[PATCH 00/23] ARM: at91: Properly handle slow clock

[PATCH 00/23] ARM: at91: Properly handle slow clock

[Alexandre Belloni]

Hi,

It was discovered that all the slow clock user were not properly claiming it.
This can end up in a system hang because the last registered user is releasing
it, and it gets disabled.

commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system hang")
was a workaround. This series is adding the slow clock to the necessary drivers
to avoid the issue and then removes that workaround.

The Documentation updates and DT patches should probably go through the AT91
tree this cycle to avoid breakage.

Then the other patches can go through each subsystem tree. They are trivial
enough to also go in this cycle.

The final clk patch depends on the other ones and may be taken for the next
cycle to avoid synchronization issues.

I've thrown in a cleanup for at91-reset as it avoids adding support for that
clock to the platform data initialization

Changes in v2:
 - statisticize the global in the atmel-st change
 - merge at91_reset_of_probe() in at91_reset_probe()
 - added patches from Boris for the TCB
 - added the slow clock to the TCB

Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-clk@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linux-pwm@vger.kernel.org
Cc: linux-watchdog@vger.kernel.org
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: rtc-linux@googlegroups.com
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wim Van Sebroeck <wim@iguana.be>

Alexandre Belloni (20):
  Documentation: dt: atmel-at91: add clocks to system timer, rstc and
    shdwc
  Documentation: watchdog: at91sam9_wdt: add clocks property
  Documentation: dt: rtc: at91rm9200: add clocks property
  ARM: at91/dt: at91rm9200: use slow clock where necessary
  ARM: at91/dt: at91sam9260: use slow clock where necessary
  ARM: at91/dt: at91sam9261: use slow clock where necessary
  ARM: at91/dt: at91sam9263: use slow clock where necessary
  ARM: at91/dt: at91sam9g45: use slow clock where necessary
  ARM: at91/dt: at91sam9n12: use slow clock where necessary
  ARM: at91/dt: at91sam9rl: use slow clock where necessary
  ARM: at91/dt: at91sam9x5: use slow clock where necessary
  ARM: at91/dt: sama5d3: use slow clock where necessary
  ARM: at91/dt: sama5d4: use slow clock where necessary
  rtc: at91rm9200: get and use slow clock
  watchdog: at91sam9: get and use slow clock
  power/reset: at91-reset: remove useless at91_reset_platform_probe()
  power/reset: at91-reset: get and use slow clock
  power/reset: at91-poweroff: get and use slow clock
  clocksource: atmel-st: get and use slow clock
  clk: at91: Revert "keep slow clk enabled to prevent system hang"

Boris Brezillon (3):
  Documentation: dt: atmel-at91: add slow clock to tcb
  clocksource: tcb_clksrc: fix setup_clkevents error path
  misc: atmel_tclib: get and use slow clock

 .../devicetree/bindings/arm/atmel-at91.txt         | 13 +++--
 .../bindings/rtc/atmel,at91rm9200-rtc.txt          |  2 +
 .../devicetree/bindings/watchdog/atmel-wdt.txt     |  2 +
 arch/arm/boot/dts/at91rm9200.dtsi                  | 10 ++--
 arch/arm/boot/dts/at91sam9260.dtsi                 | 11 +++--
 arch/arm/boot/dts/at91sam9261.dtsi                 |  7 ++-
 arch/arm/boot/dts/at91sam9263.dtsi                 |  7 ++-
 arch/arm/boot/dts/at91sam9g45.dtsi                 | 12 +++--
 arch/arm/boot/dts/at91sam9n12.dtsi                 | 12 +++--
 arch/arm/boot/dts/at91sam9rl.dtsi                  |  8 ++-
 arch/arm/boot/dts/at91sam9x5.dtsi                  | 12 +++--
 arch/arm/boot/dts/sama5d3.dtsi                     |  8 ++-
 arch/arm/boot/dts/sama5d3_tcb1.dtsi                |  4 +-
 arch/arm/boot/dts/sama5d4.dtsi                     | 12 +++--
 drivers/clk/at91/clk-slow.c                        | 27 ----------
 drivers/clocksource/tcb_clksrc.c                   | 10 +++-
 drivers/clocksource/timer-atmel-st.c               | 31 ++++++++----
 drivers/misc/atmel_tclib.c                         |  4 ++
 drivers/power/reset/at91-poweroff.c                | 13 +++++
 drivers/power/reset/at91-reset.c                   | 57 ++++++----------------
 drivers/pwm/pwm-atmel-tcb.c                        | 23 ++++++---
 drivers/rtc/rtc-at91rm9200.c                       | 27 ++++++++--
 drivers/watchdog/at91sam9_wdt.c                    | 22 ++++++++-
 include/linux/atmel_tc.h                           |  1 +
 24 files changed, 206 insertions(+), 129 deletions(-)

