drivers: watchdog: qcom: Add timeout configuration support in watchdog

This patch enhances the Qualcomm watchdog driver by introducing
support for dynamic timeout configuration. Specifically:

- Calculates and sets the bark and bite timeout values based on
  the clock rate and the requested timeout in milliseconds.
- Adds retrieval of the watchdog clock rate during probe using
  the common clock framework.
- Adds a default timeout value for ARCH_SNAPDRAGON
  in WATCHDOG_TIMEOUT_MSECS.

These changes improve the configurability and accuracy of the
watchdog timer on Qualcomm platforms.

This work builds upon the previous submission:
https://lore.kernel.org/all/20250422-b4-qcom-wdt-v3-1-730d4d5a858d@paulsajna.com/

Signed-off-by: Balaji Selvanathan <balaji.selvanathan@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250527124926.128413-1-balaji.selvanathan@oss.qualcomm.com
Signed-off-by: Casey Connolly <casey.connolly@linaro.org>

2 files changed, 24 insertions, 2 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 38519add771..45eb9b4d3f9 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -29,6 +29,7 @@ config WATCHDOG_TIMEOUT_MSECS
 	int "Watchdog timeout in msec"
 	default 128000 if ARCH_MX31 || ARCH_MX5 || ARCH_MX6
 	default 128000 if ARCH_MX7 || ARCH_VF610
+	default 30000 if ARCH_SNAPDRAGON
 	default 30000 if ARCH_SOCFPGA
 	default 16000 if ARCH_SUNXI
 	default 5376 if ULP_WATCHDOG
@@ -338,6 +339,7 @@ endif
 config WDT_QCOM
 	bool "Qualcomm watchdog timer support"
 	depends on WDT && ARCH_SNAPDRAGON
+	imply WATCHDOG
 	help
 	  Select this to enable Qualcomm watchdog timer, which can be found on
 	  some Qualcomm chips.
diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
index 3601ba93774..adbb5aacdc3 100644
--- a/drivers/watchdog/qcom-wdt.c
+++ b/drivers/watchdog/qcom-wdt.c
@@ -13,6 +13,7 @@
 #include <dm.h>
 #include <dm/device_compat.h>
 #include <wdt.h>
+#include <clk.h>
 
 #include <asm/io.h>
 
@@ -30,6 +31,7 @@ struct qcom_wdt_match_data {
 
 struct qcom_wdt {
 	void __iomem *base;
+	ulong clk_rate;
 	const u32 *layout;
 };
 
@@ -53,10 +55,14 @@ static void __iomem *wdt_addr(struct qcom_wdt *wdt, enum wdt_reg reg)
 int qcom_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
 {
 	struct qcom_wdt *wdt = dev_get_priv(dev);
+	ulong bark_timeout_s = ((timeout_ms - 1)  * wdt->clk_rate) / 1000;
+	ulong bite_timeout_s = (timeout_ms * wdt->clk_rate) / 1000;
 
 	writel(0, wdt_addr(wdt, WDT_EN));
-	writel(1, wdt_addr(wdt, WDT_RST));
-	writel(1, wdt_addr(wdt, WDT_EN));
+	writel(BIT(0), wdt_addr(wdt, WDT_RST));
+	writel(bark_timeout_s, wdt_addr(wdt, WDT_BARK_TIME));
+	writel(bite_timeout_s, wdt_addr(wdt, WDT_BITE_TIME));
+	writel(BIT(0), wdt_addr(wdt, WDT_EN));
 	if (readl(wdt_addr(wdt, WDT_EN)) != 1) {
 		dev_err(dev, "Failed to enable Qualcomm watchdog!\n");
 		return -EIO;
@@ -87,12 +93,26 @@ int qcom_wdt_reset(struct udevice *dev)
 
 static int qcom_wdt_probe(struct udevice *dev)
 {
+	struct clk clk;
+	long rate;
+	int ret;
+
 	struct qcom_wdt *wdt = dev_get_priv(dev);
 	struct qcom_wdt_match_data *data = (void *)dev_get_driver_data(dev);
 
 	wdt->base = dev_read_addr_ptr(dev);
 	wdt->layout = data->offset;
 
+	ret = clk_get_by_index(dev, 0, &clk);
+	if (ret)
+		return ret;
+
+	rate = clk_get_rate(&clk);
+	if (rate <= 0)
+		return rate < 0 ? (int)rate : -EINVAL;
+
+	wdt->clk_rate = (ulong)rate;
+
 	return 0;
 }