arm: arch_timer: move core to drivers/clocksource

The core functionality of the arch_timer driver is not directly tied to
anything under arch/arm, and can be split out.

This patch factors out the core of the arch_timer driver, so it can be
shared with other architectures. A couple of functions are added so
that architecture-specific code can interact with the driver without
needing to touch its internals.

The ARM_ARCH_TIMER config variable is moved out to
drivers/clocksource/Kconfig, existing uses in arch/arm are replaced with
HAVE_ARM_ARCH_TIMER, which selects it.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>

3 files changed, 389 insertions, 0 deletions

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 7fdcbd3f4da5..dbb085ac64d4 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -58,3 +58,6 @@ config CLKSRC_ARM_GENERIC
         def_bool y if ARM64
         help
           This option enables support for the ARM generic timer.
+
+config ARM_ARCH_TIMER
+        bool
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index f93453d01673..32f858c8eecc 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -18,3 +18,4 @@ obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835_timer.o
 obj-$(CONFIG_SUNXI_TIMER)       += sunxi_timer.o
 
 obj-$(CONFIG_CLKSRC_ARM_GENERIC)        += arm_generic.o
+obj-$(CONFIG_ARM_ARCH_TIMER)            += arm_arch_timer.o
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
new file mode 100644
index 000000000000..3e4739df0e82
--- /dev/null
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -0,0 +1,385 @@
+/*
+ *  linux/drivers/clocksource/arm_arch_timer.c
+ *
+ *  Copyright (C) 2011 ARM Ltd.
+ *  All Rights Reserved
+ *
+ * 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/kernel.h>
+#include <linux/device.h>
+#include <linux/smp.h>
+#include <linux/cpu.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/of_irq.h>
+#include <linux/io.h>
+
+#include <asm/arch_timer.h>
+
+#include <clocksource/arm_arch_timer.h>
+
+static u32 arch_timer_rate;
+
+enum ppi_nr {
+        PHYS_SECURE_PPI,
+        PHYS_NONSECURE_PPI,
+        VIRT_PPI,
+        HYP_PPI,
+        MAX_TIMER_PPI
+};
+
+static int arch_timer_ppi[MAX_TIMER_PPI];
+
+static struct clock_event_device __percpu *arch_timer_evt;
+
+static bool arch_timer_use_virtual = true;
+
+/*
+ * Architected system timer support.
+ */
+
+static inline irqreturn_t timer_handler(const int access,
+                                        struct clock_event_device *evt)
+{
+        unsigned long ctrl;
+        ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
+        if (ctrl & ARCH_TIMER_CTRL_IT_STAT) {
+                ctrl |= ARCH_TIMER_CTRL_IT_MASK;
+                arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
+                evt->event_handler(evt);
+                return IRQ_HANDLED;
+        }
+
+        return IRQ_NONE;
+}
+
+static irqreturn_t arch_timer_handler_virt(int irq, void *dev_id)
+{
+        struct clock_event_device *evt = dev_id;
+
+        return timer_handler(ARCH_TIMER_VIRT_ACCESS, evt);
+}
+
+static irqreturn_t arch_timer_handler_phys(int irq, void *dev_id)
+{
+        struct clock_event_device *evt = dev_id;
+
+        return timer_handler(ARCH_TIMER_PHYS_ACCESS, evt);
+}
+
+static inline void timer_set_mode(const int access, int mode)
+{
+        unsigned long ctrl;
+        switch (mode) {
+        case CLOCK_EVT_MODE_UNUSED:
+        case CLOCK_EVT_MODE_SHUTDOWN:
+                ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
+                ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
+                arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
+                break;
+        default:
+                break;
+        }
+}
+
+static void arch_timer_set_mode_virt(enum clock_event_mode mode,
+                                     struct clock_event_device *clk)
+{
+        timer_set_mode(ARCH_TIMER_VIRT_ACCESS, mode);
+}
+
+static void arch_timer_set_mode_phys(enum clock_event_mode mode,
+                                     struct clock_event_device *clk)
+{
+        timer_set_mode(ARCH_TIMER_PHYS_ACCESS, mode);
+}
+
+static inline void set_next_event(const int access, unsigned long evt)
+{
+        unsigned long ctrl;
+        ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
+        ctrl |= ARCH_TIMER_CTRL_ENABLE;
+        ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
+        arch_timer_reg_write(access, ARCH_TIMER_REG_TVAL, evt);
+        arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
