Message-ID: <HK2PR01MB3281885DA5822E1D10ACD07CFA970@HK2PR01MB3281.apcprd01.prod.exchangelabs.com>
Date:   Mon, 22 Jun 2020 10:03:29 +0000
From:   Johnson CH Chen (陳昭勳) 
        <JohnsonCH.Chen@...a.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        "linux@...ck-us.net" <linux@...ck-us.net>,
        Lee Jones <lee.jones@...aro.org>
Subject: [PATCH 3/3] watchdog: ds1374_wdt: Introduce Dallas/Maxim DS1374
  Watchdog driver

Here provide Watchdog function from rtc-ds1374.c which is in RTC subsystem
originally. Besides, add nowayout and implement Watchdog margin time when
DS1374 Watchdog device is found.

Signed-off-by: Johnson Chen <johnsonch.chen@...a.com>
---
 drivers/watchdog/Kconfig      |  11 ++
 drivers/watchdog/Makefile     |   1 +
 drivers/watchdog/ds1374_wdt.c | 330 ++++++++++++++++++++++++++++++++++
 3 files changed, 342 insertions(+)
 create mode 100644 drivers/watchdog/ds1374_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index b739c476955b..b4ff4b3c18da 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -316,6 +316,17 @@ config ZIIRAVE_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called ziirave_wdt.
 
+config DS1374_WATCHDOG
+	tristate "Dallas/Maxim DS1374 Watchdog timer"
+	depends on MFD_DS1374
+	select WATCHDOG_CORE
+	help
+	  If you say Y here you will get support for the watchdog timer
+	  in the Dallas/Maxim Semiconductor DS1374 real-time clock chips.
+
+	  This driver can also be built as a module. If so the module
+	  will be called ds1374_wdt.
+
 config RAVE_SP_WATCHDOG
 	tristate "RAVE SP Watchdog timer"
 	depends on RAVE_SP_CORE
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 6de2e4ceef19..1c468f5d9e5f 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -224,3 +224,4 @@ obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
 obj-$(CONFIG_MENZ069_WATCHDOG) += menz69_wdt.o
 obj-$(CONFIG_RAVE_SP_WATCHDOG) += rave-sp-wdt.o
 obj-$(CONFIG_STPMIC1_WATCHDOG) += stpmic1_wdt.o
+obj-$(CONFIG_DS1374_WATCHDOG) += ds1374_wdt.o
diff --git a/drivers/watchdog/ds1374_wdt.c b/drivers/watchdog/ds1374_wdt.c
new file mode 100644
index 000000000000..ce69e45973fd
--- /dev/null
+++ b/drivers/watchdog/ds1374_wdt.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
+ *
+ * Based on code by Randy Vinson <rvinson@...sta.com>,
+ * which was based on the m41t00.c by Mark Greer <mgreer@...sta.com>.
+ *
+ * Copyright (C) 2020 Johnson Chen <johnsonch.chen@...a.com>
+ * Copyright (C) 2014 Rose Technology
+ * Copyright (C) 2006-2007 Freescale Semiconductor
+ * Copyright (C) 2005 MontaVista Software, Inc.
+ */
+
+/*
+ * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
+ * recommened in .../Documentation/i2c/writing-clients section
+ * "Sending and receiving", using SMBus level communication is preferred.
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/ioctl.h>
+#include <linux/reboot.h>
+#include <linux/watchdog.h>
+#include <linux/workqueue.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+#include <linux/uaccess.h>
+
+#define DEVNAME                 "ds1374_wdt"
+
+#define DS1374_REG_WDALM0	0x04 /* Watchdog/Alarm */
+#define DS1374_REG_WDALM1	0x05
+#define DS1374_REG_WDALM2	0x06
+#define DS1374_REG_CR		0x07 /* Control */
+#define DS1374_REG_CR_AIE	0x01 /* Alarm Int. Enable */
+#define DS1374_REG_CR_WDSTR     0x08 /* 1=INT, 0=RST */
+#define DS1374_REG_CR_WDALM	0x20 /* 1=Watchdog, 0=Alarm */
+#define DS1374_REG_CR_WACE	0x40 /* WD/Alarm counter enable */
+
+/* Default margin */
+#define WD_TIMO                 131762
+#define TIMER_MARGIN_MIN	4096 /* 1s */
+#define TIMER_MARGIN_MAX	(60*60*24*4096) /* one day */
+
+static int wdt_margin = WD_TIMO;
+module_param(wdt_margin, int, 0);
+MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 32s)");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started default ="
+		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+struct ds1374_wdt {
+	struct i2c_client *client;
+	struct watchdog_device *wdt;
+	struct work_struct work;
+
+	/* The mutex protects alarm operations, and prevents a race
+	 * between the enable_irq() in the workqueue and the free_irq()
+	 * in the remove function.
