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watchdog: renesas_wdt: don't sleep in atomic context

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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: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20201219173415.21848-1-wsa+renesas@sang-engineering.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
This commit is contained in:
Wolfram Sang 2020-12-19 18:34:15 +01:00 committed by Wim Van Sebroeck
parent 17f0d1b9bd
commit fa01fa7003
1 changed files with 24 additions and 6 deletions

30
drivers/watchdog/renesas_wdt.c
View File

@ -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);