[ARM PATCH] 1298/1: display various PXA250 clocks on boot for better bug diagnosis

Since it's easy to overclock that chip we'd better know why some board is 
crashing randomly due to signal integrity problems.

Patch from Nicolas Pitre

1 files changed, 53 insertions, 21 deletions

diff --git a/arch/arm/mach-pxa/generic.c b/arch/arm/mach-pxa/generic.c
index 6f2194565173..d20ec67ebb72 100644
--- a/arch/arm/mach-pxa/generic.c
+++ b/arch/arm/mach-pxa/generic.c
@@ -31,31 +31,63 @@
 #include "generic.h"
 
 /*
+ * Various clock factors driven by the CCCR register.
+ */
+
+/* Crystal Frequency to Memory Frequency Multiplier (L) */
+static unsigned char L_clk_mult[32] = { 0, 27, 32, 36, 40, 45, 0, };
+
+/* Memory Frequency to Run Mode Frequency Multiplier (M) */
+static unsigned char M_clk_mult[4] = { 0, 1, 2, 0 };
+
+/* Run Mode Frequency to Turbo Mode Frequency Multiplier (N) */
+/* Note: we store the value N * 2 here. */
+static unsigned char N2_clk_mult[8] = { 0, 0, 2, 3, 4, 0, 6, 0 };
+
+/* Crystal clock */
+#define BASE_CLK	3686400
+
+
+/*
+ * Display what we were booted with.
+ */
+static int __init pxa_display_clocks(void)
+{
+	unsigned long cccr, turbo;
+	unsigned int l, L, m, M, n2, N;
+
+	cccr = CCCR;
+	asm( "mrc\tp14, 0, %0, c6, c0, 0" : "=r" (turbo) );
+
+	l  =  L_clk_mult[(cccr >> 0) & 0x1f];
+	m  =  M_clk_mult[(cccr >> 5) & 0x03];
+	n2 = N2_clk_mult[(cccr >> 7) & 0x07];
+
+	L = l * BASE_CLK;
+	M = m * L;
+	N = n2 * M / 2;
+
+	L += 5000;
+	printk( KERN_INFO "Memory clock: %d.%02dMHz (*%d)\n",
+		L / 1000000, (L % 1000000) / 10000, l );
+	M += 5000;
+	printk( KERN_INFO "Run Mode clock: %d.%02dMHz (*%d)\n",
+		M / 1000000, (M % 1000000) / 10000, m );
+	N += 5000;
+	printk( KERN_INFO "Turbo Mode clock: %d.%02dMHz (*%d.%d, %sactive)\n",
+		N / 1000000, (N % 1000000) / 10000, n2 / 2, (n2 % 2) * 5,
+		(turbo & 1) ? "" : "in" );
+
+	return 0;
+}
+
+
+/*
  * Return the current lclk requency in units of 10kHz
  */
 unsigned int get_lclk_frequency_10khz(void)
 {
-	unsigned int l;
-
-	l = CCCR & 0x1f;
-
-	switch(l)
-	{
-		case 1:
-			return 9953;
-		case 2:
-			return 11796;
-		case 3:
-			return 13271;
-		case 4:
-			return 14746;
-		case 5:
-			return 16589;
-		case 0xf:
-			return 3320;
-		default:
-			return 0;
-	}
+	return L_clk_mult[(CCCR >> 0) & 0x1f] * BASE_CLK / 10000;
 }
 
 EXPORT_SYMBOL(get_lclk_frequency_10khz);