brcm47xx: fix cpu clock detection on ASUS WL-520gU

The ASUS WL-520gU and some other similar Asus devices have a BCM5354
running at 200MHZ and not at 240 which is the default for this SoC.

This fixes #4083.

SVN-Revision: 34325

target/linux/brcm47xx/patches-3.6/520-MIPS-BCM47XX-fix-time-for-WL520G-and-other-200-MHz-C.patch

+--- 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 <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 +47,26 @@ 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 = nvram_getenv("clkfreq", buf, sizeof(buf));
++		if (len >= 0 && !strncmp(buf, "200", 4))
++			hz = 100000000;
++		len = nvram_getenv("hardware_version", buf, sizeof(buf));
++		if (len >= 0 && !strncmp(buf, "WL520G", 6))
++			hz = 100000000;
++
++	}
+ 	if (!hz)
+ 		hz = 100000000;
+