linux-kernel - [PATCH 1/4] watchdog: aspeed: Retain watchdog enabled state

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Date:   Mon, 18 Sep 2017 15:19:02 +0930
From:   Andrew Jeffery <andrew@...id.au>
To:     linux-watchdog@...r.kernel.org
Cc:     Andrew Jeffery <andrew@...id.au>, wim@...ana.be,
        linux@...ck-us.net, joel@....id.au, linux-kernel@...r.kernel.org,
        openbmc@...ts.ozlabs.org, linux-aspeed@...ts.ozlabs.org,
        ryan_chen@...eedtech.com
Subject: [PATCH 1/4] watchdog: aspeed: Retain watchdog enabled state

An unintended post-condition of probe() is that the watchdog is
disabled. Rework probe() such that we retain the value of the "enabled"
bit from the control register, and take the appropriate actions with
respect to the watchdog core if so. Otherwise, just configure the
watchdog as directed.

Signed-off-by: Andrew Jeffery <andrew@...id.au>
---
 drivers/watchdog/aspeed_wdt.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
index 79cc766cd30f..99bc6fbd8852 100644
--- a/drivers/watchdog/aspeed_wdt.c
+++ b/drivers/watchdog/aspeed_wdt.c
@@ -221,7 +221,8 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 		return -EINVAL;
 	config = ofdid->data;
 
-	wdt->ctrl = WDT_CTRL_1MHZ_CLK;
+	wdt->ctrl |= readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE;
+	wdt->ctrl |= WDT_CTRL_1MHZ_CLK;
 
 	/*
 	 * Control reset on a per-device basis to ensure the
@@ -243,11 +244,11 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 	if (of_property_read_bool(np, "aspeed,external-signal"))
 		wdt->ctrl |= WDT_CTRL_WDT_EXT;
 
-	writel(wdt->ctrl, wdt->base + WDT_CTRL);
-
-	if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE)  {
+	if (wdt->ctrl & WDT_CTRL_ENABLE) {
 		aspeed_wdt_start(&wdt->wdd);
 		set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
+	} else {
+		writel(wdt->ctrl, wdt->base + WDT_CTRL);
 	}
 
 	if (of_device_is_compatible(np, "aspeed,ast2500-wdt")) {
-- 
2.11.0