+	 */
+	struct mutex mutex;
+};
+
+static const struct watchdog_info ds1374_wdt_info = {
+	.identity       = DEVNAME,
+	.options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
+						WDIOF_MAGICCLOSE,
+};
+
+static struct watchdog_device ds1374_wdd;
+
+static int ds1374_wdt_settimeout(struct watchdog_device *wdt,
+					unsigned int timeout)
+{
+	int ret = -ENOIOCTLCMD;
+	u8 buf[4];
+	int cr, i;
+	struct ds1374_wdt *drv_data = watchdog_get_drvdata(wdt);
+
+	ret = cr = i2c_smbus_read_byte_data(drv_data->client, DS1374_REG_CR);
+	if (ret < 0)
+		goto out;
+
+	/* Disable any existing watchdog/alarm before setting the new one */
+	cr &= ~DS1374_REG_CR_WACE;
+
+	ret = i2c_smbus_write_byte_data(drv_data->client, DS1374_REG_CR, cr);
+	if (ret < 0)
+		goto out;
+
+	/* Set new watchdog time */
+	for (i = 0; i < 3; i++) {
+		buf[i] = timeout & 0xff;
+		timeout >>= 8;
+	}
+
+	ret = i2c_smbus_write_i2c_block_data(drv_data->client,
+						DS1374_REG_WDALM0, 3, buf);
+	if (ret) {
+		pr_info("couldn't set new watchdog time\n");
+		goto out;
+	}
+
+	/* Enable watchdog timer */
+	cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM;
+	cr &= ~DS1374_REG_CR_WDSTR;/* for RST PIN */
+	cr &= ~DS1374_REG_CR_AIE;
+
+	ret = i2c_smbus_write_byte_data(drv_data->client, DS1374_REG_CR, cr);
+	if (ret < 0)
+		goto out;
+
+	return 0;
+out:
+	return ret;
+}
+
+
+/*
+ * Read WD/Alarm counter to reload the watchdog timer. (ie, pat the watchdog)
+ */
+static int ds1374_wdt_ping(struct watchdog_device *wdt)
+{
+	struct ds1374_wdt *drv_data = watchdog_get_drvdata(wdt);
+	int ret;
+	u8 buf[4];
+
+	ret = i2c_smbus_read_i2c_block_data(drv_data->client,
+						DS1374_REG_WDALM0, 3, buf);
+
+	if (ret < 0 || ret < 3)
+		pr_info("WD TICK FAIL!!!!!!!!!! %i\n", ret);
+
+	return ret;
+}
+
+static int ds1374_wdt_start(struct watchdog_device *wdt)
+{
+	int ret;
+
+	ret = ds1374_wdt_settimeout(wdt, wdt_margin);
+	if (ret)
+		return ret;
+
+	ds1374_wdt_ping(wdt);
+
+	return 0;
+}
+
+static int ds1374_wdt_stop(struct watchdog_device *wdt)
+{
+	struct ds1374_wdt *drv_data = watchdog_get_drvdata(wdt);
+	int cr;
+
+	if (nowayout)
+		return 0;
+
+	cr = i2c_smbus_read_byte_data(drv_data->client, DS1374_REG_CR);
+	/* Disable watchdog timer */
+	cr &= ~DS1374_REG_CR_WACE;
+
+	return i2c_smbus_write_byte_data(drv_data->client, DS1374_REG_CR, cr);
+}
+
+/*
+ * Handle commands from user-space.
