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>

1 files changed, 60 insertions, 28 deletions

diff --git a/arch/arm/plat-nomadik/timer.c b/arch/arm/plat-nomadik/timer.c
index bd638c552f0..a04b5215b6d 100644
--- 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 =