Re: [PATCH] rtc: abx80x: add basic watchdog support

[Jeremy Gebben <jgebben@sweptlaser.com>]

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On Sat, Sep 8, 2018 at 9:10 AM Alexandre Belloni <
alexandre.belloni@bootlin.com> wrote:

> Hi,
>
> Please Cc the watchdog maintainers. Else, I have very few comments.
>

Sure, I'll add them on the next version.



> On 07/09/2018 09:17:43-0600, Jeremy Gebben wrote:
> > The abx804 and abx805 chips have support for a simple watchdog
> > function that can trigger an external reset.
> >
> > Signed-off-by: Jeremy Gebben <jgebben@sweptlaser.com>
> > ---
> >  drivers/rtc/Kconfig      |  11 +++
> >  drivers/rtc/rtc-abx80x.c | 160 ++++++++++++++++++++++++++++++++++++---
> >  2 files changed, 159 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> > index 7d7be60a2413..4771e3a89721 100644
> > --- a/drivers/rtc/Kconfig
> > +++ b/drivers/rtc/Kconfig
> > @@ -195,6 +195,17 @@ config RTC_DRV_ABX80X
> >         This driver can also be built as a module. If so, the module
> >         will be called rtc-abx80x.
> >
> > +config RTC_DRV_ABX80X_WDT
> > +     bool "Abracon ABx80x Watchdog"
> > +     default y
> > +     depends on RTC_DRV_ABX80X
> > +     help
> > +       If you say yes here you get watchdog support for Abracon ABX804
> and ABX805
> > +       clock chips. This watchdog supports timeouts up to 31 seconds
> with 1 second
> > +       granularity.
> > +
> > +          This watchdog device is part of the rtc-abx80x module.
> > +
>
> I'm not sure it is worth having a separate config option for that. You
> may as well just always include the watchdog support code. However,
> doesn't it need to depend on CONFIG_WATCHDOG?
>

Yes, you're right about CONFIG_WATCHDOG, I thought I had that already but I
guess it got dropped.



> >  config RTC_DRV_AC100
> >       tristate "X-Powers AC100"
> >       depends on MFD_AC100
> > diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c
> > index 2cefa67a1132..fa558939e944 100644
> > --- a/drivers/rtc/rtc-abx80x.c
> > +++ b/drivers/rtc/rtc-abx80x.c
> > @@ -17,6 +17,7 @@
> >  #include <linux/i2c.h>
> >  #include <linux/module.h>
> >  #include <linux/rtc.h>
> > +#include <linux/watchdog.h>
> >
> >  #define ABX8XX_REG_HTH               0x00
> >  #define ABX8XX_REG_SC                0x01
> > @@ -37,6 +38,7 @@
> >
> >  #define ABX8XX_REG_STATUS    0x0f
> >  #define ABX8XX_STATUS_AF     BIT(2)
> > +#define ABX8XX_STATUS_WDT    BIT(6)
> >
> >  #define ABX8XX_REG_CTRL1     0x10
> >  #define ABX8XX_CTRL_WRITE    BIT(0)
> > @@ -61,6 +63,14 @@
> >  #define ABX8XX_OSS_OF                BIT(1)
> >  #define ABX8XX_OSS_OMODE     BIT(4)
> >
> > +#define ABX8XX_REG_WDT               0x1b
> > +#define ABX8XX_WDT_WDS               BIT(7)
> > +#define ABX8XX_WDT_BMB_MASK  0x7c
> > +#define ABX8XX_WDT_BMB_SHIFT 2
> > +#define ABX8XX_WDT_MAX_TIME  (ABX8XX_WDT_BMB_MASK >>
> ABX8XX_WDT_BMB_SHIFT)
> > +#define ABX8XX_WDT_WRB_MASK  0x03
> > +#define ABX8XX_WDT_WRB_1HZ   0x02
> > +
> >  #define ABX8XX_REG_CFG_KEY   0x1f
> >  #define ABX8XX_CFG_KEY_OSC   0xa1
> >  #define ABX8XX_CFG_KEY_MISC  0x9d
> > @@ -80,20 +90,27 @@ enum abx80x_chip {AB0801, AB0803, AB0804, AB0805,
> >  struct abx80x_cap {
> >       u16 pn;
> >       bool has_tc;
> > +     bool has_wdog;
> >  };
> >
> >  static struct abx80x_cap abx80x_caps[] = {
> >       [AB0801] = {.pn = 0x0801},
> >       [AB0803] = {.pn = 0x0803},
> > -     [AB0804] = {.pn = 0x0804, .has_tc = true},
> > -     [AB0805] = {.pn = 0x0805, .has_tc = true},
> > +     [AB0804] = {.pn = 0x0804, .has_tc = true, .has_wdog = true},
> > +     [AB0805] = {.pn = 0x0805, .has_tc = true, .has_wdog = true},
> >       [AB1801] = {.pn = 0x1801},
> >       [AB1803] = {.pn = 0x1803},
> > -     [AB1804] = {.pn = 0x1804, .has_tc = true},
> > -     [AB1805] = {.pn = 0x1805, .has_tc = true},
> > +     [AB1804] = {.pn = 0x1804, .has_tc = true, .has_wdog = true},
> > +     [AB1805] = {.pn = 0x1805, .has_tc = true, .has_wdog = true},
> >       [ABX80X] = {.pn = 0}
> >  };
> >
> > +struct abx80x_priv {
> > +     struct rtc_device *rtc;
> > +     struct i2c_client *client;
> > +     struct watchdog_device wdog;
> > +};
> > +
>
> To make the watchdog part easier to review, you could separate the
> introduction of abx80x_priv in a preliminary patch and then introduce
> the watchdog code.
>

