Message-ID: <8417c931-7ffa-42dd-8bdf-a24d7dfeb094@roeck-us.net>
Date:   Tue, 15 Aug 2023 08:37:04 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     David Ober <dober6023@...il.com>
Cc:     linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, jdelvare@...e.com, corbet@....net,
        dober@...ovo.com, mpearson@...ovo.com
Subject: Re: [PATCH] hwmon: add in watchdog for nct6686

On Tue, Aug 15, 2023 at 07:55:15AM -0400, David Ober wrote:
> This change adds in the watchdog timer support for the nct6686
> chip so that it can be used on the Lenovo m90n IOT device
> 
> Signed-off-by: David Ober <dober6023@...il.com>
> ---
>  Documentation/hwmon/nct6683.rst |   5 +-
>  drivers/hwmon/nct6683.c         | 247 ++++++++++++++++++++++++++++++--

This should be a separate driver in drivers/watchdog/, and sneaking
in support for a new vendor with the above description is inappropriate
anyway. Besides, why would the watchdog only work for Lenovo ?

Guenter

>  2 files changed, 242 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/hwmon/nct6683.rst b/Documentation/hwmon/nct6683.rst
> index 2e1408d174bd..7421bc444365 100644
> --- a/Documentation/hwmon/nct6683.rst
> +++ b/Documentation/hwmon/nct6683.rst
> @@ -3,7 +3,7 @@ Kernel driver nct6683
>  
>  Supported chips:
>  
> -  * Nuvoton NCT6683D/NCT6687D
> +  * Nuvoton NCT6683D/NCT6686D/NCT6687D
>  
>      Prefix: 'nct6683'
>  
> @@ -49,6 +49,8 @@ The driver has only been tested with the Intel firmware, and by default
>  only instantiates on Intel boards. To enable it on non-Intel boards,
>  set the 'force' module parameter to 1.
>  
> +Implement the watchdog functionality of the NCT6686D eSIO chip
> +
>  Tested Boards and Firmware Versions
>  -----------------------------------
>  
> @@ -63,4 +65,5 @@ Intel DH87MC	NCT6683D EC firmware version 1.0 build 04/03/13
>  Intel DB85FL	NCT6683D EC firmware version 1.0 build 04/03/13
>  ASRock X570	NCT6683D EC firmware version 1.0 build 06/28/19
>  MSI B550	NCT6687D EC firmware version 1.0 build 05/07/20
> +LENOVO M90n-1	NCT6686D EC firmware version 9.0 build 04/21/21
>  =============== ===============================================
> diff --git a/drivers/hwmon/nct6683.c b/drivers/hwmon/nct6683.c
> index f673f7d07941..eb95b91c4d39 100644
> --- a/drivers/hwmon/nct6683.c
> +++ b/drivers/hwmon/nct6683.c
> @@ -24,15 +24,16 @@
>  #include <linux/acpi.h>
>  #include <linux/delay.h>
>  #include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
>  #include <linux/init.h>
>  #include <linux/io.h>
>  #include <linux/jiffies.h>
> -#include <linux/hwmon.h>
> -#include <linux/hwmon-sysfs.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
>  #include <linux/platform_device.h>
>  #include <linux/slab.h>
> +#include <linux/watchdog.h>
>  
>  enum kinds { nct6683, nct6686, nct6687 };
>  
> @@ -73,6 +74,34 @@ static const char * const nct6683_chip_names[] = {
>  #define SIO_NCT6687_ID		0xd590
>  #define SIO_ID_MASK		0xFFF0
>  
> +#define WDT_CFG			0x828    /* W/O Lock Watchdog Register */
> +#define WDT_CNT			0x829    /* R/W Watchdog Timer Register */
> +#define WDT_STS			0x82A    /* R/O Watchdog Status Register */
> +#define WDT_STS_EVT_POS		(0)
