Re: [PATCH v7 6/7] Watchdog: ahc1ec0-wdt: Add sub-device Watchdog for Advantech embedded controller

From: Guenter Roeck
Date: Thu May 06 2021 - 09:17:41 EST


On Thu, May 06, 2021 at 04:16:18PM +0800, Campion Kang wrote:
> This is one of sub-device driver for Advantech embedded controller
> AHC1EC0. This driver provide Watchdog functionality for Advantech
> related applications to restart the system.
>
> Changed in V7:
> Fix the patch according to reviewer's comment:
> - remove unnecessary variables and fix error checks
> - remove error messages that avoid clogging the kernel log
> - remove advwdt_notify_sys(), use watchdog subsystem to process
> reboot or shutdown
> - delete mutex lock, the watchdog core has processed it
>
> Changed in V6:
> - remove unnecessary header files
> - bug fixed: reboot halt if watchdog enabled
> - Kconfig: add "AHC1EC0" string to clearly define the EC name
>
> Signed-off-by: Campion Kang <campion.kang@xxxxxxxxxxxxxxxx>
> ---
> drivers/watchdog/Kconfig | 11 +++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/ahc1ec0-wdt.c | 171 +++++++++++++++++++++++++++++++++
> 3 files changed, 183 insertions(+)
> create mode 100644 drivers/watchdog/ahc1ec0-wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 355100dad60a..5fe9add0a12d 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1005,6 +1005,17 @@ config ADVANTECH_WDT
> feature. More information can be found at
> <https://www.advantech.com.tw/products/>
>
> +config AHC1EC0_WDT
> + tristate "Advantech AHC1EC0 Watchdog Function"
> + depends on MFD_AHC1EC0
> + help
> + This is sub-device for Advantech AHC1EC0 embedded controller.
> +
> + This driver provide watchdog functionality for Advantech related
> + applications to restart the system.
> + To compile this driver as a module, choose M here: the module will be
> + called ahc1ec0-wdt.
> +
> config ALIM1535_WDT
> tristate "ALi M1535 PMU Watchdog Timer"
> depends on X86 && PCI
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index a7eade8b4d45..0d78211e1412 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -142,6 +142,7 @@ obj-$(CONFIG_NI903X_WDT) += ni903x_wdt.o
> obj-$(CONFIG_NIC7018_WDT) += nic7018_wdt.o
> obj-$(CONFIG_MLX_WDT) += mlx_wdt.o
> obj-$(CONFIG_KEEMBAY_WATCHDOG) += keembay_wdt.o
> +obj-$(CONFIG_AHC1EC0_WDT) += ahc1ec0-wdt.o
>
> # M68K Architecture
> obj-$(CONFIG_M54xx_WATCHDOG) += m54xx_wdt.o
> diff --git a/drivers/watchdog/ahc1ec0-wdt.c b/drivers/watchdog/ahc1ec0-wdt.c
> new file mode 100644
> index 000000000000..efa955c41a81
> --- /dev/null
> +++ b/drivers/watchdog/ahc1ec0-wdt.c
> @@ -0,0 +1,171 @@
> +// SPDX-License-Identifier: GPL-2.0-only

GPL or GPLv2 ?

> +/*
> + * Watchdog Driver for Advantech AHC1EC0 Embedded Controller
> + *
> + * Copyright 2021, Advantech IIoT Group
> + */
> +
> +#include <linux/errno.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/notifier.h>

Unnecessary.

> +#include <linux/platform_data/ahc1ec0.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>

Unnecessary.

> +#include <linux/types.h>
> +#include <linux/watchdog.h>
> +
> +struct ec_wdt_data {
> + struct watchdog_device wdtdev;
> + struct adv_ec_ddata *ddata;
> + unsigned short timeout_in_ds; /* a decisecond */

This variable is unnecessary.

> +};
> +
> +#define EC_WDT_MIN_TIMEOUT 1 /* The watchdog devices minimum timeout value (in seconds). */
> +#define EC_WDT_MAX_TIMEOUT 600 /* The watchdog devices maximum timeout value (in seconds) */

Please use constant alignment, and "The watchdog devices " is really
unnecessary.

> +#define EC_WDT_DEFAULT_TIMEOUT 45
> +
> +static int set_delay(struct adv_ec_ddata *ddata, unsigned short delay_timeout_in_ms)
> +{
> + if (ahc1ec_write_hw_ram(ddata, EC_RESET_DELAY_TIME_L,
> + delay_timeout_in_ms & 0x00FF))
> + return -EINVAL;
> +
> + if (ahc1ec_write_hw_ram(ddata, EC_RESET_DELAY_TIME_H,
> + (delay_timeout_in_ms & 0xFF00) >> 8))

Those functions presumably return a valid error code which should be passed
on and not replaced.

> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static int ec_wdt_start(struct watchdog_device *wdd)
> +{
> + int ret;
> + struct ec_wdt_data *ec_wdt_data = watchdog_get_drvdata(wdd);
> + struct adv_ec_ddata *ddata;
> +
> + ddata = ec_wdt_data->ddata;
> +

Might as well be written as
struct adv_ec_ddata *ddata = ec_wdt_data->ddata;

> + /*
> + * Because an unit of ahc1ec0_wdt is 0.1 seconds, timeout 100 is 10 seconds
> + */
> + ec_wdt_data->timeout_in_ds = wdd->timeout * 10;

timeout_in_ds can be a local variable (if not omitted entirely).

