[PATCH 0/2] watchdog: aspeed: External reset signal properties

[PATCH 0/2] watchdog: aspeed: External reset signal properties

[Andrew Jeffery]

Hello,

This two-patch series builds on top of Chris Bostic's changes introducing the
aspeed,external-signal devicetree property (currently v5):

    https://lkml.org/lkml/2017/7/17/777

Additional characteristics such as pulse width, push-pull vs open-drain driving
and active high or low polarity can be configured. This short series defines
optional properties to do so, and adds support to the driver.

Cheers,

Andrew

Andrew Jeffery (2):
  dt-bindings: watchdog: aspeed: External reset signal properties
  watchdog: aspeed: Support configuration of external signal properties

 .../devicetree/bindings/watchdog/aspeed-wdt.txt    |  10 +-
 drivers/watchdog/aspeed_wdt.c                      | 105 ++++++++++++++++++++-
 2 files changed, 111 insertions(+), 4 deletions(-)

-- 
2.11.0

[PATCH 1/2] dt-bindings: watchdog: aspeed: External reset signal properties

[Andrew Jeffery]

For the AST2500 and compatible watchdog controllers the external reset
signal can be configured for push-pull or open-drain drive types, and in
the case of push-pull driving, active low or high.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
---
 Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
index 2b34ce9b60b9..c5077a1f5cb3 100644
--- a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
+++ b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
@@ -33,10 +33,18 @@ Optional properties:
         - none: No reset is performed on timeout. Assumes another watchdog
                 engine is responsible for this.
 
+ - aspeed,alt-boot:    If property is present then boot from alternate block.
  - aspeed,external-signal: If property is present then signal is sent to
 			external reset counter (only WDT1 and WDT2). If not
 			specified no external signal is sent.
- - aspeed,alt-boot:    If property is present then boot from alternate block.
+ - aspeed,ext-pulse-duration: External signal pulse duration in microseconds
+
+Optional properties for AST2500-compatible watchdogs:
+ - aspeed,ext-push-pull: If aspeed,external-signal is present, set the pin's
+			 drive type to push-pull. The default is open-drain.
+ - aspeed,ext-active-high: If aspeed,external-signal is present and and the pin
+			   is configured as push-pull, then set the pulse
+			   polarity to active-high. The default is active-low.
 
 Example:
 
-- 
2.11.0

[PATCH 2/2] watchdog: aspeed: Support configuration of external signal properties

[Andrew Jeffery]

Add support for configuring the drive strength and polarity on the
AST2500, and the pulse duration on both the AST2400 and AST2500.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Tested-by: Matt Spinler <mspinler@linux.vnet.ibm.com>
---
 drivers/watchdog/aspeed_wdt.c | 105 ++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 102 insertions(+), 3 deletions(-)

diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
index c707ab647922..79cc766cd30f 100644
--- a/drivers/watchdog/aspeed_wdt.c
+++ b/drivers/watchdog/aspeed_wdt.c
@@ -23,9 +23,21 @@ struct aspeed_wdt {
 	u32			ctrl;
 };
 
+struct aspeed_wdt_config {
+	u32 ext_pulse_width_mask;
+};
+
+static const struct aspeed_wdt_config ast2400_config = {
+	.ext_pulse_width_mask = 0xff,
+};
+
+static const struct aspeed_wdt_config ast2500_config = {
+	.ext_pulse_width_mask = 0xfffff,
+};
+
 static const struct of_device_id aspeed_wdt_of_table[] = {
-	{ .compatible = "aspeed,ast2400-wdt" },
-	{ .compatible = "aspeed,ast2500-wdt" },
+	{ .compatible = "aspeed,ast2400-wdt", .data = &ast2400_config },
+	{ .compatible = "aspeed,ast2500-wdt", .data = &ast2500_config },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
@@ -43,6 +55,38 @@ MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
 #define   WDT_CTRL_RESET_SYSTEM		BIT(1)
 #define   WDT_CTRL_ENABLE		BIT(0)
 
