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linux/drivers/watchdog/bd9576_wdt.c
Matti Vaittinen e3b3afd34d watchdog: bd9576: Drop "always-running" property 
The always-running (from linux,wdt-gpio.yaml) is abused by the BD9576
watchdog driver. It's defined meaning is "the watchdog is always running
and can not be stopped". The BD9576 watchdog driver has implemented it
as "start watchdog when loading the module and prevent it from being
stopped".

Furthermore, the implementation does not set the WDOG_HW_RUNNING when
enabling the watchdog due to the "always-running" at module loading.
This will end up resulting a watchdog timeout if the device is not
opened.

The culprit was pointed out by Guenter, discussion can be found from
https://lore.kernel.org/lkml/4fa3a64b-60fb-4e5e-8785-0f14da37eea2@roeck-us.net/

Drop the invalid "always-running" handling.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes: b237bcac55 ("wdt: Support wdt on ROHM BD9576MUF and BD9573MUF")
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/ZhPAt76yaJMersXf@fedora
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
2024-05-04 12:50:41 +02:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2020 ROHM Semiconductors
*
* ROHM BD9576MUF and BD9573MUF Watchdog driver
*/
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/mfd/rohm-bd957x.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/watchdog.h>
static bool nowayout;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default=\"false\")");
#define HW_MARGIN_MIN 2
#define HW_MARGIN_MAX 4416
#define BD957X_WDT_DEFAULT_MARGIN 4416
#define WATCHDOG_TIMEOUT 30
struct bd9576_wdt_priv {
struct gpio_desc *gpiod_ping;
struct gpio_desc *gpiod_en;
struct device *dev;
struct regmap *regmap;
struct watchdog_device wdd;
};
static void bd9576_wdt_disable(struct bd9576_wdt_priv *priv)
{
gpiod_set_value_cansleep(priv->gpiod_en, 0);
}
static int bd9576_wdt_ping(struct watchdog_device *wdd)
{
struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
/* Pulse */
gpiod_set_value_cansleep(priv->gpiod_ping, 1);
gpiod_set_value_cansleep(priv->gpiod_ping, 0);
return 0;
}
static int bd9576_wdt_start(struct watchdog_device *wdd)
{
struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
gpiod_set_value_cansleep(priv->gpiod_en, 1);
return bd9576_wdt_ping(wdd);
}
static int bd9576_wdt_stop(struct watchdog_device *wdd)
{
struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
bd9576_wdt_disable(priv);
return 0;
}
static const struct watchdog_info bd957x_wdt_ident = {
.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
WDIOF_SETTIMEOUT,
.identity = "BD957x Watchdog",
};
static const struct watchdog_ops bd957x_wdt_ops = {
.owner = THIS_MODULE,
.start = bd9576_wdt_start,
.stop = bd9576_wdt_stop,
.ping = bd9576_wdt_ping,
};
/* Unit is hundreds of uS */
#define FASTNG_MIN 23
static int find_closest_fast(int target, int *sel, int *val)
{
int i;
int window = FASTNG_MIN;
for (i = 0; i < 8 && window < target; i++)
window <<= 1;
*val = window;
*sel = i;
if (i == 8)
return -EINVAL;
return 0;
}
static int find_closest_slow_by_fast(int fast_val, int target, int *slowsel)
{
int sel;
static const int multipliers[] = {2, 3, 7, 15};
for (sel = 0; sel < ARRAY_SIZE(multipliers) &&
multipliers[sel] * fast_val < target; sel++)
;
if (sel == ARRAY_SIZE(multipliers))
return -EINVAL;
*slowsel = sel;
return 0;
}
static int find_closest_slow(int target, int *slow_sel, int *fast_sel)
{
static const int multipliers[] = {2, 3, 7, 15};
int i, j;
int val = 0;
int window = FASTNG_MIN;
for (i = 0; i < 8; i++) {
for (j = 0; j < ARRAY_SIZE(multipliers); j++) {
