[PATCH V3 3/4] watchdog: da9062: DA9062 watchdog driver

[S Twiss <stwiss.opensource@diasemi.com>]

From: S Twiss <stwiss.opensource@diasemi.com>

Add watchdog driver support for DA9062


Signed-off-by: Steve Twiss <stwiss.opensource@diasemi.com>

---

Changes in V3:
 - Removed unnecessary return statement in da9062_apply_window_protection()
 - Deleted dev_err() kernel noise in da9062_wdt_update_timeout_register()
 - Changed dev_alert() to be a dev_err() in da9062_wdt_stop()
 - Deleted the "watchdog ping" debug message in da9062_wdt_ping()
 - Refactored the error path inthe probe() to remove redundant error gotos
 - Altered dev_err() string to notify failures more specifically in probe()
 - Removed the space in MODULE_ALIAS string "platform: da9062-watchdog"
 - Ensure request for devm_request_threaded_irq() removal is completed

Changes in V2:
 - Removed informational dev_info() 'installed watchdog' message
 - Copyright headers GPL v2 (and later) match correct 'GPL' in MODULE_LICENSE
 - Removed the explicit 300 msecs delay from the reset_watchdog_timer()
   function and replaced it with a variable delay (depending on the
   difference since the last ping). A debug message is used to catch the
   multiple pings trying to break the 300 msecs protection barrier.
 - Fix error paths for the functions da9062_wdt_update_timeout_register()
   and da9062_wdt_stop() 
 - Add error paths in the probe() and correctly clean-up the registered
   device if there is a problem after registration.

This patch applies against linux-next and v4.1-rc3 



 drivers/watchdog/Kconfig      |   9 ++
 drivers/watchdog/Makefile     |   1 +
 drivers/watchdog/da9062_wdt.c | 253 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 263 insertions(+)
 create mode 100644 drivers/watchdog/da9062_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index e5e7c55..dfdb6c6 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -96,6 +96,15 @@ config DA9063_WATCHDOG
 
 	  This driver can be built as a module. The module name is da9063_wdt.
 