+}
+
+static int arch_timer_set_next_event_virt(unsigned long evt,
+                                          struct clock_event_device *unused)
+{
+        set_next_event(ARCH_TIMER_VIRT_ACCESS, evt);
+        return 0;
+}
+
+static int arch_timer_set_next_event_phys(unsigned long evt,
+                                          struct clock_event_device *unused)
+{
+        set_next_event(ARCH_TIMER_PHYS_ACCESS, evt);
+        return 0;
+}
+
+static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
+{
+        clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP;
+        clk->name = "arch_sys_timer";
+        clk->rating = 450;
+        if (arch_timer_use_virtual) {
+                clk->irq = arch_timer_ppi[VIRT_PPI];
+                clk->set_mode = arch_timer_set_mode_virt;
+                clk->set_next_event = arch_timer_set_next_event_virt;
+        } else {
+                clk->irq = arch_timer_ppi[PHYS_SECURE_PPI];
+                clk->set_mode = arch_timer_set_mode_phys;
+                clk->set_next_event = arch_timer_set_next_event_phys;
+        }
+
+        clk->cpumask = cpumask_of(smp_processor_id());
+
+        clk->set_mode(CLOCK_EVT_MODE_SHUTDOWN, NULL);
+
+        clockevents_config_and_register(clk, arch_timer_rate,
+                                        0xf, 0x7fffffff);
+
+        if (arch_timer_use_virtual)
+                enable_percpu_irq(arch_timer_ppi[VIRT_PPI], 0);
+        else {
+                enable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI], 0);
+                if (arch_timer_ppi[PHYS_NONSECURE_PPI])
+                        enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0);
+        }
+
+        arch_counter_set_user_access();
+
+        return 0;
+}
+
+static int arch_timer_available(void)
+{
+        u32 freq;
+
+        if (arch_timer_rate == 0) {
+                freq = arch_timer_get_cntfrq();
+
+                /* Check the timer frequency. */
+                if (freq == 0) {
+                        pr_warn("Architected timer frequency not available\n");
+                        return -EINVAL;
+                }
+
+                arch_timer_rate = freq;
+        }
+
+        pr_info_once("Architected local timer running at %lu.%02luMHz (%s).\n",
+                     (unsigned long)arch_timer_rate / 1000000,
+                     (unsigned long)(arch_timer_rate / 10000) % 100,
+                     arch_timer_use_virtual ? "virt" : "phys");
+        return 0;
+}
+
+u32 arch_timer_get_rate(void)
+{
+        return arch_timer_rate;
+}
+
+/*
+ * Some external users of arch_timer_read_counter (e.g. sched_clock) may try to
+ * call it before it has been initialised. Rather than incur a performance
+ * penalty checking for initialisation, provide a default implementation that
+ * won't lead to time appearing to jump backwards.
+ */
+static u64 arch_timer_read_zero(void)
+{
+        return 0;
+}
+
+u64 (*arch_timer_read_counter)(void) = arch_timer_read_zero;
+
+static cycle_t arch_counter_read(struct clocksource *cs)
+{
+        return arch_timer_read_counter();
+}
+
+static cycle_t arch_counter_read_cc(const struct cyclecounter *cc)
+{
+        return arch_timer_read_counter();
+}
+
+static struct clocksource clocksource_counter = {
+        .name   = "arch_sys_counter",
+        .rating = 400,
+        .read   = arch_counter_read,
+        .mask   = CLOCKSOURCE_MASK(56),
+        .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static struct cyclecounter cyclecounter = {
+        .read   = arch_counter_read_cc,
+        .mask   = CLOCKSOURCE_MASK(56),
+};
+
+static struct timecounter timecounter;
+
+struct timecounter *arch_timer_get_timecounter(void)
+{
+        return &timecounter;
+}
+
+static void __cpuinit arch_timer_stop(struct clock_event_device *clk)
+{
+        pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n",
+                 clk->irq, smp_processor_id());
+
+        if (arch_timer_use_virtual)
+                disable_percpu_irq(arch_timer_ppi[VIRT_PPI]);
+        else {
+                disable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI]);
+                if (arch_timer_ppi[PHYS_NONSECURE_PPI])
+                        disable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI]);
+        }
+
+        clk->set_mode(CLOCK_EVT_MODE_UNUSED, clk);
+}
+
+static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self,
+                                           unsigned long action, void *hcpu)
+{
+        struct clock_event_device *evt = this_cpu_ptr(arch_timer_evt);