+/*
+ * WDT_RESET_WIDTH controls the characteristics of the external pulse (if
+ * enabled), specifically:
+ *
+ * * Pulse duration
+ * * Drive mode: push-pull vs open-drain
+ * * Polarity: Active high or active low
+ *
+ * Pulse duration configuration is available on both the AST2400 and AST2500,
+ * though the field changes between SoCs:
+ *
+ * AST2400: Bits 7:0
+ * AST2500: Bits 19:0
+ *
+ * This difference is captured in struct aspeed_wdt_config.
+ *
+ * The AST2500 exposes the drive mode and polarity options, but not in a
+ * regular fashion. For read purposes, bit 31 represents active high or low,
+ * and bit 30 represents push-pull or open-drain. With respect to write, magic
+ * values need to be written to the top byte to change the state of the drive
+ * mode and polarity bits. Any other value written to the top byte has no
+ * effect on the state of the drive mode or polarity bits. However, the pulse
+ * width value must be preserved (as desired) if written.
+ */
+#define WDT_RESET_WIDTH		0x18
+#define   WDT_RESET_WIDTH_ACTIVE_HIGH	BIT(31)
+#define     WDT_ACTIVE_HIGH_MAGIC	(0xA5 << 24)
+#define     WDT_ACTIVE_LOW_MAGIC	(0x5A << 24)
+#define   WDT_RESET_WIDTH_PUSH_PULL	BIT(30)
+#define     WDT_PUSH_PULL_MAGIC		(0xA8 << 24)
+#define     WDT_OPEN_DRAIN_MAGIC	(0x8A << 24)
+
 #define WDT_RESTART_MAGIC	0x4755
 
 /* 32 bits at 1MHz, in milliseconds */
@@ -139,10 +183,13 @@ static const struct watchdog_info aspeed_wdt_info = {
 
 static int aspeed_wdt_probe(struct platform_device *pdev)
 {
+	const struct aspeed_wdt_config *config;
+	const struct of_device_id *ofdid;
 	struct aspeed_wdt *wdt;
 	struct resource *res;
 	struct device_node *np;
 	const char *reset_type;
+	u32 duration;
 	int ret;
 
 	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
@@ -167,13 +214,19 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 	wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT;
 	watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
 
+	np = pdev->dev.of_node;
+
+	ofdid = of_match_node(aspeed_wdt_of_table, np);
+	if (!ofdid)
+		return -EINVAL;
+	config = ofdid->data;
+
 	wdt->ctrl = WDT_CTRL_1MHZ_CLK;
 
 	/*
 	 * Control reset on a per-device basis to ensure the
 	 * host is not affected by a BMC reboot
 	 */
-	np = pdev->dev.of_node;
 	ret = of_property_read_string(np, "aspeed,reset-type", &reset_type);
 	if (ret) {
 		wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM;
@@ -197,6 +250,52 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 		set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
 	}
 
+	if (of_device_is_compatible(np, "aspeed,ast2500-wdt")) {
+		u32 reg = readl(wdt->base + WDT_RESET_WIDTH);
+
+		reg &= config->ext_pulse_width_mask;
+		if (of_property_read_bool(np, "aspeed,ext-push-pull"))
+			reg |= WDT_PUSH_PULL_MAGIC;
+		else
+			reg |= WDT_OPEN_DRAIN_MAGIC;
+
+		writel(reg, wdt->base + WDT_RESET_WIDTH);
+
+		reg &= config->ext_pulse_width_mask;
+		if (of_property_read_bool(np, "aspeed,ext-active-high"))
+			reg |= WDT_ACTIVE_HIGH_MAGIC;
+		else
+			reg |= WDT_ACTIVE_LOW_MAGIC;
+
+		writel(reg, wdt->base + WDT_RESET_WIDTH);
+	}
+
+	if (!of_property_read_u32(np, "aspeed,ext-pulse-duration", &duration)) {
+		u32 max_duration = config->ext_pulse_width_mask + 1;
+
+		if (duration == 0 || duration > max_duration) {
+			dev_err(&pdev->dev, "Invalid pulse duration: %uus\n",
+					duration);
+			duration = max(1U, min(max_duration, duration));
+			dev_info(&pdev->dev, "Pulse duration set to %uus\n",
+					duration);
+		}
+
+		/*
+		 * The watchdog is always configured with a 1MHz source, so
+		 * there is no need to scale the microsecond value. However we
+		 * need to offset it - from the datasheet:
+		 *
+		 * "This register decides the asserting duration of wdt_ext and
+		 * wdt_rstarm signal. The default value is 0xFF. It means the
+		 * default asserting duration of wdt_ext and wdt_rstarm is
+		 * 256us."
+		 *
+		 * This implies a value of 0 gives a 1us pulse.
+		 */
+		writel(duration - 1, wdt->base + WDT_RESET_WIDTH);
+	}
+
 	ret = devm_watchdog_register_device(&pdev->dev, &wdt->wdd);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to register\n");
-- 
2.11.0

Re: [PATCH 1/2] dt-bindings: watchdog: aspeed: External reset signal properties

[Rob Herring]

