FACP", 4)) {
+		printk(KERN_INFO "gsmi: Board is too old\n");
+		return -ENODEV;
+	}
+
+	/* Disable on board with 1.0 BIOS due to Google bug 2602657 */
+	hash = hash_oem_table_id(acpi_gbl_FADT.header.oem_table_id);
+	if (hash == QUIRKY_BOARD_HASH) {
+		const char *bios_ver = dmi_get_system_info(DMI_BIOS_VERSION);
+		if (strncmp(bios_ver, "1.0", 3) == 0) {
+			pr_info("gsmi: disabled on this board's BIOS %s\n",
+				bios_ver);
+			return -ENODEV;
+		}
+	}
+
+	/* check for valid SMI command port in ACPI FADT */
+	if (acpi_gbl_FADT.smi_command == 0) {
+		pr_info("gsmi: missing smi_command\n");
+		return -ENODEV;
+	}
+
+	/* Found */
+	return 0;
+}
+
+static struct kobject *gsmi_kobj;
+static struct efivars efivars;
+
+static __init int gsmi_init(void)
+{
+	unsigned long flags;
+	int ret;
+
+	ret = gsmi_system_valid();
+	if (ret)
+		return ret;
+
+	gsmi_dev.smi_cmd = acpi_gbl_FADT.smi_command;
+
+	/* register device */
+	gsmi_dev.pdev = platform_device_register_simple("gsmi", -1, NULL, 0);
+	if (IS_ERR(gsmi_dev.pdev)) {
+		printk(KERN_ERR "gsmi: unable to register platform device\n");
+		return PTR_ERR(gsmi_dev.pdev);
+	}
+
+	/* SMI access needs to be serialized */
+	spin_lock_init(&gsmi_dev.lock);
+
+	/* SMI callbacks require 32bit addresses */
+	gsmi_dev.pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
+	gsmi_dev.pdev->dev.dma_mask =
+		&gsmi_dev.pdev->dev.coherent_dma_mask;
+	ret = -ENOMEM;
+	gsmi_dev.dma_pool = dma_pool_create("gsmi", &gsmi_dev.pdev->dev,
+					     GSMI_BUF_SIZE, GSMI_BUF_ALIGN, 0);
+	if (!gsmi_dev.dma_pool)
+		goto out_err;
+
+	/*
+	 * pre-allocate buffers because sometimes we are called when
+	 * this is not feasible: oops, panic, die, mce, etc
+	 */
+	gsmi_dev.name_buf = gsmi_buf_alloc();
+	if (!gsmi_dev.name_buf) {
+		printk(KERN_ERR "gsmi: failed to allocate name buffer\n");
+		goto out_err;
+	}
+
+	gsmi_dev.data_buf = gsmi_buf_alloc();
+	if (!gsmi_dev.data_buf) {
+		printk(KERN_ERR "gsmi: failed to allocate data buffer\n");
+		goto out_err;
+	}
+
+	gsmi_dev.param_buf = gsmi_buf_alloc();
+	if (!gsmi_dev.param_buf) {
+		printk(KERN_ERR "gsmi: failed to allocate param buffer\n");
+		goto out_err;
+	}
+
+	/*
+	 * Determine type of handshake used to serialize the SMI
+	 * entry. See also gsmi_exec().
+	 *
+	 * There's a "behavior" present on some chipsets where writing the
+	 * SMI trigger register in the southbridge doesn't result in an
+	 * immediate SMI. Rather, the processor can execute "a few" more
+	 * instructions before the SMI takes effect. To ensure synchronous
+	 * behavior, implement a handshake between the kernel driver and the
+	 * firmware handler to spin until released. This ioctl determines
+	 * the type of handshake.
+	 *
+	 * NONE: The firmware handler does not implement any
+	 * handshake. Either it doesn't need to, or it's legacy firmware
+	 * that doesn't know it needs to and never will.
+	 *
+	 * CF: The firmware handler will clear the CF in the saved
+	 * state before returning. The driver may set the CF and test for
+	 * it to clear before proceeding.
+	 *
+	 * SPIN: The firmware handler does not implement any handshake
+	 * but the driver should spin for a hundred or so microseconds
+	 * to ensure the SMI has triggered.
+	 *
+	 * Finally, the handler will return -ENOSYS if
+	 * GSMI_CMD_HANDSHAKE_TYPE is unimplemented, which implies
+	 * HANDSHAKE_NONE.
+	 */
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+	gsmi_dev.handshake_type = GSMI_HANDSHAKE_SPIN;
+	gsmi_dev.handshake_type =
+	    gsmi_exec(GSMI_CALLBACK, GSMI_CMD_HANDSHAKE_TYPE);
+	if (gsmi_dev.handshake_type == -ENOSYS)
+		gsmi_dev.handshake_type = GSMI_HANDSHAKE_NONE;
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	/* Remove and clean up gsmi if the handshake could not complete. */
+	if (gsmi_dev.handshake_type == -ENXIO) {
+		printk(KERN_INFO "gsmi version " DRIVER_VERSION
+		       " failed to load\n");
+		ret = -ENODEV;
+		goto out_err;
+	}
+
+	printk(KERN_INFO "gsmi version " DRIVER_VERSION " loaded\n");
+
+	/* Register in the firmware directory */
+	ret = -ENOMEM;
+	gsmi_kobj = kobject_create_and_add("gsmi", firmware_kobj);
+	if (!gsmi_kobj) {
+		printk(KERN_INFO "gsmi: Failed to create firmware kobj\n");
+		goto out_err;
+	}
+
+	/* Setup eventlog access */
+	ret = sysfs_create_bin_file(gsmi_kobj, &eventlog_bin_attr);
+	if (ret) {
+		printk(KERN_INFO "gsmi: Failed to setup eventlog");
+		goto out_err;
+	}
+
+	/* Other attributes */
+	ret = sysfs_create_files(gsmi_kobj, gsmi_attrs);
+	if (ret) {
+		printk(KERN_INFO "gsmi: Failed to add attrs");
+		goto out_err;
+	}
+
+	if (register_efivars(&efivars, &efivar_ops, gsmi_kobj)) {
+		printk(KERN_INFO "gsmi: Failed to register efivars\n");
+		goto out_err;
+	}
+
+	register_reboot_notifier(&gsmi_reboot_notifier);
+	register_die_notifier(&gsmi_die_notifier);
+	atomic_notifier_chain_register(&panic_notifier_list,
+				       &gsmi_panic_notifier);
+
+	return 0;
+
+ out_err:
+	kobject_put(gsmi_kobj);
+	gsmi_buf_free(gsmi_dev.param_buf);
+	gsmi_buf_free(gsmi_dev.data_buf);
+	gsmi_buf_free(gsmi_dev.name_buf);
+	if (gsmi_dev.dma_pool)
+		dma_pool_destroy(gsmi_dev.dma_pool);
+	platform_device_unregister(gsmi_dev.pdev);
+	pr_info("gsmi: failed to load: %d\n", ret);
+	return ret;
+}
+
+static void __exit gsmi_exit(void)
+{
+	unregister_reboot_notifier(&gsmi_reboot_notifier);
+	unregister_die_notifier(&gsmi_die_notifier);
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &gsmi_panic_notifier);
+	unregister_efivars(&efivars);
+
+	kobject_put(gsmi_kobj);
+	gsmi_buf_free(gsmi_dev.param_buf);
+	gsmi_buf_free(gsmi_dev.data_buf);
+	gsmi_buf_free(gsmi_dev.name_buf);
+	dma_pool_destroy(gsmi_dev.dma_pool);
+	platform_device_unregister(gsmi_dev.pdev);
+}
+
+module_init(gsmi_init);
+module_exit(gsmi_exit);
+
+MODULE_AUTHOR("Google, Inc.");
+MODULE_LICENSE("GPL");

[PATCH v5 2/3] driver: Google Memory Console

[Mike Waychison]

This patch introduces the 'memconsole' driver.

Our firmware gives us access to an in-memory log of the firmware's
output.   This gives us visibility in a data-center of headless machines
as to what the firmware is doing.

The memory console is found by the driver by finding a header block in
the EBDA.  The buffer is then copied out, and is exported to userland in
the file /sys/firmware/log.

Signed-off-by: San Mehat <san@google.com>
Signed-off-by: Mike Waychison <mikew@google.com>
---
Changelog:
v5:
   - refreshed to next-20110429
v4:
   - Re-ordered to be before the introduction of CONFIG_GOOGLE_FIRMWARE.
v3:
   - Use dmi_check_system to only load when on a Google board.
   - Use MODULE_DEVICE_TABLE to export matching DMI strings.
   - Default to 'n' in the Kconfig.
   - Fixed Kconfig description to reflect that this change no longer
     messes with the dmesg.
v2:
   - Removed bits that had this driver muck with the kernel's ring
     dmesg buffer (log_buf).
   - Introduced the log as /sys/firmware/log, a binary file that isn't
     interpreted by the kernel.
   - Don't use C99 fixed width types; use kernel fixed width types.
   - Added file to Documentation/ABI for /sys/firmware/log
---
 Documentation/ABI/testing/sysfs-firmware-log |    7 +
 drivers/firmware/google/Kconfig              |    8 +
 drivers/firmware/google/Makefile             |    1 
 drivers/firmware/google/memconsole.c         |  166 ++++++++++++++++++++++++++
 4 files changed, 182 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-firmware-log
 create mode 100644 drivers/firmware/google/memconsole.c

