[PATCH v2 1/4] ARM: local timers: Add A15 architected timer support
Marc Zyngier
marc.zyngier at arm.com
Wed Feb 1 11:59:32 EST 2012
Add support for the A15 generic timer and clocksource.
As the timer generates interrupts on a different PPI depending
on the execution mode (normal or secure), it is possible to
register two different PPIs.
Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
arch/arm/Kconfig | 7 +
arch/arm/include/asm/arch_timer.h | 12 ++
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/arch_timer.c | 286 +++++++++++++++++++++++++++++++++++++
4 files changed, 306 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/include/asm/arch_timer.h
create mode 100644 arch/arm/kernel/arch_timer.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 24626b0..acf2813 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1522,6 +1522,13 @@ config HAVE_ARM_SCU
help
This option enables support for the ARM system coherency unit
+config ARM_ARCH_TIMER
+ bool "Architected timer support"
+ depends on CPU_V7
+ select TICK_ONESHOT
+ help
+ This option enables support for the ARM architected timer
+
config HAVE_ARM_TWD
bool
depends on SMP
diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
new file mode 100644
index 0000000..20de858
--- /dev/null
+++ b/arch/arm/include/asm/arch_timer.h
@@ -0,0 +1,12 @@
+#ifndef __ASMARM_ARCH_TIMER_H
+#define __ASMARM_ARCH_TIMER_H
+
+#include <linux/ioport.h>
+
+struct arch_timer {
+ struct resource res[2];
+};
+
+int arch_timer_register(struct arch_timer *);
+
+#endif
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 43b740d..518cea4 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -34,6 +34,7 @@ obj-$(CONFIG_HAVE_SCHED_CLOCK) += sched_clock.o
obj-$(CONFIG_SMP) += smp.o smp_tlb.o
obj-$(CONFIG_HAVE_ARM_SCU) += smp_scu.o
obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o
+obj-$(CONFIG_ARM_ARCH_TIMER) += arch_timer.o
obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
new file mode 100644
index 0000000..680cf1e
--- /dev/null
+++ b/arch/arm/kernel/arch_timer.c
@@ -0,0 +1,286 @@
+/*
+ * linux/arch/arm/kernel/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/delay.h>
+#include <linux/device.h>
+#include <linux/smp.h>
+#include <linux/cpu.h>
+#include <linux/jiffies.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+
+#include <asm/cputype.h>
+#include <asm/localtimer.h>
+#include <asm/arch_timer.h>
+
+static unsigned long arch_timer_rate;
+static int arch_timer_ppi;
+static int arch_timer_ppi2;
+
+static struct clock_event_device __percpu **arch_timer_evt;
+
+/*
+ * Architected system timer support.
+ */
+
+#define ARCH_TIMER_CTRL_ENABLE (1 << 0)
+#define ARCH_TIMER_CTRL_IT_MASK (1 << 1)
+
+#define ARCH_TIMER_REG_CTRL 0
+#define ARCH_TIMER_REG_FREQ 1
+#define ARCH_TIMER_REG_TVAL 2
+
+static void arch_timer_reg_write(int reg, u32 val)
+{
+ switch (reg) {
+ case ARCH_TIMER_REG_CTRL:
+ asm volatile("mcr p15, 0, %0, c14, c2, 1" : : "r" (val));
+ break;
+ case ARCH_TIMER_REG_TVAL:
+ asm volatile("mcr p15, 0, %0, c14, c2, 0" : : "r" (val));
+ break;
+ }
+
+ isb();
+}
+
+static u32 arch_timer_reg_read(int reg)
+{
+ u32 val;
+
+ switch (reg) {
+ case ARCH_TIMER_REG_CTRL:
+ asm volatile("mrc p15, 0, %0, c14, c2, 1" : "=r" (val));
+ break;
+ case ARCH_TIMER_REG_FREQ:
+ asm volatile("mrc p15, 0, %0, c14, c0, 0" : "=r" (val));
+ break;
+ case ARCH_TIMER_REG_TVAL:
+ asm volatile("mrc p15, 0, %0, c14, c2, 0" : "=r" (val));
+ break;
+ default:
+ BUG();
+ }
+
+ return val;
+}
+
+static irqreturn_t arch_timer_handler(int irq, void *dev_id)
+{
+ struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
+ unsigned long ctrl;
+
+ ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL);
+ if (ctrl & 0x4) {
+ ctrl |= ARCH_TIMER_CTRL_IT_MASK;
+ arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);
+ evt->event_handler(evt);
+ return IRQ_HANDLED;
+ }
+
+ return IRQ_NONE;
+}
+
+static void arch_timer_disable(void)
+{
+ unsigned long ctrl;
+
+ ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL);
+ ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
+ arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);
+}
+
+static void arch_timer_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *clk)
