Date:   Thu, 6 May 2021 06:17:34 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Campion Kang <campion.kang@...antech.com.tw>
Cc:     Lee Jones <lee.jones@...aro.org>, Rob Herring <robh+dt@...nel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <mgross@...ux.intel.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Jean Delvare <jdelvare@...e.com>,
        Jonathan Corbet <corbet@....net>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
        platform-driver-x86@...r.kernel.org,
        AceLan Kao <chia-lin.kao@...onical.com>
Subject: Re: [PATCH v7 6/7] Watchdog: ahc1ec0-wdt: Add sub-device Watchdog
 for Advantech embedded controller

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@...antech.com.tw>
> ---
>  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@...antech.com.tw>");
> +MODULE_VERSION("1.0");
> -- 
> 2.17.1
> 

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