-- 
2.1.4

[PATCH 03/23] Documentation: watchdog: at91sam9_wdt: add clocks property

[Alexandre Belloni]

The watchdog has an input clock, the slow clock. It is required as it will
not function without it.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
---
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: linux-watchdog@vger.kernel.org
 Documentation/devicetree/bindings/watchdog/atmel-wdt.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt b/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt
index a4d869744f59..86fa6de1019b 100644
--- a/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt
+++ b/Documentation/devicetree/bindings/watchdog/atmel-wdt.txt
@@ -6,6 +6,7 @@ Required properties:
 - compatible: must be "atmel,at91sam9260-wdt".
 - reg: physical base address of the controller and length of memory mapped
   region.
+- clocks: phandle to input clock.
 
 Optional properties:
 - timeout-sec: contains the watchdog timeout in seconds.
@@ -39,6 +40,7 @@ Example:
 		compatible = "atmel,at91sam9260-wdt";
 		reg = <0xfffffd40 0x10>;
 		interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>;
+		clocks = <&clk32k>;
 		timeout-sec = <15>;
 		atmel,watchdog-type = "hardware";
 		atmel,reset-type = "all";
-- 
2.1.4

[PATCH 16/23] watchdog: at91sam9: get and use slow clock

[Alexandre Belloni]

Commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system
hang") added a workaround for the slow clock as it is not properly handled
by its users.

Get and use the slow clock as it is necessary for the at91sam9 watchdog.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
---
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: linux-watchdog@vger.kernel.org
 drivers/watchdog/at91sam9_wdt.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
index e4698f7c5f93..7e6acaf3ece4 100644
--- a/drivers/watchdog/at91sam9_wdt.c
+++ b/drivers/watchdog/at91sam9_wdt.c
@@ -17,6 +17,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/clk.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
@@ -90,6 +91,7 @@ struct at91wdt {
 	unsigned long heartbeat;	/* WDT heartbeat in jiffies */
 	bool nowayout;
 	unsigned int irq;
+	struct clk *sclk;
 };
 
 /* ......................................................................... */
@@ -352,15 +354,25 @@ static int __init at91wdt_probe(struct platform_device *pdev)
 	if (IS_ERR(wdt->base))
 		return PTR_ERR(wdt->base);
 
+	wdt->sclk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(wdt->sclk))
+		return PTR_ERR(wdt->sclk);
+
+	err = clk_prepare_enable(wdt->sclk);
+	if (err) {
+		dev_err(&pdev->dev, "Could not enable slow clock\n");
+		return err;
+	}
+
 	if (pdev->dev.of_node) {
 		err = of_at91wdt_init(pdev->dev.of_node, wdt);
 		if (err)
-			return err;
+			goto err_clk;
 	}
 
 	err = at91_wdt_init(pdev, wdt);
 	if (err)
-		return err;
+		goto err_clk;
 
 	platform_set_drvdata(pdev, wdt);
 
