ARM: local timers: Add A15 architected timer support

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@arm.com>

4 files changed, 314 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index cf006d40342c..4faabbade2e9 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1543,6 +1543,12 @@ 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
+        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 000000000000..827305d77b3e
--- /dev/null
+++ b/arch/arm/include/asm/arch_timer.h
@@ -0,0 +1,19 @@
+#ifndef __ASMARM_ARCH_TIMER_H
+#define __ASMARM_ARCH_TIMER_H
+
+#include <linux/ioport.h>
+
+struct arch_timer {
+        struct resource res[2];
+};
+
+#ifdef CONFIG_ARM_ARCH_TIMER
+int arch_timer_register(struct arch_timer *);
+#else
+static inline int arch_timer_register(struct arch_timer *at)
+{
+        return -ENXIO;
+}
+#endif
+
+#endif
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 7b787d642af4..22b0f1e255f0 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -34,6 +34,7 @@ obj-$(CONFIG_ARM_CPU_SUSPEND)	+= sleep.o suspend.o
 obj-$(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 insn.o
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER)     += ftrace.o insn.o
 obj-$(CONFIG_JUMP_LABEL)        += jump_label.o insn.o patch.o
diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
new file mode 100644
index 000000000000..bb9a8b45bffa
--- /dev/null
+++ b/arch/arm/kernel/arch_timer.c
@@ -0,0 +1,288 @@
+/*
+ *  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>
+#include <asm/system_info.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_CTRL_IT_STAT         (1 << 2)
+
+#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 & ARCH_TIMER_CTRL_IT_STAT) {
+                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_once("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 ((cycle_t) 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 ((cycle_t) 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;
+}