[patch 2/2] ia64: add driver for ACPI methods to call native firmware

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

This driver for HPQ5001 devices installs a global ACPI OpRegion handler.
AML methods can use this OpRegion to call native firmware entry points.

This is required to support some hotplug functionality on HP Integrity
systems.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>

Index: w/arch/ia64/Kconfig
=================================--- w.orig/arch/ia64/Kconfig	2007-09-11 16:07:23.000000000 -0600
+++ w/arch/ia64/Kconfig	2007-09-11 16:09:53.000000000 -0600
@@ -461,6 +461,19 @@
 	  firmware extensions, such as the ability to inject memory-errors
 	  for test-purposes.  If you're unsure, say N.
 
+config IA64_HP_AML_NFW
+	tristate "Support ACPI AML calls to native firmware"
+	help
+	  This driver installs a global ACPI Operation Region handler for
+	  region 0xA1.  AML methods can use this OpRegion to call arbitrary
+	  native firmware functions.  The driver installs the OpRegion
+	  handler if there is an HPQ5001 device or if the user supplies
+	  the "force" module parameter, e.g., with the "aml_nfw.force"
+	  kernel command line option.
+
+	  This driver is required for some hotplug functionality on
+	  HP Integrity systems.
+
 source "drivers/sn/Kconfig"
 