> +#define WDT_STS_EVT_MSK		(0x3 << WDT_STS_EVT_POS)
> +#define WDT_SOFT_EN		0x87    /* Enable soft watchdog timer */
> +#define WDT_SOFT_DIS		0xAA    /* Disable soft watchdog timer */
> +
> +#define WATCHDOG_TIMEOUT	60      /* 1 minute default timeout */
> +
> +/* The timeout range is 1-255 seconds */
> +#define MIN_TIMEOUT		1
> +#define MAX_TIMEOUT		255
> +
> +static int timeout;
> +module_param(timeout, int, 0);
> +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. 1 <= timeout <= 255, default="
> +		 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
> +
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, bool, 0);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> +		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +static int early_disable;
> +module_param(early_disable, int, 0);
> +MODULE_PARM_DESC(early_disable, "Disable watchdog at boot time (default=0)");
> +
>  static inline void
>  superio_outb(int ioreg, int reg, int val)
>  {
> @@ -171,10 +200,10 @@ superio_exit(int ioreg)
>  
>  #define NCT6683_REG_CUSTOMER_ID		0x602
>  #define NCT6683_CUSTOMER_ID_INTEL	0x805
> +#define NCT6683_CUSTOMER_ID_LENOVO	0x1101
>  #define NCT6683_CUSTOMER_ID_MITAC	0xa0e
>  #define NCT6683_CUSTOMER_ID_MSI		0x201
> -#define NCT6683_CUSTOMER_ID_MSI2	0x200
> -#define NCT6683_CUSTOMER_ID_ASROCK		0xe2c
> +#define NCT6683_CUSTOMER_ID_ASROCK	0xe2c
>  #define NCT6683_CUSTOMER_ID_ASROCK2	0xe1b
>  
>  #define NCT6683_REG_BUILD_YEAR		0x604
> @@ -183,6 +212,9 @@ superio_exit(int ioreg)
>  #define NCT6683_REG_SERIAL		0x607
>  #define NCT6683_REG_VERSION_HI		0x608
>  #define NCT6683_REG_VERSION_LO		0x609
> +#define NCT6686_PAGE_REG_OFFSET		0
> +#define NCT6686_ADDR_REG_OFFSET		1
> +#define NCT6686_DATA_REG_OFFSET		2
>  
>  #define NCT6683_REG_CR_CASEOPEN		0xe8
>  #define NCT6683_CR_CASEOPEN_MASK	(1 << 7)
> @@ -304,6 +336,7 @@ struct nct6683_data {
>  
>  	struct device *hwmon_dev;
>  	const struct attribute_group *groups[6];
> +	struct watchdog_device wdt;
>  
>  	int temp_num;			/* number of temperature attributes */
>  	u8 temp_index[NCT6683_NUM_REG_MON];
> @@ -518,6 +551,39 @@ static void nct6683_write(struct nct6683_data *data, u16 reg, u16 value)
>  	outb_p(value & 0xff, data->addr + EC_DATA_REG);
>  }
>  
> +static inline void nct6686_wdt_set_bank(int base_addr, u16 reg)
> +{
> +	outb_p(0xFF, base_addr + NCT6686_PAGE_REG_OFFSET);
> +	outb_p(reg >> 8, base_addr + NCT6686_PAGE_REG_OFFSET);
> +}
> +
> +/* Not strictly necessary, but play it safe for now */
> +static inline void nct6686_wdt_reset_bank(int base_addr, u16 reg)
> +{
> +	if (reg & 0xff00)
> +		outb_p(0xFF, base_addr + NCT6686_PAGE_REG_OFFSET);
> +}
> +
> +static u8 nct6686_read(struct nct6683_data *data, u16 reg)
> +{
> +	u8 res;
> +
> +	nct6686_wdt_set_bank(data->addr, reg);
> +	outb_p(reg & 0xff, data->addr + NCT6686_ADDR_REG_OFFSET);
> +	res = inb_p(data->addr + NCT6686_DATA_REG_OFFSET);
> +
> +	nct6686_wdt_reset_bank(data->addr, reg);
> +	return res;
> +}
> +
> +static void nct6686_write(struct nct6683_data *data, u16 reg, u8 value)
> +{
> +	nct6686_wdt_set_bank(data->addr, reg);
> +	outb_p(reg & 0xff, data->addr + NCT6686_ADDR_REG_OFFSET);