+config DA9062_WATCHDOG
+	tristate "Dialog DA9062 Watchdog"
+	depends on MFD_DA9062
+	select WATCHDOG_CORE
+	help
+	  Support for the watchdog in the DA9062 PMIC.
+
+	  This driver can be built as a module. The module name is da9062_wdt.
+
 config GPIO_WATCHDOG
 	tristate "Watchdog device controlled through GPIO-line"
 	depends on OF_GPIO
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 5c19294..57ba815 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -179,6 +179,7 @@ obj-$(CONFIG_XEN_WDT) += xen_wdt.o
 # Architecture Independent
 obj-$(CONFIG_DA9052_WATCHDOG) += da9052_wdt.o
 obj-$(CONFIG_DA9055_WATCHDOG) += da9055_wdt.o
+obj-$(CONFIG_DA9062_WATCHDOG) += da9062_wdt.o
 obj-$(CONFIG_DA9063_WATCHDOG) += da9063_wdt.o
 obj-$(CONFIG_GPIO_WATCHDOG)	+= gpio_wdt.o
 obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c
new file mode 100644
index 0000000..b3a870c
--- /dev/null
+++ b/drivers/watchdog/da9062_wdt.c
@@ -0,0 +1,253 @@
+/*
+ * da9062_wdt.c - WDT device driver for DA9062
+ * Copyright (C) 2015  Dialog Semiconductor Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/watchdog.h>
+#include <linux/platform_device.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/jiffies.h>
+#include <linux/mfd/da9062/registers.h>
+#include <linux/mfd/da9062/core.h>
+#include <linux/regmap.h>
+#include <linux/of.h>
+
+static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 };
+#define DA9062_TWDSCALE_DISABLE		0
+#define DA9062_TWDSCALE_MIN		1
+#define DA9062_TWDSCALE_MAX		(ARRAY_SIZE(wdt_timeout) - 1)
+#define DA9062_WDT_MIN_TIMEOUT		wdt_timeout[DA9062_TWDSCALE_MIN]
+#define DA9062_WDT_MAX_TIMEOUT		wdt_timeout[DA9062_TWDSCALE_MAX]
+#define DA9062_WDG_DEFAULT_TIMEOUT	wdt_timeout[DA9062_TWDSCALE_MAX-1]
+#define DA9062_RESET_PROTECTION_MS	300
+
+struct da9062_watchdog {
+	struct da9062 *hw;
+	struct watchdog_device wdtdev;
+	unsigned long j_time_stamp;
+};
+
+static void da9062_set_window_start(struct da9062_watchdog *wdt)
+{
+	wdt->j_time_stamp = jiffies;
+}
+
+static void da9062_apply_window_protection(struct da9062_watchdog *wdt)
+{
+	unsigned long delay = msecs_to_jiffies(DA9062_RESET_PROTECTION_MS);
+	unsigned long timeout = wdt->j_time_stamp + delay;
+	unsigned long now = jiffies;
+	unsigned int diff_ms;
+
+	/* if time-limit has not elapsed then wait for remainder */
+	if (time_before(now, timeout)) {
+		diff_ms = jiffies_to_msecs(timeout-now);
+		dev_dbg(wdt->hw->dev,
+			"Kicked too quickly. Delaying %u msecs\n", diff_ms);
+		msleep(diff_ms);
+	}
+}
+
+static unsigned int da9062_wdt_timeout_to_sel(unsigned int secs)
+{
+	unsigned int i;
+
+	for (i = DA9062_TWDSCALE_MIN; i <= DA9062_TWDSCALE_MAX; i++) {
+		if (wdt_timeout[i] >= secs)
+			return i;
+	}
+
+	return DA9062_TWDSCALE_MAX;
+}
+
+static int da9062_reset_watchdog_timer(struct da9062_watchdog *wdt)
+{
+	int ret;
+
+	da9062_apply_window_protection(wdt);
+
+	ret = regmap_update_bits(wdt->hw->regmap,
+			   DA9062AA_CONTROL_F,
+			   DA9062AA_WATCHDOG_MASK,
+			   DA9062AA_WATCHDOG_MASK);
+
+	da9062_set_window_start(wdt);
+
+	return ret;
+}
+
+static int da9062_wdt_update_timeout_register(struct da9062_watchdog *wdt,
+					      unsigned int regval)
+{
+	struct da9062 *chip = wdt->hw;
+	int ret;
+
+	ret = da9062_reset_watchdog_timer(wdt);
+	if (ret)
+		return ret;
+
+	return regmap_update_bits(chip->regmap,
+				  DA9062AA_CONTROL_D,
+				  DA9062AA_TWDSCALE_MASK,
+				  regval);
+}
+
+static int da9062_wdt_start(struct watchdog_device *wdd)
+{
+	struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
+	unsigned int selector;
+	int ret;
+
+	selector = da9062_wdt_timeout_to_sel(wdt->wdtdev.timeout);
+	ret = da9062_wdt_update_timeout_register(wdt, selector);
+	if (ret)
+		dev_err(wdt->hw->dev, "Watchdog failed to start (err = %d)\n",
+			ret);
+
+	return ret;
+}
+
+static int da9062_wdt_stop(struct watchdog_device *wdd)
+{
+	struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
+	int ret;
+
+	ret = da9062_reset_watchdog_timer(wdt);
+	if (ret) {
+		dev_err(wdt->hw->dev, "Failed to ping the watchdog (err = %d)\n",
+			ret);
+		return ret;
+	}
+
+	ret = regmap_update_bits(wdt->hw->regmap,
+				 DA9062AA_CONTROL_D,
+				 DA9062AA_TWDSCALE_MASK,
+				 DA9062_TWDSCALE_DISABLE);
+	if (ret)
+		dev_err(wdt->hw->dev, "Watchdog failed to stop (err = %d)\n",
+			ret);
+
+	return ret;
+}
+
+static int da9062_wdt_ping(struct watchdog_device *wdd)
+{
+	struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
+	int ret;
+
+	ret = da9062_reset_watchdog_timer(wdt);
+	if (ret)
+		dev_err(wdt->hw->dev, "Failed to ping the watchdog (err = %d)\n",
+			ret);
+
+	return ret;
+}
+
+static int da9062_wdt_set_timeout(struct watchdog_device *wdd,
+				  unsigned int timeout)
+{
+	struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
+	unsigned int selector;
+	int ret;
+
+	selector = da9062_wdt_timeout_to_sel(timeout);
+	ret = da9062_wdt_update_timeout_register(wdt, selector);
+	if (ret)
+		dev_err(wdt->hw->dev, "Failed to set watchdog timeout (err = %d)\n",
+			ret);
+	else
+		wdd->timeout = wdt_timeout[selector];
+
+	return ret;
+}
+
+static const struct watchdog_info da9062_watchdog_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+	.identity = "DA9062 WDT",
+};
+
+static const struct watchdog_ops da9062_watchdog_ops = {
+	.owner = THIS_MODULE,
+	.start = da9062_wdt_start,
+	.stop = da9062_wdt_stop,
+	.ping = da9062_wdt_ping,
+	.set_timeout = da9062_wdt_set_timeout,
+};
+
+static int da9062_wdt_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct da9062 *chip;
+	struct da9062_watchdog *wdt;
+
+	chip = dev_get_drvdata(pdev->dev.parent);
+	if (!chip)
+		return -EINVAL;
+
+	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	wdt->hw = chip;
+
+	wdt->wdtdev.info = &da9062_watchdog_info;
+	wdt->wdtdev.ops = &da9062_watchdog_ops;
+	wdt->wdtdev.min_timeout = DA9062_WDT_MIN_TIMEOUT;
+	wdt->wdtdev.max_timeout = DA9062_WDT_MAX_TIMEOUT;
+	wdt->wdtdev.timeout = DA9062_WDG_DEFAULT_TIMEOUT;
+	wdt->wdtdev.status = WATCHDOG_NOWAYOUT_INIT_STATUS;
+
+	watchdog_set_drvdata(&wdt->wdtdev, wdt);
+	dev_set_drvdata(&pdev->dev, wdt);
+
+	ret = watchdog_register_device(&wdt->wdtdev);
+	if (ret < 0) {
+		dev_err(wdt->hw->dev,
+			"watchdog registration failed (%d)\n", ret);
+		return ret;
+	}
+
+	da9062_set_window_start(wdt);
+
+	ret = da9062_wdt_ping(&wdt->wdtdev);
+	if (ret < 0)
+		watchdog_unregister_device(&wdt->wdtdev);
+
+	return ret;
+}
+
+static int da9062_wdt_remove(struct platform_device *pdev)
+{
+	struct da9062_watchdog *wdt = dev_get_drvdata(&pdev->dev);
+
+	watchdog_unregister_device(&wdt->wdtdev);
+	return 0;
+}
+
+static struct platform_driver da9062_wdt_driver = {
+	.probe = da9062_wdt_probe,
+	.remove = da9062_wdt_remove,
+	.driver = {
+		.name = "da9062-watchdog",
+	},
+};
+module_platform_driver(da9062_wdt_driver);
+
+MODULE_AUTHOR("S Twiss <stwiss.opensource@diasemi.com>");
+MODULE_DESCRIPTION("WDT device driver for Dialog DA9062");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:da9062-watchdog");
-- 
end-of-patch for PATCH V3