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    Subject[PATCH v8 4/6] wdt: Support wdt on ROHM BD9576MUF and BD9573MUF
    Add Watchdog support for ROHM BD9576MUF and BD9573MUF PMICs which are
    mainly used to power the R-Car series processors. The watchdog is
    pinged using a GPIO and enabled using another GPIO. Additionally
    watchdog time-out can be configured to HW prior starting the watchdog.
    Watchdog timeout can be configured to detect only delayed ping or in
    a window mode where also too fast pings are detected.

    Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
    Reviewed-by: Guenter Roeck <linux@roeck-us.net>
    ---

    No changes since v6

    drivers/watchdog/Kconfig | 13 ++
    drivers/watchdog/Makefile | 1 +
    drivers/watchdog/bd9576_wdt.c | 291 ++++++++++++++++++++++++++++++++++
    3 files changed, 305 insertions(+)
    create mode 100644 drivers/watchdog/bd9576_wdt.c

    diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
    index 7ff941e71b79..67eff0cbd7e1 100644
    --- a/drivers/watchdog/Kconfig
    +++ b/drivers/watchdog/Kconfig
    @@ -172,6 +172,19 @@ config BD70528_WATCHDOG
    Alternatively say M to compile the driver as a module,
    which will be called bd70528_wdt.

    +config BD957XMUF_WATCHDOG
    + tristate "ROHM BD9576MUF and BD9573MUF PMIC Watchdog"
    + depends on MFD_ROHM_BD957XMUF
    + select WATCHDOG_CORE
    + help
    + Support for the watchdog in the ROHM BD9576 and BD9573 PMICs.
    + These PMIC ICs contain watchdog block which can be configured
    + to toggle reset line if SoC fails to ping watchdog via GPIO.
    +
    + Say Y here to include support for the ROHM BD9576 or BD9573
    + watchdog. Alternatively say M to compile the driver as a module,
    + which will be called bd9576_wdt.
    +
    config DA9052_WATCHDOG
    tristate "Dialog DA9052 Watchdog"
    depends on PMIC_DA9052 || COMPILE_TEST
    diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
    index 5c74ee19d441..9341f72bf0aa 100644
    --- a/drivers/watchdog/Makefile
    +++ b/drivers/watchdog/Makefile
    @@ -208,6 +208,7 @@ obj-$(CONFIG_XEN_WDT) += xen_wdt.o

    # Architecture Independent
    obj-$(CONFIG_BD70528_WATCHDOG) += bd70528_wdt.o
    +obj-$(CONFIG_BD957XMUF_WATCHDOG) += bd9576_wdt.o
    obj-$(CONFIG_DA9052_WATCHDOG) += da9052_wdt.o
    obj-$(CONFIG_DA9055_WATCHDOG) += da9055_wdt.o
    obj-$(CONFIG_DA9062_WATCHDOG) += da9062_wdt.o
    diff --git a/drivers/watchdog/bd9576_wdt.c b/drivers/watchdog/bd9576_wdt.c
    new file mode 100644
    index 000000000000..0b6999f3b6e8
    --- /dev/null
    +++ b/drivers/watchdog/bd9576_wdt.c
    @@ -0,0 +1,291 @@
    +// 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");
    --
    2.25.4

    --
    Matti Vaittinen, Linux device drivers
    ROHM Semiconductors, Finland SWDC
    Kiviharjunlenkki 1E
    90220 OULU
    FINLAND

    ~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
    Simon says - in Latin please.
    ~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
    Thanks to Simon Glass for the translation =]

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