> +	outb_p(value & 0xff, data->addr + NCT6686_DATA_REG_OFFSET);
> +	nct6686_wdt_reset_bank(data->addr, reg);
> +}
> +
>  static int get_in_reg(struct nct6683_data *data, int nr, int index)
>  {
>  	int ch = data->in_index[index];
> @@ -680,11 +746,12 @@ static umode_t nct6683_in_is_visible(struct kobject *kobj,
>  	int nr = index % 4;	/* attribute */
>  
>  	/*
> -	 * Voltage limits exist for Intel boards,
> +	 * Voltage limits exist for Intel and Lenovo boards,
>  	 * but register location and encoding is unknown
>  	 */
>  	if ((nr == 2 || nr == 3) &&
> -	    data->customer_id == NCT6683_CUSTOMER_ID_INTEL)
> +	    (data->customer_id == NCT6683_CUSTOMER_ID_INTEL ||
> +	     data->customer_id == NCT6683_CUSTOMER_ID_LENOVO))
>  		return 0;
>  
>  	return attr->mode;
> @@ -1186,6 +1253,139 @@ static void nct6683_setup_sensors(struct nct6683_data *data)
>  	}
>  }
>  
> +/*
> + * Watchdog Functions
> + */
> +static int nct6686_wdt_enable(struct watchdog_device *wdog, bool enable)
> +{
> +	struct nct6683_data *data = watchdog_get_drvdata(wdog);
> +
> +	u_char reg;
> +
> +	mutex_lock(&data->update_lock);
> +	reg = nct6686_read(data, WDT_CFG);
> +
> +	if (enable) {
> +		nct6686_write(data, WDT_CFG, reg | 0x3);
> +		mutex_unlock(&data->update_lock);
> +		return 0;
> +	}
> +
> +	nct6686_write(data, WDT_CFG, reg & ~BIT(0));
> +	mutex_unlock(&data->update_lock);
> +
> +	return 0;
> +}
> +
> +static int nct6686_wdt_set_time(struct watchdog_device *wdog)
> +{
> +	struct nct6683_data *data = watchdog_get_drvdata(wdog);
> +
> +	mutex_lock(&data->update_lock);
> +	nct6686_write(data, WDT_CNT, wdog->timeout);
> +	mutex_unlock(&data->update_lock);
> +
> +	if (wdog->timeout) {
> +		nct6686_wdt_enable(wdog, true);
> +		return 0;
> +	}
> +
> +	nct6686_wdt_enable(wdog, false);
> +	return 0;
> +}
> +
> +static int nct6686_wdt_start(struct watchdog_device *wdt)
> +{
> +	struct nct6683_data *data = watchdog_get_drvdata(wdt);
> +	u_char reg;
> +
> +	nct6686_wdt_set_time(wdt);
> +
> +	/* Enable soft watchdog timer */
> +	mutex_lock(&data->update_lock);
> +	/* reset trigger status */
> +	reg = nct6686_read(data, WDT_STS);
> +	nct6686_write(data, WDT_STS, reg & ~WDT_STS_EVT_MSK);
> +	mutex_unlock(&data->update_lock);
> +	return 0;
> +}
> +
> +static int nct6686_wdt_stop(struct watchdog_device *wdt)
> +{
> +	struct nct6683_data *data = watchdog_get_drvdata(wdt);
> +
> +	mutex_lock(&data->update_lock);
> +	nct6686_write(data, WDT_CFG, WDT_SOFT_DIS);
> +	mutex_unlock(&data->update_lock);
> +	return 0;
> +}
> +
> +static int nct6686_wdt_set_timeout(struct watchdog_device *wdt,
> +				   unsigned int timeout)
> +{
> +	struct nct6683_data *data = watchdog_get_drvdata(wdt);
> +
> +	wdt->timeout = timeout;
> +	mutex_lock(&data->update_lock);
> +	nct6686_write(data, WDT_CNT, timeout);
> +	mutex_unlock(&data->update_lock);
> +	return 0;
> +}
> +
> +static int nct6686_wdt_ping(struct watchdog_device *wdt)
> +{
> +	struct nct6683_data *data = watchdog_get_drvdata(wdt);
> +	int timeout;
> +
> +	/*
> +	 * Note:
> +	 * NCT6686 does not support refreshing WDT_TIMER_REG register when
> +	 * the watchdog is active. Please disable watchdog before feeding
> +	 * the watchdog and enable it again.
