Re: [v4, 2/2] drivers/watchdog: ASPEED reference dev tree properties for config

From: Christopher Bostic
Date: Mon Jul 10 2017 - 11:01:51 EST

On 7/8/17 9:55 AM, Guenter Roeck wrote:
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

Add optional property 'aspeed,external-signal'. If present then
configure to generate external signal on watchdog timeout.

Signed-off-by: Christopher Bostic <cbostic@xxxxxxxxxxxxxxxxxx>
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)
@@ -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 |
+ 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"))
+ 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".

Will add that check.
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


To match the original code, the default should be


Yes, true. Will make the change in line above to match original code.

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

No plan to support the other config flags at this time.


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