[PATCH V2] watchdog: max77620: Add support for watchdog timer

From: Laxman Dewangan
Date: Wed Jun 08 2016 - 06:31:14 EST

Maxim PMIC MAX77620 is Power management IC which have multiple
sub blocks like regulators (DCDC/LDOs), GPIO, RTC, Clock, Watchdog
timer etc.

Add the driver for watchdog timer under watchdog framework.
The driver implements the watchdog callbacks to start, stop,
ping and set timeout for watchodg framework.

Signed-off-by: Laxman Dewangan <ldewangan@xxxxxxxxxx>

---
Changes from V1:
- Remove the error prints from start/stop/ping to simplify the function.
- Instead of stopping running WDT, inform HW RUNNING and update the required
param accordingly.
- Resequence the param sets for wdt device to avoid race condition, move all
wdt device setting before registration.

drivers/watchdog/Kconfig | 9 ++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/max77620_wdt.c | 222 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 232 insertions(+)
create mode 100644 drivers/watchdog/max77620_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index b54f26c..ca0602d 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -516,6 +516,15 @@ config MAX63XX_WATCHDOG
help
Support for memory mapped max63{69,70,71,72,73,74} watchdog timer.

+config MAX77620_WATCHDOG
+ tristate "Maxim Max77620 Watchdog Timer"
+ depends on MFD_MAX77620
+ help
+ This is the driver for the Max77620 watchdog timer.
+ Say 'Y' here to enable the watchdog timer support for
+ MAX77620 chips. To compile this driver as a module,
+ choose M here: the module will be called max77620_wdt.
+
config IMX2_WDT
tristate "IMX2+ Watchdog"
depends on ARCH_MXC || ARCH_LAYERSCAPE
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index a46e7c1..5d38173 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -203,6 +203,7 @@ obj-$(CONFIG_TANGOX_WATCHDOG) += tangox_wdt.o
obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o
+obj-$(CONFIG_MAX77620_WATCHDOG) += max77620_wdt.o
obj-$(CONFIG_ZIIRAVE_WATCHDOG) += ziirave_wdt.o
obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
diff --git a/drivers/watchdog/max77620_wdt.c b/drivers/watchdog/max77620_wdt.c
new file mode 100644
index 0000000..a1c22c8
--- /dev/null
+++ b/drivers/watchdog/max77620_wdt.c
@@ -0,0 +1,222 @@
+/*
+ * Maxim MAX77620 Watchdog Driver
+ *
+ * Copyright (C) 2016 NVIDIA CORPORATION. All rights reserved.
+ *
+ * Author: Laxman Dewangan <ldewangan@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mfd/max77620.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/watchdog.h>
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+struct max77620_wdt {
+ struct device *dev;
+ struct regmap *rmap;
+ struct watchdog_device wdt_dev;
+};
+
+static int max77620_wdt_start(struct watchdog_device *wdt_dev)
+{
+ struct max77620_wdt *wdt = watchdog_get_drvdata(wdt_dev);
+
+ return regmap_update_bits(wdt->rmap, MAX77620_REG_CNFGGLBL2,
+ MAX77620_WDTEN, MAX77620_WDTEN);
+}
+
+static int max77620_wdt_stop(struct watchdog_device *wdt_dev)
+{
+ struct max77620_wdt *wdt = watchdog_get_drvdata(wdt_dev);
+
+ return regmap_update_bits(wdt->rmap, MAX77620_REG_CNFGGLBL2,
+ MAX77620_WDTEN, 0);
+}
+
+static int max77620_wdt_ping(struct watchdog_device *wdt_dev)
+{
+ struct max77620_wdt *wdt = watchdog_get_drvdata(wdt_dev);
+
+ return regmap_update_bits(wdt->rmap, MAX77620_REG_CNFGGLBL3,
+ MAX77620_WDTC_MASK, 0x1);
+}
+
+static int max77620_wdt_set_timeout(struct watchdog_device *wdt_dev,
+ unsigned int timeout)
+{
+ struct max77620_wdt *wdt = watchdog_get_drvdata(wdt_dev);
+ unsigned int wdt_timeout;
+ u8 regval;
+ int ret;
+
+ switch (timeout) {
+ case 0 ... 2:
+ regval = MAX77620_TWD_2s;
+ wdt_timeout = 2;
+ break;
+
+ case 3 ... 16:
+ regval = MAX77620_TWD_16s;
+ wdt_timeout = 16;
