ARM: plat-nomadik: timer: Add support for periodic timers

This adds support for a periodic mode in the MTU (Nomadik)
timer clockevent driver. It also include changes needed for
deeper powerstates where MTU block gets powered off.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jonas Aaberg <jonas.aberg@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/arch/arm/plat-nomadik/timer.c b/arch/arm/plat-nomadik/timer.c
index bd638c552f04825e26f94c376913d44a6e474e92..a04b5215b6d88a540cce085c05f301fdb619e1f9 100644 (file)
--- a/arch/arm/plat-nomadik/timer.c
+++ b/arch/arm/plat-nomadik/timer.c
@@ -23,7 +23,12 @@
 
 #include <plat/mtu.h>
 
+static bool clkevt_periodic;
+static u32 clk_prescale;
+static u32 nmdk_cycle;         /* write-once */
+
 void __iomem *mtu_base; /* Assigned by machine code */
+
 #ifdef CONFIG_NOMADIK_MTU_SCHED_CLOCK
 /*
  * Override the global weak sched_clock symbol with this
@@ -49,31 +54,55 @@ static void notrace nomadik_update_sched_clock(void)
        update_sched_clock(&cd, cyc, (u32)~0);
 }
 #endif
+
 /* Clockevent device: use one-shot mode */
+static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev)
+{
+       writel(1 << 1, mtu_base + MTU_IMSC);
+       writel(evt, mtu_base + MTU_LR(1));
+       /* Load highest value, enable device, enable interrupts */
+       writel(MTU_CRn_ONESHOT | clk_prescale |
+              MTU_CRn_32BITS | MTU_CRn_ENA,
+              mtu_base + MTU_CR(1));
+
+       return 0;
+}
+
+static void nmdk_clkevt_reset(void)
+{
+       if (clkevt_periodic) {
+
+               /* Timer: configure load and background-load, and fire it up */
+               writel(nmdk_cycle, mtu_base + MTU_LR(1));
+               writel(nmdk_cycle, mtu_base + MTU_BGLR(1));
+
+               writel(MTU_CRn_PERIODIC | clk_prescale |
+                      MTU_CRn_32BITS | MTU_CRn_ENA,
+                      mtu_base + MTU_CR(1));
+               writel(1 << 1, mtu_base + MTU_IMSC);
+       } else {
+               /* Generate an interrupt to start the clockevent again */
+               (void) nmdk_clkevt_next(nmdk_cycle, NULL);
+       }
+}
+
 static void nmdk_clkevt_mode(enum clock_event_mode mode,
                             struct clock_event_device *dev)
 {
-       u32 cr;
 
        switch (mode) {
        case CLOCK_EVT_MODE_PERIODIC:
-               pr_err("%s: periodic mode not supported\n", __func__);
+               clkevt_periodic = true;
+               nmdk_clkevt_reset();
                break;
        case CLOCK_EVT_MODE_ONESHOT:
-               /* Load highest value, enable device, enable interrupts */
-               cr = readl(mtu_base + MTU_CR(1));
-               writel(0, mtu_base + MTU_LR(1));
-               writel(cr | MTU_CRn_ENA, mtu_base + MTU_CR(1));
-               writel(1 << 1, mtu_base + MTU_IMSC);
+               clkevt_periodic = false;
                break;
        case CLOCK_EVT_MODE_SHUTDOWN:
        case CLOCK_EVT_MODE_UNUSED:
-               /* disable irq */
                writel(0, mtu_base + MTU_IMSC);
                /* disable timer */
-               cr = readl(mtu_base + MTU_CR(1));
-               cr &= ~MTU_CRn_ENA;
-               writel(cr, mtu_base + MTU_CR(1));
+               writel(0, mtu_base + MTU_CR(1));
                /* load some high default value */
                writel(0xffffffff, mtu_base + MTU_LR(1));
                break;
@@ -82,16 +111,9 @@ static void nmdk_clkevt_mode(enum clock_event_mode mode,
        }
 }
 
-static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev)
-{
-       /* writing the value has immediate effect */
-       writel(evt, mtu_base + MTU_LR(1));
-       return 0;
-}
-
 static struct clock_event_device nmdk_clkevt = {
        .name           = "mtu_1",
-       .features       = CLOCK_EVT_FEAT_ONESHOT,
+       .features       = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
        .rating         = 200,
        .set_mode       = nmdk_clkevt_mode,
        .set_next_event = nmdk_clkevt_next,
@@ -116,11 +138,23 @@ static struct irqaction nmdk_timer_irq = {
        .dev_id         = &nmdk_clkevt,
 };
 
+static void nmdk_clksrc_reset(void)
+{
+       /* Disable */
+       writel(0, mtu_base + MTU_CR(0));
+
+       /* ClockSource: configure load and background-load, and fire it up */
+       writel(nmdk_cycle, mtu_base + MTU_LR(0));
+       writel(nmdk_cycle, mtu_base + MTU_BGLR(0));
+
+       writel(clk_prescale | MTU_CRn_32BITS | MTU_CRn_ENA,
+              mtu_base + MTU_CR(0));
+}
+
 void __init nmdk_timer_init(void)
 {
        unsigned long rate;
        struct clk *clk0;
-       u32 cr = MTU_CRn_32BITS;
 
        clk0 = clk_get_sys("mtu0", NULL);
        BUG_ON(IS_ERR(clk0));
@@ -138,16 +172,16 @@ void __init nmdk_timer_init(void)
        rate = clk_get_rate(clk0);
        if (rate > 32000000) {
                rate /= 16;
-               cr |= MTU_CRn_PRESCALE_16;
+               clk_prescale = MTU_CRn_PRESCALE_16;
        } else {
-               cr |= MTU_CRn_PRESCALE_1;
+               clk_prescale = MTU_CRn_PRESCALE_1;
        }
 
+       nmdk_cycle = (rate + HZ/2) / HZ;
+
+
        /* Timer 0 is the free running clocksource */
-       writel(cr, mtu_base + MTU_CR(0));
-       writel(0, mtu_base + MTU_LR(0));
-       writel(0, mtu_base + MTU_BGLR(0));
-       writel(cr | MTU_CRn_ENA, mtu_base + MTU_CR(0));
+       nmdk_clksrc_reset();
 
        if (clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0",
                        rate, 200, 32, clocksource_mmio_readl_down))
@@ -160,8 +194,6 @@ void __init nmdk_timer_init(void)
 
        clockevents_calc_mult_shift(&nmdk_clkevt, rate, MTU_MIN_RANGE);
 
-       writel(cr | MTU_CRn_ONESHOT, mtu_base + MTU_CR(1)); /* off, currently */
-
        nmdk_clkevt.max_delta_ns =
                clockevent_delta2ns(0xffffffff, &nmdk_clkevt);
        nmdk_clkevt.min_delta_ns =