 config KEXEC
Index: w/arch/ia64/hp/common/Makefile
=================================--- w.orig/arch/ia64/hp/common/Makefile	2007-09-11 16:07:23.000000000 -0600
+++ w/arch/ia64/hp/common/Makefile	2007-09-11 16:09:41.000000000 -0600
@@ -8,3 +8,4 @@
 obj-y := sba_iommu.o
 obj-$(CONFIG_IA64_HP_ZX1_SWIOTLB) += hwsw_iommu.o
 obj-$(CONFIG_IA64_GENERIC) += hwsw_iommu.o
+obj-$(CONFIG_IA64_HP_AML_NFW) += aml_nfw.o
Index: w/arch/ia64/hp/common/aml_nfw.c
=================================--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ w/arch/ia64/hp/common/aml_nfw.c	2007-09-11 16:09:41.000000000 -0600
@@ -0,0 +1,228 @@
+/*
+ * OpRegion handler to allow AML to call native firmware
+ *
+ * (c) Copyright 2007 Hewlett-Packard Development Company, L.P.
+ *	Bjorn Helgaas <bjorn.helgaas@hp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This driver implements HP Open Source Review Board proposal 1842,
+ * which was approved on 9/20/2006.
+ *
+ * For technical documentation, see the HP SPPA Firmware EAS, Appendix F.
+ */
+
+#include <linux/module.h>
+#include <acpi/acpi_bus.h>
+#include <acpi/acpi_drivers.h>
+#include <asm/sal.h>
+
+MODULE_AUTHOR("Bjorn Helgaas <bjorn.helgaas@hp.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ACPI opregion handler for native firmware calls");
+
+static int force_register;
+module_param_named(force, force_register, bool, 0);
+MODULE_PARM_DESC(force, "Install opregion handler even without HPQ5001 device");
+
+#define AML_NFW_SPACE		0xA1
+
+struct ia64_pdesc {
+	void *ip;
+	void *gp;
+};
+
+/*
+ * N.B.  The layout of this structure is defined in the HP SPPA FW EAS, and
+ *	 the member offsets are embedded in AML methods.
+ */
+struct ia64_nfw_context {
+	u64 arg[8];
+	struct ia64_sal_retval ret;
+	u64 ip;
+	u64 gp;
+	u64 pad[2];
+};
+
+static void *virt_map(u64 address)
+{
+	if (address & (1UL << 63))
+		return (void *) (__IA64_UNCACHED_OFFSET | address);
+
+	return __va(address);
+}
+
+static void aml_nfw_execute(struct ia64_nfw_context *c)
+{
+	struct ia64_pdesc virt_entry;
+	ia64_sal_handler entry;
+
+	virt_entry.ip = virt_map(c->ip);
+	virt_entry.gp = virt_map(c->gp);
+
+	entry = (ia64_sal_handler) &virt_entry;
+
+	fw_call_lock(entry, &c->ret,
+			c->arg[0], c->arg[1], c->arg[2], c->arg[3],
+			c->arg[4], c->arg[5], c->arg[6], c->arg[7]);
+}
+
+static void aml_nfw_read_arg(u8 *offset, u32 bit_width, acpi_integer *value)
+{
+	switch (bit_width) {
+	case 8:
+		*value = *(u8 *)offset;
+		break;
+	case 16:
+		*value = *(u16 *)offset;
+		break;
+	case 32:
+		*value = *(u32 *)offset;
+		break;
+	case 64:
+		*value = *(u64 *)offset;
+		break;
+	}
+}
+
+static void aml_nfw_write_arg(u8 *offset, u32 bit_width, acpi_integer *value)
+{
+	switch (bit_width) {
+	case 8:
+		*(u8 *) offset = *value;
+		break;
+	case 16:
+		*(u16 *) offset = *value;
+		break;
+	case 32:
+		*(u32 *) offset = *value;
+		break;
+	case 64:
+		*(u64 *) offset = *value;
+		break;
+	}
+}
+
+static acpi_status aml_nfw_handler(u32 function, acpi_physical_address address,
+	u32 bit_width, acpi_integer *value, void *handler_context,
+	void *region_context)
+{
+	struct ia64_nfw_context *context = handler_context;
+	u8 *offset = (u8 *) context + address;
+
+	if (bit_width !=  8 && bit_width != 16 &&
+	    bit_width != 32 && bit_width != 64)
+		return AE_BAD_PARAMETER;
+
+	if (address + (bit_width >> 3) > sizeof(struct ia64_nfw_context))
+		return AE_BAD_PARAMETER;
+
+	switch (function) {
+	case ACPI_READ:
+		if (address = offsetof(struct ia64_nfw_context, ret))
+			aml_nfw_execute(context);
+		aml_nfw_read_arg(offset, bit_width, value);
+		break;
+	case ACPI_WRITE:
+		aml_nfw_write_arg(offset, bit_width, value);
+		break;
+	}
+
+	return AE_OK;
+}
+
+static struct ia64_nfw_context global_context;
+static int global_handler_registered;
+
+static int aml_nfw_add_global_handler(void)
+{
+	acpi_status status;
+
+	if (global_handler_registered)
+		return 0;
+
+	status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
+		AML_NFW_SPACE, aml_nfw_handler, NULL, &global_context);
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	global_handler_registered = 1;
+	printk(KERN_INFO "Global 0x%02X opregion handler registered\n",
+		AML_NFW_SPACE);
+	return 0;
+}
+
+static int aml_nfw_remove_global_handler(void)
+{
+	acpi_status status;
+
+	if (!global_handler_registered)
+		return 0;
+
+	status = acpi_remove_address_space_handler(ACPI_ROOT_OBJECT,
+		AML_NFW_SPACE, aml_nfw_handler);
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	global_handler_registered = 0;
+	printk(KERN_INFO "Global 0x%02X opregion handler removed\n",
+		AML_NFW_SPACE);
+	return 0;
+}
+
+static int aml_nfw_add(struct acpi_device *device)
+{
+	/*
+	 * We would normally allocate a new context structure and install
+	 * the address space handler for the specific device we found.
+	 * But the HP-UX implementation shares a single global context
+	 * and always puts the handler at the root, so we'll do the same.
+	 */
+	return aml_nfw_add_global_handler();
+}
+
+static int aml_nfw_remove(struct acpi_device *device, int type)
+{
+	return aml_nfw_remove_global_handler();
+}
+
+static const struct acpi_device_id aml_nfw_ids[] = {
+	{"HPQ5001", 0},
+	{"", 0}
+};
+
+static struct acpi_driver acpi_aml_nfw_driver = {
+	.name = "native firmware",
+	.ids = aml_nfw_ids,
+	.ops = {
+		.add = aml_nfw_add,
+		.remove = aml_nfw_remove,
+		},
+};
+
+static int __init aml_nfw_init(void)
+{
+	int result;
+
+	if (force_register)
+		aml_nfw_add_global_handler();
+
+	result = acpi_bus_register_driver(&acpi_aml_nfw_driver);
+	if (result < 0) {
+		aml_nfw_remove_global_handler();
+		return result;
+	}
+
+	return 0;
+}
+
+static void __exit aml_nfw_exit(void)
+{
+	acpi_bus_unregister_driver(&acpi_aml_nfw_driver);
+	aml_nfw_remove_global_handler();
+}
+
+module_init(aml_nfw_init);
+module_exit(aml_nfw_exit);