On Wed, Aug 02, 2017 at 02:15:28PM +0930, Andrew Jeffery wrote:
> For the AST2500 and compatible watchdog controllers the external reset
> signal can be configured for push-pull or open-drain drive types, and in
> the case of push-pull driving, active low or high.
> 
> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> ---
>  Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)

Acked-by: Rob Herring <robh@kernel.org>

Re: [1/2] dt-bindings: watchdog: aspeed: External reset signal properties

[Guenter Roeck]

On Wed, Aug 02, 2017 at 02:15:28PM +0930, Andrew Jeffery wrote:
> For the AST2500 and compatible watchdog controllers the external reset
> signal can be configured for push-pull or open-drain drive types, and in
> the case of push-pull driving, active low or high.
> 
> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> Acked-by: Rob Herring <robh@kernel.org>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
>  Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> index 2b34ce9b60b9..c5077a1f5cb3 100644
> --- a/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> +++ b/Documentation/devicetree/bindings/watchdog/aspeed-wdt.txt
> @@ -33,10 +33,18 @@ Optional properties:
>          - none: No reset is performed on timeout. Assumes another watchdog
>                  engine is responsible for this.
>  
> + - aspeed,alt-boot:    If property is present then boot from alternate block.
>   - aspeed,external-signal: If property is present then signal is sent to
>  			external reset counter (only WDT1 and WDT2). If not
>  			specified no external signal is sent.
> - - aspeed,alt-boot:    If property is present then boot from alternate block.
> + - aspeed,ext-pulse-duration: External signal pulse duration in microseconds
> +
> +Optional properties for AST2500-compatible watchdogs:
> + - aspeed,ext-push-pull: If aspeed,external-signal is present, set the pin's
> +			 drive type to push-pull. The default is open-drain.
> + - aspeed,ext-active-high: If aspeed,external-signal is present and and the pin
> +			   is configured as push-pull, then set the pulse
> +			   polarity to active-high. The default is active-low.
>  
>  Example:
>  

Re: [2/2] watchdog: aspeed: Support configuration of external signal properties

[Guenter Roeck]

