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Subject[RFC] ARM: OMAP2+: omap_device: add pinctrl handling
Date
Before switching to DT pinctrl states of OMAP IPs have been handled by hwmod
framework. After switching to DT-boot the pinctrl handling was dropped from
hwmod framework and, as it was recommended, OMAP IP's drivers have to be updated
to handle pinctrl states by itself using pinctrl_pm_select_xx() helpers
(see http://lists.infradead.org/pipermail/linux-arm-kernel/2013-June/173514.html)

But this is not right for OMAP2+ SoC where real IPs state is controlled
by omap_device core which enables/disables modules & clocks actually.

For example, if OMAP I2C driver will handle pinctrl state during system wide
suspend the following issue may occure:
- suspend_noirq - I2C device can be still active because of PM auto-suspend
|-_od_suspend_noirq
|- omap_i2c_suspend_noirq
|- PINs state set to SLEEP
|- pm_generic_runtime_suspend
|- omap_i2c_runtime_suspend()
|- PINs state set to IDLE <--- *oops* PINs state is IDLE and not SLEEP
|- omap_device_idle()
|- omap_hwmod_idle()
|- _idle()
|- disbale module (sysc&clocks)

- resume_noirq - I2C was active before suspend
|-_od_resume_noirq
|- omap_hwmod_enable()
|- _enable()
|- enable module (sysc&clocks)
|- pm_generic_runtime_resume
|- omap_i2c_runtime_resume()
|- PINs state set to DEFAULT <--- !!!!
|- omap_i2c_resume_noirq
|- PINs state set to DEFAULT
|- PINs state set to IDLE <--- *big oops* we have active module and its
PINs state is IDLE
(see https://patchwork.kernel.org/patch/2642101/)

Of course, everything can be handled by adding a tons of code in ecah driver to
check PM state of device and override default behavior of omap_device core, but
this not good.

Hence, add pinctrl handling in omap_device core:
1) on PM runtime resume
- switch pinctrl state to "default" (todo: "active")
2) on PM runtime suspend
- switch pinctrl state to "idle"
3) during system wide suspend
- switch pinctrl state to "sleep" or "idle" if omap_device core disables device
- switch pinctrl state to "sleep" if device is disabled already
4) during system wide resume
- switch pinctrl state to "default" (todo: "active") if omap_device core has
disabled device during suspend
- switch pinctrl state to "idle" if device was already disabled before suspend

This will enable pinctrl for all OMAP2+ IP's drivers by default -
no changes in code is needed and only DT data will need to be updated
(add "default", "active", "idle", "sleep" states).

This will enable pinctrl handling for all OMAP2+ drivers by default -
no changes in code is needed and only DT data will need to be updated
(add "default", "active", "idle", "sleep" states).

Related discussions:
- [3/3] i2c: nomadik: use pinctrl PM helpers
https://patchwork.kernel.org/patch/2670291/
- mmc: omap_hsmmc: Remux pins to support SDIO interrupt and PM runtime
https://patchwork.kernel.org/patch/2690191/
- [PATCH 00/11] drivers: Add Pinctrl PM support
https://lkml.org/lkml/2013/5/31/210

CC: Hebbar Gururaja <gururaja.hebbar@ti.com>
CC: Linus Walleij <linus.walleij@linaro.org>
CC: linux-arm-kernel@lists.infradead.org
CC: linux-omap@vger.kernel.org
CC: linux-kernel@vger.kernel.org

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
---
Hi Kevin, Tony,

I've verified this patch on OMAP4 SDP board:
- PM runtime for I2C4, UART2, UART3
- suspend/resume with I2C4, UART2, UART3

seems it works and pinctrl states have been updated as expected.

TODO:
- need to be rebased when support for "active" state will be added.
- need to be rebased when "Omap serial cleanup" patch series will be merged
https://lkml.org/lkml/2013/4/26/503

based on top of:
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
849aa58 Add linux-next specific files for 20130620

Best regards
- grygorii

arch/arm/mach-omap2/omap_device.c | 45 ++++++++++++++++++++++++++++++++-----
1 file changed, 39 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mach-omap2/omap_device.c b/arch/arm/mach-omap2/omap_device.c
index e37feb2..d8cf17b 100644
--- a/arch/arm/mach-omap2/omap_device.c
+++ b/arch/arm/mach-omap2/omap_device.c
@@ -39,6 +39,7 @@
#include "soc.h"
#include "omap_device.h"
#include "omap_hwmod.h"
+#include "iomap.h"

/* Private functions */

@@ -585,8 +586,10 @@ static int _od_runtime_suspend(struct device *dev)

ret = pm_generic_runtime_suspend(dev);

- if (!ret)
+ if (!ret) {
omap_device_idle(pdev);
+ pinctrl_pm_select_idle_state(dev);
+ }

return ret;
}
@@ -595,12 +598,26 @@ static int _od_runtime_resume(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);

+ /* TODO: should be replaced to pinctrl_pm_select_active_state() */
+ pinctrl_pm_select_default_state(dev);
+
omap_device_enable(pdev);

return pm_generic_runtime_resume(dev);
}
#endif

+void _od_suspend_sel_pinctrl_state(struct device *dev)
+{
+ if (!dev->pins)
+ return;
+ /* try to select *deepest* pinctrl state */
+ if (IS_ERR(dev->pins->sleep_state))
+ pinctrl_pm_select_idle_state(dev);
+ else
+ pinctrl_pm_select_sleep_state(dev);
+}
+
#ifdef CONFIG_SUSPEND
static int _od_suspend_noirq(struct device *dev)
{
@@ -613,12 +630,22 @@ static int _od_suspend_noirq(struct device *dev)
return 0;

ret = pm_generic_suspend_noirq(dev);
+ if (!ret) {
+ if (!pm_runtime_status_suspended(dev)) {
+ if (pm_generic_runtime_suspend(dev) == 0) {
+ if (!(od->flags & OMAP_DEVICE_NO_IDLE_ON_SUSPEND)) {
+ omap_device_idle(pdev);
+ _od_suspend_sel_pinctrl_state(dev);
+ }
+ }

- if (!ret && !pm_runtime_status_suspended(dev)) {
- if (pm_generic_runtime_suspend(dev) == 0) {
- if (!(od->flags & OMAP_DEVICE_NO_IDLE_ON_SUSPEND))
- omap_device_idle(pdev);
od->flags |= OMAP_DEVICE_SUSPENDED;
+ } else {
+ /*
+ * "idle" pinctrl state already applied -
+ * try to set "sleep" state
+ */
+ pinctrl_pm_select_sleep_state(dev);
}
}

@@ -633,9 +660,15 @@ static int _od_resume_noirq(struct device *dev)
if ((od->flags & OMAP_DEVICE_SUSPENDED) &&
!pm_runtime_status_suspended(dev)) {
od->flags &= ~OMAP_DEVICE_SUSPENDED;
- if (!(od->flags & OMAP_DEVICE_NO_IDLE_ON_SUSPEND))
+ if (!(od->flags & OMAP_DEVICE_NO_IDLE_ON_SUSPEND)) {
omap_device_enable(pdev);
+ /* TODO: should be replaced to pinctrl_pm_select_active_state() */
+ pinctrl_pm_select_default_state(dev);
+ }
pm_generic_runtime_resume(dev);
+ } else if (!pm_runtime_status_suspended(dev)) {
+ /* switch back to "idle" pinctrl state */
+ pinctrl_pm_select_idle_state(dev);
}

return pm_generic_resume_noirq(dev);
--
1.7.9.5


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