watchdog: mlx-wdt: introduce a watchdog driver for Mellanox systems.

Introduce watchdog driver for a various range of Mellanox Ethernet and
Infiniband switch systems.

Watchdog driver for Mellanox watchdog devices, implemented in
programmable logic device.

Main and auxiliary watchdog devices can exist on the same system.
There are several actions that can be defined in the watchdog:
system reset, start fans on full speed and increase a counter.
The last 2 actions are performed without a system reset.
Actions without reset are provided for auxiliary watchdog devices,
which is optional.
Access to HW registers is performed through generic
regmap interface.

There are 2 types of HW watchdog implementations.
Type 1: actual HW timeout can be defined as power of 2 msec.
e.g. timeout 20 sec will be rounded up to 32768 msec.;
maximum timeout period is 32 sec (32768 msec.);
get time-left isn't supported
Type 2: actual HW timeout is defined in sec. and it's the same as
user-defined timeout;
maximum timeout is 255 sec;
get time-left is supported;

Watchdog driver is probed from the common mlx_platform driver.

Signed-off-by: Michael Shych <michaelsh@mellanox.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/Kconfig

@@ -241,6 +241,22 @@ config RAVE_SP_WATCHDOG
 	help
 	  Support for the watchdog on RAVE SP device.
 
+config MLX_WDT
+	tristate "Mellanox Watchdog"
+	depends on MELLANOX_PLATFORM
+	select WATCHDOG_CORE
+	select REGMAP
+	help
+	  This is the driver for the hardware watchdog on Mellanox systems.
+	  If you are going to use it, say Y here, otherwise N.
+	  This driver can be used together with the watchdog daemon.
+	  It can also watch your kernel to make sure it doesn't freeze,
+	  and if it does, it reboots your system after a certain amount of
+	  time.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called mlx-wdt.
+
 # ALPHA Architecture
 
 # ARM Architecture

drivers/watchdog/Makefile

@@ -142,6 +142,7 @@ obj-$(CONFIG_INTEL_MID_WATCHDOG) += intel-mid_wdt.o
 obj-$(CONFIG_INTEL_MEI_WDT) += mei_wdt.o
 obj-$(CONFIG_NI903X_WDT) += ni903x_wdt.o
 obj-$(CONFIG_NIC7018_WDT) += nic7018_wdt.o
+obj-$(CONFIG_MLX_WDT) += mlx_wdt.o
 