> +
> + ret = set_delay(ddata, (ec_wdt_data->timeout_in_ds - 1));

Unnecessary ( ) around second parameter.

> + if (ret)
> + goto exit;

if (ret)
return ret;

> +
> + ahc1ec_write_hwram_command(ddata, EC_WDT_STOP);
> + ret = ahc1ec_write_hwram_command(ddata, EC_WDT_START);
> + if (ret)
> + goto exit;

Unnecessary.

> +
> +exit:

Unnecessary label.

> + return ret;
> +}
> +
> +static int ec_wdt_stop(struct watchdog_device *wdd)
> +{
> + struct ec_wdt_data *ec_wdt_data = watchdog_get_drvdata(wdd);
> + struct adv_ec_ddata *ddata;
> +
> + ddata = ec_wdt_data->ddata;
> +
> + return ahc1ec_write_hwram_command(ddata, EC_WDT_STOP);
> +}
> +
> +static int ec_wdt_ping(struct watchdog_device *wdd)
> +{
> + int ret;
> + struct ec_wdt_data *ec_wdt_data = watchdog_get_drvdata(wdd);
> + struct adv_ec_ddata *ddata;
> +
> + ddata = ec_wdt_data->ddata;
> +
> + ret = ahc1ec_write_hwram_command(ddata, EC_WDT_RESET);
> + if (ret)
> + return -EINVAL;

return ret;

but then above you have
return ahc1ec_write_hwram_command(ddata, EC_WDT_STOP);

Please be consistent.

> +
> + return 0;
> +}
> +
> +static int ec_wdt_set_timeout(struct watchdog_device *wdd,
> + unsigned int timeout)
> +{
> + wdd->timeout = timeout;
> +
> + if (watchdog_active(wdd))
> + return ec_wdt_start(wdd);
> +
> + return 0;
> +}
> +
> +static const struct watchdog_info ec_watchdog_info = {
> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> + .identity = "AHC1EC0 Watchdog",
> +};
> +
> +static const struct watchdog_ops ec_watchdog_ops = {
> + .owner = THIS_MODULE,
> + .start = ec_wdt_start,
> + .stop = ec_wdt_stop,
> + .ping = ec_wdt_ping,
> + .set_timeout = ec_wdt_set_timeout,
> +};
> +
> +static int adv_ec_wdt_probe(struct platform_device *pdev)
> +{
> + int ret;
> + struct device *dev = &pdev->dev;
> + struct adv_ec_ddata *ddata;
> + struct ec_wdt_data *ec_wdt_data;
> + struct watchdog_device *wdd;
> +
> + ddata = dev_get_drvdata(dev->parent);
> + if (!ddata)
> + return -EINVAL;
> +
> + ec_wdt_data = devm_kzalloc(dev, sizeof(*ec_wdt_data), GFP_KERNEL);
> + if (!ec_wdt_data)
> + return -ENOMEM;
> +
> + ec_wdt_data->ddata = ddata;
> + wdd = &ec_wdt_data->wdtdev;
> +
> + watchdog_init_timeout(&ec_wdt_data->wdtdev, 0, dev);
> +

This should be after wdd->timeout is set, and please use wdd.

> + /* watchdog_set_nowayout(&ec_wdt_data->wdtdev, WATCHDOG_NOWAYOUT); */
> + watchdog_set_drvdata(&ec_wdt_data->wdtdev, ec_wdt_data);

Please use wdd.

> + platform_set_drvdata(pdev, ec_wdt_data);

Is this used anywhere ?

> +
> + wdd->info = &ec_watchdog_info;
> + wdd->ops = &ec_watchdog_ops;
> + wdd->min_timeout = EC_WDT_MIN_TIMEOUT;
> + wdd->max_timeout = EC_WDT_MAX_TIMEOUT;
> + wdd->parent = dev;
> +
> + ec_wdt_data->wdtdev.timeout = EC_WDT_DEFAULT_TIMEOUT;

wdd->timeout = EC_WDT_DEFAULT_TIMEOUT;

> +
> + watchdog_stop_on_reboot(wdd);
> + watchdog_stop_on_unregister(wdd);
> +
> + ret = devm_watchdog_register_device(dev, wdd);
> + if (ret == 0)
> + dev_info(dev, "ahc1ec0 watchdog register success\n");

This is noise.

> +
> + return ret;
> +}
> +
> +static struct platform_driver adv_wdt_drv = {
> + .driver = {
> + .name = "ahc1ec0-wdt",
> + },
> + .probe = adv_ec_wdt_probe,
> +};
> +module_platform_driver(adv_wdt_drv);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:ahc1ec0-wdt");
> +MODULE_DESCRIPTION("Advantech Embedded Controller Watchdog Driver.");
> +MODULE_AUTHOR("Campion Kang <campion.kang@xxxxxxxxxxxxxxxx>");
> +MODULE_VERSION("1.0");
> --
> 2.17.1
>