The localtimer's clock changes with the cpu clock. After a
cpufreq transition, update the clockevent's frequency and
reprogram the next clock event.
Adds a clock called "smp_twd" that is used to determine the
twd frequency, which can also be used at init time to
avoid calibrating the twd frequency.
Clock changes are based on Rob Herring's work.
Change-Id: I413b5cd07fb2b79bc9fad8b4bf257332d1da7bcd
Signed-off-by: Colin Cross <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Russell King <[email protected]>
Cc: Santosh Shilimkar <[email protected]>
Cc: Rob Herring <[email protected]>
Tested-by: Linus Walleij <[email protected]>
---
arch/arm/kernel/smp_twd.c | 86 +++++++++++++++++++++++++++++++++++++++++---
1 files changed, 80 insertions(+), 6 deletions(-)
This patch depends on Thomas Gleixner's patch to add clockevents_update_freq
v2: Squash in changes from Linus Wallej, enable smp_twd clock during init
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index 60636f4..b5bd303 100644
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -10,13 +10,17 @@
*/
#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>
#include <linux/smp.h>
#include <linux/jiffies.h>
#include <linux/clockchips.h>
#include <linux/irq.h>
#include <linux/io.h>
+#include <linux/percpu.h>
#include <asm/smp_twd.h>
#include <asm/hardware/gic.h>
@@ -24,7 +28,9 @@
/* set up by the platform code */
void __iomem *twd_base;
+static struct clk *twd_clk;
static unsigned long twd_timer_rate;
+static DEFINE_PER_CPU(struct clock_event_device *, twd_ce);
static void twd_set_mode(enum clock_event_mode mode,
struct clock_event_device *clk)
@@ -80,6 +86,48 @@ int twd_timer_ack(void)
return 0;
}
+/*
+ * 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 *data)
+{
+ twd_timer_rate = clk_get_rate(twd_clk);
+
+ clockevents_update_freq(__get_cpu_var(twd_ce), twd_timer_rate);
+}
+
+static int twd_cpufreq_transition(struct notifier_block *nb,
+ unsigned long state, void *data)
+{
+ struct cpufreq_freqs *freqs = 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 (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
+ smp_call_function_single(freqs->cpu, twd_update_frequency,
+ NULL, 1);
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block twd_cpufreq_nb = {
+ .notifier_call = twd_cpufreq_transition,
+};
+
+static int twd_cpufreq_init(void)
+{
+ if (!IS_ERR_OR_NULL(twd_clk))
+ return cpufreq_register_notifier(&twd_cpufreq_nb,
+ CPUFREQ_TRANSITION_NOTIFIER);
+
+ return 0;
+}
+core_initcall(twd_cpufreq_init);
+
static void __cpuinit twd_calibrate_rate(void)
{
unsigned long count;
@@ -119,12 +167,39 @@ static void __cpuinit twd_calibrate_rate(void)
}
}
+static struct clk *twd_get_clock(void)
+{
+ struct clk *clk;
+ int err;
+
+ clk = clk_get_sys("smp_twd", NULL);
+ if (IS_ERR(clk)) {
+ pr_err("smp_twd: clock not found: %d\n", (int)PTR_ERR(clk));
+ return clk;
+ }
+
+ err = clk_enable(clk);
+ if (err) {
+ pr_err("smp_twd: clock failed to enable: %d\n", err);
+ clk_put(clk);
+ return ERR_PTR(err);
+ }
+
+ return clk;
+}
+
/*
* Setup the local clock events for a CPU.
*/
void __cpuinit twd_timer_setup(struct clock_event_device *clk)
{
- twd_calibrate_rate();
+ if (!twd_clk)
+ twd_clk = twd_get_clock();
+
+ if (!IS_ERR_OR_NULL(twd_clk))
+ twd_timer_rate = clk_get_rate(twd_clk);
+ else
+ twd_calibrate_rate();
clk->name = "local_timer";
clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
@@ -132,13 +207,12 @@ void __cpuinit twd_timer_setup(struct clock_event_device *clk)
clk->rating = 350;
clk->set_mode = twd_set_mode;
clk->set_next_event = twd_set_next_event;
- clk->shift = 20;
- clk->mult = div_sc(twd_timer_rate, NSEC_PER_SEC, clk->shift);
- clk->max_delta_ns = clockevent_delta2ns(0xffffffff, clk);
- clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
/* Make sure our local interrupt controller has this enabled */
gic_enable_ppi(clk->irq);
- clockevents_register_device(clk);
+ __get_cpu_var(twd_ce) = clk;
+
+ clockevents_config_and_register(clk, twd_timer_rate,
+ 0xf, 0xffffffff);
}
--
1.7.4.1
On Fri, May 20, 2011 at 2:24 AM, Colin Cross <[email protected]> wrote:
> The localtimer's clock changes with the cpu clock. ?After a
> cpufreq transition, update the clockevent's frequency and
> reprogram the next clock event.
>
> Adds a clock called "smp_twd" that is used to determine the
> twd frequency, which can also be used at init time to
> avoid calibrating the twd frequency.
