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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/of.h>
#include <linux/platform_device.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;
bool always_running;
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);
if (!priv->always_running)
bd9576_wdt_disable(priv);
else
set_bit(WDOG_HW_RUNNING, &wdd->status);
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 device_node *np = dev->parent->of_node;
struct bd9576_wdt_priv *priv;
u32 hw_margin[2];
u32 hw_margin_max = BD957X_WDT_DEFAULT_MARGIN, hw_margin_min = 0;
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_gpiod_get_from_of_node(dev, dev->parent->of_node,
"rohm,watchdog-enable-gpios",
0, 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_gpiod_get_from_of_node(dev, dev->parent->of_node,
"rohm,watchdog-ping-gpios",
0, 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");
ret = of_property_read_variable_u32_array(np, "rohm,hw-timeout-ms",
&hw_margin[0], 1, 2);
if (ret < 0 && ret != -EINVAL)
return ret;
if (ret == 1)
hw_margin_max = hw_margin[0];
if (ret == 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;
priv->always_running = of_property_read_bool(np, "always-running");
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);
if (priv->always_running)
bd9576_wdt_start(&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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