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SubjectRe: [v4, 2/2] drivers/watchdog: ASPEED reference dev tree properties for config
On Thu, Jul 06, 2017 at 07:49:00PM -0500, Christopher Bostic wrote:
> Reference the system device tree when configuring the watchdog
> engines. If property 'aspeed,reset_type' is present then set
> reset behavior based on the specified value. This can be one of
> three different mutually exclusive values
> * cpu - Reset CPU only on watchdog timeout
> * soc - Reset System on Chip
> * system - Full system reset
>
> No reset can also be specified by indicating:
> * none - No reset, assumes another watchdog is responsible for
> this.
>
> Add optional property 'aspeed,external-signal'. If present then
> configure to generate external signal on watchdog timeout.
>
> Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>
> ---
> v4 - Change the three reset type parameters to a new property
> 'aspeed,reset_type' and check assignment for one of four
> different values, cpu, soc, system, none
> v3 - Invert the logic for system reset dev tree property to
> preserve backwards compatibility. If not specified the
> default is to configure for system reset
> - Add check for 'aspeed,no-soc-reset' property and only if
> not present is SOC reset to be configured. This preserves
> backwards compatibility.
> v2 - Change of_get_property() to of_property_read_bool()
> - Remove redundant check for NULL struct device_node pointer
> - Optional property names now start with prefix 'aspeed,'
> ---
> drivers/watchdog/aspeed_wdt.c | 27 ++++++++++++++++++++++-----
> 1 file changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> index 1c65258..3ca79565 100644
> --- a/drivers/watchdog/aspeed_wdt.c
> +++ b/drivers/watchdog/aspeed_wdt.c
> @@ -36,6 +36,7 @@ struct aspeed_wdt {
> #define WDT_CTRL 0x0C
> #define WDT_CTRL_RESET_MODE_SOC (0x00 << 5)
> #define WDT_CTRL_RESET_MODE_FULL_CHIP (0x01 << 5)
> +#define WDT_CTRL_RESET_MODE_ARM_CPU (0x10 << 5)
> #define WDT_CTRL_1MHZ_CLK BIT(4)
> #define WDT_CTRL_WDT_EXT BIT(3)
> #define WDT_CTRL_WDT_INTR BIT(2)
> @@ -140,6 +141,8 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> {
> struct aspeed_wdt *wdt;
> struct resource *res;
> + struct device_node *np;
> + const char *reset_type;
> int ret;
>
> wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> @@ -164,14 +167,28 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT;
> watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
>
> + wdt->ctrl = WDT_CTRL_1MHZ_CLK;
> +
> /*
> * Control reset on a per-device basis to ensure the
> - * host is not affected by a BMC reboot, so only reset
> - * the SOC and not the full chip
> + * host is not affected by a BMC reboot
> */
> - wdt->ctrl = WDT_CTRL_RESET_MODE_SOC |
> - WDT_CTRL_1MHZ_CLK |
> - WDT_CTRL_RESET_SYSTEM;
> + np = pdev->dev.of_node;
> + ret = of_property_read_string(np, "aspeed,reset-type", &reset_type);
> + if (ret) {
> + wdt->ctrl |= WDT_CTRL_RESET_SYSTEM;
> + } else {
> + if (!strcmp(reset_type, "cpu"))
> + wdt->ctrl |= WDT_CTRL_RESET_MODE_ARM_CPU;
> + else if (!strcmp(reset_type, "soc"))
> + wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC;
> + else if (!strcmp(reset_type, "system"))
> + wdt->ctrl |= WDT_CTRL_RESET_SYSTEM;

This silently accepts 'aspeed,reset-type="junk"' as "none".
I think it would be better to explicitly check for "none".

Also, if I remember the datasheet correctly, bit 1 (WDT_CTRL_RESET_SYSTEM)
enables the reset in general, and bit 5/6 specify the reset type.
With that in mind, I don't think the above will work as expected.
I think it would have to be

WDT_CTRL_RESET_MODE_FULL_CHIP | WDT_CTRL_RESET_SYSTEM
WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM
WDT_CTRL_RESET_MODE_ARM_CPU | WDT_CTRL_RESET_SYSTEM

To match the original code, the default should be

WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM

> + }
> + if (of_property_read_bool(np, "aspeed,external-signal"))
> + wdt->ctrl |= WDT_CTRL_WDT_EXT;
> +
No plan to support the other new configuration flags ?

> + writel(wdt->ctrl, wdt->base + WDT_CTRL);
>
> if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE) {
> aspeed_wdt_start(&wdt->wdd);

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