>
> Clock changes are based on Rob Herring's work.
>
> Change-Id: I413b5cd07fb2b79bc9fad8b4bf257332d1da7bcd
> Signed-off-by: Colin Cross <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Russell King <[email protected]>
> Cc: Santosh Shilimkar <[email protected]>
> Cc: Rob Herring <[email protected]>
> Tested-by: Linus Walleij <[email protected]>
OK Thomas can you take this in through the clock/timer
branch? Works fine for me and Colin and solves many problems
apart from making the code look neat.
Yours,
Linus Walleij
On 05/19/2011 07:24 PM, Colin Cross wrote:
> The localtimer's clock changes with the cpu clock. After a
> cpufreq transition, update the clockevent's frequency and
> reprogram the next clock event.
>
> Adds a clock called "smp_twd" that is used to determine the
> twd frequency, which can also be used at init time to
> avoid calibrating the twd frequency.
>
> Clock changes are based on Rob Herring's work.
>
> Change-Id: I413b5cd07fb2b79bc9fad8b4bf257332d1da7bcd
> Signed-off-by: Colin Cross<[email protected]>
> Cc: Thomas Gleixner<[email protected]>
> Cc: Russell King<[email protected]>
> Cc: Santosh Shilimkar<[email protected]>
> Cc: Rob Herring<[email protected]>
> Tested-by: Linus Walleij<[email protected]>
Acked-by: Rob Herring <[email protected]>
> ---
> arch/arm/kernel/smp_twd.c | 86 +++++++++++++++++++++++++++++++++++++++++---
> 1 files changed, 80 insertions(+), 6 deletions(-)
>
> This patch depends on Thomas Gleixner's patch to add clockevents_update_freq
>
> v2: Squash in changes from Linus Wallej, enable smp_twd clock during init
>
> diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
> index 60636f4..b5bd303 100644
> --- a/arch/arm/kernel/smp_twd.c
> +++ b/arch/arm/kernel/smp_twd.c
> @@ -10,13 +10,17 @@
> */
> #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>
> #include<linux/smp.h>
> #include<linux/jiffies.h>
> #include<linux/clockchips.h>
> #include<linux/irq.h>
> #include<linux/io.h>
> +#include<linux/percpu.h>
>
> #include<asm/smp_twd.h>
> #include<asm/hardware/gic.h>
> @@ -24,7 +28,9 @@
> /* set up by the platform code */
> void __iomem *twd_base;
>
> +static struct clk *twd_clk;
> static unsigned long twd_timer_rate;
> +static DEFINE_PER_CPU(struct clock_event_device *, twd_ce);
>
> static void twd_set_mode(enum clock_event_mode mode,
> struct clock_event_device *clk)
> @@ -80,6 +86,48 @@ int twd_timer_ack(void)
> return 0;
> }
>
> +/*
> + * 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 *data)
> +{
> + twd_timer_rate = clk_get_rate(twd_clk);
> +
> + clockevents_update_freq(__get_cpu_var(twd_ce), twd_timer_rate);
> +}
> +
> +static int twd_cpufreq_transition(struct notifier_block *nb,
> + unsigned long state, void *data)
> +{
> + struct cpufreq_freqs *freqs = 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 (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
> + smp_call_function_single(freqs->cpu, twd_update_frequency,
> + NULL, 1);
> +
> + return NOTIFY_OK;
> +}
> +
> +static struct notifier_block twd_cpufreq_nb = {
> + .notifier_call = twd_cpufreq_transition,
> +};
> +
> +static int twd_cpufreq_init(void)
> +{
> + if (!IS_ERR_OR_NULL(twd_clk))
> + return cpufreq_register_notifier(&twd_cpufreq_nb,
> + CPUFREQ_TRANSITION_NOTIFIER);
> +
> + return 0;
> +}
> +core_initcall(twd_cpufreq_init);
> +
> static void __cpuinit twd_calibrate_rate(void)
> {
> unsigned long count;
> @@ -119,12 +167,39 @@ static void __cpuinit twd_calibrate_rate(void)
> }
> }
>
> +static struct clk *twd_get_clock(void)
> +{
> + struct clk *clk;
> + int err;
> +
> + clk = clk_get_sys("smp_twd", NULL);
> + if (IS_ERR(clk)) {
> + pr_err("smp_twd: clock not found: %d\n", (int)PTR_ERR(clk));
> + return clk;
> + }
> +
> + err = clk_enable(clk);
> + if (err) {
> + pr_err("smp_twd: clock failed to enable: %d\n", err);
> + clk_put(clk);
> + return ERR_PTR(err);
> + }
> +
> + return clk;
> +}
> +
> /*
> * Setup the local clock events for a CPU.
