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linux/drivers/watchdog/da9062_wdt.c
Primoz Fiser f8ee39b44b watchdog: da9062: da9063: use unlocked xfer function in restart 
Machine resets via da9062/da9063 PMICs are challenging since one needs
to use special i2c atomic transfers due to the fact interrupts are
disabled in such late system stages. This is the reason both PMICs don't
use regmap and have instead opted for i2c_smbus_write_byte_data() in
restart handlers.

However extensive testing revealed that even using atomic safe function
is not enough and occasional resets fail with error message "Failed to
shutdown (err =  -11)". This is due to the fact that function
i2c_smbus_write_byte_data() in turn calls __i2c_lock_bus_helper()
which might fail with -EAGAIN when bus lock is already taken and cannot
be released anymore.

Thus replace i2c_smbus_write_byte_data() with unlocked flavor of
i2c_smbus_xfer() function to avoid above dead-lock scenario. At this
system stage we don't care about proper locking anymore and only want
proper machine reset to be carried out.

Signed-off-by: Primoz Fiser <primoz.fiser@norik.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20221216083645.2574077-1-primoz.fiser@norik.com
[groeck: Fixed continuation line alignment]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
2023-02-18 15:11:30 +01:00

296 lines
7.4 KiB
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// SPDX-License-Identifier: GPL-2.0+
/*
* Watchdog device driver for DA9062 and DA9061 PMICs
* Copyright (C) 2015 Dialog Semiconductor Ltd.
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/mfd/da9062/registers.h>
#include <linux/mfd/da9062/core.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/of.h>
static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 };
#define DA9062_TWDSCALE_DISABLE 0
#define DA9062_TWDSCALE_MIN 1
#define DA9062_TWDSCALE_MAX (ARRAY_SIZE(wdt_timeout) - 1)
#define DA9062_WDT_MIN_TIMEOUT wdt_timeout[DA9062_TWDSCALE_MIN]
#define DA9062_WDT_MAX_TIMEOUT wdt_timeout[DA9062_TWDSCALE_MAX]
#define DA9062_WDG_DEFAULT_TIMEOUT wdt_timeout[DA9062_TWDSCALE_MAX-1]
#define DA9062_RESET_PROTECTION_MS 300
struct da9062_watchdog {
struct da9062 *hw;
struct watchdog_device wdtdev;
bool use_sw_pm;
};
static unsigned int da9062_wdt_read_timeout(struct da9062_watchdog *wdt)
{
unsigned int val;
regmap_read(wdt->hw->regmap, DA9062AA_CONTROL_D, &val);
return wdt_timeout[val & DA9062AA_TWDSCALE_MASK];
}
static unsigned int da9062_wdt_timeout_to_sel(unsigned int secs)
{
unsigned int i;
for (i = DA9062_TWDSCALE_MIN; i <= DA9062_TWDSCALE_MAX; i++) {
if (wdt_timeout[i] >= secs)
return i;
}
return DA9062_TWDSCALE_MAX;
}
static int da9062_reset_watchdog_timer(struct da9062_watchdog *wdt)
{
return regmap_update_bits(wdt->hw->regmap, DA9062AA_CONTROL_F,
DA9062AA_WATCHDOG_MASK,
DA9062AA_WATCHDOG_MASK);
}
static int da9062_wdt_update_timeout_register(struct da9062_watchdog *wdt,
unsigned int regval)
{
struct da9062 *chip = wdt->hw;
regmap_update_bits(chip->regmap,
DA9062AA_CONTROL_D,
DA9062AA_TWDSCALE_MASK,
DA9062_TWDSCALE_DISABLE);
usleep_range(150, 300);
return regmap_update_bits(chip->regmap,
DA9062AA_CONTROL_D,
DA9062AA_TWDSCALE_MASK,
regval);
}
static int da9062_wdt_start(struct watchdog_device *wdd)
{
struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
unsigned int selector;
int ret;
selector = da9062_wdt_timeout_to_sel(wdt->wdtdev.timeout);
ret = da9062_wdt_update_timeout_register(wdt, selector);
if (ret)
dev_err(wdt->hw->dev, "Watchdog failed to start (err = %d)\n",
ret);
return ret;
}
static int da9062_wdt_stop(struct watchdog_device *wdd)
{
struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
int ret;
ret = regmap_update_bits(wdt->hw->regmap,
DA9062AA_CONTROL_D,
DA9062AA_TWDSCALE_MASK,
DA9062_TWDSCALE_DISABLE);
if (ret)
dev_err(wdt->hw->dev, "Watchdog failed to stop (err = %d)\n",
ret);
return ret;
}
static int da9062_wdt_ping(struct watchdog_device *wdd)
{
struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
int ret;
/*
* Prevent pings from occurring late in system poweroff/reboot sequence
* and possibly locking out restart handler from accessing i2c bus.
*/
if (system_state > SYSTEM_RUNNING)
