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* RFC: A workaround for BCM43XX devices with no on-board SPROM
@ 2010-03-18 17:46 Larry Finger
  2010-03-18 19:31 ` Michael Buesch
                   ` (3 more replies)
  0 siblings, 4 replies; 27+ messages in thread
From: Larry Finger @ 2010-03-18 17:46 UTC (permalink / raw)
  To: Michael Buesch; +Cc: bcm43xx devel, wireless

Michael,

I'm switching this discussion from the kernel Bugzilla to the lists.

As you know, but I'm restating for anyone that has not read our previous
discussions, the b43 driver needs to be changed to handle some of the newer
devices do not have an on-board SPROM. It would be trivial to incorporate the
data except for the need to have a unique, reproducible MAC.

I am proposing to solve this problem using the following steps:

(1) Modify b43-fwcutter to take data from an existing SPROM, modify the MAC by
replacing the last 3 octets with random numbers, and write the resulting file to
/lib/firmware/b43. Fortunately, all affected devices seem to have Revision 8
SPROMS, which makes preparation easier. All such devices will need to use the
calibration parameters of the device from which the prototype SPROM was copied,
but that should not be a serious problem. I have chosen to implement this in
fwcutter rather than ssb_sprom because the ordinary user will not have access to
ssb_sprom; however, they do have a version of fwcutter supplied by the distro.
Unconditionally writing an additional small file to the firmware directory when
extracting firmware is small overhead and it will be transparent to the user of
whatever mechanism the distro uses. The routines needed to calculate the CRC,
etc. have been copied into fwcutter from ssb_sprom. A version of this code is
already running.

(2) Use the steps in http://bcm-v4.sipsolutions.net/802.11/IsSpromAvailable to
determine if the device has an SPROM. If not, then use the kernel's firmware
loading mechanism to get the contents of the file prepared in step 1. This file
has an 8-bit CRC, thus the validity of the file can be tested even though the
test is not very robust.

It it reasonable to keep the vendor portion of the MAC and only replace the
"serial number", or would it be better to randomize all 6 octants?

Is there a better way to load a file into the kernel?

Thanks,

Larry

^ permalink raw reply	[flat|nested] 27+ messages in thread
* [PATCH V3] ssb: do not read SPROM if it does not exist
@ 2010-03-31 19:39 John W. Linville
  2010-03-31 19:42 ` Rafał Miłecki
                   ` (2 more replies)
  0 siblings, 3 replies; 27+ messages in thread
From: John W. Linville @ 2010-03-31 19:39 UTC (permalink / raw)
  To: linux-wireless
  Cc: John W. Linville, Rafał Miłecki, Larry Finger,
	Michael Buesch

Attempting to read registers that don't exist on the SSB bus can cause
hangs on some boxes.  At least some b43 devices are 'in the wild' that
don't have SPROMs at all.  When the SSB bus support loads, it attempts
to read these (non-existant) SPROMs and causes hard hangs on the box --
no console output, etc.

This patch adds some intelligence to determine whether or not the SPROM
is present before attempting to read it.  This avoids those hard hangs
on those devices with no SPROM attached to their SSB bus.  The
SSB-attached devices (e.g. b43, et al.) won't work, but at least the box
will survive to test further patches. :-)

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Cc: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Michael Buesch <mb@bu3sch.de>
---
V2: adapt to updated specs, drop some warning-causing braces
V3: updated specs again, drop PCMCIA part

OK, so hopefully we have it figured out now.

However I have no idea what PCMCIA tuples are. Do we need similar check for
some PCMCIA code?

I feel badly pretending to be John. Did I really get your tip correct, Larry?
---
 drivers/ssb/driver_chipcommon.c           |    2 ++
 drivers/ssb/pci.c                         |    5 +++++
 drivers/ssb/sprom.c                       |   14 ++++++++++++++
 include/linux/ssb/ssb.h                   |    3 +++
 include/linux/ssb/ssb_driver_chipcommon.h |   15 +++++++++++++++
 5 files changed, 39 insertions(+), 0 deletions(-)

