4 files changed, 359 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/arm/global_timer.txt b/Documentation/devicetree/bindings/arm/global_timer.txt
new file mode 100644
index 000000000000..1e548981eda4
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/global_timer.txt
@@ -0,0 +1,24 @@
+
+* ARM Global Timer
+        Cortex-A9 are often associated with a per-core Global timer.
+
+** Timer node required properties:
+
+- compatible : Should be "arm,cortex-a9-global-timer"
+                Driver supports versions r2p0 and above.
+
+- interrupts : One interrupt to each core
+
+- reg : Specify the base address and the size of the GT timer
+        register window.
+
+- clocks : Should be phandle to a clock.
+
+Example:
+
+        timer@2c000600 {
+                compatible = "arm,cortex-a9-global-timer";
+                reg = <0x2c000600 0x20>;
+                interrupts = <1 13 0xf01>;
+                clocks = <&arm_periph_clk>;
+        };
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index c082e3e4bd0a..42c8eccb1e86 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -72,6 +72,19 @@ config ARM_ARCH_TIMER
         bool
         select CLKSRC_OF if OF
 
+config ARM_GLOBAL_TIMER
+        bool
+        select CLKSRC_OF if OF
+        help
+          This options enables support for the ARM global timer unit
+
+config CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
+        bool
+        depends on ARM_GLOBAL_TIMER
+        default y
+        help
+         Use ARM global timer clock source as sched_clock
+
 config CLKSRC_METAG_GENERIC
         def_bool y if METAG
         help
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 49bea7fad85c..8b00c5cebfa4 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -31,5 +31,6 @@ obj-$(CONFIG_CLKSRC_SAMSUNG_PWM)	+= samsung_pwm_timer.o
 obj-$(CONFIG_VF_PIT_TIMER)      += vf_pit_timer.o
 
 obj-$(CONFIG_ARM_ARCH_TIMER)            += arm_arch_timer.o
+obj-$(CONFIG_ARM_GLOBAL_TIMER)          += arm_global_timer.o
 obj-$(CONFIG_CLKSRC_METAG_GENERIC)      += metag_generic.o
 obj-$(CONFIG_ARCH_HAS_TICK_BROADCAST)   += dummy_timer.o
diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clocksource/arm_global_timer.c
new file mode 100644
index 000000000000..db8afc7427a6
--- /dev/null
+++ b/drivers/clocksource/arm_global_timer.c
@@ -0,0 +1,321 @@
+/*
+ * drivers/clocksource/arm_global_timer.c
+ *
+ * Copyright (C) 2013 STMicroelectronics (R&D) Limited.
+ * Author: Stuart Menefy <stuart.menefy@st.com>
+ * Author: Srinivas Kandagatla <srinivas.kandagatla@st.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/sched_clock.h>
+
+#include <asm/cputype.h>
+
+#define GT_COUNTER0     0x00
+#define GT_COUNTER1     0x04
+
+#define GT_CONTROL      0x08
+#define GT_CONTROL_TIMER_ENABLE         BIT(0)  /* this bit is NOT banked */
+#define GT_CONTROL_COMP_ENABLE          BIT(1)  /* banked */
+#define GT_CONTROL_IRQ_ENABLE           BIT(2)  /* banked */
+#define GT_CONTROL_AUTO_INC             BIT(3)  /* banked */
+
+#define GT_INT_STATUS   0x0c
+#define GT_INT_STATUS_EVENT_FLAG        BIT(0)
+
+#define GT_COMP0        0x10
+#define GT_COMP1        0x14
+#define GT_AUTO_INC     0x18
+
+/*
+ * We are expecting to be clocked by the ARM peripheral clock.
+ *
+ * Note: it is assumed we are using a prescaler value of zero, so this is
+ * the units for all operations.
+ */
+static void __iomem *gt_base;
+static unsigned long gt_clk_rate;
+static int gt_ppi;
+static struct clock_event_device __percpu *gt_evt;
+
+/*
+ * To get the value from the Global Timer Counter register proceed as follows:
+ * 1. Read the upper 32-bit timer counter register
+ * 2. Read the lower 32-bit timer counter register
+ * 3. Read the upper 32-bit timer counter register again. If the value is
+ *  different to the 32-bit upper value read previously, go back to step 2.
+ *  Otherwise the 64-bit timer counter value is correct.
