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();
+}