diff --git a/Documentation/ABI/testing/sysfs-firmware-log b/Documentation/ABI/testing/sysfs-firmware-log
new file mode 100644
index 0000000..9b58e7c
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-log
@@ -0,0 +1,7 @@
+What:		/sys/firmware/log
+Date:		February 2011
+Contact:	Mike Waychison <mikew@google.com>
+Description:
+		The /sys/firmware/log is a binary file that represents a
+		read-only copy of the firmware's log if one is
+		available.
diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig
index 4a03835..640dc6b 100644
--- a/drivers/firmware/google/Kconfig
+++ b/drivers/firmware/google/Kconfig
@@ -7,3 +7,11 @@ config GOOGLE_SMI
 	  platforms.  This provides an interface for writing to and
 	  clearing the EFI event log and reading and writing NVRAM
 	  variables.
+
+config GOOGLE_MEMCONSOLE
+	tristate "Firmware Memory Console"
+	depends on DMI
+	help
+	  This option enables the kernel to search for a firmware log in
+	  the EBDA on Google servers.  If found, this log is exported to
+	  userland in the file /sys/firmware/log.
diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile
index fb127d7..54a294e 100644
--- a/drivers/firmware/google/Makefile
+++ b/drivers/firmware/google/Makefile
@@ -1,2 +1,3 @@
 
 obj-$(CONFIG_GOOGLE_SMI)		+= gsmi.o
+obj-$(CONFIG_GOOGLE_MEMCONSOLE)		+= memconsole.o
diff --git a/drivers/firmware/google/memconsole.c b/drivers/firmware/google/memconsole.c
new file mode 100644
index 0000000..2a90ba6
--- /dev/null
+++ b/drivers/firmware/google/memconsole.c
@@ -0,0 +1,166 @@
+/*
+ * memconsole.c
+ *
+ * Infrastructure for importing the BIOS memory based console
+ * into the kernel log ringbuffer.
+ *
+ * Copyright 2010 Google Inc. All rights reserved.
+ */
+
+#include <linux/ctype.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/kobject.h>
+#include <linux/module.h>
+#include <linux/dmi.h>
+#include <asm/bios_ebda.h>
+
+#define BIOS_MEMCONSOLE_V1_MAGIC	0xDEADBABE
+#define BIOS_MEMCONSOLE_V2_MAGIC	(('M')|('C'<<8)|('O'<<16)|('N'<<24))
+
+struct biosmemcon_ebda {
+	u32 signature;
+	union {
+		struct {
+			u8  enabled;
+			u32 buffer_addr;
+			u16 start;
+			u16 end;
+			u16 num_chars;
+			u8  wrapped;
+		} __packed v1;
+		struct {
+			u32 buffer_addr;
+			/* Misdocumented as number of pages! */
+			u16 num_bytes;
+			u16 start;
+			u16 end;
+		} __packed v2;
+	};
+} __packed;
+
+static char *memconsole_baseaddr;
+static size_t memconsole_length;
+
+static ssize_t memconsole_read(struct file *filp, struct kobject *kobp,
+			       struct bin_attribute *bin_attr, char *buf,
+			       loff_t pos, size_t count)
+{
+	return memory_read_from_buffer(buf, count, &pos, memconsole_baseaddr,
+				       memconsole_length);
+}
+
+static struct bin_attribute memconsole_bin_attr = {
+	.attr = {.name = "log", .mode = 0444},
+	.read = memconsole_read,
+};
+
+
+static void found_v1_header(struct biosmemcon_ebda *hdr)
+{
+	printk(KERN_INFO "BIOS console v1 EBDA structure found at %p\n", hdr);
+	printk(KERN_INFO "BIOS console buffer at 0x%.8x, "
+	       "start = %d, end = %d, num = %d\n",
+	       hdr->v1.buffer_addr, hdr->v1.start,
+	       hdr->v1.end, hdr->v1.num_chars);
+
+	memconsole_length = hdr->v1.num_chars;
+	memconsole_baseaddr = phys_to_virt(hdr->v1.buffer_addr);
+}
+
+static void found_v2_header(struct biosmemcon_ebda *hdr)
+{
+	printk(KERN_INFO "BIOS console v2 EBDA structure found at %p\n", hdr);
+	printk(KERN_INFO "BIOS console buffer at 0x%.8x, "
+	       "start = %d, end = %d, num_bytes = %d\n",
+	       hdr->v2.buffer_addr, hdr->v2.start,
+	       hdr->v2.end, hdr->v2.num_bytes);
+
+	memconsole_length = hdr->v2.end - hdr->v2.start;
+	memconsole_baseaddr = phys_to_virt(hdr->v2.buffer_addr
+					   + hdr->v2.start);
+}
+
+/*
+ * Search through the EBDA for the BIOS Memory Console, and
+ * set the global variables to point to it.  Return true if found.
+ */
+static bool found_memconsole(void)
+{
+	unsigned int address;
+	size_t length, cur;
+
+	address = get_bios_ebda();
+	if (!address) {
+		printk(KERN_INFO "BIOS EBDA non-existent.\n");
+		return false;
+	}
+
+	/* EBDA length is byte 0 of EBDA (in KB) */
+	length = *(u8 *)phys_to_virt(address);
+	length <<= 10; /* convert to bytes */
+
+	/*
+	 * Search through EBDA for BIOS memory console structure
+	 * note: signature is not necessarily dword-aligned
+	 */
+	for (cur = 0; cur < length; cur++) {
+		struct biosmemcon_ebda *hdr = phys_to_virt(address + cur);
+
+		/* memconsole v1 */
+		if (hdr->signature == BIOS_MEMCONSOLE_V1_MAGIC) {
+			found_v1_header(hdr);
+			return true;
+		}
+
+		/* memconsole v2 */
+		if (hdr->signature == BIOS_MEMCONSOLE_V2_MAGIC) {
+			found_v2_header(hdr);
+			return true;
+		}
+	}
+
+	printk(KERN_INFO "BIOS console EBDA structure not found!\n");
+	return false;
+}
+
+static struct dmi_system_id memconsole_dmi_table[] __initdata = {
+	{
+		.ident = "Google Board",
+		.matches = {
+			DMI_MATCH(DMI_BOARD_VENDOR, "Google, Inc."),
+		},
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(dmi, memconsole_dmi_table);
+
+static int __init memconsole_init(void)
+{
+	int ret;
+
+	if (!dmi_check_system(memconsole_dmi_table))
+		return -ENODEV;
+
+	if (!found_memconsole())
+		return -ENODEV;
+
+	memconsole_bin_attr.size = memconsole_length;
+
+	ret = sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr);
+
+	return ret;
+}
+
+static void __exit memconsole_exit(void)
+{
+	sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr);
+}
+
+module_init(memconsole_init);
+module_exit(memconsole_exit);
+
+MODULE_AUTHOR("Google, Inc.");
+MODULE_LICENSE("GPL");

[PATCH v5 3/3] Introduce CONFIG_GOOGLE_FIRMWARE

[Mike Waychison]

In order to keep Google's firmware drivers organized amongst themselves,
all Google firmware drivers are gated on CONFIG_GOOGLE_FIRMWARE=y, which
defaults to 'n' in the kernel build.

Signed-off-by: Mike Waychison <mikew@google.com>

---
Changelog:
v5:
   - refreshed to next-20110429
v4:
   - Moved to end of series.
v3:
   - Removed comment about 'other implementations' in Kconfig message as
     per gregkh.
---
 drivers/firmware/Makefile       |    2 +-
 drivers/firmware/google/Kconfig |   14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index d7d6009..47338c9791 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -14,4 +14,4 @@ obj-$(CONFIG_ISCSI_IBFT)	+= iscsi_ibft.o
 obj-$(CONFIG_FIRMWARE_MEMMAP)	+= memmap.o
 obj-$(CONFIG_SIGMA)		+= sigma.o
 
-obj-y  += google/
+obj-$(CONFIG_GOOGLE_FIRMWARE)	+= google/
diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig
index 640dc6b..87096b6 100644
--- a/drivers/firmware/google/Kconfig
+++ b/drivers/firmware/google/Kconfig
@@ -1,3 +1,15 @@
+config GOOGLE_FIRMWARE
+	bool "Google Firmware Drivers"
+	depends on X86
+	default n
+	help
+	  These firmware drivers are used by Google's servers.  They are
+	  only useful if you are working directly on one of their
+	  proprietary servers.  If in doubt, say "N".
+
+menu "Google Firmware Drivers"
+	depends on GOOGLE_FIRMWARE
+
 config GOOGLE_SMI
 	tristate "SMI interface for Google platforms"
 	depends on ACPI && DMI
@@ -15,3 +27,5 @@ config GOOGLE_MEMCONSOLE
 	  This option enables the kernel to search for a firmware log in
 	  the EBDA on Google servers.  If found, this log is exported to
 	  userland in the file /sys/firmware/log.
+
+endmenu

Re: [PATCH v4 1/3] driver: Google EFI SMI

[Randy Dunlap]

On Fri, 29 Apr 2011 15:55:51 -0700 Mike Waychison wrote:


> +static int gsmi_die_callback(struct notifier_block *nb,
> +			     unsigned long reason, void *arg)
> +{
> +	if (reason == DIE_NMIWATCHDOG)
> +		gsmi_shutdown_reason(GSMI_SHUTDOWN_NMIWDT);
> +	else if (reason == DIE_OOPS)
> +		gsmi_shutdown_reason(GSMI_SHUTDOWN_OOPS);
> +	return NOTIFY_DONE;
> +}


Where is DIE_NMIWATCHDOG defined?
Do I need more that patches 1,2,3/3 applied?


lnx-2639-rc5/drivers/firmware/google/gsmi.c: In function 'gsmi_die_callback':
lnx-2639-rc5/drivers/firmware/google/gsmi.c:660: error: 'DIE_NMIWATCHDOG' undeclared (first use in this function)
lnx-2639-rc5/drivers/firmware/google/gsmi.c:660: error: (Each undeclared identifier is reported only once
lnx-2639-rc5/drivers/firmware/google/gsmi.c:660: error: for each function it appears in.)


