Re: [PATCH 2/3] watchdog: Add Mstar MSC313e WDT driver
From: Guenter Roeck
Date: Tue May 25 2021 - 15:52:33 EST
On 5/25/21 11:44 AM, Romain Perier wrote:
From: Daniel Palmer <daniel@xxxxxxxx>
It adds a driver for the IP block handling the watchdog timer found for
Mstar MSC313e SoCs and newer.
Signed-off-by: Daniel Palmer <daniel@xxxxxxxx>
Co-developed-by: Romain Perier <romain.perier@xxxxxxxxx>
Signed-off-by: Romain Perier <romain.perier@xxxxxxxxx>
---
MAINTAINERS | 1 +
drivers/watchdog/Kconfig | 13 +++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/msc313e_wdt.c | 173 +++++++++++++++++++++++++++++++++
4 files changed, 188 insertions(+)
create mode 100644 drivers/watchdog/msc313e_wdt.c
diff --git a/MAINTAINERS b/MAINTAINERS
index a0f37adb9e64..fcc10c57298c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2177,6 +2177,7 @@ F: arch/arm/mach-mstar/
F: drivers/clk/mstar/
F: drivers/gpio/gpio-msc313.c
F: drivers/pinctrl/pinctrl-msc313.c
+F: drivers/watchdog/msc313e_wdt.c
F: include/dt-bindings/clock/mstar-*
F: include/dt-bindings/gpio/msc313-gpio.h
F: include/soc/mstar/
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 355100dad60a..f53634ea0de6 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -980,6 +980,19 @@ config VISCONTI_WATCHDOG
Say Y here to include support for the watchdog timer in Toshiba
Visconti SoCs.
+config MSC313E_WATCHDOG
+ tristate "MStar MSC313e watchdog"
+ depends on ARCH_MSTARV7 || COMPILE_TEST
+ depends on OF
+ select WATCHDOG_CORE
+ help
+ Say Y here to include support for the Watchdog timer embedded
+ into MStar MSC313e chips. This will reboot your system when the
+ timeout is reached.
+
+ To compile this driver as a module, choose M here: the
+ module will be called msc313e_wdt.
+
# X86 (i386 + ia64 + x86_64) Architecture
config ACQUIRE_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index a7eade8b4d45..7fa392ae3000 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -92,6 +92,7 @@ obj-$(CONFIG_SPRD_WATCHDOG) += sprd_wdt.o
obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o
obj-$(CONFIG_ARM_SMC_WATCHDOG) += arm_smc_wdt.o
obj-$(CONFIG_VISCONTI_WATCHDOG) += visconti_wdt.o
+obj-$(CONFIG_MSC313E_WATCHDOG) += msc313e_wdt.o
# X86 (i386 + ia64 + x86_64) Architecture
obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o
diff --git a/drivers/watchdog/msc313e_wdt.c b/drivers/watchdog/msc313e_wdt.c
new file mode 100644
index 000000000000..434259256967
--- /dev/null
+++ b/drivers/watchdog/msc313e_wdt.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MStar WDT driver
+ *
+ * Copyright (C) 2019 - 2021 Daniel Palmer
+ * Copyright (C) 2021 Romain Perier
+ *
+ */
+
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/module.h>
+#include <linux/watchdog.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/interrupt.h>
Alphabetic order, please. Also, pelase drop unneeded include files.
The driver doesn't support interrupts, so any interrupt related
include file is unnecessary. I also don't see any devicetree specific
code except for of_device_id, and that is declared in mod_devicetable.h,
not in an of_xxx.h include file.
+
+#define REG_WDT_CLR 0x0
+#define REG_WDT_MAX_PRD_L 0x10
+#define REG_WDT_MAX_PRD_H 0x14
+
+#define MSC313E_WDT_DEFAULT_TIMEOUT 30
+/* Supports 1 - 350 sec */
Doesn't that depend on the clock freqneucy ?
More on that see below.
+#define MSC313E_WDT_MIN_TIMEOUT 1
+#define MSC313E_WDT_MAX_TIMEOUT 350
+
+static unsigned int timeout;
+
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
+
+struct msc313e_wdt_priv {
+ void __iomem *base;
+ struct device *dev;
I don't immediately see where 'dev' is used.
+ struct watchdog_device wdev;
+ struct clk *clk;
+};
+
+static int msc313e_wdt_start(struct watchdog_device *wdev)
+{
+ struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
+ u32 timeout;
+ int err;
+
+ err = clk_prepare_enable(priv->clk);
+ if (err) {
+ dev_err(priv->dev, "failed to enable clock\n");
Ah, here. I am not sure if I like that error message - it is going to be
persistent and may create a lot of noise if it is ever seen, and pretty much
useless otherwise. Either case, if you insist on the message, I'd suggest
to use wdev->parent.
