[PATCH v2 1/3] dt-bindings: Add Raspberry Pi compatible string for watchdog

[PATCH v2 1/3] dt-bindings: Add Raspberry Pi compatible string for watchdog

[Noralf Trønnes]

The Raspberry Pi has changed how its firmware detects a poweroff
and needs special handling for this.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---

v2: Fix typo in commit message


 Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt b/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt
index f801d71..1a80931 100644
--- a/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt
+++ b/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt
@@ -2,7 +2,8 @@ BCM2835 Watchdog timer

 Required properties:

-- compatible : should be "brcm,bcm2835-pm-wdt"
+- compatible : should be "brcm,raspberrypi-pm-wdt" for the Raspberry Pi and
+	       "brcm,bcm2835-pm-wdt" for others.
 - reg : Specifies base physical address and size of the registers.

 Optional properties:
--
2.2.2

[PATCH v2 2/3] watchdog: bcm2835: Add poweroff code for the Raspberry Pi

[Noralf Trønnes]

This adds a new poweroff function to the watchdog driver for the
Raspberry Pi. Currently poweroff/halt results in a reboot.

The Raspberry Pi firmware uses the RSTS register to know which
partiton to boot from. The partiton value is spread into bits
0, 2, 4, 6, 8, 10. Partiton 63 is a special partition used by
the firmware to indicate halt.

The firmware made this change in 19 Aug 2013 and was matched
by the downstream commit:
Changes for new NOOBS multi partition booting from gsh

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/watchdog/bcm2835_wdt.c | 38 ++++++++++++++++++++++++++++++++++----
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c
index 7116968..fdf0d7d 100644
--- a/drivers/watchdog/bcm2835_wdt.c
+++ b/drivers/watchdog/bcm2835_wdt.c
@@ -36,6 +36,13 @@
 #define PM_RSTC_WRCFG_FULL_RESET	0x00000020
 #define PM_RSTC_RESET			0x00000102
 
+/*
+ * The Raspberry Pi firmware uses the RSTS register to know which partiton
+ * to boot from. The partiton value is spread into bits 0, 2, 4, 6, 8, 10.
+ * Partiton 63 is a special partition used by the firmware to indicate halt.
+ */
+#define PM_RSTS_RASPBERRYPI_HALT	0x555
+
 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
 
@@ -159,6 +166,24 @@ static void bcm2835_power_off(void)
 	bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL);
 }
 
+static void rpi_power_off(void)
+{
+	struct device_node *np =
+		of_find_compatible_node(NULL, NULL, "brcm,raspberrypi-pm-wdt");
+	struct platform_device *pdev = of_find_device_by_node(np);
+	struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
+	u32 val;
+
+	val = readl_relaxed(wdt->base + PM_RSTS);
+	val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
+	writel_relaxed(val, wdt->base + PM_RSTS);
+
+	/* Continue with normal reset mechanism */
+	bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL);
+}
+
+static const struct of_device_id bcm2835_wdt_of_match[];
+
 static int bcm2835_wdt_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -192,8 +217,12 @@ static int bcm2835_wdt_probe(struct platform_device *pdev)
 	wdt->restart_handler.notifier_call = bcm2835_restart;
 	wdt->restart_handler.priority = 128;
 	register_restart_handler(&wdt->restart_handler);
-	if (pm_power_off == NULL)
-		pm_power_off = bcm2835_power_off;
+	if (!pm_power_off) {
+		const struct of_device_id *match;
+
+		match = of_match_node(bcm2835_wdt_of_match, pdev->dev.of_node);
+		pm_power_off = match->data;
+	}
 
 	dev_info(dev, "Broadcom BCM2835 watchdog timer");
 	return 0;
@@ -204,7 +233,7 @@ static int bcm2835_wdt_remove(struct platform_device *pdev)
 	struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 
 	unregister_restart_handler(&wdt->restart_handler);
-	if (pm_power_off == bcm2835_power_off)
+	if (pm_power_off == bcm2835_power_off || pm_power_off == rpi_power_off)
 		pm_power_off = NULL;
 	watchdog_unregister_device(&bcm2835_wdt_wdd);
 	iounmap(wdt->base);
@@ -218,7 +247,8 @@ static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 }
 
 static const struct of_device_id bcm2835_wdt_of_match[] = {
-	{ .compatible = "brcm,bcm2835-pm-wdt", },
+	{ .compatible = "brcm,bcm2835-pm-wdt", .data = bcm2835_power_off },
+	{ .compatible = "brcm,raspberrypi-pm-wdt", .data = rpi_power_off },
 	{},
 };
 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
-- 
2.2.2

