ssb: do not read SPROM if it does not exist

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>

diff --git a/drivers/ssb/driver_chipcommon.c b/drivers/ssb/driver_chipcommon.c
index 59c3c0fdbecde30f14188cac0a5f6eab95f2ec9a..59ae76bace14cb740483484b1a6a21b08157f259 100644 (file)
--- 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 9e50896233aa969e5fa145bcf630dd0ba9055363..a4b2b99f2c802d3d0e57ec92ee8f1d2731ae9b6b 100644 (file)
--- 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 d0e6762fec50c6316193eae92a1b787320cbb276..83bc088b941d25e454ec02a8feaa45e55b570502 100644 (file)
--- 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 24f9885473610d66c01d0a8e0bc8d056bca3ba12..3b4da233e31d474122d95143f31f3f7765f96d7b 100644 (file)
--- 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 4e27acf0a92f91f3f3052f96dcdfa4d142ca369e..2cdf249b4e5f0627980e4140bf96170cb8546ad0 100644 (file)
--- 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;