+ */
+static long ds1374_wdt_ioctl(struct watchdog_device *wdt, unsigned int cmd,
+				unsigned long arg)
+{
+	int new_margin, options;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		return copy_to_user((struct watchdog_info __user *)arg,
+		&ds1374_wdt_info, sizeof(ds1374_wdt_info)) ? -EFAULT : 0;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		return put_user(0, (int __user *)arg);
+	case WDIOC_KEEPALIVE:
+		ds1374_wdt_ping(wdt);
+		return 0;
+	case WDIOC_SETTIMEOUT:
+		if (get_user(new_margin, (int __user *)arg))
+			return -EFAULT;
+
+		/* the hardware's tick rate is 4096 Hz, so
+		 * the counter value needs to be scaled accordingly
+		 */
+		new_margin <<= 12;
+		if (new_margin < 1 || new_margin > 16777216)
+			return -EINVAL;
+
+		wdt_margin = new_margin;
+		ds1374_wdt_settimeout(wdt, new_margin);
+		ds1374_wdt_ping(wdt);
+		fallthrough;
+	case WDIOC_GETTIMEOUT:
+		/* when returning ... inverse is true */
+		return put_user((wdt_margin >> 12), (int __user *)arg);
+	case WDIOC_SETOPTIONS:
+		if (copy_from_user(&options, (int __user *)arg, sizeof(int)))
+			return -EFAULT;
+
+		if (options & WDIOS_DISABLECARD) {
+			pr_info("disable watchdog\n");
+			ds1374_wdt_stop(wdt);
+			return 0;
+		}
+
+		if (options & WDIOS_ENABLECARD) {
+			pr_info("enable watchdog\n");
+			ds1374_wdt_settimeout(wdt, wdt_margin);
+			ds1374_wdt_ping(wdt);
+			return 0;
+		}
+		return -EINVAL;
+	}
+	return -ENOTTY;
+}
+
+static int ds1374_wdt_notify_sys(struct notifier_block *this,
+			unsigned long code, void *unused)
+{
+	if (code == SYS_DOWN || code == SYS_HALT)
+		/* Disable Watchdog */
+		ds1374_wdt_stop(&ds1374_wdd);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block ds1374_wdt_notifier = {
+	.notifier_call = ds1374_wdt_notify_sys,
+};
+
+static int ds1374_wdt_probe(struct platform_device *pdev)
+{
+	struct ds1374_wdt *drv_data;
+	struct i2c_client *client = to_i2c_client(pdev->dev.parent);
+	int ret;
+
+	drv_data = devm_kzalloc(&pdev->dev, sizeof(struct ds1374_wdt),
+				GFP_KERNEL);
+	if (!drv_data)
+		return -ENOMEM;
+
+	drv_data->wdt = &ds1374_wdd;
+	drv_data->client = client;
+	mutex_init(&drv_data->mutex);
+
+	watchdog_init_timeout(drv_data->wdt, wdt_margin, &pdev->dev);
+	watchdog_set_nowayout(drv_data->wdt, nowayout);
+
+	watchdog_set_drvdata(drv_data->wdt, drv_data);
+	platform_set_drvdata(pdev, drv_data);
+
+	ret = watchdog_register_device(drv_data->wdt);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register Watchdog device\n");
+		return ret;
+	}
+
+	ret = register_reboot_notifier(&ds1374_wdt_notifier);
+	if (ret) {
+		watchdog_unregister_device(drv_data->wdt);
+		return ret;
+	}
+
+	ds1374_wdt_settimeout(drv_data->wdt, wdt_margin);
+	dev_info(&pdev->dev, "Dallas/Maxim DS1374 watchdog device enabled\n");
+
+	return 0;
+}
+
+static int ds1374_wdt_remove(struct platform_device *pdev)
+{
+	struct ds1374_wdt *drv_data = platform_get_drvdata(pdev);
+
+	dev_warn(&pdev->dev, "Unregister DS1374 watchdog device\n");
+	watchdog_unregister_device(drv_data->wdt);
+	unregister_reboot_notifier(&ds1374_wdt_notifier);
+
+	return 0;
+}
+
+static void ds1374_wdt_shutdown(struct platform_device *pdev)
+{
+	struct ds1374_wdt *drv_data = platform_get_drvdata(pdev);
+
+	mutex_lock(&drv_data->mutex);
+	ds1374_wdt_stop(drv_data->wdt);
+	mutex_unlock(&drv_data->mutex);
+}
+
+static const struct watchdog_ops ds1374_wdt_fops = {
+	.owner          = THIS_MODULE,
+	.start          = ds1374_wdt_start,
+	.stop           = ds1374_wdt_stop,
+	.ping           = ds1374_wdt_ping,
+	.set_timeout    = ds1374_wdt_settimeout,
+	.ioctl          = ds1374_wdt_ioctl,
+};
+
+static struct watchdog_device ds1374_wdd = {
+	.info           = &ds1374_wdt_info,
+	.ops            = &ds1374_wdt_fops,
+	.min_timeout    = TIMER_MARGIN_MIN,
+	.max_timeout    = TIMER_MARGIN_MAX,
+};
+
+static struct platform_driver ds1374_wdt = {
+	.driver         = {
+		.owner  = THIS_MODULE,
+		.name   = DEVNAME,
+	},
+	.probe          = ds1374_wdt_probe,
+	.remove         = ds1374_wdt_remove,
+	.shutdown       = ds1374_wdt_shutdown,
+};
+
+module_platform_driver(ds1374_wdt);
+
+MODULE_AUTHOR("Johnson Chen <johnsonch.chen@...a.com>");
+MODULE_DESCRIPTION("Dallas/Maxim DS1374 Watchdog Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("Platform:ds1374_wdt");
-- 
2.20.1

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