@@ -368,6 +380,11 @@ static int __init at91wdt_probe(struct platform_device *pdev)
 		wdt->wdd.timeout, wdt->nowayout);
 
 	return 0;
+
+err_clk:
+	clk_disable_unprepare(wdt->sclk);
+
+	return err;
 }
 
 static int __exit at91wdt_remove(struct platform_device *pdev)
@@ -377,6 +394,7 @@ static int __exit at91wdt_remove(struct platform_device *pdev)
 
 	pr_warn("I quit now, hardware will probably reboot!\n");
 	del_timer(&wdt->timer);
+	clk_disable_unprepare(wdt->sclk);
 
 	return 0;
 }
-- 
2.1.4

Re: [PATCH 00/23] ARM: at91: Properly handle slow clock

[Boris Brezillon]

Hi Alexandre,

On Fri, 31 Jul 2015 11:39:36 +0200
Alexandre Belloni <alexandre.belloni@free-electrons.com> wrote:

> Hi,
> 
> It was discovered that all the slow clock user were not properly claiming it.
> This can end up in a system hang because the last registered user is releasing
> it, and it gets disabled.
> 
> commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system hang")
> was a workaround. This series is adding the slow clock to the necessary drivers
> to avoid the issue and then removes that workaround.
> 
> The Documentation updates and DT patches should probably go through the AT91
> tree this cycle to avoid breakage.
> 
> Then the other patches can go through each subsystem tree. They are trivial
> enough to also go in this cycle.
> 
> The final clk patch depends on the other ones and may be taken for the next
> cycle to avoid synchronization issues.
> 
> I've thrown in a cleanup for at91-reset as it avoids adding support for that
> clock to the platform data initialization

I would have squashed commit 5 to 14 into a single patch, but apart
from that it looks good to me.

Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>

Thanks,

Boris

> 
> Changes in v2:
>  - statisticize the global in the atmel-st change
>  - merge at91_reset_of_probe() in at91_reset_probe()
>  - added patches from Boris for the TCB
>  - added the slow clock to the TCB
> 
> Cc: Alessandro Zummo <a.zummo@towertech.it>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-clk@vger.kernel.org
> Cc: linux-pm@vger.kernel.org
> Cc: linux-pwm@vger.kernel.org
> Cc: linux-watchdog@vger.kernel.org
> Cc: Michael Turquette <mturquette@baylibre.com>
> Cc: rtc-linux@googlegroups.com
> Cc: Sebastian Reichel <sre@kernel.org>
> Cc: Stephen Boyd <sboyd@codeaurora.org>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Wim Van Sebroeck <wim@iguana.be>
> 
> Alexandre Belloni (20):
>   Documentation: dt: atmel-at91: add clocks to system timer, rstc and
>     shdwc
>   Documentation: watchdog: at91sam9_wdt: add clocks property
>   Documentation: dt: rtc: at91rm9200: add clocks property
>   ARM: at91/dt: at91rm9200: use slow clock where necessary