 # M68K Architecture
 obj-$(CONFIG_M54xx_WATCHDOG) += m54xx_wdt.o

drivers/watchdog/mlx_wdt.c

@@ -0,0 +1,290 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Mellanox watchdog driver
+ *
+ * Copyright (C) 2019 Mellanox Technologies
+ * Copyright (C) 2019 Michael Shych <mshych@mellanox.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/platform_data/mlxreg.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+#define MLXREG_WDT_CLOCK_SCALE		1000
+#define MLXREG_WDT_MAX_TIMEOUT_TYPE1	32
+#define MLXREG_WDT_MAX_TIMEOUT_TYPE2	255
+#define MLXREG_WDT_MIN_TIMEOUT		1
+#define MLXREG_WDT_OPTIONS_BASE (WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | \
+				 WDIOF_SETTIMEOUT)
+
+/**
+ * struct mlxreg_wdt - wd private data:
+ *
+ * @wdd:	watchdog device;
+ * @device:	basic device;
+ * @pdata:	data received from platform driver;
+ * @regmap:	register map of parent device;
+ * @timeout:	defined timeout in sec.;
+ * @action_idx:	index for direct access to action register;
+ * @timeout_idx:index for direct access to TO register;
+ * @tleft_idx:	index for direct access to time left register;
+ * @ping_idx:	index for direct access to ping register;
+ * @reset_idx:	index for direct access to reset cause register;
+ * @wd_type:	watchdog HW type;
+ */
+struct mlxreg_wdt {
+	struct watchdog_device wdd;
+	struct mlxreg_core_platform_data *pdata;
+	void *regmap;
+	int action_idx;
+	int timeout_idx;
+	int tleft_idx;
+	int ping_idx;
+	int reset_idx;
+	enum mlxreg_wdt_type wdt_type;
+};
+
+static void mlxreg_wdt_check_card_reset(struct mlxreg_wdt *wdt)
+{
+	struct mlxreg_core_data *reg_data;
+	u32 regval;
+	int rc;
+
+	if (wdt->reset_idx == -EINVAL)
+		return;
+
+	if (!(wdt->wdd.info->options & WDIOF_CARDRESET))
+		return;
+
+	reg_data = &wdt->pdata->data[wdt->reset_idx];
+	rc = regmap_read(wdt->regmap, reg_data->reg, &regval);
+	if (!rc) {
+		if (regval & ~reg_data->mask) {
+			wdt->wdd.bootstatus = WDIOF_CARDRESET;
+			dev_info(wdt->wdd.parent,
+				 "watchdog previously reset the CPU\n");
+		}
+	}
+}
+
+static int mlxreg_wdt_start(struct watchdog_device *wdd)
+{
+	struct mlxreg_wdt *wdt = watchdog_get_drvdata(wdd);
+	struct mlxreg_core_data *reg_data = &wdt->pdata->data[wdt->action_idx];
+
+	return regmap_update_bits(wdt->regmap, reg_data->reg, ~reg_data->mask,
+				  BIT(reg_data->bit));
+}
+
+static int mlxreg_wdt_stop(struct watchdog_device *wdd)
+{
+	struct mlxreg_wdt *wdt = watchdog_get_drvdata(wdd);
+	struct mlxreg_core_data *reg_data = &wdt->pdata->data[wdt->action_idx];
+
+	return regmap_update_bits(wdt->regmap, reg_data->reg, ~reg_data->mask,
+				  ~BIT(reg_data->bit));
+}
+
+static int mlxreg_wdt_ping(struct watchdog_device *wdd)
+{
+	struct mlxreg_wdt *wdt = watchdog_get_drvdata(wdd);
+	struct mlxreg_core_data *reg_data = &wdt->pdata->data[wdt->ping_idx];
+
+	return regmap_update_bits_base(wdt->regmap, reg_data->reg,
+				       ~reg_data->mask, BIT(reg_data->bit),
+				       NULL, false, true);
+}
+
+static int mlxreg_wdt_set_timeout(struct watchdog_device *wdd,
+				  unsigned int timeout)
+{
+	struct mlxreg_wdt *wdt = watchdog_get_drvdata(wdd);
+	struct mlxreg_core_data *reg_data = &wdt->pdata->data[wdt->timeout_idx];
+	u32 regval, set_time, hw_timeout;
+	int rc;
+
+	if (wdt->wdt_type == MLX_WDT_TYPE1) {
+		rc = regmap_read(wdt->regmap, reg_data->reg, &regval);
+		if (rc)
+			return rc;
+
+		hw_timeout = order_base_2(timeout * MLXREG_WDT_CLOCK_SCALE);
+		regval = (regval & reg_data->mask) | hw_timeout;
+		/* Rowndown to actual closest number of sec. */
+		set_time = BIT(hw_timeout) / MLXREG_WDT_CLOCK_SCALE;
+	} else {
+		set_time = timeout;
+		regval = timeout;
+	}
+
+	wdd->timeout = set_time;
+	rc = regmap_write(wdt->regmap, reg_data->reg, regval);
+
+	if (!rc) {
+		/*
+		 * Restart watchdog with new timeout period
+		 * if watchdog is already started.
+		 */
+		if (watchdog_active(wdd)) {
+			rc = mlxreg_wdt_stop(wdd);
+			if (!rc)
+				rc = mlxreg_wdt_start(wdd);
+		}
+	}
+
+	return rc;
+}
+
+static unsigned int mlxreg_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct mlxreg_wdt *wdt = watchdog_get_drvdata(wdd);