return 0;
ret = da9062_reset_watchdog_timer(wdt);
if (ret)
dev_err(wdt->hw->dev, "Failed to ping the watchdog (err = %d)\n",
ret);
return ret;
}
static int da9062_wdt_set_timeout(struct watchdog_device *wdd,
unsigned int timeout)
{
struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
unsigned int selector;
int ret;
selector = da9062_wdt_timeout_to_sel(timeout);
ret = da9062_wdt_update_timeout_register(wdt, selector);
if (ret)
dev_err(wdt->hw->dev, "Failed to set watchdog timeout (err = %d)\n",
ret);
else
wdd->timeout = wdt_timeout[selector];
return ret;
}
static int da9062_wdt_restart(struct watchdog_device *wdd, unsigned long action,
void *data)
{
struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
struct i2c_client *client = to_i2c_client(wdt->hw->dev);
union i2c_smbus_data msg;
int ret;
/*
* Don't use regmap because it is not atomic safe. Additionally, use
* unlocked flavor of i2c_smbus_xfer to avoid scenario where i2c bus
* might be previously locked by some process unable to release the
* lock due to interrupts already being disabled at this late stage.
*/
msg.byte = DA9062AA_SHUTDOWN_MASK;
ret = __i2c_smbus_xfer(client->adapter, client->addr, client->flags,
I2C_SMBUS_WRITE, DA9062AA_CONTROL_F,
I2C_SMBUS_BYTE_DATA, &msg);
if (ret < 0)
dev_alert(wdt->hw->dev, "Failed to shutdown (err = %d)\n",
ret);
/* wait for reset to assert... */
mdelay(500);
return ret;
}
static const struct watchdog_info da9062_watchdog_info = {
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
.identity = "DA9062 WDT",
};
static const struct watchdog_ops da9062_watchdog_ops = {
.owner = THIS_MODULE,
.start = da9062_wdt_start,
.stop = da9062_wdt_stop,
.ping = da9062_wdt_ping,
.set_timeout = da9062_wdt_set_timeout,
.restart = da9062_wdt_restart,
};
static const struct of_device_id da9062_compatible_id_table[] = {
{ .compatible = "dlg,da9062-watchdog", },
{ },
};
MODULE_DEVICE_TABLE(of, da9062_compatible_id_table);
static int da9062_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
unsigned int timeout;
struct da9062 *chip;
struct da9062_watchdog *wdt;
chip = dev_get_drvdata(dev->parent);
if (!chip)
return -EINVAL;
wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
if (!wdt)
return -ENOMEM;
wdt->use_sw_pm = device_property_present(dev, "dlg,use-sw-pm");
wdt->hw = chip;
wdt->wdtdev.info = &da9062_watchdog_info;
wdt->wdtdev.ops = &da9062_watchdog_ops;
wdt->wdtdev.min_timeout = DA9062_WDT_MIN_TIMEOUT;
wdt->wdtdev.max_timeout = DA9062_WDT_MAX_TIMEOUT;
wdt->wdtdev.min_hw_heartbeat_ms = DA9062_RESET_PROTECTION_MS;
wdt->wdtdev.timeout = DA9062_WDG_DEFAULT_TIMEOUT;
wdt->wdtdev.status = WATCHDOG_NOWAYOUT_INIT_STATUS;
wdt->wdtdev.parent = dev;
watchdog_set_restart_priority(&wdt->wdtdev, 128);
watchdog_set_drvdata(&wdt->wdtdev, wdt);
dev_set_drvdata(dev, &wdt->wdtdev);
timeout = da9062_wdt_read_timeout(wdt);
if (timeout)
wdt->wdtdev.timeout = timeout;
/* Set timeout from DT value if available */
watchdog_init_timeout(&wdt->wdtdev, 0, dev);
if (timeout) {
da9062_wdt_set_timeout(&wdt->wdtdev, wdt->wdtdev.timeout);
set_bit(WDOG_HW_RUNNING, &wdt->wdtdev.status);
}
return devm_watchdog_register_device(dev, &wdt->wdtdev);
}
static int __maybe_unused da9062_wdt_suspend(struct device *dev)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
if (!wdt->use_sw_pm)
return 0;
if (watchdog_active(wdd))
return da9062_wdt_stop(wdd);
return 0;
}
static int __maybe_unused da9062_wdt_resume(struct device *dev)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
if (!wdt->use_sw_pm)
return 0;
if (watchdog_active(wdd))
return da9062_wdt_start(wdd);
return 0;
}
static SIMPLE_DEV_PM_OPS(da9062_wdt_pm_ops,
da9062_wdt_suspend, da9062_wdt_resume);
static struct platform_driver da9062_wdt_driver = {
.probe = da9062_wdt_probe,
.driver = {
.name = "da9062-watchdog",
.pm = &da9062_wdt_pm_ops,
.of_match_table = da9062_compatible_id_table,
},
};
module_platform_driver(da9062_wdt_driver);
MODULE_AUTHOR("S Twiss <stwiss.opensource@diasemi.com>");
MODULE_DESCRIPTION("WDT device driver for Dialog DA9062 and DA9061");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:da9062-watchdog");
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