---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***

Re: [PATCH v4 1/3] driver: Google EFI SMI

[Mike Waychison]

On Fri, Apr 29, 2011 at 4:47 PM, Randy Dunlap <randy.dunlap@oracle.com> wrote:
> On Fri, 29 Apr 2011 15:55:51 -0700 Mike Waychison wrote:
>
>
>> +static int gsmi_die_callback(struct notifier_block *nb,
>> +                          unsigned long reason, void *arg)
>> +{
>> +     if (reason == DIE_NMIWATCHDOG)
>> +             gsmi_shutdown_reason(GSMI_SHUTDOWN_NMIWDT);
>> +     else if (reason == DIE_OOPS)
>> +             gsmi_shutdown_reason(GSMI_SHUTDOWN_OOPS);
>> +     return NOTIFY_DONE;
>> +}
>
>
> Where is DIE_NMIWATCHDOG defined?

My bad.  I didn't rebase these 3 patches to v2.6.39-rc5 when sending
out v4.  Seems it got dropped in rc1 in 02ca752e.  Looking at how to
wire this into whatever replaced die_nmi() now.

[PATCH v4 2/3] driver: Google Memory Console

[Mike Waychison]

This patch introduces the 'memconsole' driver.

Our firmware gives us access to an in-memory log of the firmware's
output.   This gives us visibility in a data-center of headless machines
as to what the firmware is doing.

The memory console is found by the driver by finding a header block in
the EBDA.  The buffer is then copied out, and is exported to userland in
the file /sys/firmware/log.

Signed-off-by: San Mehat <san@google.com>
Signed-off-by: Mike Waychison <mikew@google.com>
---
Changelog:
v4:
   - Re-ordered to be before the introduction of CONFIG_GOOGLE_FIRMWARE.
v3:
   - Use dmi_check_system to only load when on a Google board.
   - Use MODULE_DEVICE_TABLE to export matching DMI strings.
   - Default to 'n' in the Kconfig.
   - Fixed Kconfig description to reflect that this change no longer
     messes with the dmesg.
v2:
   - Removed bits that had this driver muck with the kernel's ring
     dmesg buffer (log_buf).
   - Introduced the log as /sys/firmware/log, a binary file that isn't
     interpreted by the kernel.
   - Don't use C99 fixed width types; use kernel fixed width types.
   - Added file to Documentation/ABI for /sys/firmware/log
---
 Documentation/ABI/testing/sysfs-firmware-log |    7 +
 drivers/firmware/google/Kconfig              |    8 +
 drivers/firmware/google/Makefile             |    1 
 drivers/firmware/google/memconsole.c         |  166 ++++++++++++++++++++++++++
 4 files changed, 182 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-firmware-log
 create mode 100644 drivers/firmware/google/memconsole.c

diff --git a/Documentation/ABI/testing/sysfs-firmware-log b/Documentation/ABI/testing/sysfs-firmware-log
new file mode 100644
index 0000000..9b58e7c
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-log
@@ -0,0 +1,7 @@
+What:		/sys/firmware/log
+Date:		February 2011
+Contact:	Mike Waychison <mikew@google.com>
+Description:
+		The /sys/firmware/log is a binary file that represents a
+		read-only copy of the firmware's log if one is
+		available.
diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig
index 4a03835..640dc6b 100644
--- a/drivers/firmware/google/Kconfig
+++ b/drivers/firmware/google/Kconfig
@@ -7,3 +7,11 @@ config GOOGLE_SMI
 	  platforms.  This provides an interface for writing to and
 	  clearing the EFI event log and reading and writing NVRAM
 	  variables.
+
+config GOOGLE_MEMCONSOLE
+	tristate "Firmware Memory Console"
+	depends on DMI
+	help
+	  This option enables the kernel to search for a firmware log in
+	  the EBDA on Google servers.  If found, this log is exported to
+	  userland in the file /sys/firmware/log.
diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile
index fb127d7..54a294e 100644
--- a/drivers/firmware/google/Makefile
+++ b/drivers/firmware/google/Makefile
@@ -1,2 +1,3 @@
 
 obj-$(CONFIG_GOOGLE_SMI)		+= gsmi.o
+obj-$(CONFIG_GOOGLE_MEMCONSOLE)		+= memconsole.o
diff --git a/drivers/firmware/google/memconsole.c b/drivers/firmware/google/memconsole.c
new file mode 100644
index 0000000..2a90ba6
--- /dev/null
+++ b/drivers/firmware/google/memconsole.c
@@ -0,0 +1,166 @@
+/*
+ * memconsole.c
+ *
+ * Infrastructure for importing the BIOS memory based console
+ * into the kernel log ringbuffer.
+ *
+ * Copyright 2010 Google Inc. All rights reserved.
+ */
+
+#include <linux/ctype.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/kobject.h>
+#include <linux/module.h>
+#include <linux/dmi.h>
+#include <asm/bios_ebda.h>
+
+#define BIOS_MEMCONSOLE_V1_MAGIC	0xDEADBABE
+#define BIOS_MEMCONSOLE_V2_MAGIC	(('M')|('C'<<8)|('O'<<16)|('N'<<24))
+
+struct biosmemcon_ebda {
+	u32 signature;
+	union {
+		struct {
+			u8  enabled;
+			u32 buffer_addr;
+			u16 start;
+			u16 end;
+			u16 num_chars;
+			u8  wrapped;
+		} __packed v1;
+		struct {
+			u32 buffer_addr;
+			/* Misdocumented as number of pages! */
+			u16 num_bytes;
+			u16 start;
+			u16 end;
+		} __packed v2;
+	};
+} __packed;
+
+static char *memconsole_baseaddr;
+static size_t memconsole_length;
+
+static ssize_t memconsole_read(struct file *filp, struct kobject *kobp,
+			       struct bin_attribute *bin_attr, char *buf,
+			       loff_t pos, size_t count)
+{
+	return memory_read_from_buffer(buf, count, &pos, memconsole_baseaddr,
+				       memconsole_length);
+}
+
+static struct bin_attribute memconsole_bin_attr = {
+	.attr = {.name = "log", .mode = 0444},
+	.read = memconsole_read,
+};
+
+
+static void found_v1_header(struct biosmemcon_ebda *hdr)
+{
+	printk(KERN_INFO "BIOS console v1 EBDA structure found at %p\n", hdr);
+	printk(KERN_INFO "BIOS console buffer at 0x%.8x, "
+	       "start = %d, end = %d, num = %d\n",
+	       hdr->v1.buffer_addr, hdr->v1.start,
+	       hdr->v1.end, hdr->v1.num_chars);
+
+	memconsole_length = hdr->v1.num_chars;
+	memconsole_baseaddr = phys_to_virt(hdr->v1.buffer_addr);
+}
+
+static void found_v2_header(struct biosmemcon_ebda *hdr)
+{
+	printk(KERN_INFO "BIOS console v2 EBDA structure found at %p\n", hdr);
+	printk(KERN_INFO "BIOS console buffer at 0x%.8x, "
+	       "start = %d, end = %d, num_bytes = %d\n",
+	       hdr->v2.buffer_addr, hdr->v2.start,
+	       hdr->v2.end, hdr->v2.num_bytes);
+
+	memconsole_length = hdr->v2.end - hdr->v2.start;
+	memconsole_baseaddr = phys_to_virt(hdr->v2.buffer_addr
+					   + hdr->v2.start);
+}
+
+/*
+ * Search through the EBDA for the BIOS Memory Console, and
+ * set the global variables to point to it.  Return true if found.
+ */
+static bool found_memconsole(void)
+{
+	unsigned int address;
+	size_t length, cur;
+
+	address = get_bios_ebda();
+	if (!address) {
+		printk(KERN_INFO "BIOS EBDA non-existent.\n");
+		return false;
+	}
+
+	/* EBDA length is byte 0 of EBDA (in KB) */
+	length = *(u8 *)phys_to_virt(address);
+	length <<= 10; /* convert to bytes */
+
+	/*
+	 * Search through EBDA for BIOS memory console structure
+	 * note: signature is not necessarily dword-aligned
+	 */
+	for (cur = 0; cur < length; cur++) {
+		struct biosmemcon_ebda *hdr = phys_to_virt(address + cur);
+
+		/* memconsole v1 */
+		if (hdr->signature == BIOS_MEMCONSOLE_V1_MAGIC) {
+			found_v1_header(hdr);
+			return true;
+		}
+
+		/* memconsole v2 */
+		if (hdr->signature == BIOS_MEMCONSOLE_V2_MAGIC) {
+			found_v2_header(hdr);
+			return true;
+		}
+	}
+
+	printk(KERN_INFO "BIOS console EBDA structure not found!\n");
+	return false;
+}
+
+static struct dmi_system_id memconsole_dmi_table[] __initdata = {
+	{
+		.ident = "Google Board",
+		.matches = {
+			DMI_MATCH(DMI_BOARD_VENDOR, "Google, Inc."),
+		},
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(dmi, memconsole_dmi_table);
+
+static int __init memconsole_init(void)
+{
+	int ret;
+
+	if (!dmi_check_system(memconsole_dmi_table))
+		return -ENODEV;
+
+	if (!found_memconsole())
+		return -ENODEV;
+
+	memconsole_bin_attr.size = memconsole_length;
+
+	ret = sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr);
+
+	return ret;
+}
+
+static void __exit memconsole_exit(void)
+{
+	sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr);
+}
+
+module_init(memconsole_init);
+module_exit(memconsole_exit);
+
+MODULE_AUTHOR("Google, Inc.");
+MODULE_LICENSE("GPL");

[PATCH v4 3/3] Introduce CONFIG_GOOGLE_FIRMWARE

[Mike Waychison]

In order to keep Google's firmware drivers organized amongst themselves,
all Google firmware drivers are gated on CONFIG_GOOGLE_FIRMWARE=y, which
defaults to 'n' in the kernel build.