+{
+ switch (mode) {
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ arch_timer_disable();
+ break;
+ default:
+ break;
+ }
+}
+
+static int arch_timer_set_next_event(unsigned long evt,
+ struct clock_event_device *unused)
+{
+ unsigned long ctrl;
+
+ ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL);
+ ctrl |= ARCH_TIMER_CTRL_ENABLE;
+ ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
+
+ arch_timer_reg_write(ARCH_TIMER_REG_TVAL, evt);
+ arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);
+
+ return 0;
+}
+
+static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
+{
+ /* Be safe... */
+ arch_timer_disable();
+
+ clk->features = CLOCK_EVT_FEAT_ONESHOT;
+ clk->name = "arch_sys_timer";
+ clk->rating = 450;
+ clk->set_mode = arch_timer_set_mode;
+ clk->set_next_event = arch_timer_set_next_event;
+ clk->irq = arch_timer_ppi;
+
+ clockevents_config_and_register(clk, arch_timer_rate,
+ 0xf, 0x7fffffff);
+
+ *__this_cpu_ptr(arch_timer_evt) = clk;
+
+ enable_percpu_irq(clk->irq, 0);
+ if (arch_timer_ppi2)
+ enable_percpu_irq(arch_timer_ppi2, 0);
+
+ return 0;
+}
+
+/* Is the optional system timer available? */
+static int local_timer_is_architected(void)
+{
+ return (cpu_architecture() >= CPU_ARCH_ARMv7) &&
+ ((read_cpuid_ext(CPUID_EXT_PFR1) >> 16) & 0xf) == 1;
+}
+
+static int arch_timer_available(void)
+{
+ unsigned long freq;
+
+ if (!local_timer_is_architected())
+ return -ENXIO;
+
+ if (arch_timer_rate == 0) {
+ arch_timer_reg_write(ARCH_TIMER_REG_CTRL, 0);
+ freq = arch_timer_reg_read(ARCH_TIMER_REG_FREQ);
+
+ /* Check the timer frequency. */
+ if (freq == 0) {
+ pr_warn("Architected timer frequency not available\n");
+ return -EINVAL;
+ }
+
+ arch_timer_rate = freq;
+ pr_info("Architected local timer running at %lu.%02luMHz.\n",
+ arch_timer_rate / 1000000, (arch_timer_rate / 10000) % 100);
+ }
+
+ return 0;
+}
+
+static inline cycle_t arch_counter_get_cntpct(void)
+{
+ u32 cvall, cvalh;
+
+ asm volatile("mrrc p15, 0, %0, %1, c14" : "=r" (cvall), "=r" (cvalh));
+
+ return ((u64) cvalh << 32) | cvall;
+}
+
+static inline cycle_t arch_counter_get_cntvct(void)
+{
+ u32 cvall, cvalh;
+
+ asm volatile("mrrc p15, 1, %0, %1, c14" : "=r" (cvall), "=r" (cvalh));
+
+ return ((u64) cvalh << 32) | cvall;
+}
+
+static cycle_t arch_counter_read(struct clocksource *cs)
+{
+ return arch_counter_get_cntpct();
+}
+
+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 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());
+ disable_percpu_irq(clk->irq);
+ if (arch_timer_ppi2)
+ disable_percpu_irq(arch_timer_ppi2);
+ arch_timer_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
+}
+
+static struct local_timer_ops arch_timer_ops __cpuinitdata = {
+ .setup = arch_timer_setup,
+ .stop = arch_timer_stop,
+};
+
+int __init arch_timer_register(struct arch_timer *at)
+{
+ int err;
+
+ if (at->res[0].start <= 0 || !(at->res[0].flags & IORESOURCE_IRQ))
+ return -EINVAL;
+
+ err = arch_timer_available();
+ if (err)
+ return err;
+
+ arch_timer_evt = alloc_percpu(struct clock_event_device *);
+ if (!arch_timer_evt)
+ return -ENOMEM;
+
+ clocksource_register_hz(&clocksource_counter, arch_timer_rate);
+
+ arch_timer_ppi = at->res[0].start;
+ err = request_percpu_irq(arch_timer_ppi, arch_timer_handler,
+ "arch_timer", arch_timer_evt);
+ if (err) {
+ pr_err("arch_timer: can't register interrupt %d (%d)\n",
+ arch_timer_ppi, err);
+ goto out_free;
+ }
+
+ if (at->res[1].start > 0 || (at->res[1].flags & IORESOURCE_IRQ)) {
+ arch_timer_ppi2 = at->res[1].start;
+ err = request_percpu_irq(arch_timer_ppi2, arch_timer_handler,
+ "arch_timer", arch_timer_evt);
+ if (err) {
+ pr_err("arch_timer: can't register interrupt %d (%d)\n",
+ arch_timer_ppi2, err);
+ arch_timer_ppi2 = 0;
+ goto out_free_irq;
+ }
+ }
+
+ err = local_timer_register(&arch_timer_ops);
+ if (err)
+ goto out_free_irq;
+
+ return 0;
+
+out_free_irq:
+ free_percpu_irq(arch_timer_ppi, arch_timer_evt);
+ if (arch_timer_ppi2)
+ free_percpu_irq(arch_timer_ppi2, arch_timer_evt);
+
+out_free:
+ free_percpu(arch_timer_evt);
+
+ return err;
+}
--
1.7.7.1
More information about the linux-arm-kernel
mailing list