Re: [PATCH 8/8] watchdog: stpmu1: add stpmu1 watchdog driver
From: Guenter Roeck
Date: Thu Jul 05 2018 - 14:49:02 EST
On 07/05/2018 08:14 AM, Pascal PAILLET-LME wrote:
From: pascal paillet <p.paillet@xxxxxx>
The stpmu1 PMIC embeds a watchdog which is disabled by default. As soon
as the watchdog is started, it must be refreshed periodically otherwise
the PMIC goes off.
Signed-off-by: pascal paillet <p.paillet@xxxxxx>
---
drivers/watchdog/Kconfig | 12 +++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/stpmu1_wdt.c | 177 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 190 insertions(+)
create mode 100644 drivers/watchdog/stpmu1_wdt.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 9af07fd..2155f4d 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -796,6 +796,18 @@ config STM32_WATCHDOG
To compile this driver as a module, choose M here: the
module will be called stm32_iwdg.
+config STPMU1_WATCHDOG
+ tristate "STPMU1 PMIC watchdog support"
+ depends on MFD_STPMU1
+ select WATCHDOG_CORE
+ help
+ Say Y here to include watchdog support embedded into STPMU1 PMIC.
+ If the watchdog timer expires, stpmu1 shut-down all its power
+ supplies.
+
+ To compile this driver as a module, choose M here: the
+ module will be called spmu1_wdt.
+
config UNIPHIER_WATCHDOG
tristate "UniPhier watchdog support"
depends on ARCH_UNIPHIER || COMPILE_TEST
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 1d3c6b0..c9eba94 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -216,3 +216,4 @@ obj-$(CONFIG_ZIIRAVE_WATCHDOG) += ziirave_wdt.o
obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
obj-$(CONFIG_RAVE_SP_WATCHDOG) += rave-sp-wdt.o
+obj-$(CONFIG_STPMU1_WATCHDOG) += stpmu1_wdt.o
diff --git a/drivers/watchdog/stpmu1_wdt.c b/drivers/watchdog/stpmu1_wdt.c
new file mode 100644
index 0000000..57e0afa
--- /dev/null
+++ b/drivers/watchdog/stpmu1_wdt.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) STMicroelectronics 2018 - All Rights Reserved
+ * Author: Philippe Peurichard <philippe.peurichard@xxxxxx>,
+ * Pascal Paillet <p.paillet@xxxxxx> for STMicroelectronics.
+ */
+
+#include <linux/kernel.h>
+#include <linux/mfd/stpmu1.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/reboot.h>
+#include <linux/slab.h>
+#include <linux/watchdog.h>
+
+/* WATCHDOG CONTROL REGISTER bit */
+#define WDT_START BIT(0)
+#define WDT_PING BIT(1)
+#define WDT_START_MASK BIT(0)
+#define WDT_PING_MASK BIT(1)
+
+#define PMIC_WDT_MIN_TIMEOUT 1
+#define PMIC_WDT_MAX_TIMEOUT 256
+
+struct stpmu1_wdt {
+ struct stpmu1_dev *pmic;
+ struct watchdog_device wdtdev;
+ struct notifier_block restart_handler;
+};
+
+static int pmic_wdt_start(struct watchdog_device *wdd)
+{
+ struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ return regmap_update_bits(wdt->pmic->regmap,
+ WCHDG_CR, WDT_START_MASK, WDT_START);
+}
+
+static int pmic_wdt_stop(struct watchdog_device *wdd)
+{
+ struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ return regmap_update_bits(wdt->pmic->regmap,
+ WCHDG_CR, WDT_START_MASK, ~WDT_START);
+}
+
+static int pmic_wdt_ping(struct watchdog_device *wdd)
+{
+ struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
+ int ret;
+
+ return regmap_update_bits(wdt->pmic->regmap,
+ WCHDG_CR, WDT_PING_MASK, WDT_PING);
+ return ret;
+}
+
+static int pmic_wdt_set_timeout(struct watchdog_device *wdd,
+ unsigned int timeout)
+{
+ struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
+ int ret;
+
+ ret = regmap_write(wdt->pmic->regmap, WCHDG_TIMER_CR, timeout);
+ if (ret)
+ dev_err(wdt->pmic->dev,
+ "Failed to set watchdog timeout (err = %d)\n", ret);
+ else
+ wdd->timeout = PMIC_WDT_MAX_TIMEOUT;
First the requested timeout is set, then the caller is notified
that the timeout was set to the maximum possible value ? That doesn't
make sense. If that is really intentional, I would expect a detailed
explanation, and I would expect that the value written into the chip
register matches the value reported back to the user.