+ */
+static u64 gt_counter_read(void)
+{
+        u64 counter;
+        u32 lower;
+        u32 upper, old_upper;
+
+        upper = readl_relaxed(gt_base + GT_COUNTER1);
+        do {
+                old_upper = upper;
+                lower = readl_relaxed(gt_base + GT_COUNTER0);
+                upper = readl_relaxed(gt_base + GT_COUNTER1);
+        } while (upper != old_upper);
+
+        counter = upper;
+        counter <<= 32;
+        counter |= lower;
+        return counter;
+}
+
+/**
+ * To ensure that updates to comparator value register do not set the
+ * Interrupt Status Register proceed as follows:
+ * 1. Clear the Comp Enable bit in the Timer Control Register.
+ * 2. Write the lower 32-bit Comparator Value Register.
+ * 3. Write the upper 32-bit Comparator Value Register.
+ * 4. Set the Comp Enable bit and, if necessary, the IRQ enable bit.
+ */
+static void gt_compare_set(unsigned long delta, int periodic)
+{
+        u64 counter = gt_counter_read();
+        unsigned long ctrl;
+
+        counter += delta;
+        ctrl = GT_CONTROL_TIMER_ENABLE;
+        writel(ctrl, gt_base + GT_CONTROL);
+        writel(lower_32_bits(counter), gt_base + GT_COMP0);
+        writel(upper_32_bits(counter), gt_base + GT_COMP1);
+
+        if (periodic) {
+                writel(delta, gt_base + GT_AUTO_INC);
+                ctrl |= GT_CONTROL_AUTO_INC;
+        }
+
+        ctrl |= GT_CONTROL_COMP_ENABLE | GT_CONTROL_IRQ_ENABLE;
+        writel(ctrl, gt_base + GT_CONTROL);
+}
+
+static void gt_clockevent_set_mode(enum clock_event_mode mode,
+                                   struct clock_event_device *clk)
+{
+        unsigned long ctrl;
+
+        switch (mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+                gt_compare_set(DIV_ROUND_CLOSEST(gt_clk_rate, HZ), 1);
+                break;
+        case CLOCK_EVT_MODE_ONESHOT:
+        case CLOCK_EVT_MODE_UNUSED:
+        case CLOCK_EVT_MODE_SHUTDOWN:
+                ctrl = readl(gt_base + GT_CONTROL);
+                ctrl &= ~(GT_CONTROL_COMP_ENABLE |
+                                GT_CONTROL_IRQ_ENABLE | GT_CONTROL_AUTO_INC);
+                writel(ctrl, gt_base + GT_CONTROL);
+                break;
+        default:
+                break;
+        }
+}
+
+static int gt_clockevent_set_next_event(unsigned long evt,
+                                        struct clock_event_device *unused)
+{
+        gt_compare_set(evt, 0);
+        return 0;
+}
+
+static irqreturn_t gt_clockevent_interrupt(int irq, void *dev_id)
+{
+        struct clock_event_device *evt = dev_id;
+
+        if (!(readl_relaxed(gt_base + GT_INT_STATUS) &
+                                GT_INT_STATUS_EVENT_FLAG))
+                return IRQ_NONE;
+
+        /**
+         * ERRATA 740657( Global Timer can send 2 interrupts for
+         * the same event in single-shot mode)
+         * Workaround:
+         *      Either disable single-shot mode.
+         *      Or
+         *      Modify the Interrupt Handler to avoid the
+         *      offending sequence. This is achieved by clearing
+         *      the Global Timer flag _after_ having incremented
+         *      the Comparator register value to a higher value.