Signed-off-by: Mike Waychison <mikew@google.com>

---
Changelog:
v4:
   - Moved to end of series.
v3:
   - Removed comment about 'other implementations' in Kconfig message as
     per gregkh.
---
 drivers/firmware/Makefile       |    2 +-
 drivers/firmware/google/Kconfig |   14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 9fcf3b2..5a7e273 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -13,4 +13,4 @@ obj-$(CONFIG_ISCSI_IBFT_FIND)	+= iscsi_ibft_find.o
 obj-$(CONFIG_ISCSI_IBFT)	+= iscsi_ibft.o
 obj-$(CONFIG_FIRMWARE_MEMMAP)	+= memmap.o
 
-obj-y  += google/
+obj-$(CONFIG_GOOGLE_FIRMWARE)	+= google/
diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig
index 640dc6b..87096b6 100644
--- a/drivers/firmware/google/Kconfig
+++ b/drivers/firmware/google/Kconfig
@@ -1,3 +1,15 @@
+config GOOGLE_FIRMWARE
+	bool "Google Firmware Drivers"
+	depends on X86
+	default n
+	help
+	  These firmware drivers are used by Google's servers.  They are
+	  only useful if you are working directly on one of their
+	  proprietary servers.  If in doubt, say "N".
+
+menu "Google Firmware Drivers"
+	depends on GOOGLE_FIRMWARE
+
 config GOOGLE_SMI
 	tristate "SMI interface for Google platforms"
 	depends on ACPI && DMI
@@ -15,3 +27,5 @@ config GOOGLE_MEMCONSOLE
 	  This option enables the kernel to search for a firmware log in
 	  the EBDA on Google servers.  If found, this log is exported to
 	  userland in the file /sys/firmware/log.
+
+endmenu

Re: [PATCH v4 3/3] Introduce CONFIG_GOOGLE_FIRMWARE

[Alan Cox]

On Fri, 29 Apr 2011 15:56:02 -0700
Mike Waychison <mikew@google.com> wrote:

> In order to keep Google's firmware drivers organized amongst themselves,
> all Google firmware drivers are gated on CONFIG_GOOGLE_FIRMWARE=y, which
> defaults to 'n' in the kernel build.

All 3 Acked-by: Alan Cox <alan@linux.intel.com>

> +	  These firmware drivers are used by Google's servers.  They are
> +	  only useful if you are working directly on one of their
> +	  proprietary servers.  If in doubt, say "N".

[or until people start adding them to other devices!]

Alan

[PATCH v3 4/5] driver: Google EFI SMI

[Mike Waychison]

The "gsmi" driver bridges userland with firmware specific routines for
accessing hardware.

Currently, this driver only supports NVRAM and eventlog information.
Deprecated functions have been removed from the driver, though their
op-codes are left in place so that they are not re-used.

This driver works by trampolining into the firmware via the smi_command
outlined in the FADT table.  Three protocols are used due to various
limitations over time, but all are included herein.

This driver should only ever load on Google boards, identified by either
a "Google, Inc." board vendor string in DMI, or "GOOGLE" in the OEM
strings of the FADT ACPI table.  This logic happens in
gsmi_system_valid().

Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Aaron Durbin <adurbin@google.com>
Signed-off-by: Mike Waychison <mikew@google.com>
---
Changelog:
v3:
   - Require a match on a dmi_system_id, and export table via
     MODULE_DEVICE_TABLE.
   - Mark gsmi_system_valid as __init.
   - Allow driver to be compiled as a removable module.
   - Default to 'n' in Kconfig.
v2:
   - Use ARRAY_SIZE() rather than open coded construct.
   - Fix off-by-one in array lookup.
   - Removed superfluous memset.
   - Removed superfluous variable clear.
   - switch from posix integer types to linux kernel integer types.
   - Replaced use of dropped oops_notifier_list with die_notifier_list.
   - Added dependency on CONFIG_DMI.
   - Fixed a bug which crashed the kernel if no DMI tables were found.
   - Replace nvram ioctls with efivars interface at
     /sys/firmware/gsmi/vars.
   - Removed NOOP command that is unused.
   - Change gsmi_dev to not be statically allocated.
   - Removed ioctl interface
   - Removed chardev interface
   - Removed header as user ABI is all done via sysfs.
   - Fix output clobber for firmware call so that we don't clobber the
     compiler-cached value for 'cmd'.
   - Added docs to Documentation/ABI for exposed system call interface.
---
 Documentation/ABI/testing/sysfs-firmware-gsmi |   58 ++
 drivers/firmware/google/Kconfig               |   10 
 drivers/firmware/google/Makefile              |    1 
 drivers/firmware/google/gsmi.c                |  941 +++++++++++++++++++++++++
 4 files changed, 1010 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-firmware-gsmi
 create mode 100644 drivers/firmware/google/gsmi.c

diff --git a/Documentation/ABI/testing/sysfs-firmware-gsmi b/Documentation/ABI/testing/sysfs-firmware-gsmi
new file mode 100644
index 0000000..0faa0aa
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-gsmi
@@ -0,0 +1,58 @@
+What:		/sys/firmware/gsmi
+Date:		March 2011
+Contact:	Mike Waychison <mikew@google.com>
+Description:
+		Some servers used internally at Google have firmware
+		that provides callback functionality via explicit SMI
+		triggers.  Some of the callbacks are similar to those
+		provided by the EFI runtime services page, but due to
+		historical reasons this different entry-point has been
+		used.
+
+		The gsmi driver implements the kernel's abstraction for
+		these firmware callbacks.  Currently, this functionality
+		is limited to handling the system event log and getting
+		access to EFI-style variables stored in nvram.
+
+		Layout:
+
+		/sys/firmware/gsmi/vars:
+
+			This directory has the same layout (and
+			underlying implementation as /sys/firmware/efi/vars.
+			See Documentation/ABI/*/sysfs-firmware-efi-vars
+			for more information on how to interact with
+			this structure.
+
+		/sys/firmware/gsmi/append_to_eventlog - write-only:
+
+			This file takes a binary blob and passes it onto
+			the firmware to be timestamped and appended to
+			the system eventlog.  The binary format is
+			interpreted by the firmware and may change from
+			platform to platform.  The only kernel-enforced
+			requirement is that the blob be prefixed with a
+			32bit host-endian type used as part of the
+			firmware call.
+
+		/sys/firmware/gsmi/clear_config - write-only:
+
+			Writing any value to this file will cause the
+			entire firmware configuration to be reset to
+			"factory defaults".  Callers should assume that
+			a reboot is required for the configuration to be
+			cleared.
+
+		/sys/firmware/gsmi/clear_eventlog - write-only:
+
+			This file is used to clear out a portion/the
+			whole of the system event log.  Values written
+			should be values between 1 and 100 inclusive (in
+			ASCII) representing the fraction of the log to
+			clear.  Not all platforms support fractional
+			clearing though, and this writes to this file
+			will error out if the firmware doesn't like your
+			submitted fraction.
+
+			Callers should assume that a reboot is needed
+			for this operation to complete.
diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig
index 02a7366..8190103 100644
--- a/drivers/firmware/google/Kconfig
+++ b/drivers/firmware/google/Kconfig
@@ -10,4 +10,14 @@ config GOOGLE_FIRMWARE
 menu "Google Firmware Drivers"
 	depends on GOOGLE_FIRMWARE
 
+config GOOGLE_SMI
+	tristate "SMI interface for Google platforms"
+	depends on ACPI && DMI
+	select EFI_VARS
+	help
+	  Say Y here if you want to enable SMI callbacks for Google
+	  platforms.  This provides an interface for writing to and
+	  clearing the EFI event log and reading and writing NVRAM
+	  variables.
+
 endmenu
diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile
index 8b13789..fb127d7 100644
--- a/drivers/firmware/google/Makefile
+++ b/drivers/firmware/google/Makefile
@@ -1 +1,2 @@
 
