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SubjectRe: [v2,1/1] hwmon: (nct7904) Add watchdog function
On Wed, Mar 25, 2020 at 08:22:37AM +0000, yuechao.zhao@advantech.com.cn wrote:
> From: Yuechao Zhao <yuechao.zhao@advantech.com.cn>
>
> implement watchdong functionality into the "hwmon/nct7904.c"
>
> Signed-off-by: Yuechao Zhao <yuechao.zhao@advantech.com.cn>
> ---
> v2:
> - Modify dependency of NC7904 into "drivers/hwmon/Kconfig".
> ---
> drivers/hwmon/Kconfig | 6 +-
> drivers/hwmon/nct7904.c | 157 +++++++++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 160 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 05a3083..cd0ae82 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1340,10 +1340,12 @@ config SENSORS_NCT7802
>
> config SENSORS_NCT7904
> tristate "Nuvoton NCT7904"
> - depends on I2C
> + depends on I2C && WATCHDOG
> + select WATCHDOG_CORE
> help
> If you say yes here you get support for the Nuvoton NCT7904
> - hardware monitoring chip, including manual fan speed control.
> + hardware monitoring chip, including manual fan speed control
> + and support for the integrated watchdog.
>
> This driver can also be built as a module. If so, the module
> will be called nct7904.
> diff --git a/drivers/hwmon/nct7904.c b/drivers/hwmon/nct7904.c
> index 1f5743d..137199c 100644
> --- a/drivers/hwmon/nct7904.c
> +++ b/drivers/hwmon/nct7904.c
> @@ -8,6 +8,9 @@
> * Copyright (c) 2019 Advantech
> * Author: Amy.Shih <amy.shih@advantech.com.tw>
> *
> + * Copyright (c) 2020 Advantech
> + * Author: Yuechao Zhao <yuechao.zhao@advantech.com.cn>
> + *
> * Supports the following chips:
> *
> * Chip #vin #fan #pwm #temp #dts chip ID
> @@ -20,6 +23,7 @@
> #include <linux/i2c.h>
> #include <linux/mutex.h>
> #include <linux/hwmon.h>
> +#include <linux/watchdog.h>
>
> #define VENDOR_ID_REG 0x7A /* Any bank */
> #define NUVOTON_ID 0x50
> @@ -87,18 +91,39 @@
> #define FANCTL1_FMR_REG 0x00 /* Bank 3; 1 reg per channel */
> #define FANCTL1_OUT_REG 0x10 /* Bank 3; 1 reg per channel */
>
> +#define WDT_LOCK_REG 0xE0 /* W/O Lock Watchdog Register */
> +#define WDT_EN_REG 0xE1 /* R/O Watchdog Enable Register */
> +#define WDT_STS_REG 0xE2 /* R/O Watchdog Status Register */
> +#define WDT_TIMER_REG 0xE3 /* R/W Watchdog Timer Register */
> +#define WDT_SOFT_EN 0x55 /* Enable soft watchdog timer */
> +#define WDT_SOFT_DIS 0xAA /* Disable soft watchdog timer */
> +
> #define VOLT_MONITOR_MODE 0x0
> #define THERMAL_DIODE_MODE 0x1
> #define THERMISTOR_MODE 0x3
>
> #define ENABLE_TSI BIT(1)
>
> +#define WATCHDOG_TIMEOUT 1 /* 1 minute default timeout */

> +static int ping_timeout = WATCHDOG_TIMEOUT; /* default feeding timeout */

Please no static variables; at least in theory there could be multiple
NCT7904 in the system. Just use wdt->timeout / 60.

> +
> +static int timeout = WATCHDOG_TIMEOUT;
> +module_param(timeout, int, 0);
> +MODULE_PARM_DESC(timeout, "Watchdog timeout in minutes. 1 <= timeout <= 255, default="
> + __MODULE_STRING(WATCHODOG_TIMEOUT) ".");
> +
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, bool, 0);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started once started (default="
> + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> static const unsigned short normal_i2c[] = {
> 0x2d, 0x2e, I2C_CLIENT_END
> };
>
> struct nct7904_data {
> struct i2c_client *client;
> + struct watchdog_device wdt;
> struct mutex bank_lock;
> int bank_sel;
> u32 fanin_mask;
> @@ -889,6 +914,91 @@ static int nct7904_detect(struct i2c_client *client,
> .info = nct7904_info,
> };
>
> +/*
> + * Wathcdog Function
> + */
> +static int nct7904_wdt_start(struct watchdog_device *wdt)
> +{
> + int ret;
> + struct nct7904_data *data = watchdog_get_drvdata(wdt);
> +
> + /* Disable soft watchdog timer first */
> + ret = nct7904_write_reg(data, BANK_0, WDT_LOCK_REG, WDT_SOFT_DIS);
> + if (ret < 0)
> + return ret;
> +
Is that really necessary ?

> + /* Enable soft watchdog timer */
> + ret = nct7904_write_reg(data, BANK_0, WDT_LOCK_REG, WDT_SOFT_EN);
> + return ret;

Just return immediately here, without assigning to ret.

> +}
> +
> +static int nct7904_wdt_stop(struct watchdog_device *wdt)
> +{
> + struct nct7904_data *data = watchdog_get_drvdata(wdt);
> + int ret;
> +
> + ret = nct7904_write_reg(data, BANK_0, WDT_LOCK_REG, WDT_SOFT_DIS);
> +
> + return ret;

Same here. 'ret' is unnecessary.