[PATCH v2 3/3] ARM: dts: bcm2835-rpi: Add "brcm,raspberrypi-pm-wdt" to wdt compatible

[Noralf Trønnes]

The Raspberry Pi uses a new value for halt in the PM_RSTS watchdog
register. Expand the compatible string to cover this.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 arch/arm/boot/dts/bcm2835-rpi.dtsi | 4 ++++
 arch/arm/boot/dts/bcm2835.dtsi     | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/bcm2835-rpi.dtsi b/arch/arm/boot/dts/bcm2835-rpi.dtsi
index 46780bb..feb1282 100644
--- a/arch/arm/boot/dts/bcm2835-rpi.dtsi
+++ b/arch/arm/boot/dts/bcm2835-rpi.dtsi
@@ -16,6 +16,10 @@
 	};
 };
 
+&watchdog {
+	compatible = "brcm,raspberrypi-pm-wdt", "brcm,bcm2835-pm-wdt";
+};
+
 &gpio {
 	pinctrl-names = "default";
 
diff --git a/arch/arm/boot/dts/bcm2835.dtsi b/arch/arm/boot/dts/bcm2835.dtsi
index 301c73f..3445bb3 100644
--- a/arch/arm/boot/dts/bcm2835.dtsi
+++ b/arch/arm/boot/dts/bcm2835.dtsi
@@ -52,7 +52,7 @@
 			#interrupt-cells = <2>;
 		};
 
-		watchdog@7e100000 {
+		watchdog: watchdog@7e100000 {
 			compatible = "brcm,bcm2835-pm-wdt";
 			reg = <0x7e100000 0x28>;
 		};
-- 
2.2.2

Re: [PATCH v2 2/3] watchdog: bcm2835: Add poweroff code for the Raspberry Pi

[Stephen Warren]

On 06/13/2015 05:39 AM, Noralf Trønnes wrote:
> This adds a new poweroff function to the watchdog driver for the
> Raspberry Pi. Currently poweroff/halt results in a reboot.
> 
> The Raspberry Pi firmware uses the RSTS register to know which
> partiton to boot from. The partiton value is spread into bits
> 0, 2, 4, 6, 8, 10. Partiton 63 is a special partition used by
> the firmware to indicate halt.
> 
> The firmware made this change in 19 Aug 2013 and was matched
> by the downstream commit:
> Changes for new NOOBS multi partition booting from gsh

I don't understand why we need a new compatible value here; why not
simply modify the existing bcm2835_power_off() function. That is written
to do something that's interpreted by the RPi firmware, not something
that the bcm2835 HW does.

Admittedly the current name is a bit misleading, but fixing that should
be a separate change to fixing the implementation to do what the current
firmware expects.

Re: [PATCH v2 3/3] ARM: dts: bcm2835-rpi: Add "brcm,raspberrypi-pm-wdt" to wdt compatible

[Stephen Warren]

On 06/13/2015 05:39 AM, Noralf Trønnes wrote:
> The Raspberry Pi uses a new value for halt in the PM_RSTS watchdog
> register. Expand the compatible string to cover this.

FWIW, the series,
Tested-by: Stephen Warren <swarren@wwwdotorg.org>

... but that doesn't imply my ack for the patches.

Re: [PATCH v2 2/3] watchdog: bcm2835: Add poweroff code for the Raspberry Pi

[Noralf Trønnes]

Den 16.06.2015 05:07, skrev Stephen Warren:
> On 06/13/2015 05:39 AM, Noralf Trønnes wrote:
>> This adds a new poweroff function to the watchdog driver for the
>> Raspberry Pi. Currently poweroff/halt results in a reboot.
>>
>> The Raspberry Pi firmware uses the RSTS register to know which
>> partiton to boot from. The partiton value is spread into bits
>> 0, 2, 4, 6, 8, 10. Partiton 63 is a special partition used by
>> the firmware to indicate halt.
>>
>> The firmware made this change in 19 Aug 2013 and was matched
>> by the downstream commit:
>> Changes for new NOOBS multi partition booting from gsh
> I don't understand why we need a new compatible value here; why not
> simply modify the existing bcm2835_power_off() function. That is written
> to do something that's interpreted by the RPi firmware, not something
> that the bcm2835 HW does.
>
> Admittedly the current name is a bit misleading, but fixing that should
> be a separate change to fixing the implementation to do what the current
> firmware expects.