int slow;
slow = window * multipliers[j];
if (slow >= target && (!val || slow < val)) {
val = slow;
*fast_sel = i;
*slow_sel = j;
}
}
window <<= 1;
}
if (!val)
return -EINVAL;
return 0;
}
#define BD957X_WDG_TYPE_WINDOW BIT(5)
#define BD957X_WDG_TYPE_SLOW 0
#define BD957X_WDG_TYPE_MASK BIT(5)
#define BD957X_WDG_NG_RATIO_MASK 0x18
#define BD957X_WDG_FASTNG_MASK 0x7
static int bd957x_set_wdt_mode(struct bd9576_wdt_priv *priv, int hw_margin,
int hw_margin_min)
{
int ret, fastng, slowng, type, reg, mask;
struct device *dev = priv->dev;
/* convert to 100uS */
hw_margin *= 10;
hw_margin_min *= 10;
if (hw_margin_min) {
int min;
type = BD957X_WDG_TYPE_WINDOW;
dev_dbg(dev, "Setting type WINDOW 0x%x\n", type);
ret = find_closest_fast(hw_margin_min, &fastng, &min);
if (ret) {
dev_err(dev, "bad WDT window for fast timeout\n");
return ret;
}
ret = find_closest_slow_by_fast(min, hw_margin, &slowng);
if (ret) {
dev_err(dev, "bad WDT window\n");
return ret;
}
} else {
type = BD957X_WDG_TYPE_SLOW;
dev_dbg(dev, "Setting type SLOW 0x%x\n", type);
ret = find_closest_slow(hw_margin, &slowng, &fastng);
if (ret) {
dev_err(dev, "bad WDT window\n");
return ret;
}
}
slowng <<= ffs(BD957X_WDG_NG_RATIO_MASK) - 1;
reg = type | slowng | fastng;
mask = BD957X_WDG_TYPE_MASK | BD957X_WDG_NG_RATIO_MASK |
BD957X_WDG_FASTNG_MASK;
ret = regmap_update_bits(priv->regmap, BD957X_REG_WDT_CONF,
mask, reg);
return ret;
}
static int bd9576_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct bd9576_wdt_priv *priv;
u32 hw_margin[2];
u32 hw_margin_max = BD957X_WDT_DEFAULT_MARGIN, hw_margin_min = 0;
int count;
int ret;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
platform_set_drvdata(pdev, priv);
priv->dev = dev;
priv->regmap = dev_get_regmap(dev->parent, NULL);
if (!priv->regmap) {
dev_err(dev, "No regmap found\n");
return -ENODEV;
}
priv->gpiod_en = devm_fwnode_gpiod_get(dev, dev_fwnode(dev->parent),
"rohm,watchdog-enable",
GPIOD_OUT_LOW,
"watchdog-enable");
if (IS_ERR(priv->gpiod_en))
return dev_err_probe(dev, PTR_ERR(priv->gpiod_en),
"getting watchdog-enable GPIO failed\n");
priv->gpiod_ping = devm_fwnode_gpiod_get(dev, dev_fwnode(dev->parent),
"rohm,watchdog-ping",
GPIOD_OUT_LOW,
"watchdog-ping");
if (IS_ERR(priv->gpiod_ping))
return dev_err_probe(dev, PTR_ERR(priv->gpiod_ping),
"getting watchdog-ping GPIO failed\n");
count = device_property_count_u32(dev->parent, "rohm,hw-timeout-ms");
if (count < 0 && count != -EINVAL)
return count;
if (count > 0) {
if (count > ARRAY_SIZE(hw_margin))
return -EINVAL;
ret = device_property_read_u32_array(dev->parent,
"rohm,hw-timeout-ms",
hw_margin, count);
if (ret < 0)
return ret;
if (count == 1)
hw_margin_max = hw_margin[0];
if (count == 2) {
hw_margin_max = hw_margin[1];
hw_margin_min = hw_margin[0];
}
}
ret = bd957x_set_wdt_mode(priv, hw_margin_max, hw_margin_min);
if (ret)
return ret;
watchdog_set_drvdata(&priv->wdd, priv);
priv->wdd.info = &bd957x_wdt_ident;
priv->wdd.ops = &bd957x_wdt_ops;
priv->wdd.min_hw_heartbeat_ms = hw_margin_min;
priv->wdd.max_hw_heartbeat_ms = hw_margin_max;
priv->wdd.parent = dev;
priv->wdd.timeout = WATCHDOG_TIMEOUT;
watchdog_init_timeout(&priv->wdd, 0, dev);
watchdog_set_nowayout(&priv->wdd, nowayout);
watchdog_stop_on_reboot(&priv->wdd);
return devm_watchdog_register_device(dev, &priv->wdd);
}
static struct platform_driver bd9576_wdt_driver = {
.driver = {
.name = "bd9576-wdt",
},
.probe = bd9576_wdt_probe,
};
module_platform_driver(bd9576_wdt_driver);
MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:bd9576-wdt");
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