+
+        switch (action & ~CPU_TASKS_FROZEN) {
+        case CPU_STARTING:
+                arch_timer_setup(evt);
+                break;
+        case CPU_DYING:
+                arch_timer_stop(evt);
+                break;
+        }
+
+        return NOTIFY_OK;
+}
+
+static struct notifier_block arch_timer_cpu_nb __cpuinitdata = {
+        .notifier_call = arch_timer_cpu_notify,
+};
+
+static int __init arch_timer_register(void)
+{
+        int err;
+        int ppi;
+
+        err = arch_timer_available();
+        if (err)
+                goto out;
+
+        arch_timer_evt = alloc_percpu(struct clock_event_device);
+        if (!arch_timer_evt) {
+                err = -ENOMEM;
+                goto out;
+        }
+
+        clocksource_register_hz(&clocksource_counter, arch_timer_rate);
+        cyclecounter.mult = clocksource_counter.mult;
+        cyclecounter.shift = clocksource_counter.shift;
+        timecounter_init(&timecounter, &cyclecounter,
+                         arch_counter_get_cntpct());
+
+        if (arch_timer_use_virtual) {
+                ppi = arch_timer_ppi[VIRT_PPI];
+                err = request_percpu_irq(ppi, arch_timer_handler_virt,
+                                         "arch_timer", arch_timer_evt);
+        } else {
+                ppi = arch_timer_ppi[PHYS_SECURE_PPI];
+                err = request_percpu_irq(ppi, arch_timer_handler_phys,
+                                         "arch_timer", arch_timer_evt);
+                if (!err && arch_timer_ppi[PHYS_NONSECURE_PPI]) {
+                        ppi = arch_timer_ppi[PHYS_NONSECURE_PPI];
+                        err = request_percpu_irq(ppi, arch_timer_handler_phys,
+                                                 "arch_timer", arch_timer_evt);
+                        if (err)
+                                free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
+                                                arch_timer_evt);
+                }
+        }
+
+        if (err) {
+                pr_err("arch_timer: can't register interrupt %d (%d)\n",
+                       ppi, err);
+                goto out_free;
+        }
+
+        err = register_cpu_notifier(&arch_timer_cpu_nb);
+        if (err)
+                goto out_free_irq;
+
+        /* Immediately configure the timer on the boot CPU */
+        arch_timer_setup(this_cpu_ptr(arch_timer_evt));
+
+        return 0;
+
+out_free_irq:
+        if (arch_timer_use_virtual)
+                free_percpu_irq(arch_timer_ppi[VIRT_PPI], arch_timer_evt);
+        else {
+                free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
+                                arch_timer_evt);
+                if (arch_timer_ppi[PHYS_NONSECURE_PPI])
+                        free_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI],
+                                        arch_timer_evt);
+        }
+
+out_free:
+        free_percpu(arch_timer_evt);
+out:
+        return err;
+}
+
+static const struct of_device_id arch_timer_of_match[] __initconst = {
+        { .compatible   = "arm,armv7-timer",    },
+        {},
+};
+
+int __init arch_timer_init(void)
+{
+        struct device_node *np;
+        u32 freq;
+        int i;
+
+        np = of_find_matching_node(NULL, arch_timer_of_match);
+        if (!np) {
+                pr_err("arch_timer: can't find DT node\n");
+                return -ENODEV;
+        }
+
+        /* Try to determine the frequency from the device tree or CNTFRQ */
+        if (!of_property_read_u32(np, "clock-frequency", &freq))
+                arch_timer_rate = freq;
+
+        for (i = PHYS_SECURE_PPI; i < MAX_TIMER_PPI; i++)
+                arch_timer_ppi[i] = irq_of_parse_and_map(np, i);
+
+        of_node_put(np);
+
+        /*
+         * If no interrupt provided for virtual timer, we'll have to
+         * stick to the physical timer. It'd better be accessible...
+         */
+        if (!arch_timer_ppi[VIRT_PPI]) {
+                arch_timer_use_virtual = false;
+
+                if (!arch_timer_ppi[PHYS_SECURE_PPI] ||
+                    !arch_timer_ppi[PHYS_NONSECURE_PPI]) {
+                        pr_warn("arch_timer: No interrupt available, giving up\n");
+                        return -EINVAL;
+                }
+        }
+
+        if (arch_timer_use_virtual)
+                arch_timer_read_counter = arch_counter_get_cntvct;
+        else
+                arch_timer_read_counter = arch_counter_get_cntpct;
+
+        return arch_timer_register();
+}