> +	 */
> +	/* Disable soft watchdog timer */
> +	nct6686_wdt_enable(wdt, false);
> +
> +	/* feed watchdog */
> +	timeout = wdt->timeout;
> +	mutex_lock(&data->update_lock);
> +	nct6686_write(data, WDT_CNT, timeout);
> +	mutex_unlock(&data->update_lock);
> +
> +	/* Enable soft watchdog timer */
> +	nct6686_wdt_enable(wdt, true);
> +	return 0;
> +}
> +
> +static unsigned int nct6686_wdt_get_timeleft(struct watchdog_device *wdt)
> +{
> +	struct nct6683_data *data = watchdog_get_drvdata(wdt);
> +	int ret;
> +
> +	mutex_lock(&data->update_lock);
> +	ret = nct6686_read(data, WDT_CNT);
> +	mutex_unlock(&data->update_lock);
> +	if (ret < 0)
> +		return 0;
> +
> +	return ret;
> +}
> +
> +static const struct watchdog_info nct6686_wdt_info = {
> +	.options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
> +			  WDIOF_MAGICCLOSE,
> +	.identity       = "nct6686 watchdog",
> +};
> +
> +static const struct watchdog_ops nct6686_wdt_ops = {
> +	.owner          = THIS_MODULE,
> +	.start          = nct6686_wdt_start,
> +	.stop           = nct6686_wdt_stop,
> +	.ping           = nct6686_wdt_ping,
> +	.set_timeout    = nct6686_wdt_set_timeout,
> +	.get_timeleft   = nct6686_wdt_get_timeleft,
> +};
> +
>  static int nct6683_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -1195,7 +1395,9 @@ static int nct6683_probe(struct platform_device *pdev)
>  	struct device *hwmon_dev;
>  	struct resource *res;
>  	int groups = 0;
> +	int ret;
>  	char build[16];
> +	u_char reg;
>  
>  	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
>  	if (!devm_request_region(dev, res->start, IOREGION_LENGTH, DRVNAME))
> @@ -1215,14 +1417,14 @@ static int nct6683_probe(struct platform_device *pdev)
>  
>  	/* By default only instantiate driver if the customer ID is known */
>  	switch (data->customer_id) {
> +	case NCT6683_CUSTOMER_ID_LENOVO:
> +		break;
>  	case NCT6683_CUSTOMER_ID_INTEL:
>  		break;
>  	case NCT6683_CUSTOMER_ID_MITAC:
>  		break;
>  	case NCT6683_CUSTOMER_ID_MSI:
>  		break;
> -	case NCT6683_CUSTOMER_ID_MSI2:
> -		break;
>  	case NCT6683_CUSTOMER_ID_ASROCK:
>  		break;
>  	case NCT6683_CUSTOMER_ID_ASROCK2:
> @@ -1294,7 +1496,34 @@ static int nct6683_probe(struct platform_device *pdev)
>  
>  	hwmon_dev = devm_hwmon_device_register_with_groups(dev,
>  			nct6683_device_names[data->kind], data, data->groups);
> -	return PTR_ERR_OR_ZERO(hwmon_dev);
> +
> +	ret = PTR_ERR_OR_ZERO(hwmon_dev);
> +	if (ret)
> +		return ret;
> +
> +	if (data->kind == nct6686 && data->customer_id == NCT6683_CUSTOMER_ID_LENOVO) {
> +		/* Watchdog initialization */
> +		data->wdt.ops = &nct6686_wdt_ops;
> +		data->wdt.info = &nct6686_wdt_info;
> +
> +		data->wdt.timeout = WATCHDOG_TIMEOUT; /* Set default timeout */
> +		data->wdt.min_timeout = MIN_TIMEOUT;
> +		data->wdt.max_timeout = MAX_TIMEOUT;
> +		data->wdt.parent = &pdev->dev;
> +
> +		watchdog_init_timeout(&data->wdt, timeout, &pdev->dev);
> +		watchdog_set_nowayout(&data->wdt, nowayout);
> +		watchdog_set_drvdata(&data->wdt, data);
> +
> +		/* reset trigger status */
> +		reg = nct6686_read(data, WDT_STS);
> +		nct6686_write(data, WDT_STS, reg & ~WDT_STS_EVT_MSK);
> +
> +		watchdog_stop_on_unregister(&data->wdt);
> +
> +		return devm_watchdog_register_device(dev, &data->wdt);
> +	}
> +	return ret;
>  }
>  
>  #ifdef CONFIG_PM
> -- 
> 2.34.1
> 

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