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Diffstat (limited to 'arch/arm/kernel/smp_twd.c')
-rw-r--r--arch/arm/kernel/smp_twd.c112
1 files changed, 89 insertions, 23 deletions
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index fef42b21cec..49f335d301b 100644
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -11,7 +11,6 @@
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/clk.h>
-#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
@@ -32,6 +31,8 @@ static void __iomem *twd_base;
static struct clk *twd_clk;
static unsigned long twd_timer_rate;
+static bool common_setup_called;
+static DEFINE_PER_CPU(bool, percpu_setup_called);
static struct clock_event_device __percpu **twd_evt;
static int twd_ppi;
@@ -43,10 +44,10 @@ static void twd_set_mode(enum clock_event_mode mode,
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
- /* timer load already set up */
ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
| TWD_TIMER_CONTROL_PERIODIC;
- __raw_writel(twd_timer_rate / HZ, twd_base + TWD_TIMER_LOAD);
+ __raw_writel(DIV_ROUND_CLOSEST(twd_timer_rate, HZ),
+ twd_base + TWD_TIMER_LOAD);
break;
case CLOCK_EVT_MODE_ONESHOT:
/* period set, and timer enabled in 'next_event' hook */
@@ -96,7 +97,52 @@ static void twd_timer_stop(struct clock_event_device *clk)
disable_percpu_irq(clk->irq);
}
-#ifdef CONFIG_CPU_FREQ
+#ifdef CONFIG_COMMON_CLK
+
+/*
+ * Updates clockevent frequency when the cpu frequency changes.
+ * Called on the cpu that is changing frequency with interrupts disabled.
+ */
+static void twd_update_frequency(void *new_rate)
+{
+ twd_timer_rate = *((unsigned long *) new_rate);
+
+ clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
+}
+
+static int twd_rate_change(struct notifier_block *nb,
+ unsigned long flags, void *data)
+{
+ struct clk_notifier_data *cnd = data;
+
+ /*
+ * The twd clock events must be reprogrammed to account for the new
+ * frequency. The timer is local to a cpu, so cross-call to the
+ * changing cpu.
+ */
+ if (flags == POST_RATE_CHANGE)
+ smp_call_function(twd_update_frequency,
+ (void *)&cnd->new_rate, 1);
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block twd_clk_nb = {
+ .notifier_call = twd_rate_change,
+};
+
+static int twd_clk_init(void)
+{
+ if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
+ return clk_notifier_register(twd_clk, &twd_clk_nb);
+
+ return 0;
+}
+core_initcall(twd_clk_init);
+
+#elif defined (CONFIG_CPU_FREQ)
+
+#include <linux/cpufreq.h>
/*
* Updates clockevent frequency when the cpu frequency changes.
@@ -204,17 +250,9 @@ static struct clk *twd_get_clock(void)
return clk;
}
- err = clk_prepare(clk);
- if (err) {
- pr_err("smp_twd: clock failed to prepare: %d\n", err);
- clk_put(clk);
- return ERR_PTR(err);
- }
-
- err = clk_enable(clk);
+ err = clk_prepare_enable(clk);
if (err) {
- pr_err("smp_twd: clock failed to enable: %d\n", err);
- clk_unprepare(clk);
+ pr_err("smp_twd: clock failed to prepare+enable: %d\n", err);
clk_put(clk);
return ERR_PTR(err);
}
@@ -228,15 +266,45 @@ static struct clk *twd_get_clock(void)
static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
{
struct clock_event_device **this_cpu_clk;
+ int cpu = smp_processor_id();
+
+ /*
+ * If the basic setup for this CPU has been done before don't
+ * bother with the below.
+ */
+ if (per_cpu(percpu_setup_called, cpu)) {
+ __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
+ clockevents_register_device(*__this_cpu_ptr(twd_evt));
+ enable_percpu_irq(clk->irq, 0);
+ return 0;
+ }
+ per_cpu(percpu_setup_called, cpu) = true;
- if (!twd_clk)
+ /*
+ * This stuff only need to be done once for the entire TWD cluster
+ * during the runtime of the system.
+ */
+ if (!common_setup_called) {
twd_clk = twd_get_clock();
- if (!IS_ERR_OR_NULL(twd_clk))
- twd_timer_rate = clk_get_rate(twd_clk);
- else
- twd_calibrate_rate();
+ /*
+ * We use IS_ERR_OR_NULL() here, because if the clock stubs
+ * are active we will get a valid clk reference which is
+ * however NULL and will return the rate 0. In that case we
+ * need to calibrate the rate instead.
+ */
+ if (!IS_ERR_OR_NULL(twd_clk))
+ twd_timer_rate = clk_get_rate(twd_clk);
+ else
+ twd_calibrate_rate();
+
+ common_setup_called = true;
+ }
+ /*
+ * The following is done once per CPU the first time .setup() is
+ * called.
+ */
__raw_writel(0, twd_base + TWD_TIMER_CONTROL);
clk->name = "local_timer";
@@ -322,10 +390,8 @@ void __init twd_local_timer_of_register(void)
int err;
np = of_find_matching_node(NULL, twd_of_match);
- if (!np) {
- err = -ENODEV;
- goto out;
- }
+ if (!np)
+ return;
twd_ppi = irq_of_parse_and_map(np, 0);
if (!twd_ppi) {