Commit 057b52b4 authored by Marco Felsch's avatar Marco Felsch Committed by Wim Van Sebroeck

watchdog: da9062: make restart handler atomic safe

The restart handler is executed during the shutdown phase which is
atomic/irq-less. The i2c framework supports atomic transfers since
commit 63b96983 ("i2c: core: introduce callbacks for atomic
transfers") to address this use case. Using regmap within an atomic
context is allowed only if the regmap type is MMIO and the cache type
'flat' or no cache is used. Using the i2c_smbus_write_byte_data()
function can be done without additional tests because:
 1) the DA9062 is an i2c-only device and
 2) the i2c framework emulates the smbus protocol if the host adapter
    does not support smbus_xfer by using the master_xfer.
Signed-off-by: default avatarMarco Felsch <m.felsch@pengutronix.de>
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Reviewed-by: default avatarStefan Lengfeld <contact@stefanchrist.eu>
Tested-by: default avatarStefan Lengfeld <contact@stefanchrist.eu>
Reviewed-by: default avatarAdam Thomson <Adam.Thomson.Opensource@diasemi.com>
Link: https://lore.kernel.org/r/20200115162307.7336-1-m.felsch@pengutronix.deSigned-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarWim Van Sebroeck <wim@linux-watchdog.org>
parent 9e5236e7
...@@ -11,6 +11,7 @@ ...@@ -11,6 +11,7 @@
#include <linux/platform_device.h> #include <linux/platform_device.h>
#include <linux/uaccess.h> #include <linux/uaccess.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/delay.h> #include <linux/delay.h>
#include <linux/jiffies.h> #include <linux/jiffies.h>
#include <linux/mfd/da9062/registers.h> #include <linux/mfd/da9062/registers.h>
...@@ -147,12 +148,13 @@ static int da9062_wdt_restart(struct watchdog_device *wdd, unsigned long action, ...@@ -147,12 +148,13 @@ static int da9062_wdt_restart(struct watchdog_device *wdd, unsigned long action,
void *data) void *data)
{ {
struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd); struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
struct i2c_client *client = to_i2c_client(wdt->hw->dev);
int ret; int ret;
ret = regmap_write(wdt->hw->regmap, /* Don't use regmap because it is not atomic safe */
DA9062AA_CONTROL_F, ret = i2c_smbus_write_byte_data(client, DA9062AA_CONTROL_F,
DA9062AA_SHUTDOWN_MASK); DA9062AA_SHUTDOWN_MASK);
if (ret) if (ret < 0)
dev_alert(wdt->hw->dev, "Failed to shutdown (err = %d)\n", dev_alert(wdt->hw->dev, "Failed to shutdown (err = %d)\n",
ret); ret);
......
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