arm: arch_timer: divorce from local_timer api

Currently, the arch_timer driver is tied to the arm port, as it relies
on code in arch/arm/smp.c to setup and teardown timers as cores are
hotplugged on and off. The timer is registered through an arm-specific
registration mechanism, preventing sharing the driver with the arm64
port.

This patch moves the driver to using a cpu notifier instead, making it
easier to port.

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>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

1 files changed, 29 insertions, 23 deletions

diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
index e973cc0eaad1..c8dfec052f2d 100644
--- a/arch/arm/kernel/arch_timer.c
+++ b/arch/arm/kernel/arch_timer.c
@@ -21,7 +21,6 @@
 #include <linux/io.h>
 
 #include <asm/delay.h>
-#include <asm/localtimer.h>
 #include <asm/arch_timer.h>
 #include <asm/sched_clock.h>
 
@@ -37,7 +36,7 @@ enum ppi_nr {
 
 static int arch_timer_ppi[MAX_TIMER_PPI];
 
-static struct clock_event_device __percpu **arch_timer_evt;
+static struct clock_event_device __percpu *arch_timer_evt;
 static struct delay_timer arch_delay_timer;
 
 static bool arch_timer_use_virtual = true;
@@ -63,14 +62,14 @@ static irqreturn_t inline timer_handler(const int access,
 
 static irqreturn_t arch_timer_handler_virt(int irq, void *dev_id)
 {
-        struct clock_event_device *evt = *(struct clock_event_device **)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 = *(struct clock_event_device **)dev_id;
+        struct clock_event_device *evt = dev_id;
 
         return timer_handler(ARCH_TIMER_PHYS_ACCESS, evt);
 }
@@ -141,13 +140,13 @@ static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
                 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);
 
-        *__this_cpu_ptr(arch_timer_evt) = clk;
-
         if (arch_timer_use_virtual)
                 enable_percpu_irq(arch_timer_ppi[VIRT_PPI], 0);
         else {
@@ -251,12 +250,26 @@ static void __cpuinit arch_timer_stop(struct clock_event_device *clk)
         clk->set_mode(CLOCK_EVT_MODE_UNUSED, clk);
 }
 
-static struct local_timer_ops arch_timer_ops __cpuinitdata = {
-        .setup  = arch_timer_setup,
-        .stop   = arch_timer_stop,
-};
+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 clock_event_device arch_timer_global_evt;
+static struct notifier_block arch_timer_cpu_nb __cpuinitdata = {
+        .notifier_call = arch_timer_cpu_notify,
+};
 
 static int __init arch_timer_register(void)
 {
@@ -267,7 +280,7 @@ static int __init arch_timer_register(void)
         if (err)
                 goto out;
 
-        arch_timer_evt = alloc_percpu(struct clock_event_device *);
+        arch_timer_evt = alloc_percpu(struct clock_event_device);
         if (!arch_timer_evt) {
                 err = -ENOMEM;
                 goto out;
@@ -303,20 +316,13 @@ static int __init arch_timer_register(void)
                 goto out_free;
         }
 
-        err = local_timer_register(&arch_timer_ops);
-        if (err) {
-                /*
-                 * We couldn't register as a local timer (could be
-                 * because we're on a UP platform, or because some
-                 * other local timer is already present...). Try as a
-                 * global timer instead.
-                 */
-                arch_timer_global_evt.cpumask = cpumask_of(0);
-                err = arch_timer_setup(&arch_timer_global_evt);
-        }
+        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));
+
         /* Use the architected timer for the delay loop. */
         arch_delay_timer.read_current_timer = &arch_timer_read_current_timer;
         arch_delay_timer.freq = arch_timer_rate;