+ return err;
+ }
+ timeout = wdev->timeout * clk_get_rate(priv->clk);
How is it guaranteed that this won't overflow ? The maximum timeout is not
tied to the clock frequency. This will overflow if the clock frequency is
above 0xffffffff / 350 = 12271335 Hz and the timeout is sufficiently large.
+ writew(timeout & 0xffff, priv->base + REG_WDT_MAX_PRD_L);
+ writew((timeout >> 16) & 0xffff, priv->base + REG_WDT_MAX_PRD_H);
+ writew(1, priv->base + REG_WDT_CLR);
+ return 0;
+}
+
+static int msc313e_wdt_ping(struct watchdog_device *wdev)
+{
+ struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ writew(1, priv->base + REG_WDT_CLR);
+ return 0;
+}
+
+static int msc313e_wdt_stop(struct watchdog_device *wdev)
+{
+ struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ writew(0, priv->base + REG_WDT_MAX_PRD_L);
+ writew(0, priv->base + REG_WDT_MAX_PRD_H);
+ writew(0, priv->base + REG_WDT_CLR);
+ clk_disable_unprepare(priv->clk);
+ return 0;
+}
+
+static int msc313e_wdt_settimeout(struct watchdog_device *wdev, unsigned int new_time)
+{
+ wdev->timeout = new_time;
+
+ return msc313e_wdt_start(wdev);
+}
+
+static const struct watchdog_info msc313e_wdt_ident = {
+ .identity = "MSC313e watchdog",
+ .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+};
+
+static const struct watchdog_ops msc313e_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = msc313e_wdt_start,
+ .stop = msc313e_wdt_stop,
+ .ping = msc313e_wdt_ping,
+ .set_timeout = msc313e_wdt_settimeout,
+};
+
+static const struct of_device_id msc313e_wdt_of_match[] = {
+ { .compatible = "mstar,msc313e-wdt", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, msc313e_wdt_of_match);
+
+static int msc313e_wdt_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct msc313e_wdt_priv *priv;
+
+ priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(priv->base))
+ return PTR_ERR(priv->base);
+
+ priv->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(priv->clk)) {
+ dev_err(dev, "No input clock\n");
+ return PTR_ERR(priv->clk);
+ }
+
+ priv->dev = dev;
+ priv->wdev.info = &msc313e_wdt_ident,
+ priv->wdev.ops = &msc313e_wdt_ops,
+ priv->wdev.parent = dev;
+ priv->wdev.min_timeout = MSC313E_WDT_MIN_TIMEOUT;
+ priv->wdev.max_timeout = MSC313E_WDT_MAX_TIMEOUT;
+ priv->wdev.timeout = MSC313E_WDT_DEFAULT_TIMEOUT;
+
+ watchdog_set_drvdata(&priv->wdev, priv);
+
+ watchdog_init_timeout(&priv->wdev, timeout, dev);
+ watchdog_stop_on_reboot(&priv->wdev);
+ watchdog_stop_on_unregister(&priv->wdev);
+
+ return devm_watchdog_register_device(dev, &priv->wdev);
+}
+
+static int __maybe_unused msc313e_wdt_suspend(struct device *dev)
+{
+ struct msc313e_wdt_priv *priv = dev_get_drvdata(dev);
+
+ if (watchdog_active(&priv->wdev))
+ msc313e_wdt_stop(&priv->wdev);
+
+ return 0;
+}
+
+static int __maybe_unused msc313e_wdt_resume(struct device *dev)
+{
+ struct msc313e_wdt_priv *priv = dev_get_drvdata(dev);
+
+ if (watchdog_active(&priv->wdev))
+ msc313e_wdt_start(&priv->wdev);
+
+ return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(msc313e_wdt_pm_ops, msc313e_wdt_suspend, msc313e_wdt_resume);
+
+static struct platform_driver msc313e_wdt_driver = {
+ .driver = {
+ .name = "msc313e-wdt",
+ .of_match_table = msc313e_wdt_of_match,
+ .pm = &msc313e_wdt_pm_ops,
+ },
+ .probe = msc313e_wdt_probe,
+};
+module_platform_driver(msc313e_wdt_driver);
+
+MODULE_AUTHOR("Daniel Palmer <daniel@xxxxxxxxx>");
+MODULE_DESCRIPTION("Watchdog driver for MStar MSC313e");
+MODULE_LICENSE("GPL v2");