+         */
+        if (evt->mode == CLOCK_EVT_MODE_ONESHOT)
+                gt_compare_set(ULONG_MAX, 0);
+
+        writel_relaxed(GT_INT_STATUS_EVENT_FLAG, gt_base + GT_INT_STATUS);
+        evt->event_handler(evt);
+
+        return IRQ_HANDLED;
+}
+
+static int __cpuinit gt_clockevents_init(struct clock_event_device *clk)
+{
+        int cpu = smp_processor_id();
+
+        clk->name = "arm_global_timer";
+        clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+        clk->set_mode = gt_clockevent_set_mode;
+        clk->set_next_event = gt_clockevent_set_next_event;
+        clk->cpumask = cpumask_of(cpu);
+        clk->rating = 300;
+        clk->irq = gt_ppi;
+        clockevents_config_and_register(clk, gt_clk_rate,
+                                        1, 0xffffffff);
+        enable_percpu_irq(clk->irq, IRQ_TYPE_NONE);
+        return 0;
+}
+
+static void gt_clockevents_stop(struct clock_event_device *clk)
+{
+        gt_clockevent_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
+        disable_percpu_irq(clk->irq);
+}
+
+static cycle_t gt_clocksource_read(struct clocksource *cs)
+{
+        return gt_counter_read();
+}
+
+static struct clocksource gt_clocksource = {
+        .name   = "arm_global_timer",
+        .rating = 300,
+        .read   = gt_clocksource_read,
+        .mask   = CLOCKSOURCE_MASK(64),
+        .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
+static u32 notrace gt_sched_clock_read(void)
+{
+        return gt_counter_read();
+}
+#endif
+
+static void __init gt_clocksource_init(void)
+{
+        writel(0, gt_base + GT_CONTROL);
+        writel(0, gt_base + GT_COUNTER0);
+        writel(0, gt_base + GT_COUNTER1);
+        /* enables timer on all the cores */
+        writel(GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
+
+#ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
+        setup_sched_clock(gt_sched_clock_read, 32, gt_clk_rate);
+#endif
+        clocksource_register_hz(&gt_clocksource, gt_clk_rate);
+}
+
+static int __cpuinit gt_cpu_notify(struct notifier_block *self,
+                                           unsigned long action, void *hcpu)
+{
+        switch (action & ~CPU_TASKS_FROZEN) {
+        case CPU_STARTING:
+                gt_clockevents_init(this_cpu_ptr(gt_evt));
+                break;
+        case CPU_DYING:
+                gt_clockevents_stop(this_cpu_ptr(gt_evt));
+                break;
+        }
+
+        return NOTIFY_OK;
+}
+static struct notifier_block gt_cpu_nb __cpuinitdata = {
+        .notifier_call = gt_cpu_notify,
+};
+
+static void __init global_timer_of_register(struct device_node *np)
+{
+        struct clk *gt_clk;
+        int err = 0;
+
+        /*
+         * In r2p0 the comparators for each processor with the global timer
+         * fire when the timer value is greater than or equal to. In previous
+         * revisions the comparators fired when the timer value was equal to.
+         */
+        if ((read_cpuid_id() & 0xf0000f) < 0x200000) {
+                pr_warn("global-timer: non support for this cpu version.\n");
+                return;
+        }
+
+        gt_ppi = irq_of_parse_and_map(np, 0);
+        if (!gt_ppi) {
+                pr_warn("global-timer: unable to parse irq\n");
+                return;
+        }
+
+        gt_base = of_iomap(np, 0);
+        if (!gt_base) {
+                pr_warn("global-timer: invalid base address\n");
+                return;
+        }
+
+        gt_clk = of_clk_get(np, 0);
+        if (!IS_ERR(gt_clk)) {
+                err = clk_prepare_enable(gt_clk);
+                if (err)
+                        goto out_unmap;
+        } else {
+                pr_warn("global-timer: clk not found\n");
+                err = -EINVAL;
+                goto out_unmap;
+        }
+
+        gt_clk_rate = clk_get_rate(gt_clk);
+        gt_evt = alloc_percpu(struct clock_event_device);
+        if (!gt_evt) {
+                pr_warn("global-timer: can't allocate memory\n");
+                err = -ENOMEM;
+                goto out_clk;
+        }
+
+        err = request_percpu_irq(gt_ppi, gt_clockevent_interrupt,
+                                 "gt", gt_evt);
+        if (err) {
+                pr_warn("global-timer: can't register interrupt %d (%d)\n",
+                        gt_ppi, err);
+                goto out_free;
+        }
+
+        err = register_cpu_notifier(&gt_cpu_nb);
+        if (err) {
+                pr_warn("global-timer: unable to register cpu notifier.\n");
+                goto out_irq;
+        }
+
+        /* Immediately configure the timer on the boot CPU */
+        gt_clocksource_init();
+        gt_clockevents_init(this_cpu_ptr(gt_evt));
+
+        return;
+
+out_irq:
+        free_percpu_irq(gt_ppi, gt_evt);
+out_free:
+        free_percpu(gt_evt);
+out_clk:
+        clk_disable_unprepare(gt_clk);
+out_unmap:
+        iounmap(gt_base);
+        WARN(err, "ARM Global timer register failed (%d)\n", err);
+}
+
+/* Only tested on r2p2 and r3p0  */
+CLOCKSOURCE_OF_DECLARE(arm_gt, "arm,cortex-a9-global-timer",
+                        global_timer_of_register);