>   ARM: at91/dt: at91sam9260: use slow clock where necessary
>   ARM: at91/dt: at91sam9261: use slow clock where necessary
>   ARM: at91/dt: at91sam9263: use slow clock where necessary
>   ARM: at91/dt: at91sam9g45: use slow clock where necessary
>   ARM: at91/dt: at91sam9n12: use slow clock where necessary
>   ARM: at91/dt: at91sam9rl: use slow clock where necessary
>   ARM: at91/dt: at91sam9x5: use slow clock where necessary
>   ARM: at91/dt: sama5d3: use slow clock where necessary
>   ARM: at91/dt: sama5d4: use slow clock where necessary
>   rtc: at91rm9200: get and use slow clock
>   watchdog: at91sam9: get and use slow clock
>   power/reset: at91-reset: remove useless at91_reset_platform_probe()
>   power/reset: at91-reset: get and use slow clock
>   power/reset: at91-poweroff: get and use slow clock
>   clocksource: atmel-st: get and use slow clock
>   clk: at91: Revert "keep slow clk enabled to prevent system hang"
> 
> Boris Brezillon (3):
>   Documentation: dt: atmel-at91: add slow clock to tcb
>   clocksource: tcb_clksrc: fix setup_clkevents error path
>   misc: atmel_tclib: get and use slow clock
> 
>  .../devicetree/bindings/arm/atmel-at91.txt         | 13 +++--
>  .../bindings/rtc/atmel,at91rm9200-rtc.txt          |  2 +
>  .../devicetree/bindings/watchdog/atmel-wdt.txt     |  2 +
>  arch/arm/boot/dts/at91rm9200.dtsi                  | 10 ++--
>  arch/arm/boot/dts/at91sam9260.dtsi                 | 11 +++--
>  arch/arm/boot/dts/at91sam9261.dtsi                 |  7 ++-
>  arch/arm/boot/dts/at91sam9263.dtsi                 |  7 ++-
>  arch/arm/boot/dts/at91sam9g45.dtsi                 | 12 +++--
>  arch/arm/boot/dts/at91sam9n12.dtsi                 | 12 +++--
>  arch/arm/boot/dts/at91sam9rl.dtsi                  |  8 ++-
>  arch/arm/boot/dts/at91sam9x5.dtsi                  | 12 +++--
>  arch/arm/boot/dts/sama5d3.dtsi                     |  8 ++-
>  arch/arm/boot/dts/sama5d3_tcb1.dtsi                |  4 +-
>  arch/arm/boot/dts/sama5d4.dtsi                     | 12 +++--
>  drivers/clk/at91/clk-slow.c                        | 27 ----------
>  drivers/clocksource/tcb_clksrc.c                   | 10 +++-
>  drivers/clocksource/timer-atmel-st.c               | 31 ++++++++----
>  drivers/misc/atmel_tclib.c                         |  4 ++
>  drivers/power/reset/at91-poweroff.c                | 13 +++++
>  drivers/power/reset/at91-reset.c                   | 57 ++++++----------------
>  drivers/pwm/pwm-atmel-tcb.c                        | 23 ++++++---
>  drivers/rtc/rtc-at91rm9200.c                       | 27 ++++++++--
>  drivers/watchdog/at91sam9_wdt.c                    | 22 ++++++++-
>  include/linux/atmel_tc.h                           |  1 +
>  24 files changed, 206 insertions(+), 129 deletions(-)
> 



