MIPS: BCM47XX: Support SPROM prefixes for PCI devices

Support parsing SPROMs with prefixes defined like devpath1=pci/1/1

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Patchwork: https://patchwork.linux-mips.org/patch/9552/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/arch/mips/bcm47xx/sprom.c b/arch/mips/bcm47xx/sprom.c
index 2eff7fe99c6b..eff920560689 100644
--- a/arch/mips/bcm47xx/sprom.c
+++ b/arch/mips/bcm47xx/sprom.c
@@ -836,6 +836,38 @@ static int bcm47xx_get_sprom_ssb(struct ssb_bus *bus, struct ssb_sprom *out)
 #endif
 
 #if defined(CONFIG_BCM47XX_BCMA)
+/*
+ * Having many NVRAM entries for PCI devices led to repeating prefixes like
+ * pci/1/1/ all the time and wasting flash space. So at some point Broadcom
+ * decided to introduce prefixes like 0: 1: 2: etc.
+ * If we find e.g. devpath0=pci/2/1 or devpath0=pci/2/1/ we should use 0:
+ * instead of pci/2/1/.
+ */
+static void bcm47xx_sprom_apply_prefix_alias(char *prefix, size_t prefix_size)
+{
+        size_t prefix_len = strlen(prefix);
+        size_t short_len = prefix_len - 1;
+        char nvram_var[10];
+        char buf[20];
+        int i;
+
+        /* Passed prefix has to end with a slash */
+        if (prefix_len <= 0 || prefix[prefix_len - 1] != '/')
+                return;
+
+        for (i = 0; i < 3; i++) {
+                if (snprintf(nvram_var, sizeof(nvram_var), "devpath%d", i) <= 0)
+                        continue;
+                if (bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf)) < 0)
+                        continue;
+                if (!strcmp(buf, prefix) ||
+                    (short_len && strlen(buf) == short_len && !strncmp(buf, prefix, short_len))) {
+                        snprintf(prefix, prefix_size, "%d:", i);
+                        return;
+                }
+        }
+}
+
 static int bcm47xx_get_sprom_bcma(struct bcma_bus *bus, struct ssb_sprom *out)
 {
         char prefix[10];
@@ -847,6 +879,7 @@ static int bcm47xx_get_sprom_bcma(struct bcma_bus *bus, struct ssb_sprom *out)
                 snprintf(prefix, sizeof(prefix), "pci/%u/%u/",
                          bus->host_pci->bus->number + 1,
                          PCI_SLOT(bus->host_pci->devfn));
+                bcm47xx_sprom_apply_prefix_alias(prefix, sizeof(prefix));
                 bcm47xx_fill_sprom(out, prefix, false);
                 return 0;
         case BCMA_HOSTTYPE_SOC: