linux-kernel - [PATCH 1/1] drivers: watchdog: stm32_iwdg: set WDOG_HW

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 21 Nov 2019 09:28:13 +0100
From:   Christophe Roullier <christophe.roullier@...com>
To:     <wim@...ux-watchdog.org>, <linux@...ck-us.net>,
        <mcoquelin.stm32@...il.com>, <alexandre.torgue@...com>
CC:     <linux-watchdog@...r.kernel.org>, <christophe.roullier@...com>,
        <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: [PATCH  1/1] drivers: watchdog: stm32_iwdg: set WDOG_HW_RUNNING at probe

If the watchdog hardware is already enabled during the boot process,
when the Linux watchdog driver loads, it should reset the watchdog and
tell the watchdog framework. As a result, ping can be generated from
the watchdog framework (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set),
until the userspace watchdog daemon takes over control

Fixes:4332d113c66a ("watchdog: Add STM32 IWDG driver")
Signed-off-by: Christophe Roullier <christophe.roullier@...com>
---
 drivers/watchdog/stm32_iwdg.c | 57 ++++++++++++++++++++++++-----------
 1 file changed, 40 insertions(+), 17 deletions(-)

diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c
index a3a329011a06..2b3be3b1c15b 100644
--- a/drivers/watchdog/stm32_iwdg.c
+++ b/drivers/watchdog/stm32_iwdg.c
@@ -87,8 +87,23 @@ static inline void reg_write(void __iomem *base, u32 reg, u32 val)
 static int stm32_iwdg_start(struct watchdog_device *wdd)
 {
 	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
-	u32 tout, presc, iwdg_rlr, iwdg_pr, iwdg_sr;
-	int ret;
+
+	dev_dbg(wdd->parent, "%s\n", __func__);
+
+	/*  Start the watchdog */
+	reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE);
+
+	/* reload watchdog */
+	reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
+
+	set_bit(WDOG_HW_RUNNING, &wdd->status);
+	return 0;
+}
+
+static int stm32_iwdg_setprescaler(struct watchdog_device *wdd)
+{
+	struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
+	u32 tout, presc, iwdg_rlr, iwdg_pr;
 
 	dev_dbg(wdd->parent, "%s\n", __func__);
 
@@ -108,19 +123,6 @@ static int stm32_iwdg_start(struct watchdog_device *wdd)
 	/* set prescaler & reload registers */
 	reg_write(wdt->regs, IWDG_PR, iwdg_pr);
 	reg_write(wdt->regs, IWDG_RLR, iwdg_rlr);
-	reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE);
-
-	/* wait for the registers to be updated (max 100ms) */
-	ret = readl_relaxed_poll_timeout(wdt->regs + IWDG_SR, iwdg_sr,
-					 !(iwdg_sr & (SR_PVU | SR_RVU)),
-					 SLEEP_US, TIMEOUT_US);
-	if (ret) {
-		dev_err(wdd->parent, "Fail to set prescaler, reload regs\n");
-		return ret;
-	}
-
-	/* reload watchdog */
-	reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
 
 	return 0;
 }
@@ -131,6 +133,9 @@ static int stm32_iwdg_ping(struct watchdog_device *wdd)
 
 	dev_dbg(wdd->parent, "%s\n", __func__);
 
+	/*  Start the watchdog */
+	reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE);
+
 	/* reload watchdog */
 	reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
 
@@ -140,12 +145,21 @@ static int stm32_iwdg_ping(struct watchdog_device *wdd)
 static int stm32_iwdg_set_timeout(struct watchdog_device *wdd,
 				  unsigned int timeout)
 {
+	int ret;
+
 	dev_dbg(wdd->parent, "%s timeout: %d sec\n", __func__, timeout);
 
 	wdd->timeout = timeout;
 
-	if (watchdog_active(wdd))
-		return stm32_iwdg_start(wdd);
+	if (watchdog_active(wdd)) {
+		ret = stm32_iwdg_setprescaler(wdd);
+		if (ret) {
+			dev_err(wdd->parent, "failed to set prescaler\n");
+			return ret;
+		} else {
+			return stm32_iwdg_start(wdd);
+		}
+	}
 
 	return 0;
 }
@@ -262,12 +276,21 @@ static int stm32_iwdg_probe(struct platform_device *pdev)
 	watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT);
 	watchdog_init_timeout(wdd, 0, dev);
 
+	/* Make sure the watchdog is serviced */
+	set_bit(WDOG_HW_RUNNING, &wdd->status);
+
 	ret = devm_watchdog_register_device(dev, wdd);
 	if (ret)
 		return ret;
 
 	platform_set_drvdata(pdev, wdt);
 
+	ret = stm32_iwdg_setprescaler(wdd);
+	if (ret) {
+		dev_err(dev, "failed to set prescaler\n");
+		return ret;
+	}
+
 	return 0;
 }
 
-- 
2.17.1