OMAP35x GP TIMER as a wakeup trigger

OMAP35x GP TIMER as a wakeup trigger

[Ashwin Bihari]

Greetings,

I need to implement a timer as a wake up trigger while my custom board
is in the suspended state. I read in the TRM that all of the GPTIMERs
have the capability of generating a wake up interrupt. I'm using the
2.6.28-rc8 PM Kernel which contains the patch to enable all the
GPTIMERS as wake up sources.

Could someone familiar with this scheme quickly elaborate all the
steps that I need to go through to get the system to come out of
suspend purely on the timer? Is it is just enough to setup the timer
correctly, enable the interrupt in the appropriate register and assume
that the PM layer will get the interrupt and do the right thing, or is
there more that I have to do?

Also, as as additional thing, if the PM layer handles the interrupt
and begins the wake-up process, if I could know where that
specifically happens, that'd be great since I need to know that the
wake-up process is being triggered by the GPTIMER as opposed to the
other wakeup triggers and deal with that differently.

Regards
-- Ashwin

RE: OMAP35x GP TIMER as a wakeup trigger

[Premi, Sanjeev]

> -----Original Message-----
> From: linux-omap-owner@vger.kernel.org 
> [mailto:linux-omap-owner@vger.kernel.org] On Behalf Of Ashwin Bihari
> Sent: Monday, April 27, 2009 9:20 PM
> To: linux-omap@vger.kernel.org Mailing List
> Subject: OMAP35x GP TIMER as a wakeup trigger
> 
> Greetings,
> 
> I need to implement a timer as a wake up trigger while my custom board
> is in the suspended state. I read in the TRM that all of the GPTIMERs
> have the capability of generating a wake up interrupt. I'm using the
> 2.6.28-rc8 PM Kernel which contains the patch to enable all the
> GPTIMERS as wake up sources.

Are you refering to the "suspend" state coming from:
echo mem > /sys/power/state
OR
One of the idle states C0-C6?

To understand the wakeup sequence from suspend; take a look at:
arch/arm/mach-omap2/serial.c
...esp the IOPAD configuration.

You will have to do something similar.

~sanjeev

> 
> Could someone familiar with this scheme quickly elaborate all the
> steps that I need to go through to get the system to come out of
> suspend purely on the timer? Is it is just enough to setup the timer
> correctly, enable the interrupt in the appropriate register and assume
> that the PM layer will get the interrupt and do the right thing, or is
> there more that I have to do?
> 
> Also, as as additional thing, if the PM layer handles the interrupt
> and begins the wake-up process, if I could know where that
> specifically happens, that'd be great since I need to know that the
> wake-up process is being triggered by the GPTIMER as opposed to the
> other wakeup triggers and deal with that differently.
> 
> Regards
> -- Ashwin
> --
> To unsubscribe from this list: send the line "unsubscribe 
> linux-omap" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> 

Re: OMAP35x GP TIMER as a wakeup trigger

[Ashwin Bihari]

On Mon, Apr 27, 2009 at 12:08 PM, Premi, Sanjeev <premi@ti.com> wrote:
>> -----Original Message-----
>> From: linux-omap-owner@vger.kernel.org
>> [mailto:linux-omap-owner@vger.kernel.org] On Behalf Of Ashwin Bihari
>> Sent: Monday, April 27, 2009 9:20 PM
>> To: linux-omap@vger.kernel.org Mailing List
>> Subject: OMAP35x GP TIMER as a wakeup trigger
>>
>> Greetings,
>>
>> I need to implement a timer as a wake up trigger while my custom board
>> is in the suspended state. I read in the TRM that all of the GPTIMERs
>> have the capability of generating a wake up interrupt. I'm using the
>> 2.6.28-rc8 PM Kernel which contains the patch to enable all the
>> GPTIMERS as wake up sources.
>
> Are you refering to the "suspend" state coming from:
> echo mem > /sys/power/state
> OR
> One of the idle states C0-C6?
>
> To understand the wakeup sequence from suspend; take a look at:
> arch/arm/mach-omap2/serial.c
> ...esp the IOPAD configuration.
>
> You will have to do something similar.
>
> ~sanjeev
>
Sanjeev,

I was talking about the former (echo mem > /sys/power/state) and I
will take a look at the serial.c file and might return with more
questions. :)

Regards
-- Ashwin

RE: OMAP35x GP TIMER as a wakeup trigger

[Dasgupta, Romit]

Ashwin,
              Please see below:
>Could someone familiar with this scheme quickly elaborate all the
>steps that I need to go through to get the system to come out of
>suspend purely on the timer? Is it is just enough to setup the timer
>correctly, enable the interrupt in the appropriate register and assume
>that the PM layer will get the interrupt and do the right thing, or is
>there more that I have to do?
[Romit] Already this is being done during the CPU Idle path. Yes you need to program the GPT 1 into oneshot mode with expiry time as appropriate. Also set the CM_CLKSEL_WKUP.CLKSEL_GPT1 to sys_32K clock. 
PM_MPUGRPSEL_WKUP.GRPSEL_GPT1, PM_WKEN_WKUP.EN_GPT1 should be set.

