MIPS: BCM47XX: Fix clock detection for BCM5354 with 200MHz clock

Some BCM5354 SoCs are running at 200MHz, but it is not possible to read
the clock from a register like it is done on some other SoC in ssb and
bcma. These devices should have a clkfreq nvram configuration value set
to 200, read it and set the clock to the correct value.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5842/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/mips/bcm47xx/time.c b/arch/mips/bcm47xx/time.c
index 536374dcba78..5e5d797fa90a 100644
--- a/arch/mips/bcm47xx/time.c
+++ b/arch/mips/bcm47xx/time.c
@@ -27,10 +27,14 @@
 #include <linux/ssb/ssb.h>
 #include <asm/time.h>
 #include <bcm47xx.h>
+#include <bcm47xx_nvram.h>
 
 void __init plat_time_init(void)
 {
         unsigned long hz = 0;
+        u16 chip_id = 0;
+        char buf[10];
+        int len;
 
         /*
          * Use deterministic values for initial counter interrupt
@@ -43,15 +47,23 @@ void __init plat_time_init(void)
 #ifdef CONFIG_BCM47XX_SSB
         case BCM47XX_BUS_TYPE_SSB:
                 hz = ssb_cpu_clock(&bcm47xx_bus.ssb.mipscore) / 2;
+                chip_id = bcm47xx_bus.ssb.chip_id;
                 break;
 #endif
 #ifdef CONFIG_BCM47XX_BCMA
         case BCM47XX_BUS_TYPE_BCMA:
                 hz = bcma_cpu_clock(&bcm47xx_bus.bcma.bus.drv_mips) / 2;
+                chip_id = bcm47xx_bus.bcma.bus.chipinfo.id;
                 break;
 #endif
         }
 
+        if (chip_id == 0x5354) {
+                len = bcm47xx_nvram_getenv("clkfreq", buf, sizeof(buf));
+                if (len >= 0 && !strncmp(buf, "200", 4))
+                        hz = 100000000;
+        }
+
         if (!hz)
                 hz = 100000000;