Ok.

>  static int abx80x_is_rc_mode(struct i2c_client *client)
> >  {
> >       int flags = 0;
> > @@ -218,7 +235,8 @@ static int abx80x_rtc_set_time(struct device *dev,
> struct rtc_time *tm)
> >  static irqreturn_t abx80x_handle_irq(int irq, void *dev_id)
> >  {
> >       struct i2c_client *client = dev_id;
> > -     struct rtc_device *rtc = i2c_get_clientdata(client);
> > +     struct abx80x_priv *priv = i2c_get_clientdata(client);
> > +     struct rtc_device *rtc = priv->rtc;
> >       int status;
> >
> >       status = i2c_smbus_read_byte_data(client, ABX8XX_REG_STATUS);
> > @@ -228,6 +246,13 @@ static irqreturn_t abx80x_handle_irq(int irq, void
> *dev_id)
> >       if (status & ABX8XX_STATUS_AF)
> >               rtc_update_irq(rtc, 1, RTC_AF | RTC_IRQF);
> >
> > +     /*
> > +      * It is unclear if we'll get an interrupt before the external
> > +      * reset kicks in.
> > +      */
> > +     if (status & ABX8XX_STATUS_WDT)
> > +             dev_err(&client->dev, "watchdog timeout interrupt!\n");
> > +
>
> dev_alert maybe?
>


Ok.