>
>Also, as as additional thing, if the PM layer handles the interrupt
>and begins the wake-up process, if I could know where that
>specifically happens, that'd be great since I need to know that the
>wake-up process is being triggered by the GPTIMER as opposed to the
>other wakeup triggers and deal with that differently.

 [Romit] prcm_interrupt_handler. Look for PM_WKST_WKUP.

Thanks,
-Romit

Re: OMAP35x GP TIMER as a wakeup trigger

[Kevin Hilman]

Ashwin Bihari <abihari@gmail.com> writes:

> I need to implement a timer as a wake up trigger while my custom board
> is in the suspended state. I read in the TRM that all of the GPTIMERs
> have the capability of generating a wake up interrupt. I'm using the
> 2.6.28-rc8 PM Kernel which contains the patch to enable all the
> GPTIMERS as wake up sources.

Try the patch below on the current PM branch.  I use this for
debugging PM code when no other wakeup sources (keypad, UART, etc. are
working.) 

Kevin


>From bf81b7cce8967a425f1aa3d73782c1eb0367ce1a Mon Sep 17 00:00:00 2001
From: Kevin Hilman <khilman@deeprootsystems.com>
Date: Fri, 24 Apr 2009 16:13:47 -0700
Subject: [PATCH] OMAP3: PM: Add feature to wake from suspend on timer

If a non-zero value is written to /sys/power/wakeup_timer_seconds,
A timer wakeup event will wake the system and resume after the
configured number of seconds.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
---
 arch/arm/mach-omap2/pm.c       |   15 +++++++++++++--
 arch/arm/mach-omap2/pm.h       |    3 +++
 arch/arm/mach-omap2/pm34xx.c   |   22 ++++++++++++++++++++++
 arch/arm/mach-omap2/timer-gp.c |    2 ++
 4 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-omap2/pm.c b/arch/arm/mach-omap2/pm.c
index 50d95cd..dde0af3 100644
--- a/arch/arm/mach-omap2/pm.c
+++ b/arch/arm/mach-omap2/pm.c
@@ -42,6 +42,7 @@ unsigned short enable_dyn_sleep;
 unsigned short clocks_off_while_idle;
 unsigned short enable_off_mode;
 unsigned short voltage_off_while_idle;
+unsigned short wakeup_timer_seconds;
 atomic_t sleep_block = ATOMIC_INIT(0);
 
 static ssize_t idle_show(struct kobject *, struct kobj_attribute *, char *);
@@ -76,6 +77,9 @@ static struct kobj_attribute vdd2_lock_attr =
 
 #endif
 
+static struct kobj_attribute wakeup_timer_seconds_attr =
+	__ATTR(wakeup_timer_seconds, 0644, idle_show, idle_store);
+
 static ssize_t idle_show(struct kobject *kobj, struct kobj_attribute *attr,
 			 char *buf)
 {
@@ -87,6 +91,8 @@ static ssize_t idle_show(struct kobject *kobj, struct kobj_attribute *attr,
 		return sprintf(buf, "%hu\n", enable_off_mode);
 	else if (attr == &voltage_off_while_idle_attr)
 		return sprintf(buf, "%hu\n", voltage_off_while_idle);
+	else if (attr == &wakeup_timer_seconds_attr)
+		return sprintf(buf, "%hu\n", wakeup_timer_seconds);
 	else
 		return -EINVAL;
 }
@@ -96,8 +102,7 @@ static ssize_t idle_store(struct kobject *kobj, struct kobj_attribute *attr,
 {
 	unsigned short value;
 
-	if (sscanf(buf, "%hu", &value) != 1 ||
-	    (value != 0 && value != 1)) {
+	if (sscanf(buf, "%hu", &value) != 1) {
 		printk(KERN_ERR "idle_store: Invalid value\n");
 		return -EINVAL;
 	}
@@ -109,6 +114,8 @@ static ssize_t idle_store(struct kobject *kobj, struct kobj_attribute *attr,
 	} else if (attr == &enable_off_mode_attr) {
 		enable_off_mode = value;
 		omap3_pm_off_mode_enable(enable_off_mode);
+	} else if (attr == &wakeup_timer_seconds_attr) {
+		wakeup_timer_seconds = value;
 	} else if (attr == &voltage_off_while_idle_attr) {
 		voltage_off_while_idle = value;
 		if (voltage_off_while_idle)
@@ -255,6 +262,10 @@ static int __init omap_pm_init(void)
 		printk(KERN_ERR "sysfs_create_file failed: %d\n", error);
 		return error;
 	}
+	error = sysfs_create_file(power_kobj,
+				  &wakeup_timer_seconds_attr.attr);
+	if (error)
+		printk(KERN_ERR "sysfs_create_file failed: %d\n", error);
 #ifdef CONFIG_OMAP_PM_SRF
 	error = sysfs_create_file(power_kobj,
 				  &vdd1_opp_attr.attr);
diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
index 942a990..66effed 100644
--- a/arch/arm/mach-omap2/pm.h
+++ b/arch/arm/mach-omap2/pm.h
@@ -30,6 +30,9 @@ extern unsigned short voltage_off_while_idle;
 extern atomic_t sleep_block;
 extern void *omap3_secure_ram_storage;
 
