linux-kernel - [PATCH 2/3] watchdog: dw_wdt: get reset lines from dt

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Date:   Thu, 22 Sep 2016 09:02:31 +0200
From:   Steffen Trumtrar <s.trumtrar@...gutronix.de>
To:     linux-watchdog@...r.kernel.org
Cc:     kernel@...gutronix.de,
        Steffen Trumtrar <s.trumtrar@...gutronix.de>,
        Wim Van Sebroeck <wim@...ana.be>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] watchdog: dw_wdt: get reset lines from dt

The dw_wdt has an external reset line, that can keep the device in reset
and therefore rendering it useless and also is the only way of stopping
the watchdog once it was started.

Get the reset lines for this core from the devicetree.
If resets are not specified just warn but don't fail probing to be compatible
with all users.

Signed-off-by: Steffen Trumtrar <s.trumtrar@...gutronix.de>
Cc: Wim Van Sebroeck <wim@...ana.be>
Cc: Guenter Roeck <linux@...ck-us.net>
Cc: linux-watchdog@...r.kernel.org
---
 drivers/watchdog/dw_wdt.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
index 2acb51cf5504..e024722e8b3b 100644
--- a/drivers/watchdog/dw_wdt.c
+++ b/drivers/watchdog/dw_wdt.c
@@ -31,6 +31,7 @@
 #include <linux/pm.h>
 #include <linux/platform_device.h>
 #include <linux/reboot.h>
+#include <linux/reset.h>
 #include <linux/watchdog.h>
 
 #define WDOG_CONTROL_REG_OFFSET		    0x00
@@ -56,6 +57,7 @@ struct dw_wdt {
 	struct clk		*clk;
 	struct notifier_block	restart_handler;
 	struct watchdog_device	wdd;
+	struct reset_control	*rst;
 };
 
 #define to_dw_wdt(wdd)	container_of(wdd, struct dw_wdt, wdd)
@@ -231,6 +233,10 @@ static int dw_wdt_drv_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	dw_wdt->rst = devm_reset_control_get(&pdev->dev, "dw-wdt");
+	if (IS_ERR(dw_wdt->rst))
+		dev_warn(dev, "No reset lines. Will not be able to stop once started.\n");
+
 	wdd = &dw_wdt->wdd;
 	wdd->info = &dw_wdt_ident;
 	wdd->ops = &dw_wdt_ops;
@@ -268,6 +274,9 @@ static int dw_wdt_drv_probe(struct platform_device *pdev)
 	if (ret)
 		pr_warn("cannot register restart handler\n");
 
+	if (dw_wdt->rst)
+		reset_control_deassert(dw_wdt->rst);
+
 	return 0;
 
 out_disable_clk:
-- 
2.8.1