+
+ return ret;
+}
+
+static int pmic_wdt_restart_handler(struct notifier_block *this,
+ unsigned long mode, void *cmd)
+{
+ struct stpmu1_wdt *wdt = container_of(this,
+ struct stpmu1_wdt,
+ restart_handler);
+
+ dev_info(wdt->pmic->dev,
+ "PMIC Watchdog Elapsed (timeout %d), shutdown of PMIC initiated\n",
+ wdt->wdtdev.timeout);
+
Register a restart handler just to issue a message ? That is quite pointless.
A restart handler is supposed to restart the system. Besides, the message
is highly misleading; there is no reason to believe that it will be called
after the watchdog expired.
This function should restart the system. If it doesn't, drop it.
+ return NOTIFY_DONE;
+}
+
+static const struct watchdog_info pmic_watchdog_info = {
+ .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+ .identity = "STPMU1 PMIC Watchdog",
+};
+
+static const struct watchdog_ops pmic_watchdog_ops = {
+ .owner = THIS_MODULE,
+ .start = pmic_wdt_start,
+ .stop = pmic_wdt_stop,
+ .ping = pmic_wdt_ping,
+ .set_timeout = pmic_wdt_set_timeout,
+};
+
+static int pmic_wdt_probe(struct platform_device *pdev)
+{
+ int ret;
+ struct stpmu1_dev *pmic;
+ struct stpmu1_wdt *wdt;
+
+ if (!pdev->dev.parent)
+ return -EINVAL;
+
+ pmic = dev_get_drvdata(pdev->dev.parent);
+ if (!pmic)
+ return -EINVAL;
+
+ wdt = devm_kzalloc(&pdev->dev, sizeof(struct stpmu1_wdt), GFP_KERNEL);
+ if (!wdt)
+ return -ENOMEM;
+
+ wdt->pmic = pmic;
+
+ wdt->wdtdev.info = &pmic_watchdog_info;
+ wdt->wdtdev.ops = &pmic_watchdog_ops;
+ wdt->wdtdev.min_timeout = PMIC_WDT_MIN_TIMEOUT;
+ wdt->wdtdev.max_timeout = PMIC_WDT_MAX_TIMEOUT;
+ wdt->wdtdev.timeout = PMIC_WDT_MAX_TIMEOUT;
256 seconds default timeout ? Unusual, just making sure that this is what you want.
+
+ 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)
+ return ret;
+
+ wdt->restart_handler.notifier_call = pmic_wdt_restart_handler;
+ wdt->restart_handler.priority = 128;
+ ret = register_restart_handler(&wdt->restart_handler);
Why is the restart handler provided by the watchdog core not sufficient ?
+ if (ret) {
+ dev_err(wdt->pmic->dev, "failed to register restart handler\n");
+ return ret;
+ }
+
+ dev_dbg(wdt->pmic->dev, "PMIC Watchdog driver probed\n");
The only reasons not to use the devm_ function to register the watchdog
are the restart handler, which 1) doesn't do anything and 2) should use
the watchdog core, and this debug message. I would suggest to use the
devm_ function to register the watchdog instead.
+ return 0;
+}
+
+static int pmic_wdt_remove(struct platform_device *pdev)
+{
+ struct stpmu1_wdt *wdt = dev_get_drvdata(&pdev->dev);
+
+ unregister_restart_handler(&wdt->restart_handler);
+ watchdog_unregister_device(&wdt->wdtdev);
+
+ return 0;
+}
+
+static const struct of_device_id of_pmic_wdt_match[] = {
+ { .compatible = "st,stpmu1-wdt" },
+ { },
+};
+
+MODULE_DEVICE_TABLE(of, of_pmic_wdt_match);
+
+static struct platform_driver stpmu1_wdt_driver = {
+ .probe = pmic_wdt_probe,
+ .remove = pmic_wdt_remove,
+ .driver = {
+ .name = "stpmu1-wdt",
+ .of_match_table = of_pmic_wdt_match,
+ },
+};
+module_platform_driver(stpmu1_wdt_driver);
+
+MODULE_AUTHOR("philippe.peurichard@xxxxxx>");
+MODULE_DESCRIPTION("Watchdog driver for STPMU1 device");
+MODULE_LICENSE("GPL");