+extern unsigned short wakeup_timer_seconds;
+extern struct omap_dm_timer *gptimer_wakeup;
+
 extern void omap2_block_sleep(void);
 extern void omap2_allow_sleep(void);
 #ifdef CONFIG_ARCH_OMAP3
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index d8795b5..3f41417 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -26,6 +26,7 @@
 #include <linux/module.h>
 #include <linux/list.h>
 #include <linux/err.h>
+#include <linux/clk.h>
 
 #include <mach/gpio.h>
 #include <mach/sram.h>
@@ -41,6 +42,8 @@
 #include <mach/dma.h>
 #include <mach/gpmc.h>
 #include <mach/dma.h>
+#include <mach/dmtimer.h>
+
 #include <asm/tlbflush.h>
 
 #include "cm.h"
@@ -552,6 +555,22 @@ out:
 static void (*saved_idle)(void);
 static suspend_state_t suspend_state;
 
+static void omap2_pm_wakeup_on_timer(u32 seconds)
+{
+	u32 tick_rate, cycles;
+
+	if (!seconds)
+		return;
+
+	tick_rate = clk_get_rate(omap_dm_timer_get_fclk(gptimer_wakeup));
+	cycles = tick_rate * seconds;
+	omap_dm_timer_stop(gptimer_wakeup);
+	omap_dm_timer_set_load_start(gptimer_wakeup, 0, 0xffffffff - cycles);
+
+	pr_info("PM: Resume timer in %d secs (%d ticks at %d ticks/sec.)\n",
+		seconds, cycles, tick_rate);
+}
+
 static int omap3_pm_prepare(void)
 {
 	saved_idle = pm_idle;
@@ -564,6 +583,9 @@ static int omap3_pm_suspend(void)
 	struct power_state *pwrst;
 	int state, ret = 0;
 
+	if (wakeup_timer_seconds)
+		omap2_pm_wakeup_on_timer(wakeup_timer_seconds);
+
 	/* Read current next_pwrsts */
 	list_for_each_entry(pwrst, &pwrst_list, node)
 		pwrst->saved_state = pwrdm_read_next_pwrst(pwrst->pwrdm);
diff --git a/arch/arm/mach-omap2/timer-gp.c b/arch/arm/mach-omap2/timer-gp.c
index 8351a34..83dd4b1 100644
--- a/arch/arm/mach-omap2/timer-gp.c
+++ b/arch/arm/mach-omap2/timer-gp.c
@@ -38,6 +38,7 @@
 
 static struct omap_dm_timer *gptimer;
 static struct clock_event_device clockevent_gpt;
+struct omap_dm_timer *gptimer_wakeup;
 
 static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id)
 {
@@ -101,6 +102,7 @@ static void __init omap2_gp_clockevent_init(void)
 
 	gptimer = omap_dm_timer_request_specific(CONFIG_OMAP_TICK_GPTIMER);
 	BUG_ON(gptimer == NULL);
+	gptimer_wakeup = gptimer;
 
 #if defined(CONFIG_OMAP_32K_TIMER)
 	omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_32_KHZ);
-- 
1.6.2.2

Re: OMAP35x GP TIMER as a wakeup trigger

[Ashwin Bihari]

On Mon, Apr 27, 2009 at 6:17 PM, Kevin Hilman
<khilman@deeprootsystems.com> wrote:
> Ashwin Bihari <abihari@gmail.com> writes:
>
>> I need to implement a timer as a wake up trigger while my custom board
>> is in the suspended state. I read in the TRM that all of the GPTIMERs
>> have the capability of generating a wake up interrupt. I'm using the
>> 2.6.28-rc8 PM Kernel which contains the patch to enable all the
>> GPTIMERS as wake up sources.
>
> Try the patch below on the current PM branch.  I use this for
> debugging PM code when no other wakeup sources (keypad, UART, etc. are
> working.)
>
> Kevin
>

Kevin.

The patch worked like a charm, thank you very much.

-- Ashwin
--
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