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Subject[PATCH v2 11/28] ARM: tegra: timer: Add idle and suspend support to timers
Date
The Tegra processor cannot be woken from idle by the internal
ARM timers. Reserve timer 4 to be used as a wake source
during idle.

Implement read_persistent_clock by reading the Tegra RTC
registers that stay running during suspend.

Save and restore the timer configuration register and the
sched_clock value in LP0.

Signed-off-by: Colin Cross <ccross@android.com>
---
arch/arm/mach-tegra/timer.c | 95 ++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 93 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-tegra/timer.c b/arch/arm/mach-tegra/timer.c
index 36b53a7..2d0b76f 100644
--- a/arch/arm/mach-tegra/timer.c
+++ b/arch/arm/mach-tegra/timer.c
@@ -38,6 +38,10 @@
#include "board.h"
#include "clock.h"

+#define RTC_SECONDS 0x08
+#define RTC_SHADOW_SECONDS 0x0c
+#define RTC_MILLISECONDS 0x10
+
#define TIMERUS_CNTR_1US 0x10
#define TIMERUS_USEC_CFG 0x14
#define TIMERUS_CNTR_FREEZE 0x4c
@@ -50,9 +54,11 @@
#define TIMER_PTV 0x0
#define TIMER_PCR 0x4

-struct tegra_timer;
-
static void __iomem *timer_reg_base = IO_ADDRESS(TEGRA_TMR1_BASE);
+static void __iomem *rtc_base = IO_ADDRESS(TEGRA_RTC_BASE);
+
+static struct timespec persistent_ts;
+static u64 persistent_ms, last_persistent_ms;

#define timer_writel(value, reg) \
__raw_writel(value, (u32)timer_reg_base + (reg))
@@ -133,6 +139,42 @@ static void notrace tegra_update_sched_clock(void)
update_sched_clock(&cd, cyc, (u32)~0);
}

+/*
+ * tegra_rtc_read - Reads the Tegra RTC registers
+ * Care must be taken that this funciton is not called while the
+ * tegra_rtc driver could be executing to avoid race conditions
+ * on the RTC shadow register
+ */
+u64 tegra_rtc_read_ms(void)
+{
+ u32 ms = readl(rtc_base + RTC_MILLISECONDS);
+ u32 s = readl(rtc_base + RTC_SHADOW_SECONDS);
+ return (u64)s * MSEC_PER_SEC + ms;
+}
+
+/*
+ * read_persistent_clock - Return time from a persistent clock.
+ *
+ * Reads the time from a source which isn't disabled during PM, the
+ * 32k sync timer. Convert the cycles elapsed since last read into
+ * nsecs and adds to a monotonically increasing timespec.
+ * Care must be taken that this funciton is not called while the
+ * tegra_rtc driver could be executing to avoid race conditions
+ * on the RTC shadow register
+ */
+void read_persistent_clock(struct timespec *ts)
+{
+ u64 delta;
+ struct timespec *tsp = &persistent_ts;
+
+ last_persistent_ms = persistent_ms;
+ persistent_ms = tegra_rtc_read_ms();
+ delta = persistent_ms - last_persistent_ms;
+
+ timespec_add_ns(tsp, delta * NSEC_PER_MSEC);
+ *ts = *tsp;
+}
+
static irqreturn_t tegra_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = (struct clock_event_device *)dev_id;
@@ -149,6 +191,20 @@ static struct irqaction tegra_timer_irq = {
.irq = INT_TMR3,
};

+static irqreturn_t tegra_lp2wake_interrupt(int irq, void *dev_id)
+{
+ timer_writel(1<<30, TIMER4_BASE + TIMER_PCR);
+ return IRQ_HANDLED;
+}
+
+static struct irqaction tegra_lp2wake_irq = {
+ .name = "timer_lp2wake",
+ .flags = IRQF_DISABLED,
+ .handler = tegra_lp2wake_interrupt,
+ .dev_id = NULL,
+ .irq = INT_TMR4,
+};
+
static void __init tegra_init_timer(void)
{
unsigned long rate = clk_measure_input_freq();
@@ -189,6 +245,12 @@ static void __init tegra_init_timer(void)
BUG();
}

+ ret = setup_irq(tegra_lp2wake_irq.irq, &tegra_lp2wake_irq);
+ if (ret) {
+ printk(KERN_ERR "Failed to register LP2 timer IRQ: %d\n", ret);
+ BUG();
+ }
+
clockevents_calc_mult_shift(&tegra_clockevent, 1000000, 5);
tegra_clockevent.max_delta_ns =
clockevent_delta2ns(0x1fffffff, &tegra_clockevent);
@@ -204,3 +266,32 @@ static void __init tegra_init_timer(void)
struct sys_timer tegra_timer = {
.init = tegra_init_timer,
};
+
+void tegra_lp2_set_trigger(unsigned long cycles)
+{
+ timer_writel(0, TIMER4_BASE + TIMER_PTV);
+ if (cycles) {
+ u32 reg = 0x80000000ul | min(0x1ffffffful, cycles);
+ timer_writel(reg, TIMER4_BASE + TIMER_PTV);
+ }
+}
+EXPORT_SYMBOL(tegra_lp2_set_trigger);
+
+unsigned long tegra_lp2_timer_remain(void)
+{
+ return timer_readl(TIMER4_BASE + TIMER_PCR) & 0x1ffffffful;
+}
+
+#ifdef CONFIG_PM
+static u32 usec_config;
+
+void tegra_timer_suspend(void)
+{
+ usec_config = timer_readl(TIMERUS_USEC_CFG);
+}
+
+void tegra_timer_resume(void)
+{
+ timer_writel(usec_config, TIMERUS_USEC_CFG);
+}
+#endif
--
1.7.3.1


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