-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

Re: [PATCH 00/23] ARM: at91: Properly handle slow clock

[Alexandre Belloni]

Hi,

On 31/07/2015 at 11:59:03 +0200, Boris Brezillon wrote :
> I would have squashed commit 5 to 14 into a single patch, but apart
> from that it looks good to me.
> 

I wanted to clearly list were the slow clock was needed for each soc. It
actually allowed me to find one that was missing.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

Re: [PATCH 00/23] ARM: at91: Properly handle slow clock

[Alexandre Belloni]

Hi,

I realize now that I forgot to add the v2 tag in the subject lines. This
is really v2 :)

On 31/07/2015 at 11:39:36 +0200, Alexandre Belloni wrote :
> Hi,
> 
> It was discovered that all the slow clock user were not properly claiming it.
> This can end up in a system hang because the last registered user is releasing
> it, and it gets disabled.
> 
> commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system hang")
> was a workaround. This series is adding the slow clock to the necessary drivers
> to avoid the issue and then removes that workaround.
> 
> The Documentation updates and DT patches should probably go through the AT91
> tree this cycle to avoid breakage.
> 
> Then the other patches can go through each subsystem tree. They are trivial
> enough to also go in this cycle.
> 
> The final clk patch depends on the other ones and may be taken for the next
> cycle to avoid synchronization issues.
> 
> I've thrown in a cleanup for at91-reset as it avoids adding support for that
> clock to the platform data initialization
> 
> Changes in v2:
>  - statisticize the global in the atmel-st change
>  - merge at91_reset_of_probe() in at91_reset_probe()
>  - added patches from Boris for the TCB
>  - added the slow clock to the TCB
> 
> Cc: Alessandro Zummo <a.zummo@towertech.it>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-clk@vger.kernel.org
> Cc: linux-pm@vger.kernel.org
> Cc: linux-pwm@vger.kernel.org
> Cc: linux-watchdog@vger.kernel.org
> Cc: Michael Turquette <mturquette@baylibre.com>
> Cc: rtc-linux@googlegroups.com
> Cc: Sebastian Reichel <sre@kernel.org>
> Cc: Stephen Boyd <sboyd@codeaurora.org>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Wim Van Sebroeck <wim@iguana.be>
> 
> Alexandre Belloni (20):
>   Documentation: dt: atmel-at91: add clocks to system timer, rstc and
>     shdwc
>   Documentation: watchdog: at91sam9_wdt: add clocks property
>   Documentation: dt: rtc: at91rm9200: add clocks property
>   ARM: at91/dt: at91rm9200: use slow clock where necessary
>   ARM: at91/dt: at91sam9260: use slow clock where necessary
>   ARM: at91/dt: at91sam9261: use slow clock where necessary
>   ARM: at91/dt: at91sam9263: use slow clock where necessary
>   ARM: at91/dt: at91sam9g45: use slow clock where necessary
>   ARM: at91/dt: at91sam9n12: use slow clock where necessary
>   ARM: at91/dt: at91sam9rl: use slow clock where necessary
>   ARM: at91/dt: at91sam9x5: use slow clock where necessary
>   ARM: at91/dt: sama5d3: use slow clock where necessary
>   ARM: at91/dt: sama5d4: use slow clock where necessary
>   rtc: at91rm9200: get and use slow clock
>   watchdog: at91sam9: get and use slow clock
>   power/reset: at91-reset: remove useless at91_reset_platform_probe()
>   power/reset: at91-reset: get and use slow clock
>   power/reset: at91-poweroff: get and use slow clock
>   clocksource: atmel-st: get and use slow clock
>   clk: at91: Revert "keep slow clk enabled to prevent system hang"
> 
> Boris Brezillon (3):
>   Documentation: dt: atmel-at91: add slow clock to tcb
>   clocksource: tcb_clksrc: fix setup_clkevents error path
>   misc: atmel_tclib: get and use slow clock
> 
>  .../devicetree/bindings/arm/atmel-at91.txt         | 13 +++--
>  .../bindings/rtc/atmel,at91rm9200-rtc.txt          |  2 +
>  .../devicetree/bindings/watchdog/atmel-wdt.txt     |  2 +
>  arch/arm/boot/dts/at91rm9200.dtsi                  | 10 ++--
>  arch/arm/boot/dts/at91sam9260.dtsi                 | 11 +++--
>  arch/arm/boot/dts/at91sam9261.dtsi                 |  7 ++-
>  arch/arm/boot/dts/at91sam9263.dtsi                 |  7 ++-
>  arch/arm/boot/dts/at91sam9g45.dtsi                 | 12 +++--
>  arch/arm/boot/dts/at91sam9n12.dtsi                 | 12 +++--
>  arch/arm/boot/dts/at91sam9rl.dtsi                  |  8 ++-
>  arch/arm/boot/dts/at91sam9x5.dtsi                  | 12 +++--
>  arch/arm/boot/dts/sama5d3.dtsi                     |  8 ++-
>  arch/arm/boot/dts/sama5d3_tcb1.dtsi                |  4 +-
>  arch/arm/boot/dts/sama5d4.dtsi                     | 12 +++--
>  drivers/clk/at91/clk-slow.c                        | 27 ----------
>  drivers/clocksource/tcb_clksrc.c                   | 10 +++-
>  drivers/clocksource/timer-atmel-st.c               | 31 ++++++++----
>  drivers/misc/atmel_tclib.c                         |  4 ++
>  drivers/power/reset/at91-poweroff.c                | 13 +++++
>  drivers/power/reset/at91-reset.c                   | 57 ++++++----------------
>  drivers/pwm/pwm-atmel-tcb.c                        | 23 ++++++---
>  drivers/rtc/rtc-at91rm9200.c                       | 27 ++++++++--
>  drivers/watchdog/at91sam9_wdt.c                    | 22 ++++++++-
>  include/linux/atmel_tc.h                           |  1 +
>  24 files changed, 206 insertions(+), 129 deletions(-)
> 
> -- 
> 2.1.4
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com