+obj-$(CONFIG_GOOGLE_SMI)		+= gsmi.o
diff --git a/drivers/firmware/google/gsmi.c b/drivers/firmware/google/gsmi.c
new file mode 100644
index 0000000..34b1ffa
--- /dev/null
+++ b/drivers/firmware/google/gsmi.c
@@ -0,0 +1,941 @@
+/*
+ * Copyright 2010 Google Inc. All Rights Reserved.
+ * Author: dlaurie@google.com (Duncan Laurie)
+ *
+ * Re-worked to expose sysfs APIs by mikew@google.com (Mike Waychison)
+ *
+ * EFI SMI interface for Google platforms
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/spinlock.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/ioctl.h>
+#include <linux/acpi.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <linux/dmi.h>
+#include <linux/kdebug.h>
+#include <linux/reboot.h>
+#include <linux/efi.h>
+
+#define GSMI_SHUTDOWN_CLEAN	0	/* Clean Shutdown */
+#define GSMI_SHUTDOWN_NMIWDT	1	/* NMI Watchdog */
+#define GSMI_SHUTDOWN_PANIC	2	/* Panic */
+#define GSMI_SHUTDOWN_OOPS	3	/* Oops */
+#define GSMI_SHUTDOWN_DIE	4	/* Die -- No longer meaningful */
+#define GSMI_SHUTDOWN_MCE	5	/* Machine Check */
+#define GSMI_SHUTDOWN_SOFTWDT	6	/* Software Watchdog */
+#define GSMI_SHUTDOWN_MBE	7	/* Uncorrected ECC */
+#define GSMI_SHUTDOWN_TRIPLE	8	/* Triple Fault */
+
+#define DRIVER_VERSION		"1.0"
+#define GSMI_GUID_SIZE		16
+#define GSMI_BUF_SIZE		1024
+#define GSMI_BUF_ALIGN		sizeof(u64)
+#define GSMI_CALLBACK		0xef
+
+/* SMI return codes */
+#define GSMI_SUCCESS		0x00
+#define GSMI_UNSUPPORTED2	0x03
+#define GSMI_LOG_FULL		0x0b
+#define GSMI_VAR_NOT_FOUND	0x0e
+#define GSMI_HANDSHAKE_SPIN	0x7d
+#define GSMI_HANDSHAKE_CF	0x7e
+#define GSMI_HANDSHAKE_NONE	0x7f
+#define GSMI_INVALID_PARAMETER	0x82
+#define GSMI_UNSUPPORTED	0x83
+#define GSMI_BUFFER_TOO_SMALL	0x85
+#define GSMI_NOT_READY		0x86
+#define GSMI_DEVICE_ERROR	0x87
+#define GSMI_NOT_FOUND		0x8e
+
+#define QUIRKY_BOARD_HASH 0x78a30a50
+
+/* Internally used commands passed to the firmware */
+#define GSMI_CMD_GET_NVRAM_VAR		0x01
+#define GSMI_CMD_GET_NEXT_VAR		0x02
+#define GSMI_CMD_SET_NVRAM_VAR		0x03
+#define GSMI_CMD_SET_EVENT_LOG		0x08
+#define GSMI_CMD_CLEAR_EVENT_LOG	0x09
+#define GSMI_CMD_CLEAR_CONFIG		0x20
+#define GSMI_CMD_HANDSHAKE_TYPE		0xC1
+
+/* Magic entry type for kernel events */
+#define GSMI_LOG_ENTRY_TYPE_KERNEL     0xDEAD
+
+/* SMI buffers must be in 32bit physical address space */
+struct gsmi_buf {
+	u8 *start;			/* start of buffer */
+	size_t length;			/* length of buffer */
+	dma_addr_t handle;		/* dma allocation handle */
+	u32 address;			/* physical address of buffer */
+};
+
+struct gsmi_device {
+	struct platform_device *pdev;	/* platform device */
+	struct gsmi_buf *name_buf;	/* variable name buffer */
+	struct gsmi_buf *data_buf;	/* generic data buffer */
+	struct gsmi_buf *param_buf;	/* parameter buffer */
+	spinlock_t lock;		/* serialize access to SMIs */
+	u16 smi_cmd;			/* SMI command port */
+	int handshake_type;		/* firmware handler interlock type */
+	struct dma_pool *dma_pool;	/* DMA buffer pool */
+} gsmi_dev;
+
+/* Packed structures for communicating with the firmware */
+struct gsmi_nvram_var_param {
+	efi_guid_t	guid;
+	u32		name_ptr;
+	u32		attributes;
+	u32		data_len;
+	u32		data_ptr;
+} __packed;
+
+struct gsmi_get_next_var_param {
+	u8	guid[GSMI_GUID_SIZE];
+	u32	name_ptr;
+	u32	name_len;
+} __packed;
+
+struct gsmi_set_eventlog_param {
+	u32	data_ptr;
+	u32	data_len;
+	u32	type;
+} __packed;
+
+/* Event log formats */
+struct gsmi_log_entry_type_1 {
+	u16	type;
+	u32	instance;
+} __packed;
+
+
+/*
+ * Some platforms don't have explicit SMI handshake
+ * and need to wait for SMI to complete.
+ */
+#define GSMI_DEFAULT_SPINCOUNT	0x10000
+static unsigned int spincount = GSMI_DEFAULT_SPINCOUNT;
+module_param(spincount, uint, 0600);
+MODULE_PARM_DESC(spincount,
+	"The number of loop iterations to use when using the spin handshake.");
+
+static struct gsmi_buf *gsmi_buf_alloc(void)
+{
+	struct gsmi_buf *smibuf;
+
+	smibuf = kzalloc(sizeof(*smibuf), GFP_KERNEL);
+	if (!smibuf) {
+		printk(KERN_ERR "gsmi: out of memory\n");
+		return NULL;
+	}
+
+	/* allocate buffer in 32bit address space */
+	smibuf->start = dma_pool_alloc(gsmi_dev.dma_pool, GFP_KERNEL,
+				       &smibuf->handle);
+	if (!smibuf->start) {
+		printk(KERN_ERR "gsmi: failed to allocate name buffer\n");
+		kfree(smibuf);
+		return NULL;
+	}
+
+	/* fill in the buffer handle */
+	smibuf->length = GSMI_BUF_SIZE;
+	smibuf->address = (u32)virt_to_phys(smibuf->start);
+
+	return smibuf;
+}
+
+static void gsmi_buf_free(struct gsmi_buf *smibuf)
+{
+	if (smibuf) {
+		if (smibuf->start)
+			dma_pool_free(gsmi_dev.dma_pool, smibuf->start,
+				      smibuf->handle);
+		kfree(smibuf);
+	}
+}
+
+/*
+ * Make a call to gsmi func(sub).  GSMI error codes are translated to
+ * in-kernel errnos (0 on success, -ERRNO on error).
+ */
+static int gsmi_exec(u8 func, u8 sub)
+{
+	u16 cmd = (sub << 8) | func;
+	u16 result = 0;
+	int rc = 0;
+
+	/*
+	 * AH  : Subfunction number
+	 * AL  : Function number
+	 * EBX : Parameter block address
+	 * DX  : SMI command port
+	 *
+	 * Three protocols here. See also the comment in gsmi_init().
+	 */
+	if (gsmi_dev.handshake_type == GSMI_HANDSHAKE_CF) {
+		/*
+		 * If handshake_type == HANDSHAKE_CF then set CF on the
+		 * way in and wait for the handler to clear it; this avoids
+		 * corrupting register state on those chipsets which have
+		 * a delay between writing the SMI trigger register and
+		 * entering SMM.
+		 */
+		asm volatile (
+			"stc\n"
+			"outb %%al, %%dx\n"
+		"1:      jc 1b\n"
+			: "=a" (result)
+			: "0" (cmd),
+			  "d" (gsmi_dev.smi_cmd),
+			  "b" (gsmi_dev.param_buf->address)
+			: "memory", "cc"
+		);
+	} else if (gsmi_dev.handshake_type == GSMI_HANDSHAKE_SPIN) {
+		/*
+		 * If handshake_type == HANDSHAKE_SPIN we spin a
+		 * hundred-ish usecs to ensure the SMI has triggered.
+		 */
+		asm volatile (
+			"outb %%al, %%dx\n"
+		"1:      loop 1b\n"
+			: "=a" (result)
+			: "0" (cmd),
+			  "d" (gsmi_dev.smi_cmd),
+			  "b" (gsmi_dev.param_buf->address),
+			  "c" (spincount)
+			: "memory", "cc"
+		);
+	} else {
+		/*
+		 * If handshake_type == HANDSHAKE_NONE we do nothing;
+		 * either we don't need to or it's legacy firmware that
+		 * doesn't understand the CF protocol.
+		 */
+		asm volatile (
+			"outb %%al, %%dx\n\t"
+			: "=a" (result)
+			: "0" (cmd),
+			  "d" (gsmi_dev.smi_cmd),
+			  "b" (gsmi_dev.param_buf->address)
+			: "memory", "cc"
+		);
+	}
+
+	/* check return code from SMI handler */
+	switch (result) {
+	case GSMI_SUCCESS:
+		break;
+	case GSMI_VAR_NOT_FOUND:
+		/* not really an error, but let the caller know */
+		rc = 1;
+		break;
+	case GSMI_INVALID_PARAMETER:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Invalid parameter\n", cmd);
+		rc = -EINVAL;
+		break;
+	case GSMI_BUFFER_TOO_SMALL:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Buffer too small\n", cmd);
+		rc = -ENOMEM;
+		break;
+	case GSMI_UNSUPPORTED:
+	case GSMI_UNSUPPORTED2:
+		if (sub != GSMI_CMD_HANDSHAKE_TYPE)
+			printk(KERN_ERR "gsmi: exec 0x%04x: Not supported\n",
+			       cmd);
+		rc = -ENOSYS;
+		break;
+	case GSMI_NOT_READY:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Not ready\n", cmd);
+		rc = -EBUSY;
+		break;
+	case GSMI_DEVICE_ERROR:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Device error\n", cmd);
+		rc = -EFAULT;
+		break;
+	case GSMI_NOT_FOUND:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Data not found\n", cmd);
+		rc = -ENOENT;
+		break;
+	case GSMI_LOG_FULL:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Log full\n", cmd);
+		rc = -ENOSPC;
+		break;
+	case GSMI_HANDSHAKE_CF:
+	case GSMI_HANDSHAKE_SPIN:
+	case GSMI_HANDSHAKE_NONE:
+		rc = result;
+		break;
+	default:
+		printk(KERN_ERR "gsmi: exec 0x%04x: Unknown error 0x%04x\n",
+		       cmd, result);
+		rc = -ENXIO;
+	}
+
+	return rc;
+}
+
+/* Return the number of unicode characters in data */
+static size_t
+utf16_strlen(efi_char16_t *data, unsigned long maxlength)
+{
+	unsigned long length = 0;
+
+	while (*data++ != 0 && length < maxlength)
+		length++;
+	return length;
+}
+
+static efi_status_t gsmi_get_variable(efi_char16_t *name,
+				      efi_guid_t *vendor, u32 *attr,
+				      unsigned long *data_size,
+				      void *data)
+{
+	struct gsmi_nvram_var_param param = {
+		.name_ptr = gsmi_dev.name_buf->address,
+		.data_ptr = gsmi_dev.data_buf->address,
