[PATCH v8 4/6] wdt: Support wdt on ROHM BD9576MUF and BD9573MUF

Matti Vaittinen
2021-02-11T09:53:52Z

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");