ARM: gemini: convert to GENERIC_CLOCKEVENTS

This converts the gemini machine to use generic clockevents
by rewriting the timer driver.

Cc: arm@kernel.org
Cc: Hans Ulli Kroll <ulli.kroll@googlemail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>

1 files changed, 89 insertions, 8 deletions

diff --git a/arch/arm/mach-gemini/time.c b/arch/arm/mach-gemini/time.c
index 21dc5a89d1c4..0a63c4d25b64 100644
--- a/arch/arm/mach-gemini/time.c
+++ b/arch/arm/mach-gemini/time.c
@@ -13,6 +13,8 @@
 #include <mach/hardware.h>
 #include <mach/global_reg.h>
 #include <asm/mach/time.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
 
 /*
  * Register definitions for the timers
@@ -33,19 +35,89 @@
 #define TIMER_3_CR_CLOCK                (1 << 7)
 #define TIMER_3_CR_INT                  (1 << 8)
 
+static unsigned int tick_rate;
+
+static int gemini_timer_set_next_event(unsigned long cycles,
+                                       struct clock_event_device *evt)
+{
+        u32 cr;
+
+        cr = readl(TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
+
+        /* This may be overdoing it, feel free to test without this */
+        cr &= ~TIMER_2_CR_ENABLE;
+        cr &= ~TIMER_2_CR_INT;
+        writel(cr, TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
+
+        /* Set next event */
+        writel(cycles, TIMER_COUNT(IO_ADDRESS(GEMINI_TIMER2_BASE)));
+        writel(cycles, TIMER_LOAD(IO_ADDRESS(GEMINI_TIMER2_BASE)));
+        cr |= TIMER_2_CR_ENABLE;
+        cr |= TIMER_2_CR_INT;
+        writel(cr, TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
+
+        return 0;
+}
+
+static void gemini_timer_set_mode(enum clock_event_mode mode,
+                                  struct clock_event_device *evt)
+{
+        u32 period = DIV_ROUND_CLOSEST(tick_rate, HZ);
+        u32 cr;
+
+        switch (mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+                /* Start the timer */
+                writel(period,
+                       TIMER_COUNT(IO_ADDRESS(GEMINI_TIMER2_BASE)));
+                writel(period,
+                       TIMER_LOAD(IO_ADDRESS(GEMINI_TIMER2_BASE)));
+                cr = readl(TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
+                cr |= TIMER_2_CR_ENABLE;
+                cr |= TIMER_2_CR_INT;
+                writel(cr, TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
+                break;
+        case CLOCK_EVT_MODE_ONESHOT:
+        case CLOCK_EVT_MODE_UNUSED:
+        case CLOCK_EVT_MODE_SHUTDOWN:
+        case CLOCK_EVT_MODE_RESUME:
+                /*
+                 * Disable also for oneshot: the set_next() call will
+                 * arm the timer instead.
+                 */
+                cr = readl(TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
+                cr &= ~TIMER_2_CR_ENABLE;
+                cr &= ~TIMER_2_CR_INT;
+                writel(cr, TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
+                break;
+        default:
+                break;
+        }
+}
+
+/* Use TIMER2 as clock event */
+static struct clock_event_device gemini_clockevent = {
+        .name           = "TIMER2",
+        .rating         = 300, /* Reasonably fast and accurate clock event */
+        .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+        .set_next_event = gemini_timer_set_next_event,
+        .set_mode       = gemini_timer_set_mode,
+};
+
 /*
  * IRQ handler for the timer
  */
 static irqreturn_t gemini_timer_interrupt(int irq, void *dev_id)
 {
-        timer_tick();
+        struct clock_event_device *evt = &gemini_clockevent;
 
+        evt->event_handler(evt);
         return IRQ_HANDLED;
 }
 
 static struct irqaction gemini_timer_irq = {
         .name           = "Gemini Timer Tick",
-        .flags          = IRQF_DISABLED | IRQF_TIMER,
+        .flags          = IRQF_TIMER,
         .handler        = gemini_timer_interrupt,
 };
 
@@ -54,9 +126,9 @@ static struct irqaction gemini_timer_irq = {
  */
 void __init gemini_timer_init(void)
 {
-        unsigned int tick_rate, reg_v;
+        u32 reg_v;
 
-        reg_v = __raw_readl(IO_ADDRESS(GEMINI_GLOBAL_BASE + GLOBAL_STATUS));
+        reg_v = readl(IO_ADDRESS(GEMINI_GLOBAL_BASE + GLOBAL_STATUS));
         tick_rate = REG_TO_AHB_SPEED(reg_v) * 1000000;
 
         printk(KERN_INFO "Bus: %dMHz", tick_rate / 1000000);
@@ -82,8 +154,17 @@ void __init gemini_timer_init(void)
          * Make irqs happen for the system timer
          */
         setup_irq(IRQ_TIMER2, &gemini_timer_irq);
-        /* Start the timer */
-        __raw_writel(tick_rate / HZ, TIMER_COUNT(IO_ADDRESS(GEMINI_TIMER2_BASE)));
-        __raw_writel(tick_rate / HZ, TIMER_LOAD(IO_ADDRESS(GEMINI_TIMER2_BASE)));
-        __raw_writel(TIMER_2_CR_ENABLE | TIMER_2_CR_INT, TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
+
+        /* Enable and use TIMER1 as clock source */
+        writel(0xffffffff, TIMER_COUNT(IO_ADDRESS(GEMINI_TIMER1_BASE)));
+        writel(0xffffffff, TIMER_LOAD(IO_ADDRESS(GEMINI_TIMER1_BASE)));
+        writel(TIMER_1_CR_ENABLE, TIMER_CR(IO_ADDRESS(GEMINI_TIMER_BASE)));
+        if (clocksource_mmio_init(TIMER_COUNT(IO_ADDRESS(GEMINI_TIMER1_BASE)),
+                                  "TIMER1", tick_rate, 300, 32,
+                                  clocksource_mmio_readl_up))
+                pr_err("timer: failed to initialize gemini clock source\n");
+
+        /* Configure and register the clockevent */
+        clockevents_config_and_register(&gemini_clockevent, tick_rate,
+                                        1, 0xffffffff);
 }