+ break;
+
+ case 17 ... 64:
+ regval = MAX77620_TWD_64s;
+ wdt_timeout = 64;
+ break;
+
+ default:
+ regval = MAX77620_TWD_128s;
+ wdt_timeout = 128;
+ break;
+ }
+
+ ret = regmap_update_bits(wdt->rmap, MAX77620_REG_CNFGGLBL3,
+ MAX77620_WDTC_MASK, 0x1);
+ if (ret < 0)
+ return ret;
+
+ ret = regmap_update_bits(wdt->rmap, MAX77620_REG_CNFGGLBL2,
+ MAX77620_TWD_MASK, regval);
+ if (ret < 0)
+ return ret;
+
+ wdt_dev->timeout = wdt_timeout;
+
+ return 0;
+}
+
+static const struct watchdog_info max77620_wdt_info = {
+ .identity = "max77620-watchdog",
+ .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+};
+
+static const struct watchdog_ops max77620_wdt_ops = {
+ .start = max77620_wdt_start,
+ .stop = max77620_wdt_stop,
+ .ping = max77620_wdt_ping,
+ .set_timeout = max77620_wdt_set_timeout,
+};
+
+static int max77620_wdt_probe(struct platform_device *pdev)
+{
+ struct max77620_wdt *wdt;
+ struct watchdog_device *wdt_dev;
+ unsigned int regval;
+ int ret;
+
+ wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+ if (!wdt)
+ return -ENOMEM;
+
+ wdt->dev = &pdev->dev;
+ wdt->rmap = dev_get_regmap(pdev->dev.parent, NULL);
+ if (!wdt->rmap) {
+ dev_err(wdt->dev, "Failed to get parent regmap\n");
+ return -ENODEV;
+ }
+
+ wdt_dev = &wdt->wdt_dev;
+ wdt_dev->info = &max77620_wdt_info;
+ wdt_dev->ops = &max77620_wdt_ops;
+ wdt_dev->min_timeout = 2;
+ wdt_dev->max_timeout = 128;
+ wdt_dev->max_hw_heartbeat_ms = 128 * 1000;
+
+ platform_set_drvdata(pdev, wdt);
+
+ /* Enable WD_RST_WK - WDT expire results in a restart */
+ ret = regmap_update_bits(wdt->rmap, MAX77620_REG_ONOFFCNFG2,
+ MAX77620_ONOFFCNFG2_WD_RST_WK,
+ MAX77620_ONOFFCNFG2_WD_RST_WK);
+ if (ret < 0) {
+ dev_err(wdt->dev, "Failed to set WD_RST_WK: %d\n", ret);
+ return ret;
+ }
+
+ /* Set WDT clear in OFF and sleep mode */
+ ret = regmap_update_bits(wdt->rmap, MAX77620_REG_CNFGGLBL2,
+ MAX77620_WDTOFFC | MAX77620_WDTSLPC,
+ MAX77620_WDTOFFC | MAX77620_WDTSLPC);
+ if (ret < 0) {
+ dev_err(wdt->dev, "Failed to set WDT OFF mode: %d\n", ret);
+ return ret;
+ }
+
+ /* Check if WDT running and ig yes then set flags properly */
+ ret = regmap_read(wdt->rmap, MAX77620_REG_CNFGGLBL2, &regval);
+ if (ret < 0) {
+ dev_err(wdt->dev, "Failed to read WDT CFG register: %d\n", ret);
+ return ret;
+ }
+
+ if (regval & MAX77620_WDTEN) {
+ regval = regval & MAX77620_TWD_MASK;
+ if (regval == MAX77620_TWD_2s)
+ wdt_dev->timeout = 2;
+ else if (regval == MAX77620_TWD_16s)
+ wdt_dev->timeout = 16;
+ else if (regval == MAX77620_TWD_64s)
+ wdt_dev->timeout = 64;
+ else
+ wdt_dev->timeout = 128;
+ set_bit(WDOG_HW_RUNNING, &wdt_dev->status);
+ }
+
+ watchdog_set_nowayout(wdt_dev, nowayout);
+ watchdog_set_drvdata(wdt_dev, wdt);
+
+ ret = watchdog_register_device(wdt_dev);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "watchdog registration failed: %d\n", ret);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int max77620_wdt_remove(struct platform_device *pdev)
+{
+ struct max77620_wdt *wdt = platform_get_drvdata(pdev);
+
+ max77620_wdt_stop(&wdt->wdt_dev);
+ watchdog_unregister_device(&wdt->wdt_dev);
+
+ return 0;
+}
+
+static struct platform_device_id max77620_wdt_devtype[] = {
+ { .name = "max77620-watchdog", },
+ { },
+};
+
+static struct platform_driver max77620_wdt_driver = {
+ .driver = {
+ .name = "max77620-watchdog",
+ },
+ .probe = max77620_wdt_probe,
+ .remove = max77620_wdt_remove,
+ .id_table = max77620_wdt_devtype,
+};
+
+module_platform_driver(max77620_wdt_driver);
+
+MODULE_DESCRIPTION("Max77620 watchdog timer driver");
+
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
+ "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+MODULE_AUTHOR("Laxman Dewangan <ldewangan@xxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
--
2.1.4