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Date: Mon, 30 Mar 2020 08:33:44 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Chris Packham <chris.packham@...iedtelesis.co.nz>,
a.zummo@...ertech.it, alexandre.belloni@...tlin.com,
wim@...ux-watchdog.org
Cc: linux-rtc@...r.kernel.org, linux-watchdog@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] rtc: ds1307: add support for watchdog timer on ds1388
On 3/29/20 7:55 PM, Chris Packham wrote:
> The DS1388 variant has watchdog timer capabilities. When using a DS1388
> and having enabled CONFIG_WATCHDOG_CORE register a watchdog device for
> the DS1388.
>
> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> ---
> Changes in v3:
> - Address review comments from Guenter. Add select WATCHDOG_CORE, remove
> unnecessary wdt member, add set_timeout op, use devm_watchdog_register
> Changes in v2:
> - Address review comments from Alexandre, the only functional change is setting
> the hundredths of seconds to 0 instead of 99.
>
> drivers/rtc/Kconfig | 1 +
> drivers/rtc/rtc-ds1307.c | 115 +++++++++++++++++++++++++++++++++++++++
> 2 files changed, 116 insertions(+)
>
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 34c8b6c7e095..729851a38511 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -241,6 +241,7 @@ config RTC_DRV_AS3722
> config RTC_DRV_DS1307
> tristate "Dallas/Maxim DS1307/37/38/39/40/41, ST M41T00, EPSON RX-8025, ISL12057"
> select REGMAP_I2C
> + select WATCHDOG_CORE if WATCHDOG
> help
> If you say yes here you get support for various compatible RTC
> chips (often with battery backup) connected with I2C. This driver
> diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
> index 31a38d468378..fad042118862 100644
> --- a/drivers/rtc/rtc-ds1307.c
> +++ b/drivers/rtc/rtc-ds1307.c
> @@ -22,6 +22,7 @@
> #include <linux/hwmon-sysfs.h>
> #include <linux/clk-provider.h>
> #include <linux/regmap.h>
> +#include <linux/watchdog.h>
>
> /*
> * We can't determine type by probing, but if we expect pre-Linux code
> @@ -144,8 +145,15 @@ enum ds_type {
> # define M41TXX_BIT_CALIB_SIGN BIT(5)
> # define M41TXX_M_CALIBRATION GENMASK(4, 0)
>
> +#define DS1388_REG_WDOG_HUN_SECS 0x08
> +#define DS1388_REG_WDOG_SECS 0x09
> #define DS1388_REG_FLAG 0x0b
> +# define DS1388_BIT_WF BIT(6)
> # define DS1388_BIT_OSF BIT(7)
> +#define DS1388_REG_CONTROL 0x0c
> +# define DS1388_BIT_RST BIT(0)
> +# define DS1388_BIT_WDE BIT(1)
> +
> /* negative offset step is -2.034ppm */
> #define M41TXX_NEG_OFFSET_STEP_PPB 2034
> /* positive offset step is +4.068ppm */
> @@ -854,6 +862,72 @@ static int m41txx_rtc_set_offset(struct device *dev, long offset)
> ctrl_reg);
> }
>
> +#ifdef CONFIG_WATCHDOG_CORE
> +static int ds1388_wdt_start(struct watchdog_device *wdt_dev)
> +{
> + struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
> + u8 regs[2];
> + int ret;
> +
> + ret = regmap_update_bits(ds1307->regmap, DS1388_REG_FLAG,
> + DS1388_BIT_WF, 0);
> + if (ret)
> + return ret;
> +
> + ret = regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
> + DS1388_BIT_WDE | DS1388_BIT_RST, 0);
> + if (ret)
> + return ret;
> +
> + /*
> + * watchdog timeouts are measured in seconds. So ignore hundredths of
> + * seconds field.
> + */
> + regs[0] = 0;
> + regs[1] = bin2bcd(wdt_dev->timeout);
> +
> + ret = regmap_bulk_write(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
> + sizeof(regs));
> + if (ret)
> + return ret;
> +
> + return regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
> + DS1388_BIT_WDE | DS1388_BIT_RST,
> + DS1388_BIT_WDE | DS1388_BIT_RST);
> +}
> +
> +static int ds1388_wdt_stop(struct watchdog_device *wdt_dev)
> +{
> + struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
> +
> + return regmap_update_bits(ds1307->regmap, DS1388_REG_CONTROL,
> + DS1388_BIT_WDE | DS1388_BIT_RST, 0);
> +}
> +
> +static int ds1388_wdt_ping(struct watchdog_device *wdt_dev)
> +{
> + struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
> + u8 regs[2];
> +
> + return regmap_bulk_read(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
> + sizeof(regs));
> +}
> +
> +static int ds1388_wdt_set_timeout(struct watchdog_device *wdt_dev,
> + unsigned int val)
> +{
> + struct ds1307 *ds1307 = watchdog_get_drvdata(wdt_dev);
> + u8 regs[2];
> +
> + wdt_dev->timeout = val;
> + regs[0] = 0;
> + regs[1] = bin2bcd(wdt_dev->timeout);
> +
> + return regmap_bulk_write(ds1307->regmap, DS1388_REG_WDOG_HUN_SECS, regs,
> + sizeof(regs));
> +}
> +#endif
> +
> static const struct rtc_class_ops rx8130_rtc_ops = {
> .read_time = ds1307_get_time,
> .set_time = ds1307_set_time,
> @@ -1576,6 +1650,46 @@ static void ds1307_clks_register(struct ds1307 *ds1307)
>
> #endif /* CONFIG_COMMON_CLK */
>
> +#ifdef CONFIG_WATCHDOG_CORE
> +static const struct watchdog_info ds1388_wdt_info = {
> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> + .identity = "DS1388 watchdog",
> +};
> +
> +static const struct watchdog_ops ds1388_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = ds1388_wdt_start,
> + .stop = ds1388_wdt_stop,
> + .ping = ds1388_wdt_ping,
> + .set_timeout = ds1388_wdt_set_timeout,
> +
> +};
> +
> +static void ds1307_wdt_register(struct ds1307 *ds1307)
> +{
> + struct watchdog_device *wdt;
> +
> + if (ds1307->type != ds_1388)
> + return;
> +
> + wdt = devm_kzalloc(ds1307->dev, sizeof(*wdt), GFP_KERNEL);
> +
> + wdt->info = &ds1388_wdt_info;
> + wdt->ops = &ds1388_wdt_ops;
> + wdt->timeout = 99;
> + wdt->max_timeout = 99;
> + wdt->min_timeout = 1;
> +
> + watchdog_init_timeout(wdt, 0, ds1307->dev);
> + watchdog_set_drvdata(wdt, ds1307);
> + devm_watchdog_register_device(ds1307->dev, wdt);
> +}
> +#else
> +static void ds1307_wdt_register(struct ds1307 *ds1307)
> +{
> +}
> +#endif /* CONFIG_WATCHDOG_CORE */
> +
> static const struct regmap_config regmap_config = {
> .reg_bits = 8,
> .val_bits = 8,
> @@ -1865,6 +1979,7 @@ static int ds1307_probe(struct i2c_client *client,
>
> ds1307_hwmon_register(ds1307);
> ds1307_clks_register(ds1307);
> + ds1307_wdt_register(ds1307);
>
> return 0;
>
>
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