diff --git a/drivers/ssb/driver_chipcommon.c b/drivers/ssb/driver_chipcommon.c
index 59c3c0f..59ae76b 100644
--- a/drivers/ssb/driver_chipcommon.c
+++ b/drivers/ssb/driver_chipcommon.c
@@ -233,6 +233,8 @@ void ssb_chipcommon_init(struct ssb_chipcommon *cc)
 {
 	if (!cc->dev)
 		return; /* We don't have a ChipCommon */
+	if (cc->dev->id.revision >= 11)
+		cc->status = chipco_read32(cc, SSB_CHIPCO_CHIPSTAT);
 	ssb_pmu_init(cc);
 	chipco_powercontrol_init(cc);
 	ssb_chipco_set_clockmode(cc, SSB_CLKMODE_FAST);
diff --git a/drivers/ssb/pci.c b/drivers/ssb/pci.c
index 9e50896..a4b2b99 100644
--- a/drivers/ssb/pci.c
+++ b/drivers/ssb/pci.c
@@ -620,6 +620,11 @@ static int ssb_pci_sprom_get(struct ssb_bus *bus,
 	int err = -ENOMEM;
 	u16 *buf;
 
+	if (!ssb_is_sprom_available(bus)) {
+		ssb_printk(KERN_ERR PFX "No SPROM available!\n");
+		return -ENODEV;
+	}
+
 	buf = kcalloc(SSB_SPROMSIZE_WORDS_R123, sizeof(u16), GFP_KERNEL);
 	if (!buf)
 		goto out;
diff --git a/drivers/ssb/sprom.c b/drivers/ssb/sprom.c
index d0e6762..83bc088 100644
--- a/drivers/ssb/sprom.c
+++ b/drivers/ssb/sprom.c
@@ -175,3 +175,17 @@ const struct ssb_sprom *ssb_get_fallback_sprom(void)
 {
 	return fallback_sprom;
 }
+
+/* http://bcm-v4.sipsolutions.net/802.11/IsSpromAvailable */
+bool ssb_is_sprom_available(struct ssb_bus *bus)
+{
+	/* status register only exists on chipcomon rev >= 11 and we need check
+	   for >= 31 only */
+	/* this routine differs from specs as we do not access SPROM directly
+	   on PCMCIA */
+	if (bus->bustype == SSB_BUSTYPE_PCI &&
+	    bus->chipco.dev->id.revision >= 31)
+		return bus->chipco.capabilities & SSB_CHIPCO_CAP_SPROM;
+
+	return true;
+}
diff --git a/include/linux/ssb/ssb.h b/include/linux/ssb/ssb.h
index 24f9885..3b4da23 100644
--- a/include/linux/ssb/ssb.h
+++ b/include/linux/ssb/ssb.h
@@ -394,6 +394,9 @@ extern int ssb_bus_sdiobus_register(struct ssb_bus *bus,
 
 extern void ssb_bus_unregister(struct ssb_bus *bus);
 
+/* Does the device have an SPROM? */
+extern bool ssb_is_sprom_available(struct ssb_bus *bus);
+
 /* Set a fallback SPROM.
  * See kdoc at the function definition for complete documentation. */
 extern int ssb_arch_set_fallback_sprom(const struct ssb_sprom *sprom);
diff --git a/include/linux/ssb/ssb_driver_chipcommon.h b/include/linux/ssb/ssb_driver_chipcommon.h
index 4e27acf..2cdf249 100644
--- a/include/linux/ssb/ssb_driver_chipcommon.h
+++ b/include/linux/ssb/ssb_driver_chipcommon.h
@@ -53,6 +53,7 @@
 #define  SSB_CHIPCO_CAP_64BIT		0x08000000	/* 64-bit Backplane */
 #define  SSB_CHIPCO_CAP_PMU		0x10000000	/* PMU available (rev >= 20) */
 #define  SSB_CHIPCO_CAP_ECI		0x20000000	/* ECI available (rev >= 20) */
+#define  SSB_CHIPCO_CAP_SPROM		0x40000000	/* SPROM present */
 #define SSB_CHIPCO_CORECTL		0x0008
 #define  SSB_CHIPCO_CORECTL_UARTCLK0	0x00000001	/* Drive UART with internal clock */
 #define	 SSB_CHIPCO_CORECTL_SE		0x00000002	/* sync clk out enable (corerev >= 3) */
@@ -385,6 +386,7 @@
 
