MIPS: Add new GIC clocksource.

Add new clocksource that uses the counter present on the MIPS
Global Interrupt Controller.

Signed-off-by: Steven J. Hill <sjhill@mips.com>
Patchwork: http://patchwork.linux-mips.org/patch/4681/
Signed-off-by: John Crispin <blogic@openwrt.org>

1 files changed, 50 insertions, 33 deletions

diff --git a/arch/mips/mti-malta/malta-time.c b/arch/mips/mti-malta/malta-time.c
index 115f5bc..a144b89 100644
--- a/arch/mips/mti-malta/malta-time.c
+++ b/arch/mips/mti-malta/malta-time.c
@@ -17,7 +17,6 @@
  *
  * Setting up the clock on the MIPS boards.
  */
-
 #include <linux/types.h>
 #include <linux/i8253.h>
 #include <linux/init.h>
@@ -25,7 +24,6 @@
 #include <linux/sched.h>
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
-#include <linux/time.h>
 #include <linux/timex.h>
 #include <linux/mc146818rtc.h>
 
@@ -34,11 +32,11 @@
 #include <asm/hardirq.h>
 #include <asm/irq.h>
 #include <asm/div64.h>
-#include <asm/cpu.h>
 #include <asm/setup.h>
 #include <asm/time.h>
 #include <asm/mc146818-time.h>
 #include <asm/msc01_ic.h>
+#include <asm/gic.h>
 
 #include <asm/mips-boards/generic.h>
 #include <asm/mips-boards/prom.h>
@@ -46,6 +44,7 @@
 #include <asm/mips-boards/maltaint.h>
 
 unsigned long cpu_khz;
+int gic_frequency;
 
 static int mips_cpu_timer_irq;
 static int mips_cpu_perf_irq;
@@ -61,44 +60,50 @@ static void mips_perf_dispatch(void)
 	do_IRQ(mips_cpu_perf_irq);
 }
 
+static unsigned int freqround(unsigned int freq, unsigned int amount)
+{
+	freq += amount;
+	freq -= freq % (amount*2);
+	return freq;
+}
+
 /*
- * Estimate CPU frequency.  Sets mips_hpt_frequency as a side-effect
+ * Estimate CPU and GIC frequencies.
  */
-static unsigned int __init estimate_cpu_frequency(void)
+static void __init estimate_frequencies(void)
 {
-	unsigned int prid = read_c0_prid() & 0xffff00;
-	unsigned int count;
-
 	unsigned long flags;
-	unsigned int start;
+	unsigned int count, start;
+	unsigned int giccount = 0, gicstart = 0;
 
 	local_irq_save(flags);
 
-	/* Start counter exactly on falling edge of update flag */
+	/* Start counter exactly on falling edge of update flag. */
 	while (CMOS_READ(RTC_REG_A) & RTC_UIP);
 	while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
 
-	/* Start r4k counter. */
+	/* Initialize counters. */
 	start = read_c0_count();
+	if (gic_present)
+		GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_31_00), gicstart);
 
-	/* Read counter exactly on falling edge of update flag */
+	/* Read counter exactly on falling edge of update flag. */
 	while (CMOS_READ(RTC_REG_A) & RTC_UIP);
 	while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
 
-	count = read_c0_count() - start;
+	count = read_c0_count();
+	if (gic_present)
+		GICREAD(GIC_REG(SHARED, GIC_SH_COUNTER_31_00), giccount);
 
-	/* restore interrupts */
 	local_irq_restore(flags);
 
-	mips_hpt_frequency = count;
-	if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
-	    (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
-		count *= 2;
-
-	count += 5000;    /* round */
-	count -= count%10000;
+	count -= start;
+	if (gic_present)
+		giccount -= gicstart;
 
-	return count;
+	mips_hpt_frequency = count;
+	if (gic_present)
+		gic_frequency = giccount;
 }
 
 void read_persistent_clock(struct timespec *ts)
@@ -144,22 +149,34 @@ unsigned int __cpuinit get_c0_compare_int(void)
 
 void __init plat_time_init(void)
 {
-	unsigned int est_freq;
-
-        /* Set Data mode - binary. */
-        CMOS_WRITE(CMOS_READ(RTC_CONTROL) | RTC_DM_BINARY, RTC_CONTROL);
-
-	est_freq = estimate_cpu_frequency();
+	unsigned int prid = read_c0_prid() & 0xffff00;
+	unsigned int freq;
 
-	printk("CPU frequency %d.%02d MHz\n", est_freq/1000000,
-	       (est_freq%1000000)*100/1000000);
+	estimate_frequencies();
 
-        cpu_khz = est_freq / 1000;
+	freq = mips_hpt_frequency;
+	if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
+	    (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
+		freq *= 2;
+	freq = freqround(freq, 5000);
+	pr_debug("CPU frequency %d.%02d MHz\n", freq/1000000,
+	       (freq%1000000)*100/1000000);
+	cpu_khz = freq / 1000;
+
+	if (gic_present) {
+		freq = freqround(gic_frequency, 5000);
+		pr_debug("GIC frequency %d.%02d MHz\n", freq/1000000,
+		       (freq%1000000)*100/1000000);
+		gic_clocksource_init(gic_frequency);
+	} else
+		init_r4k_clocksource();
 
-	mips_scroll_message();
-#ifdef CONFIG_I8253		/* Only Malta has a PIT */
+#ifdef CONFIG_I8253
+	/* Only Malta has a PIT. */
 	setup_pit_timer();
 #endif
 
+	mips_scroll_message();
+
 	plat_perf_setup();
 }