> +}
> +
> +static int nct7904_wdt_set_timeout(struct watchdog_device *wdt,
> + unsigned int timeout)
> +{
> + struct nct7904_data *data = watchdog_get_drvdata(wdt);
> +
> + ping_timeout = timeout / 60;

The code should update wdt->timeout, and then use wdt->timeout as basis for
setting the chip timeout.
> +
> + return nct7904_write_reg(data, BANK_0, WDT_TIMER_REG, ping_timeout);
> +}
> +
> +static int nct7904_wdt_ping(struct watchdog_device *wdt)
> +{
> + /*
> + * Note:
> + * NCT7904 is not supported refresh WDT_TIMER_REG register when the

"does not support refreshing ..." if I understand correctly.

> + * watchdog is actiove. Please disable watchdog before fedding the

s/actiove/active/
s/fedding/feeding/

> + * watchdog and enable it again.
> + */
> + struct nct7904_data *data = watchdog_get_drvdata(wdt);
> + int ret;
> +
> + /* Disable soft watchdog timer */
> + ret = nct7904_write_reg(data, BANK_0, WDT_LOCK_REG, WDT_SOFT_DIS);
> + if (ret < 0)
> + goto ping_err;
> +
> + /* feed watchdog */
> + ret = nct7904_write_reg(data, BANK_0, WDT_TIMER_REG, ping_timeout);

This should use wdt->timeout / 60 (see above).

Is it necessary to update the timeout ? The datasheet doesn't describe it well.

If the timer register is updated, you could possibly implement
a get_timeout function.

> + if (ret < 0)
> + goto ping_err;
> +
> + /* Enable soft watchdog timer */
> + ret = nct7904_write_reg(data, BANK_0, WDT_TIMER_REG, WDT_SOFT_EN);
> + if (ret < 0)
> + goto ping_err;
> +
> + return 0;
> +
> +ping_err:
> + pr_err("nct7904 ping error\n");

I am a concerned about this; if the error is persistent, it would
clog up the log. Please just return the error.

> + return ret;
> +}
> +
> +static const struct watchdog_info nct7904_wdt_info = {
> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
> + WDIOF_MAGICCLOSE,
> + .identity = "nct7904 watchdog",
> +};
> +
> +static const struct watchdog_ops nct7904_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = nct7904_wdt_start,
> + .stop = nct7904_wdt_stop,
> + .ping = nct7904_wdt_ping,
> + .set_timeout = nct7904_wdt_set_timeout,
> +};
> +
> static int nct7904_probe(struct i2c_client *client,
> const struct i2c_device_id *id)
> {
> @@ -1012,7 +1122,51 @@ static int nct7904_probe(struct i2c_client *client,
> hwmon_dev =
> devm_hwmon_device_register_with_info(dev, client->name, data,
> &nct7904_chip_info, NULL);
> - return PTR_ERR_OR_ZERO(hwmon_dev);
> + ret = PTR_ERR_OR_ZERO(hwmon_dev);
> + if (ret)
> + return ret;
> +
> + /* Watchdog initialization */
> + data->wdt.ops = &nct7904_wdt_ops;
> + data->wdt.info = &nct7904_wdt_info;
> +
> + data->wdt.timeout = timeout * 60; /* in seconds */
> + data->wdt.min_timeout = 1;
> + data->wdt.max_timeout = 15300;

Please make it 60 * 255 (or use a respective define) to clarify
where the number comes from.

> + data->wdt.parent = &client->dev;
> +
> + watchdog_init_timeout(&data->wdt, timeout, &client->dev);
> + watchdog_set_nowayout(&data->wdt, nowayout);
> + watchdog_set_drvdata(&data->wdt, data);
> +
> + i2c_set_clientdata(client, data);
> +
> + ret = watchdog_register_device(&data->wdt);
> + if (ret)
> + return ret;

Please use devm_watchdog_register_device()

> +
> + dev_info(&client->dev, "NCT7904 HWMON and Watchdog device probed\n");
> +
I am not in favor of such noise.

> + return ret;
> +}
> +
> +static int nct7904_remove(struct i2c_client *client)
> +{
> + /*
> + * HWMON use devm_hwmon_device_register_with_info() register. So, do
> + * not need unregister it manually.
> + */
> + struct nct7904_data *data = i2c_get_clientdata(client);
> +
> + /* disable watchdog */
> + if (!nowayout)
> + nct7904_write_reg(data, BANK_0, WDT_LOCK_REG, WDT_SOFT_DIS);

Please use watchdog_stop_on_unregister().

> +
> + watchdog_unregister_device(&data->wdt);
> +
> + dev_info(&client->dev, "NCT7904 driver removed\n");
> +

Please no such noise.

> + return 0;
> }
>
> static const struct i2c_device_id nct7904_id[] = {
> @@ -1030,6 +1184,7 @@ static int nct7904_probe(struct i2c_client *client,
> .id_table = nct7904_id,
> .detect = nct7904_detect,
> .address_list = normal_i2c,
> + .remove = nct7904_remove,
> };
>
> module_i2c_driver(nct7904_driver);
> --
> 1.8.3.1
>

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