 
 /** Chip specific Chip-Status register contents. */
+#define SSB_CHIPCO_CHST_4322_SPROM_EXISTS	0x00000040 /* SPROM present */
 #define SSB_CHIPCO_CHST_4325_SPROM_OTP_SEL	0x00000003
 #define SSB_CHIPCO_CHST_4325_DEFCIS_SEL		0 /* OTP is powered up, use def. CIS, no SPROM */
 #define SSB_CHIPCO_CHST_4325_SPROM_SEL		1 /* OTP is powered up, SPROM is present */
@@ -398,6 +400,18 @@
 #define SSB_CHIPCO_CHST_4325_RCAL_VALUE_SHIFT	4
 #define SSB_CHIPCO_CHST_4325_PMUTOP_2B 		0x00000200 /* 1 for 2b, 0 for to 2a */
 
+/** Macros to determine SPROM presence based on Chip-Status register. */
+#define SSB_CHIPCO_CHST_4312_SPROM_PRESENT(status) \
+	((status & SSB_CHIPCO_CHST_4325_SPROM_OTP_SEL) != \
+		SSB_CHIPCO_CHST_4325_OTP_SEL)
+#define SSB_CHIPCO_CHST_4322_SPROM_PRESENT(status) \
+	(status & SSB_CHIPCO_CHST_4322_SPROM_EXISTS)
+#define SSB_CHIPCO_CHST_4325_SPROM_PRESENT(status) \
+	(((status & SSB_CHIPCO_CHST_4325_SPROM_OTP_SEL) != \
+		SSB_CHIPCO_CHST_4325_DEFCIS_SEL) && \
+	 ((status & SSB_CHIPCO_CHST_4325_SPROM_OTP_SEL) != \
+		SSB_CHIPCO_CHST_4325_OTP_SEL))
+
 
 
 /** Clockcontrol masks and values **/
@@ -564,6 +578,7 @@ struct ssb_chipcommon_pmu {
 struct ssb_chipcommon {
 	struct ssb_device *dev;
 	u32 capabilities;
+	u32 status;
 	/* Fast Powerup Delay constant */
 	u16 fast_pwrup_delay;
 	struct ssb_chipcommon_pmu pmu;
-- 
1.6.4.2


^ permalink raw reply related	[flat|nested] 27+ messages in thread
end of thread, other threads:[~2010-04-01 14:28 UTC | newest]

Thread overview: 27+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-03-18 17:46 RFC: A workaround for BCM43XX devices with no on-board SPROM Larry Finger
2010-03-18 19:31 ` Michael Buesch
2010-03-18 20:20   ` John W. Linville
2010-03-18 20:31     ` Johannes Berg
2010-03-18 21:38   ` Larry Finger
2010-03-19  7:36     ` Michael Buesch
2010-03-18 20:51 ` Nicolas de Pesloüan
2010-03-18 20:53 ` Johannes Berg
2010-03-18 21:10   ` Larry Finger
2010-03-18 21:20     ` Johannes Berg
2010-03-18 21:47       ` Larry Finger
2010-03-19 18:40     ` Kalle Valo
2010-03-19 19:08 ` [PATCH] ssb: do not read SPROM if it does not exist John W. Linville
2010-03-19 19:41   ` Michael Buesch
2010-03-19 19:46     ` Michael Buesch
2010-03-19 20:21     ` John W. Linville
2010-03-19 20:30       ` Michael Buesch
2010-03-19 20:31         ` John W. Linville
2010-03-19 20:33   ` [PATCH v2] " John W. Linville
2010-03-19 20:41     ` [PATCH v3] " John W. Linville
2010-03-19 21:12       ` Michael Buesch
2010-03-19 22:10         ` John W. Linville
2010-03-19 22:10         ` [PATCH v4] " John W. Linville
  -- strict thread matches above, loose matches on Subject: below --
2010-03-31 19:39 [PATCH V3] " John W. Linville
2010-03-31 19:42 ` Rafał Miłecki
2010-04-01 14:23 ` Michael Buesch
2010-04-01 14:28 ` Michael Buesch

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