[PATCH v2 2/4] ARM: meson: add watchdog driver
Carlo Caione
carlo at caione.org
Fri Sep 19 01:07:07 PDT 2014
On Fri, Sep 19, 2014 at 5:31 AM, Guenter Roeck <linux at roeck-us.net> wrote:
> 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.
It does actually.
>> +#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.
I swapped the values, you are right. About the maximum values I wish I
had proper documentation to answer your question.
Anyway your guessing is probably right so I'll change it.
>> +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 ?
Just setting a really small timeout (I'm still not sure if 100 means
actually 1ms timeout or just "the minimum timeout")
>> + 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.
It was like that in the original code. I'll check if it is necessary.
>
>> + 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.
Agree
>> + 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 ?
I'll check it.
>> + 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).
Ok. I'll fix it in v3.
>
>> + 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.
Ok
>> +
>> + 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.
Ok
>
>> +
>> + 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");
Thank you for the review.
--
Carlo Caione
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