Commit fa01fa70 authored by Wolfram Sang's avatar Wolfram Sang Committed by Wim Van Sebroeck
Browse files

watchdog: renesas_wdt: don't sleep in atomic context 



In the restart handler, we hit multiple OOPSes. One because of
usleep_range() and one because of RPM. So, instead of re-using
rwdt_start(), we implement an atomic version of it in the restart
handler. As a little bonus, reboot will occur sooner because we can now
use the smallest divider in the custom restart routine.

Signed-off-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Reviewed-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: default avatarNiklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20201219173415.21848-1-wsa+renesas@sang-engineering.com


Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarWim Van Sebroeck <wim@linux-watchdog.org>
parent 17f0d1b9

drivers/watchdog/renesas_wdt.c

+24 −6
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#include <linux/clk.h>

#include <linux/delay.h>

#include <linux/io.h>

#include <linux/iopoll.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/of.h>
@@ -50,6 +51,7 @@ struct rwdt_priv { 
	struct watchdog_device wdev;

	unsigned long clk_rate;

	u8 cks;

	struct clk *clk;

};



static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg)
@@ -125,13 +127,30 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev) 
	return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);

}



/* needs to be atomic - no RPM, no usleep_range, no scheduling! */

static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,

			void *data)

{

	struct rwdt_priv *priv = watchdog_get_drvdata(wdev);

	u8 val;



	clk_prepare_enable(priv->clk);



	/* Stop the timer before we modify any register */

	val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME;

	rwdt_write(priv, val, RWTCSRA);

	/* Delay 2 cycles before setting watchdog counter */

	udelay(DIV_ROUND_UP(2 * 1000000, priv->clk_rate));



	rwdt_start(wdev);

	rwdt_write(priv, 0xffff, RWTCNT);

	/* smallest divider to reboot soon */

	rwdt_write(priv, 0, RWTCSRA);



	readb_poll_timeout_atomic(priv->base + RWTCSRA, val,

				  !(val & RWTCSRA_WRFLG), 1, 100);



	rwdt_write(priv, RWTCSRA_TME, RWTCSRA);



	return 0;

}
@@ -191,7 +210,6 @@ static int rwdt_probe(struct platform_device *pdev) 
{

	struct device *dev = &pdev->dev;

	struct rwdt_priv *priv;

	struct clk *clk;

	unsigned long clks_per_sec;

	int ret, i;

	u8 csra;
@@ -207,13 +225,13 @@ static int rwdt_probe(struct platform_device *pdev) 
	if (IS_ERR(priv->base))

		return PTR_ERR(priv->base);



	clk = devm_clk_get(dev, NULL);

	if (IS_ERR(clk))

		return PTR_ERR(clk);

	priv->clk = devm_clk_get(dev, NULL);

	if (IS_ERR(priv->clk))

		return PTR_ERR(priv->clk);



	pm_runtime_enable(dev);

	pm_runtime_get_sync(dev);

	priv->clk_rate = clk_get_rate(clk);

	priv->clk_rate = clk_get_rate(priv->clk);

	csra = readb_relaxed(priv->base + RWTCSRA);

	priv->wdev.bootstatus = csra & RWTCSRA_WOVF ? WDIOF_CARDRESET : 0;

	pm_runtime_put(dev);