There are other boards that use the BCM2835 and I didn't want to break the
behaviour for those that use the reference firmware. Roku 2 device uses
this soc, and changing bcm2835_power_off() would break support for it.
ODROID-W also use BCM2835, but this is a Pi clone so I don't know if they
have matched their firmware behaviour to that of the Pi (admittedly not
many boards were made, their source of chips went dry).

Re: [PATCH v2 2/3] watchdog: bcm2835: Add poweroff code for the Raspberry Pi

[Stephen Warren]

On 06/16/2015 03:39 AM, Noralf Trønnes wrote:
> 
> Den 16.06.2015 05:07, skrev Stephen Warren:
>> On 06/13/2015 05:39 AM, Noralf Trønnes wrote:
>>> This adds a new poweroff function to the watchdog driver for the
>>> Raspberry Pi. Currently poweroff/halt results in a reboot.
>>>
>>> The Raspberry Pi firmware uses the RSTS register to know which
>>> partiton to boot from. The partiton value is spread into bits
>>> 0, 2, 4, 6, 8, 10. Partiton 63 is a special partition used by
>>> the firmware to indicate halt.
>>>
>>> The firmware made this change in 19 Aug 2013 and was matched
>>> by the downstream commit:
>>> Changes for new NOOBS multi partition booting from gsh
>> I don't understand why we need a new compatible value here; why not
>> simply modify the existing bcm2835_power_off() function. That is written
>> to do something that's interpreted by the RPi firmware, not something
>> that the bcm2835 HW does.
>>
>> Admittedly the current name is a bit misleading, but fixing that should
>> be a separate change to fixing the implementation to do what the current
>> firmware expects.
> 
> There are other boards that use the BCM2835 and I didn't want to break the
> behaviour for those that use the reference firmware.

We don't support those other board in mainline Linux AFAIK. In other
discussions, Eric Anholt stated that the Roku 2 for example doesn't use
the same firmware (albeit they were derived from the same base a long
way back apparently) so I have no good reason to believe this logic is a
standard across difference bcm2835 devices. Do you know more specific
details?

> Roku 2 device uses
> this soc, and changing bcm2835_power_off() would break support for it.
> ODROID-W also use BCM2835, but this is a Pi clone so I don't know if they
> have matched their firmware behaviour to that of the Pi (admittedly not
> many boards were made, their source of chips went dry).

Re: [PATCH v2 2/3] watchdog: bcm2835: Add poweroff code for the Raspberry Pi

[Noralf Trønnes]

Den 17.06.2015 03:28, skrev Stephen Warren:
> On 06/16/2015 03:39 AM, Noralf Trønnes wrote:
>> Den 16.06.2015 05:07, skrev Stephen Warren:
>>> On 06/13/2015 05:39 AM, Noralf Trønnes wrote:
>>>> This adds a new poweroff function to the watchdog driver for the
>>>> Raspberry Pi. Currently poweroff/halt results in a reboot.
>>>>
>>>> The Raspberry Pi firmware uses the RSTS register to know which
>>>> partiton to boot from. The partiton value is spread into bits
>>>> 0, 2, 4, 6, 8, 10. Partiton 63 is a special partition used by
>>>> the firmware to indicate halt.
>>>>
>>>> The firmware made this change in 19 Aug 2013 and was matched
>>>> by the downstream commit:
>>>> Changes for new NOOBS multi partition booting from gsh
>>> I don't understand why we need a new compatible value here; why not
>>> simply modify the existing bcm2835_power_off() function. That is written
>>> to do something that's interpreted by the RPi firmware, not something
>>> that the bcm2835 HW does.
>>>
>>> Admittedly the current name is a bit misleading, but fixing that should
>>> be a separate change to fixing the implementation to do what the current
>>> firmware expects.
>> There are other boards that use the BCM2835 and I didn't want to break the
>> behaviour for those that use the reference firmware.
> We don't support those other board in mainline Linux AFAIK. In other
> discussions, Eric Anholt stated that the Roku 2 for example doesn't use
> the same firmware (albeit they were derived from the same base a long
> way back apparently) so I have no good reason to believe this logic is a
> standard across difference bcm2835 devices. Do you know more specific
> details?

I didn't know that only Raspberry Pi was supported and I have no details 
about
the other boards. I'll send a new patch. Thanks.