3 files changed, 238 insertions, 0 deletions

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index d53cd0afc200..6a78073c3808 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -35,3 +35,8 @@ config CLKSRC_DBX500_PRCMU_SCHED_CLOCK
         default y
         help
           Use the always on PRCMU Timer as sched_clock
+
+config CLKSRC_ARM_GENERIC
+        def_bool y if ARM64
+        help
+          This option enables support for the ARM generic timer.
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index b65d0c56ab35..65919901a301 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_DW_APB_TIMER)	+= dw_apb_timer.o
 obj-$(CONFIG_DW_APB_TIMER_OF)   += dw_apb_timer_of.o
 obj-$(CONFIG_CLKSRC_DBX500_PRCMU)       += clksrc-dbx500-prcmu.o
 obj-$(CONFIG_ARMADA_370_XP_TIMER)       += time-armada-370-xp.o
+obj-$(CONFIG_CLKSRC_ARM_GENERIC)        += arm_generic.o
diff --git a/drivers/clocksource/arm_generic.c b/drivers/clocksource/arm_generic.c
new file mode 100644
index 000000000000..c4d9f9566c64
--- /dev/null
+++ b/drivers/clocksource/arm_generic.c
@@ -0,0 +1,232 @@
+/*
+ * Generic timers support
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ * Author: Marc Zyngier <marc.zyngier@arm.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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#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/interrupt.h>
+#include <linux/clockchips.h>
+#include <linux/of_irq.h>
+#include <linux/io.h>
+
+#include <clocksource/arm_generic.h>
+
+#include <asm/arm_generic.h>
+
+static u32 arch_timer_rate;
+static u64 sched_clock_mult __read_mostly;
+static DEFINE_PER_CPU(struct clock_event_device, arch_timer_evt);
+static int arch_timer_ppi;
+
+static irqreturn_t arch_timer_handle_irq(int irq, void *dev_id)
+{
+        struct clock_event_device *evt = dev_id;
+        unsigned long ctrl;
+
+        ctrl = arch_timer_reg_read(ARCH_TIMER_REG_CTRL);
+        if (ctrl & ARCH_TIMER_CTRL_ISTATUS) {
+                ctrl |= ARCH_TIMER_CTRL_IMASK;
+                arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);
+                evt->event_handler(evt);
+                return IRQ_HANDLED;
+        }
+
+        return IRQ_NONE;
+}
+
+static void arch_timer_stop(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_stop();
+                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_IMASK;
+
+        arch_timer_reg_write(ARCH_TIMER_REG_TVAL, evt);
+        arch_timer_reg_write(ARCH_TIMER_REG_CTRL, ctrl);
+
+        return 0;
+}
+
+static void __cpuinit arch_timer_setup(struct clock_event_device *clk)
+{
+        /* Let's make sure the timer is off before doing anything else */
+        arch_timer_stop();
+
+        clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP;
+        clk->name = "arch_sys_timer";
+        clk->rating = 400;
+        clk->set_mode = arch_timer_set_mode;
+        clk->set_next_event = arch_timer_set_next_event;
+        clk->irq = arch_timer_ppi;
+        clk->cpumask = cpumask_of(smp_processor_id());
+
+        clockevents_config_and_register(clk, arch_timer_rate,
+                                        0xf, 0x7fffffff);
+
+        enable_percpu_irq(clk->irq, 0);
+
+        /* Ensure the physical counter is visible to userspace for the vDSO. */
+        arch_counter_enable_user_access();
+}
+
+static void __init arch_timer_calibrate(void)
+{
+        if (arch_timer_rate == 0) {
+                arch_timer_reg_write(ARCH_TIMER_REG_CTRL, 0);
+                arch_timer_rate = arch_timer_reg_read(ARCH_TIMER_REG_FREQ);
+
+                /* Check the timer frequency. */
+                if (arch_timer_rate == 0)
+                        panic("Architected timer frequency is set to zero.\n"
+                              "You must set this in your .dts file\n");
+        }
+
+        /* Cache the sched_clock multiplier to save a divide in the hot path. */
+
+        sched_clock_mult = NSEC_PER_SEC / arch_timer_rate;
+
+        pr_info("Architected local timer running at %u.%02uMHz.\n",
+                 arch_timer_rate / 1000000, (arch_timer_rate / 10000) % 100);
+}
+
+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 | CLOCK_SOURCE_VALID_FOR_HRES),
+};
+
+int read_current_timer(unsigned long *timer_value)
+{
+        *timer_value = arch_counter_get_cntpct();
+        return 0;
+}
+
+unsigned long long notrace sched_clock(void)
+{
+        return arch_counter_get_cntvct() * sched_clock_mult;
+}
+
+static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self,
+                                           unsigned long action, void *hcpu)
+{
+        int cpu = (long)hcpu;
+        struct clock_event_device *clk = per_cpu_ptr(&arch_timer_evt, cpu);
+
+        switch(action) {
+        case CPU_STARTING:
+        case CPU_STARTING_FROZEN:
+                arch_timer_setup(clk);
+                break;
+
+        case CPU_DYING:
+        case CPU_DYING_FROZEN:
+                pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n",
+                         clk->irq, cpu);
+                disable_percpu_irq(clk->irq);
+                arch_timer_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
+                break;
+        }
+
+        return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata arch_timer_cpu_nb = {
+        .notifier_call = arch_timer_cpu_notify,
+};
+
+static const struct of_device_id arch_timer_of_match[] __initconst = {
+        { .compatible = "arm,armv8-timer" },
+        {},
+};
+
+int __init arm_generic_timer_init(void)
+{
+        struct device_node *np;
+        int err;
+        u32 freq;
+
+        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;
+        arch_timer_calibrate();
+
+        arch_timer_ppi = irq_of_parse_and_map(np, 0);
+        pr_info("arch_timer: found %s irq %d\n", np->name, arch_timer_ppi);
+
+        err = request_percpu_irq(arch_timer_ppi, arch_timer_handle_irq,
+                                 np->name, &arch_timer_evt);
+        if (err) {
+                pr_err("arch_timer: can't register interrupt %d (%d)\n",
+                       arch_timer_ppi, err);
+                return err;
+        }
+
+        clocksource_register_hz(&clocksource_counter, arch_timer_rate);
+
+        /* Calibrate the delay loop directly */
+        lpj_fine = arch_timer_rate / HZ;
+
+        /* Immediately configure the timer on the boot CPU */
+        arch_timer_setup(per_cpu_ptr(&arch_timer_evt, smp_processor_id()));
+
+        register_cpu_notifier(&arch_timer_cpu_nb);
+
+        return 0;
+}