linux-kernel - [PATCH v3] watchdog: sunxi_wdt: Allow watchdog to remain enabled after probe

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Message-Id: <20250225143638.1989755-2-regis.dargent@gmail.com>
Date: Tue, 25 Feb 2025 15:36:38 +0100
From: Regis Dargent <regis.dargent@...il.com>
To: 
Cc: Regis Dargent <regis.dargent@...il.com>,
	Wim Van Sebroeck <wim@...ux-watchdog.org>,
	Guenter Roeck <linux@...ck-us.net>,
	Chen-Yu Tsai <wens@...e.org>,
	Jernej Skrabec <jernej.skrabec@...il.com>,
	Samuel Holland <samuel@...lland.org>,
	linux-watchdog@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-sunxi@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: [PATCH v3] watchdog: sunxi_wdt: Allow watchdog to remain enabled after probe

If the watchdog is already running during probe, let it run on, read its
configured timeout, and set its status so that it is correctly handled by the
kernel.

Signed-off-by: Regis Dargent <regis.dargent@...il.com>

--

Changelog v1..v2:
- add sunxi_wdt_read_timeout function
- add signed-off-by tag

Changelog v2..v3:
- WDIOF_SETTIMEOUT was set twice, and other code cleanup
---
 drivers/watchdog/sunxi_wdt.c | 45 ++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/sunxi_wdt.c b/drivers/watchdog/sunxi_wdt.c
index b85354a99582..d509dbcb77ce 100644
--- a/drivers/watchdog/sunxi_wdt.c
+++ b/drivers/watchdog/sunxi_wdt.c
@@ -140,6 +140,7 @@ static int sunxi_wdt_set_timeout(struct watchdog_device *wdt_dev,
 		timeout++;
 
 	sunxi_wdt->wdt_dev.timeout = timeout;
+	sunxi_wdt->wdt_dev.max_hw_heartbeat_ms = 0;
 
 	reg = readl(wdt_base + regs->wdt_mode);
 	reg &= ~(WDT_TIMEOUT_MASK << regs->wdt_timeout_shift);
@@ -152,6 +153,32 @@ static int sunxi_wdt_set_timeout(struct watchdog_device *wdt_dev,
 	return 0;
 }
 
+static int sunxi_wdt_read_timeout(struct watchdog_device *wdt_dev)
+{
+	struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
+	void __iomem *wdt_base = sunxi_wdt->wdt_base;
+	const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs;
+	int i;
+	u32 reg;
+
+	reg = readl(wdt_base + regs->wdt_mode);
+	reg >>= regs->wdt_timeout_shift;
+	reg &= WDT_TIMEOUT_MASK;
+
+	/* Start at 0 which actually means 0.5s */
+	for (i = 0; (i < WDT_MAX_TIMEOUT) && (wdt_timeout_map[i] != reg); i++)
+		;
+	if (i == 0) {
+		wdt_dev->timeout = 1;
+		wdt_dev->max_hw_heartbeat_ms = 500;
+	} else {
+		wdt_dev->timeout = i;
+		wdt_dev->max_hw_heartbeat_ms = 0;
+	}
+
+	return 0;
+}
+
 static int sunxi_wdt_stop(struct watchdog_device *wdt_dev)
 {
 	struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
@@ -192,6 +219,16 @@ static int sunxi_wdt_start(struct watchdog_device *wdt_dev)
 	return 0;
 }
 
+static bool sunxi_wdt_enabled(struct sunxi_wdt_dev *wdt)
+{
+	void __iomem *wdt_base = wdt->wdt_base;
+	const struct sunxi_wdt_reg *regs = wdt->wdt_regs;
+	u32 reg;
+
+	reg = readl(wdt_base + regs->wdt_mode);
+	return !!(reg & WDT_MODE_EN);
+}
+
 static const struct watchdog_info sunxi_wdt_info = {
 	.identity	= DRV_NAME,
 	.options	= WDIOF_SETTIMEOUT |
@@ -275,8 +312,12 @@ static int sunxi_wdt_probe(struct platform_device *pdev)
 
 	watchdog_set_drvdata(&sunxi_wdt->wdt_dev, sunxi_wdt);
 
-	sunxi_wdt_stop(&sunxi_wdt->wdt_dev);
-
+	if (sunxi_wdt_enabled(sunxi_wdt)) {
+		sunxi_wdt_read_timeout(&sunxi_wdt->wdt_dev);
+		set_bit(WDOG_HW_RUNNING, &sunxi_wdt->wdt_dev.status);
+	} else {
+		sunxi_wdt_stop(&sunxi_wdt->wdt_dev);
+	}
 	watchdog_stop_on_reboot(&sunxi_wdt->wdt_dev);
 	err = devm_watchdog_register_device(dev, &sunxi_wdt->wdt_dev);
 	if (unlikely(err))
-- 
2.25.1