+		.data_len = (u32)*data_size,
+	};
+	efi_status_t ret = EFI_SUCCESS;
+	unsigned long flags;
+	size_t name_len = utf16_strlen(name, GSMI_BUF_SIZE / 2);
+	int rc;
+
+	if (name_len >= GSMI_BUF_SIZE / 2)
+		return EFI_BAD_BUFFER_SIZE;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* Vendor guid */
+	memcpy(&param.guid, vendor, sizeof(param.guid));
+
+	/* variable name, already in UTF-16 */
+	memset(gsmi_dev.name_buf->start, 0, gsmi_dev.name_buf->length);
+	memcpy(gsmi_dev.name_buf->start, name, name_len * 2);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_GET_NVRAM_VAR);
+	if (rc < 0) {
+		printk(KERN_ERR "gsmi: Get Variable failed\n");
+		ret = EFI_LOAD_ERROR;
+	} else if (rc == 1) {
+		/* variable was not found */
+		ret = EFI_NOT_FOUND;
+	} else {
+		/* Get the arguments back */
+		memcpy(&param, gsmi_dev.param_buf->start, sizeof(param));
+
+		/* The size reported is the min of all of our buffers */
+		*data_size = min(*data_size, gsmi_dev.data_buf->length);
+		*data_size = min_t(unsigned long, *data_size, param.data_len);
+
+		/* Copy data back to return buffer. */
+		memcpy(data, gsmi_dev.data_buf->start, *data_size);
+
+		/* All variables are have the following attributes */
+		*attr = EFI_VARIABLE_NON_VOLATILE |
+			EFI_VARIABLE_BOOTSERVICE_ACCESS |
+			EFI_VARIABLE_RUNTIME_ACCESS;
+	}
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return ret;
+}
+
+static efi_status_t gsmi_get_next_variable(unsigned long *name_size,
+					   efi_char16_t *name,
+					   efi_guid_t *vendor)
+{
+	struct gsmi_get_next_var_param param = {
+		.name_ptr = gsmi_dev.name_buf->address,
+		.name_len = gsmi_dev.name_buf->length,
+	};
+	efi_status_t ret = EFI_SUCCESS;
+	int rc;
+	unsigned long flags;
+
+	/* For the moment, only support buffers that exactly match in size */
+	if (*name_size != GSMI_BUF_SIZE)
+		return EFI_BAD_BUFFER_SIZE;
+
+	/* Let's make sure the thing is at least null-terminated */
+	if (utf16_strlen(name, GSMI_BUF_SIZE / 2) == GSMI_BUF_SIZE / 2)
+		return EFI_INVALID_PARAMETER;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* guid */
+	memcpy(&param.guid, vendor, sizeof(param.guid));
+
+	/* variable name, already in UTF-16 */
+	memcpy(gsmi_dev.name_buf->start, name, *name_size);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_GET_NEXT_VAR);
+	if (rc < 0) {
+		printk(KERN_ERR "gsmi: Get Next Variable Name failed\n");
+		ret = EFI_LOAD_ERROR;
+	} else if (rc == 1) {
+		/* variable not found -- end of list */
+		ret = EFI_NOT_FOUND;
+	} else {
+		/* copy variable data back to return buffer */
+		memcpy(&param, gsmi_dev.param_buf->start, sizeof(param));
+
+		/* Copy the name back */
+		memcpy(name, gsmi_dev.name_buf->start, GSMI_BUF_SIZE);
+		*name_size = utf16_strlen(name, GSMI_BUF_SIZE / 2) * 2;
+
+		/* copy guid to return buffer */
+		memcpy(vendor, &param.guid, sizeof(param.guid));
+		ret = EFI_SUCCESS;
+	}
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return ret;
+}
+
+static efi_status_t gsmi_set_variable(efi_char16_t *name,
+				      efi_guid_t *vendor,
+				      unsigned long attr,
+				      unsigned long data_size,
+				      void *data)
+{
+	struct gsmi_nvram_var_param param = {
+		.name_ptr = gsmi_dev.name_buf->address,
+		.data_ptr = gsmi_dev.data_buf->address,
+		.data_len = (u32)data_size,
+		.attributes = EFI_VARIABLE_NON_VOLATILE |
+			      EFI_VARIABLE_BOOTSERVICE_ACCESS |
+			      EFI_VARIABLE_RUNTIME_ACCESS,
+	};
+	size_t name_len = utf16_strlen(name, GSMI_BUF_SIZE / 2);
+	efi_status_t ret = EFI_SUCCESS;
+	int rc;
+	unsigned long flags;
+
+	if (name_len >= GSMI_BUF_SIZE / 2)
+		return EFI_BAD_BUFFER_SIZE;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* guid */
+	memcpy(&param.guid, vendor, sizeof(param.guid));
+
+	/* variable name, already in UTF-16 */
+	memset(gsmi_dev.name_buf->start, 0, gsmi_dev.name_buf->length);
+	memcpy(gsmi_dev.name_buf->start, name, name_len * 2);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+	memcpy(gsmi_dev.data_buf->start, data, data_size);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_NVRAM_VAR);
+	if (rc < 0) {
+		printk(KERN_ERR "gsmi: Set Variable failed\n");
+		ret = EFI_INVALID_PARAMETER;
+	}
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return ret;
+}
+
+static const struct efivar_operations efivar_ops = {
+	.get_variable = gsmi_get_variable,
+	.set_variable = gsmi_set_variable,
+	.get_next_variable = gsmi_get_next_variable,
+};
+
+static ssize_t eventlog_write(struct file *filp, struct kobject *kobj,
+			       struct bin_attribute *bin_attr,
+			       char *buf, loff_t pos, size_t count)
+{
+	struct gsmi_set_eventlog_param param = {
+		.data_ptr = gsmi_dev.data_buf->address,
+	};
+	int rc = 0;
+	unsigned long flags;
+
+	/* Pull the type out */
+	if (count < sizeof(u32))
+		return -EINVAL;
+	param.type = *(u32 *)buf;
+	count -= sizeof(u32);
+	buf += sizeof(u32);
+
+	/* The remaining buffer is the data payload */
+	if (count > gsmi_dev.data_buf->length)
+		return -EINVAL;
+	param.data_len = count - sizeof(u32);
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+	memcpy(gsmi_dev.data_buf->start, buf, param.data_len);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_EVENT_LOG);
+	if (rc < 0)
+		printk(KERN_ERR "gsmi: Set Event Log failed\n");
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	return rc;
+
+}
+
+static struct bin_attribute eventlog_bin_attr = {
+	.attr = {.name = "append_to_eventlog", .mode = 0200},
+	.write = eventlog_write,
+};
+
+static ssize_t gsmi_clear_eventlog_store(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 const char *buf, size_t count)
+{
+	int rc;
+	unsigned long flags;
+	unsigned long val;
+	struct {
+		u32 percentage;
+		u32 data_type;
+	} param;
+
+	rc = strict_strtoul(buf, 0, &val);
+	if (rc)
+		return rc;
+
+	/*
+	 * Value entered is a percentage, 0 through 100, anything else
+	 * is invalid.
+	 */
+	if (val > 100)
+		return -EINVAL;
+
+	/* data_type here selects the smbios event log. */
+	param.percentage = val;
+	param.data_type = 0;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_CLEAR_EVENT_LOG);
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	if (rc)
+		return rc;
+	return count;
+}
+
+static struct kobj_attribute gsmi_clear_eventlog_attr = {
+	.attr = {.name = "clear_eventlog", .mode = 0200},
+	.store = gsmi_clear_eventlog_store,
+};
+
+static ssize_t gsmi_clear_config_store(struct kobject *kobj,
+				       struct kobj_attribute *attr,
+				       const char *buf, size_t count)
+{
+	int rc;
+	unsigned long flags;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	/* clear parameter buffer */
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_CLEAR_CONFIG);
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	if (rc)
+		return rc;
+	return count;
+}
+
+static struct kobj_attribute gsmi_clear_config_attr = {
+	.attr = {.name = "clear_config", .mode = 0200},
+	.store = gsmi_clear_config_store,
+};
+
+static const struct attribute *gsmi_attrs[] = {
+	&gsmi_clear_config_attr.attr,
+	&gsmi_clear_eventlog_attr.attr,
+	NULL,
+};
+
+static int gsmi_shutdown_reason(int reason)
+{
+	struct gsmi_log_entry_type_1 entry = {
+		.type     = GSMI_LOG_ENTRY_TYPE_KERNEL,
+		.instance = reason,
+	};
+	struct gsmi_set_eventlog_param param = {
+		.data_len = sizeof(entry),
+		.type     = 1,
+	};
+	static int saved_reason;
+	int rc = 0;
+	unsigned long flags;
+
+	/* avoid duplicate entries in the log */
+	if (saved_reason & (1 << reason))
+		return 0;
+
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+
+	saved_reason |= (1 << reason);
+
+	/* data pointer */
+	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
+	memcpy(gsmi_dev.data_buf->start, &entry, sizeof(entry));
+
+	/* parameter buffer */
+	param.data_ptr = gsmi_dev.data_buf->address;
+	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
+	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));
+
+	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_EVENT_LOG);
+
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	if (rc < 0)
+		printk(KERN_ERR "gsmi: Log Shutdown Reason failed\n");
+	else
+		printk(KERN_EMERG "gsmi: Log Shutdown Reason 0x%02x\n",
+		       reason);
+
+	return rc;
+}
+
+static int gsmi_reboot_callback(struct notifier_block *nb,
+				unsigned long reason, void *arg)
+{