+	struct mlxreg_core_data *reg_data = &wdt->pdata->data[wdt->tleft_idx];
+	u32 regval;
+	int rc;
+
+	rc = regmap_read(wdt->regmap, reg_data->reg, &regval);
+	/* Return 0 timeleft in case of failure register read. */
+	return rc == 0 ? regval : 0;
+}
+
+static const struct watchdog_ops mlxreg_wdt_ops_type1 = {
+	.start		= mlxreg_wdt_start,
+	.stop		= mlxreg_wdt_stop,
+	.ping		= mlxreg_wdt_ping,
+	.set_timeout	= mlxreg_wdt_set_timeout,
+	.owner		= THIS_MODULE,
+};
+
+static const struct watchdog_ops mlxreg_wdt_ops_type2 = {
+	.start		= mlxreg_wdt_start,
+	.stop		= mlxreg_wdt_stop,
+	.ping		= mlxreg_wdt_ping,
+	.set_timeout	= mlxreg_wdt_set_timeout,
+	.get_timeleft	= mlxreg_wdt_get_timeleft,
+	.owner		= THIS_MODULE,
+};
+
+static const struct watchdog_info mlxreg_wdt_main_info = {
+	.options	= MLXREG_WDT_OPTIONS_BASE
+			| WDIOF_CARDRESET,
+	.identity	= "mlx-wdt-main",
+};
+
+static const struct watchdog_info mlxreg_wdt_aux_info = {
+	.options	= MLXREG_WDT_OPTIONS_BASE
+			| WDIOF_ALARMONLY,
+	.identity	= "mlx-wdt-aux",
+};
+
+static void mlxreg_wdt_config(struct mlxreg_wdt *wdt,
+			      struct mlxreg_core_platform_data *pdata)
+{
+	struct mlxreg_core_data *data = pdata->data;
+	int i;
+
+	wdt->reset_idx = -EINVAL;
+	for (i = 0; i < pdata->counter; i++, data++) {
+		if (strnstr(data->label, "action", sizeof(data->label)))
+			wdt->action_idx = i;
+		else if (strnstr(data->label, "timeout", sizeof(data->label)))
+			wdt->timeout_idx = i;
+		else if (strnstr(data->label, "timeleft", sizeof(data->label)))
+			wdt->tleft_idx = i;
+		else if (strnstr(data->label, "ping", sizeof(data->label)))
+			wdt->ping_idx = i;
+		else if (strnstr(data->label, "reset", sizeof(data->label)))
+			wdt->reset_idx = i;
+	}
+
+	wdt->pdata = pdata;
+	if (strnstr(pdata->identity, mlxreg_wdt_main_info.identity,
+		    sizeof(mlxreg_wdt_main_info.identity)))
+		wdt->wdd.info = &mlxreg_wdt_main_info;
+	else
+		wdt->wdd.info = &mlxreg_wdt_aux_info;
+
+	wdt->wdt_type = pdata->version;
+	if (wdt->wdt_type == MLX_WDT_TYPE2) {
+		wdt->wdd.ops = &mlxreg_wdt_ops_type2;
+		wdt->wdd.max_timeout = MLXREG_WDT_MAX_TIMEOUT_TYPE2;
+	} else {
+		wdt->wdd.ops = &mlxreg_wdt_ops_type1;
+		wdt->wdd.max_timeout = MLXREG_WDT_MAX_TIMEOUT_TYPE1;
+	}
+	wdt->wdd.min_timeout = MLXREG_WDT_MIN_TIMEOUT;
+}
+
+static int mlxreg_wdt_init_timeout(struct mlxreg_wdt *wdt,
+				   struct mlxreg_core_platform_data *pdata)
+{
+	u32 timeout;
+
+	timeout = pdata->data[wdt->timeout_idx].health_cntr;
+	return mlxreg_wdt_set_timeout(&wdt->wdd, timeout);
+}
+
+static int mlxreg_wdt_probe(struct platform_device *pdev)
+{
+	struct mlxreg_core_platform_data *pdata;
+	struct mlxreg_wdt *wdt;
+	int rc;
+
+	pdata = dev_get_platdata(&pdev->dev);
+	if (!pdata) {
+		dev_err(&pdev->dev, "Failed to get platform data.\n");
+		return -EINVAL;
+	}
+	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	wdt->wdd.parent = &pdev->dev;
+	wdt->regmap = pdata->regmap;
+	mlxreg_wdt_config(wdt, pdata);
+
+	if ((pdata->features & MLXREG_CORE_WD_FEATURE_NOWAYOUT))
+		watchdog_set_nowayout(&wdt->wdd, WATCHDOG_NOWAYOUT);
+	watchdog_stop_on_reboot(&wdt->wdd);
+	watchdog_stop_on_unregister(&wdt->wdd);
+	watchdog_set_drvdata(&wdt->wdd, wdt);
+	rc = mlxreg_wdt_init_timeout(wdt, pdata);
+	if (rc)
+		goto register_error;
+
+	if ((pdata->features & MLXREG_CORE_WD_FEATURE_START_AT_BOOT)) {
+		rc = mlxreg_wdt_start(&wdt->wdd);
+		if (rc)
+			goto register_error;
+		set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
+	}
+	mlxreg_wdt_check_card_reset(wdt);
+	rc = devm_watchdog_register_device(&pdev->dev, &wdt->wdd);
+
+register_error:
+	if (rc)
+		dev_err(&pdev->dev,
+			"Cannot register watchdog device (err=%d)\n", rc);
+	return rc;
+}
+
+static struct platform_driver mlxreg_wdt_driver = {
+	.probe	= mlxreg_wdt_probe,
+	.driver	= {
+			.name = "mlx-wdt",
+	},
+};
+
+module_platform_driver(mlxreg_wdt_driver);
+
+MODULE_AUTHOR("Michael Shych <michaelsh@mellanox.com>");
+MODULE_DESCRIPTION("Mellanox watchdog driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:mlx-wdt");