> */
> void __cpuinit twd_timer_setup(struct clock_event_device *clk)
> {
> - twd_calibrate_rate();
> + if (!twd_clk)
> + twd_clk = twd_get_clock();
> +
> + if (!IS_ERR_OR_NULL(twd_clk))
> + twd_timer_rate = clk_get_rate(twd_clk);
> + else
> + twd_calibrate_rate();
>
> clk->name = "local_timer";
> clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
> @@ -132,13 +207,12 @@ void __cpuinit twd_timer_setup(struct clock_event_device *clk)
> clk->rating = 350;
> clk->set_mode = twd_set_mode;
> clk->set_next_event = twd_set_next_event;
> - clk->shift = 20;
> - clk->mult = div_sc(twd_timer_rate, NSEC_PER_SEC, clk->shift);
> - clk->max_delta_ns = clockevent_delta2ns(0xffffffff, clk);
> - clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
>
> /* Make sure our local interrupt controller has this enabled */
> gic_enable_ppi(clk->irq);
>
> - clockevents_register_device(clk);
> + __get_cpu_var(twd_ce) = clk;
> +
> + clockevents_config_and_register(clk, twd_timer_rate,
> + 0xf, 0xffffffff);
> }
On 5/20/2011 5:54 AM, Colin Cross wrote:
> The localtimer's clock changes with the cpu clock. After a
> cpufreq transition, update the clockevent's frequency and
> reprogram the next clock event.
>
> Adds a clock called "smp_twd" that is used to determine the
> twd frequency, which can also be used at init time to
> avoid calibrating the twd frequency.
>
> Clock changes are based on Rob Herring's work.
>
> Change-Id: I413b5cd07fb2b79bc9fad8b4bf257332d1da7bcd
> Signed-off-by: Colin Cross<[email protected]>
> Cc: Thomas Gleixner<[email protected]>
> Cc: Russell King<[email protected]>
> Cc: Santosh Shilimkar<[email protected]>
> Cc: Rob Herring<[email protected]>
> Tested-by: Linus Walleij<[email protected]>
> ---
Acked-by: Santosh Shilimkar <[email protected]>
What about the clock-node patches?
Do you want those to get merged via sub-arch tree's once this
patch + Thomas's new API gets merged ?
Regards
Santosh
On Fri, May 20, 2011 at 11:29 PM, Santosh Shilimkar
<[email protected]> wrote:
> On 5/20/2011 5:54 AM, Colin Cross wrote:
>>
>> The localtimer's clock changes with the cpu clock. ?After a
>> cpufreq transition, update the clockevent's frequency and
>> reprogram the next clock event.
>>
>> Adds a clock called "smp_twd" that is used to determine the
>> twd frequency, which can also be used at init time to
>> avoid calibrating the twd frequency.
>>
>> Clock changes are based on Rob Herring's work.
>>
>> Change-Id: I413b5cd07fb2b79bc9fad8b4bf257332d1da7bcd
>> Signed-off-by: Colin Cross<[email protected]>
>> Cc: Thomas Gleixner<[email protected]>
>> Cc: Russell King<[email protected]>
>> Cc: Santosh Shilimkar<[email protected]>
>> Cc: Rob Herring<[email protected]>
>> Tested-by: Linus Walleij<[email protected]>
>> ---
>
> Acked-by: Santosh Shilimkar <[email protected]>
>
> What about the clock-node patches?
> Do you want those to get merged via sub-arch tree's once this
> patch + Thomas's new API gets merged ?
The clock-node patches can be merged independently - twd scaling just
won't work until they are both merged.
On 5/23/2011 10:48 AM, Colin Cross wrote:
> On Fri, May 20, 2011 at 11:29 PM, Santosh Shilimkar
> <[email protected]> wrote:
>> On 5/20/2011 5:54 AM, Colin Cross wrote:
>>>
>>> The localtimer's clock changes with the cpu clock. After a
>>> cpufreq transition, update the clockevent's frequency and
>>> reprogram the next clock event.
>>>
>>> Adds a clock called "smp_twd" that is used to determine the
>>> twd frequency, which can also be used at init time to
>>> avoid calibrating the twd frequency.
>>>
>>> Clock changes are based on Rob Herring's work.
>>>
>>> Change-Id: I413b5cd07fb2b79bc9fad8b4bf257332d1da7bcd
>>> Signed-off-by: Colin Cross<[email protected]>
>>> Cc: Thomas Gleixner<[email protected]>
>>> Cc: Russell King<[email protected]>
>>> Cc: Santosh Shilimkar<[email protected]>
>>> Cc: Rob Herring<[email protected]>
>>> Tested-by: Linus Walleij<[email protected]>
>>> ---
>>
>> Acked-by: Santosh Shilimkar<[email protected]>
>>
>> What about the clock-node patches?
>> Do you want those to get merged via sub-arch tree's once this
>> patch + Thomas's new API gets merged ?
>
> The clock-node patches can be merged independently - twd scaling just
> won't work until they are both merged.
Yep. That should be ok.
Regards
Santosh
2011/5/20 Colin Cross <[email protected]>:
> The localtimer's clock changes with the cpu clock. ?After a
> cpufreq transition, update the clockevent's frequency and
> reprogram the next clock event.
Colin can you put this into Russells patch tracker with all the ACKs?
Actually I think this is -rc material since it fixes a real bug for us
atleast, maybe that's just me.
Yours,
Linus Walleij