+	gsmi_shutdown_reason(GSMI_SHUTDOWN_CLEAN);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block gsmi_reboot_notifier = {
+	.notifier_call = gsmi_reboot_callback
+};
+
+static int gsmi_die_callback(struct notifier_block *nb,
+			     unsigned long reason, void *arg)
+{
+	if (reason == DIE_NMIWATCHDOG)
+		gsmi_shutdown_reason(GSMI_SHUTDOWN_NMIWDT);
+	else if (reason == DIE_OOPS)
+		gsmi_shutdown_reason(GSMI_SHUTDOWN_OOPS);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block gsmi_die_notifier = {
+	.notifier_call = gsmi_die_callback
+};
+
+static int gsmi_panic_callback(struct notifier_block *nb,
+			       unsigned long reason, void *arg)
+{
+	gsmi_shutdown_reason(GSMI_SHUTDOWN_PANIC);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block gsmi_panic_notifier = {
+	.notifier_call = gsmi_panic_callback,
+};
+
+/*
+ * This hash function was blatantly copied from include/linux/hash.h.
+ * It is used by this driver to obfuscate a board name that requires a
+ * quirk within this driver.
+ *
+ * Please do not remove this copy of the function as any changes to the
+ * global utility hash_64() function would break this driver's ability
+ * to identify a board and provide the appropriate quirk -- mikew@google.com
+ */
+static u64 __init local_hash_64(u64 val, unsigned bits)
+{
+	u64 hash = val;
+
+	/*  Sigh, gcc can't optimise this alone like it does for 32 bits. */
+	u64 n = hash;
+	n <<= 18;
+	hash -= n;
+	n <<= 33;
+	hash -= n;
+	n <<= 3;
+	hash += n;
+	n <<= 3;
+	hash -= n;
+	n <<= 4;
+	hash += n;
+	n <<= 2;
+	hash += n;
+
+	/* High bits are more random, so use them. */
+	return hash >> (64 - bits);
+}
+
+static u32 __init hash_oem_table_id(char s[8])
+{
+	u64 input;
+	memcpy(&input, s, 8);
+	return local_hash_64(input, 32);
+}
+
+static struct dmi_system_id gsmi_dmi_table[] __initdata = {
+	{
+		.ident = "Google Board",
+		.matches = {
+			DMI_MATCH(DMI_BOARD_VENDOR, "Google, Inc."),
+		},
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(dmi, gsmi_dmi_table);
+
+static __init int gsmi_system_valid(void)
+{
+	u32 hash;
+
+	if (!dmi_check_system(gsmi_dmi_table))
+		return -ENODEV;
+
+	/*
+	 * Only newer firmware supports the gsmi interface.  All older
+	 * firmware that didn't support this interface used to plug the
+	 * table name in the first four bytes of the oem_table_id field.
+	 * Newer firmware doesn't do that though, so use that as the
+	 * discriminant factor.  We have to do this in order to
+	 * whitewash our board names out of the public driver.
+	 */
+	if (!strncmp(acpi_gbl_FADT.header.oem_table_id, "FACP", 4)) {
+		printk(KERN_INFO "gsmi: Board is too old\n");
+		return -ENODEV;
+	}
+
+	/* Disable on board with 1.0 BIOS due to Google bug 2602657 */
+	hash = hash_oem_table_id(acpi_gbl_FADT.header.oem_table_id);
+	if (hash == QUIRKY_BOARD_HASH) {
+		const char *bios_ver = dmi_get_system_info(DMI_BIOS_VERSION);
+		if (strncmp(bios_ver, "1.0", 3) == 0) {
+			pr_info("gsmi: disabled on this board's BIOS %s\n",
+				bios_ver);
+			return -ENODEV;
+		}
+	}
+
+	/* check for valid SMI command port in ACPI FADT */
+	if (acpi_gbl_FADT.smi_command == 0) {
+		pr_info("gsmi: missing smi_command\n");
+		return -ENODEV;
+	}
+
+	/* Found */
+	return 0;
+}
+
+static struct kobject *gsmi_kobj;
+static struct efivars efivars;
+
+static __init int gsmi_init(void)
+{
+	unsigned long flags;
+	int ret;
+
+	ret = gsmi_system_valid();
+	if (ret)
+		return ret;
+
+	gsmi_dev.smi_cmd = acpi_gbl_FADT.smi_command;
+
+	/* register device */
+	gsmi_dev.pdev = platform_device_register_simple("gsmi", -1, NULL, 0);
+	if (IS_ERR(gsmi_dev.pdev)) {
+		printk(KERN_ERR "gsmi: unable to register platform device\n");
+		return PTR_ERR(gsmi_dev.pdev);
+	}
+
+	/* SMI access needs to be serialized */
+	spin_lock_init(&gsmi_dev.lock);
+
+	/* SMI callbacks require 32bit addresses */
+	gsmi_dev.pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
+	gsmi_dev.pdev->dev.dma_mask =
+		&gsmi_dev.pdev->dev.coherent_dma_mask;
+	ret = -ENOMEM;
+	gsmi_dev.dma_pool = dma_pool_create("gsmi", &gsmi_dev.pdev->dev,
+					     GSMI_BUF_SIZE, GSMI_BUF_ALIGN, 0);
+	if (!gsmi_dev.dma_pool)
+		goto out_err;
+
+	/*
+	 * pre-allocate buffers because sometimes we are called when
+	 * this is not feasible: oops, panic, die, mce, etc
+	 */
+	gsmi_dev.name_buf = gsmi_buf_alloc();
+	if (!gsmi_dev.name_buf) {
+		printk(KERN_ERR "gsmi: failed to allocate name buffer\n");
+		goto out_err;
+	}
+
+	gsmi_dev.data_buf = gsmi_buf_alloc();
+	if (!gsmi_dev.data_buf) {
+		printk(KERN_ERR "gsmi: failed to allocate data buffer\n");
+		goto out_err;
+	}
+
+	gsmi_dev.param_buf = gsmi_buf_alloc();
+	if (!gsmi_dev.param_buf) {
+		printk(KERN_ERR "gsmi: failed to allocate param buffer\n");
+		goto out_err;
+	}
+
+	/*
+	 * Determine type of handshake used to serialize the SMI
+	 * entry. See also gsmi_exec().
+	 *
+	 * There's a "behavior" present on some chipsets where writing the
+	 * SMI trigger register in the southbridge doesn't result in an
+	 * immediate SMI. Rather, the processor can execute "a few" more
+	 * instructions before the SMI takes effect. To ensure synchronous
+	 * behavior, implement a handshake between the kernel driver and the
+	 * firmware handler to spin until released. This ioctl determines
+	 * the type of handshake.
+	 *
+	 * NONE: The firmware handler does not implement any
+	 * handshake. Either it doesn't need to, or it's legacy firmware
+	 * that doesn't know it needs to and never will.
+	 *
+	 * CF: The firmware handler will clear the CF in the saved
+	 * state before returning. The driver may set the CF and test for
+	 * it to clear before proceeding.
+	 *
+	 * SPIN: The firmware handler does not implement any handshake
+	 * but the driver should spin for a hundred or so microseconds
+	 * to ensure the SMI has triggered.
+	 *
+	 * Finally, the handler will return -ENOSYS if
+	 * GSMI_CMD_HANDSHAKE_TYPE is unimplemented, which implies
+	 * HANDSHAKE_NONE.
+	 */
+	spin_lock_irqsave(&gsmi_dev.lock, flags);
+	gsmi_dev.handshake_type = GSMI_HANDSHAKE_SPIN;
+	gsmi_dev.handshake_type =
+	    gsmi_exec(GSMI_CALLBACK, GSMI_CMD_HANDSHAKE_TYPE);
+	if (gsmi_dev.handshake_type == -ENOSYS)
+		gsmi_dev.handshake_type = GSMI_HANDSHAKE_NONE;
+	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
+
+	/* Remove and clean up gsmi if the handshake could not complete. */
+	if (gsmi_dev.handshake_type == -ENXIO) {
+		printk(KERN_INFO "gsmi version " DRIVER_VERSION
+		       " failed to load\n");
+		ret = -ENODEV;
+		goto out_err;
+	}
+
+	printk(KERN_INFO "gsmi version " DRIVER_VERSION " loaded\n");
+
+	/* Register in the firmware directory */
+	ret = -ENOMEM;
+	gsmi_kobj = kobject_create_and_add("gsmi", firmware_kobj);
+	if (!gsmi_kobj) {
+		printk(KERN_INFO "gsmi: Failed to create firmware kobj\n");
+		goto out_err;
+	}
+
+	/* Setup eventlog access */
+	ret = sysfs_create_bin_file(gsmi_kobj, &eventlog_bin_attr);
+	if (ret) {
+		printk(KERN_INFO "gsmi: Failed to setup eventlog");
+		goto out_err;
+	}
+
+	/* Other attributes */
+	ret = sysfs_create_files(gsmi_kobj, gsmi_attrs);
+	if (ret) {
+		printk(KERN_INFO "gsmi: Failed to add attrs");
+		goto out_err;
+	}
+
+	if (register_efivars(&efivars, &efivar_ops, gsmi_kobj)) {
+		printk(KERN_INFO "gsmi: Failed to register efivars\n");
+		goto out_err;
+	}
+
+	register_reboot_notifier(&gsmi_reboot_notifier);
+	register_die_notifier(&gsmi_die_notifier);
+	atomic_notifier_chain_register(&panic_notifier_list,
+				       &gsmi_panic_notifier);
+
+	return 0;
+
+ out_err:
+	kobject_put(gsmi_kobj);
+	gsmi_buf_free(gsmi_dev.param_buf);
+	gsmi_buf_free(gsmi_dev.data_buf);
+	gsmi_buf_free(gsmi_dev.name_buf);
+	if (gsmi_dev.dma_pool)
+		dma_pool_destroy(gsmi_dev.dma_pool);
+	platform_device_unregister(gsmi_dev.pdev);
+	pr_info("gsmi: failed to load: %d\n", ret);
+	return ret;
+}
+
+static void __exit gsmi_exit(void)
+{
+	unregister_reboot_notifier(&gsmi_reboot_notifier);
+	unregister_die_notifier(&gsmi_die_notifier);
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &gsmi_panic_notifier);
+	unregister_efivars(&efivars);
+
+	kobject_put(gsmi_kobj);
+	gsmi_buf_free(gsmi_dev.param_buf);
+	gsmi_buf_free(gsmi_dev.data_buf);
+	gsmi_buf_free(gsmi_dev.name_buf);
+	dma_pool_destroy(gsmi_dev.dma_pool);
+	platform_device_unregister(gsmi_dev.pdev);
+}
+
+module_init(gsmi_init);
+module_exit(gsmi_exit);
+
+MODULE_AUTHOR("Google, Inc.");
+MODULE_LICENSE("GPL");

