1 files changed, 33 insertions, 79 deletions

diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c
index 3284b9b4ecac..52075426c373 100644
--- a/arch/mips/kernel/time.c
+++ b/arch/mips/kernel/time.c
@@ -50,14 +50,6 @@ int update_persistent_clock(struct timespec now)
         return rtc_mips_set_mmss(now.tv_sec);
 }
 
-/*
- * High precision timer functions for a R4k-compatible timer.
- */
-static cycle_t c0_hpt_read(void)
-{
-        return read_c0_count();
-}
-
 int (*mips_timer_state)(void);
 
 int null_perf_irq(void)
@@ -84,55 +76,6 @@ EXPORT_SYMBOL(perf_irq);
 
 unsigned int mips_hpt_frequency;
 
-static struct clocksource clocksource_mips = {
-        .name           = "MIPS",
-        .read           = c0_hpt_read,
-        .mask           = CLOCKSOURCE_MASK(32),
-        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
-};
-
-static unsigned int __init calibrate_hpt(void)
-{
-        cycle_t frequency, hpt_start, hpt_end, hpt_count, hz;
-
-        const int loops = HZ / 10;
-        int log_2_loops = 0;
-        int i;
-
-        /*
-         * We want to calibrate for 0.1s, but to avoid a 64-bit
-         * division we round the number of loops up to the nearest
-         * power of 2.
-         */
-        while (loops > 1 << log_2_loops)
-                log_2_loops++;
-        i = 1 << log_2_loops;
-
-        /*
-         * Wait for a rising edge of the timer interrupt.
-         */
-        while (mips_timer_state());
-        while (!mips_timer_state());
-
-        /*
-         * Now see how many high precision timer ticks happen
-         * during the calculated number of periods between timer
-         * interrupts.
-         */
-        hpt_start = clocksource_mips.read();
-        do {
-                while (mips_timer_state());
-                while (!mips_timer_state());
-        } while (--i);
-        hpt_end = clocksource_mips.read();
-
-        hpt_count = (hpt_end - hpt_start) & clocksource_mips.mask;
-        hz = HZ;
-        frequency = hpt_count * hz;
-
-        return frequency >> log_2_loops;
-}
-
 void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
 {
         u64 temp;
@@ -166,16 +109,6 @@ void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
         cd->mult = (u32) temp;
 }
 
-static void __init init_mips_clocksource(void)
-{
-        /* Calclate a somewhat reasonable rating value */
-        clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
-
-        clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
-
-        clocksource_register(&clocksource_mips);
-}
-
 void __init __weak plat_time_init(void)
 {
 }
@@ -194,21 +127,42 @@ void __init plat_timer_setup(void)
         BUG();
 }
 
+static __init int cpu_has_mfc0_count_bug(void)
+{
+        switch (current_cpu_type()) {
+        case CPU_R4000PC:
+        case CPU_R4000SC:
+        case CPU_R4000MC:
+                /*
+                 * V3.0 is documented as suffering from the mfc0 from count bug.
+                 * Afaik this is the last version of the R4000.  Later versions
+                 * were marketed as R4400.
+                 */
+                return 1;
+
+        case CPU_R4400PC:
+        case CPU_R4400SC:
+        case CPU_R4400MC:
+                /*
+                 * The published errata for the R4400 upto 3.0 say the CPU
+                 * has the mfc0 from count bug.
+                 */
+                if ((current_cpu_data.processor_id & 0xff) <= 0x30)
+                        return 1;
+
+                /*
+                 * I don't have erratas for newer R4400 so be paranoid.
+                 */
+                return 1;
+        }
+
+        return 0;
+}
+
 void __init time_init(void)
 {
         plat_time_init();
 
-        if (cpu_has_counter && (mips_hpt_frequency || mips_timer_state)) {
-                /* We know counter frequency.  Or we can get it.  */
-                if (!mips_hpt_frequency)
-                        mips_hpt_frequency = calibrate_hpt();
-
-                /* Report the high precision timer rate for a reference.  */
-                printk("Using %u.%03u MHz high precision timer.\n",
-                       ((mips_hpt_frequency + 500) / 1000) / 1000,
-                       ((mips_hpt_frequency + 500) / 1000) % 1000);
+        if (mips_clockevent_init() || !cpu_has_mfc0_count_bug())
                 init_mips_clocksource();
-        }
-
-        mips_clockevent_init();
 }