[PATCH v3 4/4] watchdog: add Gateworks System Controller support

[Tim Harvey <tharvey@gateworks.com>]

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
---
 drivers/watchdog/Kconfig   |  10 ++++
 drivers/watchdog/Makefile  |   1 +
 drivers/watchdog/gsc_wdt.c | 146 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 157 insertions(+)
 create mode 100644 drivers/watchdog/gsc_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index ca200d1..c9d4b2e 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -150,6 +150,16 @@ config GPIO_WATCHDOG_ARCH_INITCALL
 	  arch_initcall.
 	  If in doubt, say N.
 
+config GSC_WATCHDOG
+	tristate "Gateworks System Controller (GSC) Watchdog support"
+	depends on MFD_GATEWORKS_GSC
+	select WATCHDOG_CORE
+	help
+	  Say Y here to include support for the GSC Watchdog.
+
+	  This driver can also be built as a module. If so the module
+	  will be called gsc_wdt.
+
 config MENF21BMC_WATCHDOG
 	tristate "MEN 14F021P00 BMC Watchdog"
 	depends on MFD_MENF21BMC || COMPILE_TEST
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 715a210..499327e 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -215,6 +215,7 @@ 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-$(CONFIG_GSC_WATCHDOG)	+= gsc_wdt.o
 obj-$(CONFIG_TANGOX_WATCHDOG) += tangox_wdt.o
 obj-$(CONFIG_WDAT_WDT) += wdat_wdt.o
 obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
diff --git a/drivers/watchdog/gsc_wdt.c b/drivers/watchdog/gsc_wdt.c
new file mode 100644
index 0000000..b43d083
--- /dev/null
+++ b/drivers/watchdog/gsc_wdt.c
@@ -0,0 +1,146 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2018 Gateworks Corporation
+ *
+ * This driver registers a Linux Watchdog for the GSC
+ */
+#include <linux/mfd/gsc.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/watchdog.h>
+
+#define WDT_DEFAULT_TIMEOUT	60
+
+struct gsc_wdt {
+	struct watchdog_device wdt_dev;
+	struct gsc_dev *gsc;
+};
+
+static int gsc_wdt_start(struct watchdog_device *wdd)
+{
+	struct gsc_wdt *wdt = watchdog_get_drvdata(wdd);
+	unsigned int reg = (1 << GSC_CTRL_1_WDT_ENABLE);
+	int ret;
+
+	dev_dbg(wdd->parent, "%s timeout=%d\n", __func__, wdd->timeout);
+
+	/* clear first as regmap_update_bits will not write if no change */
+	ret = regmap_update_bits(wdt->gsc->regmap, GSC_CTRL_1, reg, 0);
+	if (ret)
+		return ret;
+	return regmap_update_bits(wdt->gsc->regmap, GSC_CTRL_1, reg, reg);
+}
+
+static int gsc_wdt_stop(struct watchdog_device *wdd)
+{
+	struct gsc_wdt *wdt = watchdog_get_drvdata(wdd);
+	unsigned int reg = (1 << GSC_CTRL_1_WDT_ENABLE);
+
+	dev_dbg(wdd->parent, "%s\n", __func__);
+
+	return regmap_update_bits(wdt->gsc->regmap, GSC_CTRL_1, reg, 0);
+}
+
+static int gsc_wdt_set_timeout(struct watchdog_device *wdd,
+			       unsigned int timeout)
+{
+	struct gsc_wdt *wdt = watchdog_get_drvdata(wdd);
+	unsigned int long_sel = 0;
+
+	dev_dbg(wdd->parent, "%s: %d\n", __func__, timeout);
+
+	switch (timeout) {
+	case 60:
+		long_sel = (1 << GSC_CTRL_1_WDT_TIME);
+	case 30:
+		regmap_update_bits(wdt->gsc->regmap, GSC_CTRL_1,
+				   (1 << GSC_CTRL_1_WDT_TIME),
+				   (long_sel << GSC_CTRL_1_WDT_TIME));
+		wdd->timeout = timeout;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static const struct watchdog_info gsc_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+	.identity = "GSC Watchdog"
+};
+
+static const struct watchdog_ops gsc_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= gsc_wdt_start,
+	.stop		= gsc_wdt_stop,
+	.set_timeout	= gsc_wdt_set_timeout,
+};
+
+static int gsc_wdt_probe(struct platform_device *pdev)
+{
+	struct gsc_dev *gsc = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	struct gsc_wdt *wdt;
+	int ret;
+	unsigned int reg;
+
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	/* ensure GSC fw supports WD functionality */
+	if (gsc->fwver < 44) {
+		dev_err(dev, "fw v44 or newer required for wdt function\n");
+		return -EINVAL;
+	}
+
+	/* ensure WD bit enabled */
+	if (regmap_read(gsc->regmap, GSC_CTRL_1, &reg))
+		return -EIO;
+	if (!(reg & (1 << GSC_CTRL_1_WDT_ENABLE))) {
+		dev_err(dev, "not enabled - must be manually enabled\n");
+		return -EINVAL;
+	}
+
+	platform_set_drvdata(pdev, wdt);
+
+	wdt->gsc = gsc;
+	wdt->wdt_dev.info = &gsc_wdt_info;
+	wdt->wdt_dev.ops = &gsc_wdt_ops;
+	wdt->wdt_dev.status = 0;
+	wdt->wdt_dev.min_timeout = 30;
+	wdt->wdt_dev.max_timeout = 60;
+	wdt->wdt_dev.parent = dev;
+
+	watchdog_set_nowayout(&wdt->wdt_dev, 1);
+	watchdog_init_timeout(&wdt->wdt_dev, WDT_DEFAULT_TIMEOUT, dev);
+
+	watchdog_set_drvdata(&wdt->wdt_dev, wdt);
+	ret = devm_watchdog_register_device(dev, &wdt->wdt_dev);
+	if (ret)
+		return ret;
+
+	dev_info(dev, "watchdog driver (timeout=%d sec)\n",
+		 wdt->wdt_dev.timeout);
+
+	return 0;
+}
+
+static const struct of_device_id gsc_wdt_dt_ids[] = {
+	{ .compatible = "gw,gsc-watchdog", },
+	{}
+};
+
+static struct platform_driver gsc_wdt_driver = {
+	.probe		= gsc_wdt_probe,
+	.driver		= {
+		.name	= "gsc-wdt",
+		.of_match_table = gsc_wdt_dt_ids,
+	},
+};
+
+module_platform_driver(gsc_wdt_driver);
+
+MODULE_AUTHOR("Tim Harvey <tharvey@gateworks.com>");
+MODULE_DESCRIPTION("Gateworks System Controller Watchdog driver");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4