[PATCH] watchdog: aspeed: Fix clock behaviour for ast2600

[Joel Stanley]

The ast2600 no longer uses bit 4 in the control register to indicate a
1MHz clock (It now controls weather this watchdog is reset by a SOC
reset). This means we do not want to set it. It also does not need to be
set for the ast2500, as it is read-only on that SoC.

The comment next to the clock rate selection wandered away from where it
was set, so put it back next to the register setting it's describing.

Fixes: b3528b487448 ("watchdog: aspeed: Add support for AST2600")
Signed-off-by: Joel Stanley <joel at jms.id.au>
---
 drivers/watchdog/aspeed_wdt.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
index 4ec0906bf12c..7e00960651fa 100644
--- a/drivers/watchdog/aspeed_wdt.c
+++ b/drivers/watchdog/aspeed_wdt.c
@@ -258,11 +258,6 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 	if (IS_ERR(wdt->base))
 		return PTR_ERR(wdt->base);
 
-	/*
-	 * The ast2400 wdt can run at PCLK, or 1MHz. The ast2500 only
-	 * runs at 1MHz. We chose to always run at 1MHz, as there's no
-	 * good reason to have a faster watchdog counter.
-	 */
 	wdt->wdd.info = &aspeed_wdt_info;
 	wdt->wdd.ops = &aspeed_wdt_ops;
 	wdt->wdd.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT_MS;
@@ -278,7 +273,16 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 		return -EINVAL;
 	config = ofdid->data;
 
-	wdt->ctrl = WDT_CTRL_1MHZ_CLK;
+	/*
+	 * On clock rates:
+	 *  - ast2400 wdt can run at PCLK, or 1MHz
+	 *  - ast2500 only runs at 1MHz, hard coding bit 4 to 1
+	 *  - ast2600 always runs at 1MHz
+	 *
+	 * Set the ast2400 to run at 1MHz as it simplifies the driver.
+	 */
+	if (of_device_is_compatible(np, "aspeed,ast2400-wdt"))
+		wdt->ctrl = WDT_CTRL_1MHZ_CLK;
 
 	/*
 	 * Control reset on a per-device basis to ensure the
-- 
2.24.0.rc1