On Wed, Aug 02, 2017 at 02:15:29PM +0930, Andrew Jeffery wrote:
> Add support for configuring the drive strength and polarity on the
> AST2500, and the pulse duration on both the AST2400 and AST2500.
> 
> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> Tested-by: Matt Spinler <mspinler@linux.vnet.ibm.com>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
>  drivers/watchdog/aspeed_wdt.c | 105 ++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 102 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> index c707ab647922..79cc766cd30f 100644
> --- a/drivers/watchdog/aspeed_wdt.c
> +++ b/drivers/watchdog/aspeed_wdt.c
> @@ -23,9 +23,21 @@ struct aspeed_wdt {
>  	u32			ctrl;
>  };
>  
> +struct aspeed_wdt_config {
> +	u32 ext_pulse_width_mask;
> +};
> +
> +static const struct aspeed_wdt_config ast2400_config = {
> +	.ext_pulse_width_mask = 0xff,
> +};
> +
> +static const struct aspeed_wdt_config ast2500_config = {
> +	.ext_pulse_width_mask = 0xfffff,
> +};
> +
>  static const struct of_device_id aspeed_wdt_of_table[] = {
> -	{ .compatible = "aspeed,ast2400-wdt" },
> -	{ .compatible = "aspeed,ast2500-wdt" },
> +	{ .compatible = "aspeed,ast2400-wdt", .data = &ast2400_config },
> +	{ .compatible = "aspeed,ast2500-wdt", .data = &ast2500_config },
>  	{ },
>  };
>  MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
> @@ -43,6 +55,38 @@ MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
>  #define   WDT_CTRL_RESET_SYSTEM		BIT(1)
>  #define   WDT_CTRL_ENABLE		BIT(0)
>  
> +/*
> + * WDT_RESET_WIDTH controls the characteristics of the external pulse (if
> + * enabled), specifically:
> + *
> + * * Pulse duration
> + * * Drive mode: push-pull vs open-drain
> + * * Polarity: Active high or active low
> + *
> + * Pulse duration configuration is available on both the AST2400 and AST2500,
> + * though the field changes between SoCs:
> + *
> + * AST2400: Bits 7:0
> + * AST2500: Bits 19:0
> + *
> + * This difference is captured in struct aspeed_wdt_config.
> + *
> + * The AST2500 exposes the drive mode and polarity options, but not in a
> + * regular fashion. For read purposes, bit 31 represents active high or low,
> + * and bit 30 represents push-pull or open-drain. With respect to write, magic
> + * values need to be written to the top byte to change the state of the drive
> + * mode and polarity bits. Any other value written to the top byte has no
> + * effect on the state of the drive mode or polarity bits. However, the pulse
> + * width value must be preserved (as desired) if written.
> + */
> +#define WDT_RESET_WIDTH		0x18
> +#define   WDT_RESET_WIDTH_ACTIVE_HIGH	BIT(31)
> +#define     WDT_ACTIVE_HIGH_MAGIC	(0xA5 << 24)
> +#define     WDT_ACTIVE_LOW_MAGIC	(0x5A << 24)
> +#define   WDT_RESET_WIDTH_PUSH_PULL	BIT(30)
> +#define     WDT_PUSH_PULL_MAGIC		(0xA8 << 24)
> +#define     WDT_OPEN_DRAIN_MAGIC	(0x8A << 24)
> +
>  #define WDT_RESTART_MAGIC	0x4755
>  
>  /* 32 bits at 1MHz, in milliseconds */
> @@ -139,10 +183,13 @@ static const struct watchdog_info aspeed_wdt_info = {
>  
>  static int aspeed_wdt_probe(struct platform_device *pdev)
>  {
> +	const struct aspeed_wdt_config *config;
> +	const struct of_device_id *ofdid;
>  	struct aspeed_wdt *wdt;
>  	struct resource *res;
>  	struct device_node *np;
>  	const char *reset_type;
> +	u32 duration;
>  	int ret;
>  
>  	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> @@ -167,13 +214,19 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
>  	wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT;
>  	watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
>  
> +	np = pdev->dev.of_node;
> +
> +	ofdid = of_match_node(aspeed_wdt_of_table, np);
> +	if (!ofdid)
> +		return -EINVAL;
> +	config = ofdid->data;
> +
>  	wdt->ctrl = WDT_CTRL_1MHZ_CLK;
>  
>  	/*
>  	 * Control reset on a per-device basis to ensure the
>  	 * host is not affected by a BMC reboot
>  	 */
> -	np = pdev->dev.of_node;
>  	ret = of_property_read_string(np, "aspeed,reset-type", &reset_type);
>  	if (ret) {
>  		wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM;
> @@ -197,6 +250,52 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
>  		set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
>  	}
>  
> +	if (of_device_is_compatible(np, "aspeed,ast2500-wdt")) {
> +		u32 reg = readl(wdt->base + WDT_RESET_WIDTH);
> +
> +		reg &= config->ext_pulse_width_mask;
> +		if (of_property_read_bool(np, "aspeed,ext-push-pull"))
> +			reg |= WDT_PUSH_PULL_MAGIC;
> +		else
> +			reg |= WDT_OPEN_DRAIN_MAGIC;
> +
> +		writel(reg, wdt->base + WDT_RESET_WIDTH);
> +
> +		reg &= config->ext_pulse_width_mask;
> +		if (of_property_read_bool(np, "aspeed,ext-active-high"))
> +			reg |= WDT_ACTIVE_HIGH_MAGIC;
> +		else
> +			reg |= WDT_ACTIVE_LOW_MAGIC;
> +
> +		writel(reg, wdt->base + WDT_RESET_WIDTH);
> +	}
> +
> +	if (!of_property_read_u32(np, "aspeed,ext-pulse-duration", &duration)) {
> +		u32 max_duration = config->ext_pulse_width_mask + 1;
> +
> +		if (duration == 0 || duration > max_duration) {
> +			dev_err(&pdev->dev, "Invalid pulse duration: %uus\n",
> +					duration);
> +			duration = max(1U, min(max_duration, duration));
> +			dev_info(&pdev->dev, "Pulse duration set to %uus\n",
> +					duration);
> +		}
> +
> +		/*
> +		 * The watchdog is always configured with a 1MHz source, so
> +		 * there is no need to scale the microsecond value. However we
> +		 * need to offset it - from the datasheet:
> +		 *
> +		 * "This register decides the asserting duration of wdt_ext and
> +		 * wdt_rstarm signal. The default value is 0xFF. It means the
> +		 * default asserting duration of wdt_ext and wdt_rstarm is
> +		 * 256us."
> +		 *
> +		 * This implies a value of 0 gives a 1us pulse.
> +		 */
> +		writel(duration - 1, wdt->base + WDT_RESET_WIDTH);
> +	}
> +
>  	ret = devm_watchdog_register_device(&pdev->dev, &wdt->wdd);
>  	if (ret) {
>  		dev_err(&pdev->dev, "failed to register\n");