[PATCH v2 2/4] ARM: meson: add watchdog driver
Guenter Roeck
linux at roeck-us.net
Thu Sep 18 20:31:27 PDT 2014
On 09/17/2014 01:12 PM, Carlo Caione wrote:
> This patch adds the watchdog driver for the Amlogic Meson SoCs used also
> to reboot the device.
>
> Signed-off-by: Carlo Caione <carlo at caione.org>
> ---
> drivers/watchdog/Kconfig | 10 ++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/meson_wdt.c | 237 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 248 insertions(+)
> create mode 100644 drivers/watchdog/meson_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index f57312f..836cb00 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -443,6 +443,16 @@ config TEGRA_WATCHDOG
> To compile this driver as a module, choose M here: the
> module will be called tegra_wdt.
>
> +config MESON_WATCHDOG
> + tristate "Amlogic Meson SoCs watchdog support"
> + depends on ARCH_MESON
> + select WATCHDOG_CORE
> + help
> + Say Y here to include support for the watchdog timer
> + in Amlogic Meson SoCs.
> + To compile this driver as a module, choose M here: the
> + module will be called meson_wdt.
> +
> # AVR32 Architecture
>
> config AT32AP700X_WDT
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 468c320..e7a9259 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -59,6 +59,7 @@ obj-$(CONFIG_MOXART_WDT) += moxart_wdt.o
> obj-$(CONFIG_SIRFSOC_WATCHDOG) += sirfsoc_wdt.o
> obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o
> obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
> +obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
>
> # AVR32 Architecture
> obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> diff --git a/drivers/watchdog/meson_wdt.c b/drivers/watchdog/meson_wdt.c
> new file mode 100644
> index 0000000..3fbe147
> --- /dev/null
> +++ b/drivers/watchdog/meson_wdt.c
> @@ -0,0 +1,237 @@
> +/*
> + * Meson Watchdog Driver
> + *
> + * Copyright (c) 2014 Carlo Caione
> + *
> + * 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.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/notifier.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>
> +#include <linux/types.h>
> +#include <linux/watchdog.h>
> +
> +#define DRV_NAME "meson_wdt"
> +
> +#define MESON_WDT_TC 0x00
> +#define MESON_WDT_TC_EN BIT(22)
> +#define MESON_WDT_TC_TM_MASK 0x3fffff
> +#define MESON_WDT_DC_RESET (3 << 24)
> +
> +#define MESON_WDT_RESET 0x04
> +
Does this all use the same indentation ? Looks a bit odd.
> +#define MESON_WDT_TIMEOUT 40
> +#define MESON_WDT_MIN_TIMEOUT 1
> +#define MESON_WDT_MAX_TIMEOUT 30
> +
Default timeout is 40 seconds, maximum timeout is 30 seconds ?
That doesn't really make much sense. What is the real maximum timeout ?
If it is 0x3fffff / 100000, as the code suggests, you should set
MAX_TIMEOUT to 41 or possibly (0x3fffff / 100000) so people understand
what is going on.
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +static unsigned int timeout = MESON_WDT_TIMEOUT;
> +
> +struct meson_wdt_dev {
> + struct watchdog_device wdt_dev;
> + void __iomem *wdt_base;
> + struct notifier_block restart_handler;
> +};
> +
> +static int meson_restart_handle(struct notifier_block *this, unsigned long mode,
> + void *cmd)
> +{
> + u32 tc_reboot = MESON_WDT_DC_RESET | MESON_WDT_TC_EN | 100;
What does the magic 100 do ?
> + struct meson_wdt_dev *meson_wdt = container_of(this,
> + struct meson_wdt_dev,
> + restart_handler);
> +
> + writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
> + writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
> +
Is this sequence necessary ? Just asking, looks a bit odd.
> + while (1) {
> + mdelay(5);
> + writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
> + }
> +
> + return NOTIFY_DONE;
> +}
> +
> +static int meson_wdt_ping(struct watchdog_device *wdt_dev)
> +{
> + struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
> +
> + writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
> +
> + return 0;
> +}
> +
> +static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
> + unsigned int timeout)
> +{
> + struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
> + u32 reg;
> +
> + meson_wdt->wdt_dev.timeout = timeout;
> +
> + reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
> + reg &= ~MESON_WDT_TC_TM_MASK;
> + reg |= (timeout * 100 * 1000);
A define for the clock rate might be helpful.
> + writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
> +
> + meson_wdt_ping(wdt_dev);
> +
> + return 0;
> +}
> +
> +static int meson_wdt_stop(struct watchdog_device *wdt_dev)
> +{
> + struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
> + u32 reg;
> +
> + writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
Is this final ping really needed here ?
> + reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
> + reg &= ~MESON_WDT_TC_EN;
> + writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
> +
> + return 0;
> +}
> +
> +static int meson_wdt_start(struct watchdog_device *wdt_dev)
> +{
> + struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
> + u32 reg;
> + int ret;
> +
> + ret = meson_wdt_set_timeout(&meson_wdt->wdt_dev,
> + meson_wdt->wdt_dev.timeout);
Not really sure if that is such a good idea here, as the set_timeout
function does a bit more than just writing the timeout into the register.
If you don't want to hard-code it here, I would suggest to write a
little helper function which only writes it into the register
(which would be called from both here and from meson_wdt_set_timeout).
> + if (ret < 0)
> + return ret;
> +
> + writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
> + reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
> + reg |= MESON_WDT_TC_EN;
> + writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
> +
> + return 0;
> +}
> +
> +static const struct watchdog_info meson_wdt_info = {
> + .identity = DRV_NAME,
> + .options = WDIOF_SETTIMEOUT |
> + WDIOF_KEEPALIVEPING |
> + WDIOF_MAGICCLOSE,
> +};
> +
> +static const struct watchdog_ops meson_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = meson_wdt_start,
> + .stop = meson_wdt_stop,
> + .ping = meson_wdt_ping,
> + .set_timeout = meson_wdt_set_timeout,
> +};
> +
> +static int meson_wdt_probe(struct platform_device *pdev)
> +{
> + struct resource *res;
> + struct meson_wdt_dev *meson_wdt;
> + int err;
> +
> + meson_wdt = devm_kzalloc(&pdev->dev, sizeof(*meson_wdt), GFP_KERNEL);
> + if (!meson_wdt)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + meson_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(meson_wdt->wdt_base))
> + return PTR_ERR(meson_wdt->wdt_base);
> +
> + meson_wdt->wdt_dev.parent = &pdev->dev;
> + meson_wdt->wdt_dev.info = &meson_wdt_info;
> + meson_wdt->wdt_dev.ops = &meson_wdt_ops;
> + meson_wdt->wdt_dev.timeout = MESON_WDT_TIMEOUT;
> + meson_wdt->wdt_dev.max_timeout = MESON_WDT_MAX_TIMEOUT;
> + meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
> +
> + watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
> +
> + watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, &pdev->dev);
> + watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
> +
> + meson_wdt_stop(&meson_wdt->wdt_dev);
> +
> + err = watchdog_register_device(&meson_wdt->wdt_dev);
> + if (unlikely(err))
> + return err;
Please drop the unlikely.
> +
> + platform_set_drvdata(pdev, meson_wdt);
> +
> + meson_wdt->restart_handler.notifier_call = meson_restart_handle;
> + meson_wdt->restart_handler.priority = 128;
> + err = register_restart_handler(&meson_wdt->restart_handler);
> + if (err)
> + dev_err(&pdev->dev,
> + "cannot register restart handler (err=%d)\n", err);
> +
> + dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
> + meson_wdt->wdt_dev.timeout, nowayout);
> +
> + return 0;
> +}
> +
> +static int meson_wdt_remove(struct platform_device *pdev)
> +{
> + struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
> +
> + unregister_restart_handler(&meson_wdt->restart_handler);
> +
> + watchdog_unregister_device(&meson_wdt->wdt_dev);
> + watchdog_set_drvdata(&meson_wdt->wdt_dev, NULL);
Unnecessary.
> +
> + return 0;
> +}
> +
> +static void meson_wdt_shutdown(struct platform_device *pdev)
> +{
> + struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
> +
> + meson_wdt_stop(&meson_wdt->wdt_dev);
> +}
> +
> +static const struct of_device_id meson_wdt_dt_ids[] = {
> + { .compatible = "amlogic,meson-wdt" },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
> +
> +static struct platform_driver meson_wdt_driver = {
> + .probe = meson_wdt_probe,
> + .remove = meson_wdt_remove,
> + .shutdown = meson_wdt_shutdown,
> + .driver = {
> + .owner = THIS_MODULE,
> + .name = DRV_NAME,
> + .of_match_table = meson_wdt_dt_ids,
> + },
> +};
> +
> +module_platform_driver(meson_wdt_driver);
> +
> +module_param(timeout, uint, 0);
> +MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
> +
> +module_param(nowayout, bool, 0);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
> + "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Carlo Caione <carlo at caione.org>");
> +MODULE_DESCRIPTION("Meson Watchdog Timer Driver");
>
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