[PATCH v3 5/5] driver: Google Memory Console

[Mike Waychison]

This patch introduces the 'memconsole' driver.

Our firmware gives us access to an in-memory log of the firmware's
output.   This gives us visibility in a data-center of headless machines
as to what the firmware is doing.

The memory console is found by the driver by finding a header block in
the EBDA.  The buffer is then copied out, and is exported to userland in
the file /sys/firmware/log.

Signed-off-by: San Mehat <san@google.com>
Signed-off-by: Mike Waychison <mikew@google.com>
---
Changelog:
v3:
   - Use dmi_check_system to only load when on a Google board.
   - Use MODULE_DEVICE_TABLE to export matching DMI strings.
   - Default to 'n' in the Kconfig.
   - Fixed Kconfig description to reflect that this change no longer
     messes with the dmesg.
v2:
   - Removed bits that had this driver muck with the kernel's ring
     dmesg buffer (log_buf).
   - Introduced the log as /sys/firmware/log, a binary file that isn't
     interpreted by the kernel.
   - Don't use C99 fixed width types; use kernel fixed width types.
   - Added file to Documentation/ABI for /sys/firmware/log
---
 Documentation/ABI/testing/sysfs-firmware-log |    7 +
 drivers/firmware/google/Kconfig              |    8 +
 drivers/firmware/google/Makefile             |    1 
 drivers/firmware/google/memconsole.c         |  166 ++++++++++++++++++++++++++
 4 files changed, 182 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-firmware-log
 create mode 100644 drivers/firmware/google/memconsole.c

diff --git a/Documentation/ABI/testing/sysfs-firmware-log b/Documentation/ABI/testing/sysfs-firmware-log
new file mode 100644
index 0000000..9b58e7c
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-log
@@ -0,0 +1,7 @@
+What:		/sys/firmware/log
+Date:		February 2011
+Contact:	Mike Waychison <mikew@google.com>
+Description:
+		The /sys/firmware/log is a binary file that represents a
+		read-only copy of the firmware's log if one is
+		available.
diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig
index 8190103..87096b6 100644
--- a/drivers/firmware/google/Kconfig
+++ b/drivers/firmware/google/Kconfig
@@ -20,4 +20,12 @@ config GOOGLE_SMI
 	  clearing the EFI event log and reading and writing NVRAM
 	  variables.
 
+config GOOGLE_MEMCONSOLE
+	tristate "Firmware Memory Console"
+	depends on DMI
+	help
+	  This option enables the kernel to search for a firmware log in
+	  the EBDA on Google servers.  If found, this log is exported to
+	  userland in the file /sys/firmware/log.
+
 endmenu
diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile
index fb127d7..54a294e 100644
--- a/drivers/firmware/google/Makefile
+++ b/drivers/firmware/google/Makefile
@@ -1,2 +1,3 @@
 
 obj-$(CONFIG_GOOGLE_SMI)		+= gsmi.o
+obj-$(CONFIG_GOOGLE_MEMCONSOLE)		+= memconsole.o
diff --git a/drivers/firmware/google/memconsole.c b/drivers/firmware/google/memconsole.c
new file mode 100644
index 0000000..2a90ba6
--- /dev/null
+++ b/drivers/firmware/google/memconsole.c
@@ -0,0 +1,166 @@
+/*
+ * memconsole.c
+ *
+ * Infrastructure for importing the BIOS memory based console
+ * into the kernel log ringbuffer.
+ *
+ * Copyright 2010 Google Inc. All rights reserved.
+ */
+
+#include <linux/ctype.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/kobject.h>
+#include <linux/module.h>
+#include <linux/dmi.h>
+#include <asm/bios_ebda.h>
+
+#define BIOS_MEMCONSOLE_V1_MAGIC	0xDEADBABE
+#define BIOS_MEMCONSOLE_V2_MAGIC	(('M')|('C'<<8)|('O'<<16)|('N'<<24))
+
+struct biosmemcon_ebda {
+	u32 signature;
+	union {
+		struct {
+			u8  enabled;
+			u32 buffer_addr;
+			u16 start;
+			u16 end;
+			u16 num_chars;
+			u8  wrapped;
+		} __packed v1;
+		struct {
+			u32 buffer_addr;
+			/* Misdocumented as number of pages! */
+			u16 num_bytes;
+			u16 start;
+			u16 end;
+		} __packed v2;
+	};
+} __packed;
+
+static char *memconsole_baseaddr;
+static size_t memconsole_length;
+
+static ssize_t memconsole_read(struct file *filp, struct kobject *kobp,
+			       struct bin_attribute *bin_attr, char *buf,
+			       loff_t pos, size_t count)
+{
+	return memory_read_from_buffer(buf, count, &pos, memconsole_baseaddr,
+				       memconsole_length);
+}
+
+static struct bin_attribute memconsole_bin_attr = {
+	.attr = {.name = "log", .mode = 0444},
+	.read = memconsole_read,
+};
+
+
+static void found_v1_header(struct biosmemcon_ebda *hdr)
+{
+	printk(KERN_INFO "BIOS console v1 EBDA structure found at %p\n", hdr);
+	printk(KERN_INFO "BIOS console buffer at 0x%.8x, "
+	       "start = %d, end = %d, num = %d\n",
+	       hdr->v1.buffer_addr, hdr->v1.start,
+	       hdr->v1.end, hdr->v1.num_chars);
+
+	memconsole_length = hdr->v1.num_chars;
+	memconsole_baseaddr = phys_to_virt(hdr->v1.buffer_addr);
+}
+
+static void found_v2_header(struct biosmemcon_ebda *hdr)
+{
+	printk(KERN_INFO "BIOS console v2 EBDA structure found at %p\n", hdr);
+	printk(KERN_INFO "BIOS console buffer at 0x%.8x, "
+	       "start = %d, end = %d, num_bytes = %d\n",
+	       hdr->v2.buffer_addr, hdr->v2.start,
+	       hdr->v2.end, hdr->v2.num_bytes);
+
+	memconsole_length = hdr->v2.end - hdr->v2.start;
+	memconsole_baseaddr = phys_to_virt(hdr->v2.buffer_addr
+					   + hdr->v2.start);
+}
+
+/*
+ * Search through the EBDA for the BIOS Memory Console, and
+ * set the global variables to point to it.  Return true if found.
+ */
+static bool found_memconsole(void)
+{
+	unsigned int address;
+	size_t length, cur;
+
+	address = get_bios_ebda();
+	if (!address) {
+		printk(KERN_INFO "BIOS EBDA non-existent.\n");
+		return false;
+	}
+
+	/* EBDA length is byte 0 of EBDA (in KB) */
+	length = *(u8 *)phys_to_virt(address);
+	length <<= 10; /* convert to bytes */
+
+	/*
+	 * Search through EBDA for BIOS memory console structure
+	 * note: signature is not necessarily dword-aligned
+	 */
+	for (cur = 0; cur < length; cur++) {
+		struct biosmemcon_ebda *hdr = phys_to_virt(address + cur);
+
+		/* memconsole v1 */
+		if (hdr->signature == BIOS_MEMCONSOLE_V1_MAGIC) {
+			found_v1_header(hdr);
+			return true;
+		}
+
+		/* memconsole v2 */
+		if (hdr->signature == BIOS_MEMCONSOLE_V2_MAGIC) {
+			found_v2_header(hdr);
+			return true;
+		}
+	}
+
+	printk(KERN_INFO "BIOS console EBDA structure not found!\n");
+	return false;
+}
+
+static struct dmi_system_id memconsole_dmi_table[] __initdata = {
+	{
+		.ident = "Google Board",
+		.matches = {
+			DMI_MATCH(DMI_BOARD_VENDOR, "Google, Inc."),
+		},
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(dmi, memconsole_dmi_table);
+
+static int __init memconsole_init(void)
+{
+	int ret;
+
+	if (!dmi_check_system(memconsole_dmi_table))
+		return -ENODEV;
+
+	if (!found_memconsole())
+		return -ENODEV;
+
+	memconsole_bin_attr.size = memconsole_length;
+
+	ret = sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr);
+
+	return ret;
+}
+
+static void __exit memconsole_exit(void)
+{
+	sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr);
+}
+
+module_init(memconsole_init);
+module_exit(memconsole_exit);
+
+MODULE_AUTHOR("Google, Inc.");
+MODULE_LICENSE("GPL");

Re: [PATCH v3 5/5] driver: Google Memory Console

[Ingo Molnar]

* Mike Waychison <mikew@google.com> wrote:

> +static struct dmi_system_id memconsole_dmi_table[] __initdata = {
> +	{
> +		.ident = "Google Board",
> +		.matches = {
> +			DMI_MATCH(DMI_BOARD_VENDOR, "Google, Inc."),
> +		},
> +	},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(dmi, memconsole_dmi_table);
> +
> +static int __init memconsole_init(void)
> +{
> +	int ret;
> +
> +	if (!dmi_check_system(memconsole_dmi_table))
> +		return -ENODEV;
> +
> +	if (!found_memconsole())
> +		return -ENODEV;

Ok, that's a much safer method of discovery.

Acked-by: Ingo Molnar <mingo@elte.hu>

Thanks,

	Ingo