ssb: Add SPROM fallback support

This adds SSB functionality to register a fallback SPROM image from the
architecture setup code.

Weird architectures exist that have half-assed SSB devices without SPROM attached to
their PCI busses. The architecture can register a fallback SPROM image that is
used if no SPROM is found on the SSB device.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Cc: Florian Fainelli <florian@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

4 files changed, 54 insertions, 1 deletions

diff --git a/drivers/ssb/pci.c b/drivers/ssb/pci.c
index c958ac16423c..40ea41762247 100644
--- a/drivers/ssb/pci.c
+++ b/drivers/ssb/pci.c
@@ -564,6 +564,7 @@ static int sprom_extract(struct ssb_bus *bus, struct ssb_sprom *out,
 static int ssb_pci_sprom_get(struct ssb_bus *bus,
                              struct ssb_sprom *sprom)
 {
+        const struct ssb_sprom *fallback;
         int err = -ENOMEM;
         u16 *buf;
 
@@ -583,12 +584,23 @@ static int ssb_pci_sprom_get(struct ssb_bus *bus,
                 bus->sprom_size = SSB_SPROMSIZE_WORDS_R4;
                 sprom_do_read(bus, buf);
                 err = sprom_check_crc(buf, bus->sprom_size);
-                if (err)
+                if (err) {
+                        /* All CRC attempts failed.
+                         * Maybe there is no SPROM on the device?
+                         * If we have a fallback, use that. */
+                        fallback = ssb_get_fallback_sprom();
+                        if (fallback) {
+                                memcpy(sprom, fallback, sizeof(*sprom));
+                                err = 0;
+                                goto out_free;
+                        }
                         ssb_printk(KERN_WARNING PFX "WARNING: Invalid"
                                    " SPROM CRC (corrupt SPROM)\n");
+                }
         }
         err = sprom_extract(bus, sprom, buf, bus->sprom_size);
 
+out_free:
         kfree(buf);
 out:
         return err;
diff --git a/drivers/ssb/sprom.c b/drivers/ssb/sprom.c
index 3668edb39315..8943015a3eef 100644
--- a/drivers/ssb/sprom.c
+++ b/drivers/ssb/sprom.c
@@ -14,6 +14,9 @@
 #include "ssb_private.h"
 
 
+static const struct ssb_sprom *fallback_sprom;
+
+
 static int sprom2hex(const u16 *sprom, char *buf, size_t buf_len,
                      size_t sprom_size_words)
 {
@@ -131,3 +134,36 @@ out:
                 return res;
         return err ? err : count;
 }
+
+/**
+ * ssb_arch_set_fallback_sprom - Set a fallback SPROM for use if no SPROM is found.
+ *
+ * @sprom: The SPROM data structure to register.
+ *
+ * With this function the architecture implementation may register a fallback
+ * SPROM data structure. The fallback is only used for PCI based SSB devices,
+ * where no valid SPROM can be found in the shadow registers.
+ *
+ * This function is useful for weird architectures that have a half-assed SSB device
+ * hardwired to their PCI bus.
+ *
+ * Note that it does only work with PCI attached SSB devices. PCMCIA devices currently
+ * don't use this fallback.
+ * Architectures must provide the SPROM for native SSB devices anyway,
+ * so the fallback also isn't used for native devices.
+ *
+ * This function is available for architecture code, only. So it is not exported.
+ */
+int ssb_arch_set_fallback_sprom(const struct ssb_sprom *sprom)
+{
+        if (fallback_sprom)
+                return -EEXIST;
+        fallback_sprom = sprom;
+
+        return 0;
+}
+
+const struct ssb_sprom *ssb_get_fallback_sprom(void)
+{
+        return fallback_sprom;
+}
diff --git a/drivers/ssb/ssb_private.h b/drivers/ssb/ssb_private.h
index ebc32d8fe15f..57fa482abb94 100644
--- a/drivers/ssb/ssb_private.h
+++ b/drivers/ssb/ssb_private.h
@@ -131,6 +131,7 @@ ssize_t ssb_attr_sprom_store(struct ssb_bus *bus,
                              const char *buf, size_t count,
                              int (*sprom_check_crc)(const u16 *sprom, size_t size),
                              int (*sprom_write)(struct ssb_bus *bus, const u16 *sprom));
+extern const struct ssb_sprom *ssb_get_fallback_sprom(void);
 
 
 /* core.c */
diff --git a/include/linux/ssb/ssb.h b/include/linux/ssb/ssb.h
index 17d9b58f6379..5ae8fa22d331 100644
--- a/include/linux/ssb/ssb.h
+++ b/include/linux/ssb/ssb.h
@@ -339,6 +339,10 @@ extern int ssb_bus_pcmciabus_register(struct ssb_bus *bus,
 
 extern void ssb_bus_unregister(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);
+
 /* Suspend a SSB bus.
  * Call this from the parent bus suspend routine. */
 extern int ssb_bus_suspend(struct ssb_bus *bus);