Thanks,

Jeremy


>
> >       i2c_smbus_write_byte_data(client, ABX8XX_REG_STATUS, 0);
> >
> >       return IRQ_HANDLED;
> > @@ -529,11 +554,110 @@ static void rtc_calib_remove_sysfs_group(void
> *_dev)
> >       sysfs_remove_group(&dev->kobj, &rtc_calib_attr_group);
> >  }
> >
> > +#ifdef CONFIG_RTC_DRV_ABX80X_WDT
> > +
> > +static inline u8 timeout_bits(unsigned int timeout)
> > +{
> > +     return ((timeout << ABX8XX_WDT_BMB_SHIFT) & ABX8XX_WDT_BMB_MASK) |
> > +              ABX8XX_WDT_WRB_1HZ;
> > +}
> > +
> > +static int __abx80x_wdog_set_timeout(struct watchdog_device *wdog,
> > +                                 unsigned int timeout)
> > +{
> > +     struct abx80x_priv *priv = watchdog_get_drvdata(wdog);
> > +     u8 val = ABX8XX_WDT_WDS | timeout_bits(timeout);
> > +
> > +     /*
> > +      * Writing any timeout to the WDT register resets the watchdog
> timer.
> > +      * Writing 0 disables it.
> > +      */
> > +     return i2c_smbus_write_byte_data(priv->client, ABX8XX_REG_WDT,
> val);
> > +}
> > +
> > +static int abx80x_wdog_set_timeout(struct watchdog_device *wdog,
> > +                             unsigned int new_timeout)
> > +{
> > +     int err = __abx80x_wdog_set_timeout(wdog, new_timeout);
> > +
> > +     if (err)
> > +             return err;
> > +
> > +     wdog->timeout = new_timeout;
> > +     return 0;
> > +}
> > +
> > +static int abx80x_wdog_ping(struct watchdog_device *wdog)
> > +{
> > +     return __abx80x_wdog_set_timeout(wdog, wdog->timeout);
> > +}
> > +
> > +static int abx80x_wdog_start(struct watchdog_device *wdog)
> > +{
> > +     int err = __abx80x_wdog_set_timeout(wdog, wdog->timeout);
> > +
> > +     if (err)
> > +             return err;
> > +
> > +     set_bit(WDOG_HW_RUNNING, &wdog->status);
> > +     return 0;
> > +}
> > +
> > +static int abx80x_wdog_stop(struct watchdog_device *wdog)
> > +{
> > +     int err = __abx80x_wdog_set_timeout(wdog, 0);
> > +
> > +     if (err)
> > +             return err;
> > +
> > +     clear_bit(WDOG_HW_RUNNING, &wdog->status);
> > +     return 0;
> > +}
> > +
> > +static const struct watchdog_info abx80x_wdog_info = {
> > +     .identity = "abx80x watchdog",
> > +     .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
> WDIOF_MAGICCLOSE,
> > +};
> > +
> > +static const struct watchdog_ops abx80x_wdog_ops = {
> > +     .owner = THIS_MODULE,
> > +     .start = abx80x_wdog_start,
> > +     .stop = abx80x_wdog_stop,
> > +     .ping = abx80x_wdog_ping,
> > +     .set_timeout = abx80x_wdog_set_timeout,
> > +};
> > +
> > +static int abx80x_setup_watchdog(struct abx80x_priv *priv)
> > +{
> > +     int err;
> > +
> > +     priv->wdog.ops = &abx80x_wdog_ops;
> > +     priv->wdog.info = &abx80x_wdog_info;
> > +     priv->wdog.min_timeout = 1;
> > +     priv->wdog.max_timeout = ABX8XX_WDT_MAX_TIME;
> > +
> > +     err = devm_watchdog_register_device(&priv->client->dev,
> > +                                         &priv->wdog);
> > +     if (err)
> > +             return err;
> > +
> > +     watchdog_set_drvdata(&priv->wdog, priv);
> > +     watchdog_init_timeout(&priv->wdog, ABX8XX_WDT_MAX_TIME,
> > +                           &priv->client->dev);
> > +     return 0;
> > +}
> > +#else
> > +static int abx80x_setup_watchdog(struct abx80x_priv *priv)
> > +{
> > +     return 0;
> > +}
> > +#endif
> > +
> >  static int abx80x_probe(struct i2c_client *client,
> >                       const struct i2c_device_id *id)
> >  {
> >       struct device_node *np = client->dev.of_node;
> > -     struct rtc_device *rtc;
> > +     struct abx80x_priv *priv;
> >       int i, data, err, trickle_cfg = -EINVAL;
> >       char buf[7];
> >       unsigned int part = id->driver_data;
> > @@ -610,13 +734,25 @@ static int abx80x_probe(struct i2c_client *client,
> >       if (err)
> >               return err;
> >
> > -     rtc = devm_rtc_allocate_device(&client->dev);
> > -     if (IS_ERR(rtc))
> > -             return PTR_ERR(rtc);
> > +     priv = devm_kzalloc(&client->dev, sizeof(struct abx80x_priv),
> > +                         GFP_KERNEL);
> > +     if (priv == NULL)
> > +             return -ENOMEM;
> > +
> > +     priv->rtc = devm_rtc_allocate_device(&client->dev);
> > +     if (IS_ERR(priv->rtc))
> > +             return PTR_ERR(priv->rtc);
> >
> > -     rtc->ops = &abx80x_rtc_ops;
> > +     priv->rtc->ops = &abx80x_rtc_ops;
> > +     priv->client = client;
> >
> > -     i2c_set_clientdata(client, rtc);
> > +     i2c_set_clientdata(client, priv);
> > +
> > +     if (abx80x_caps[part].has_wdog) {
> > +             err = abx80x_setup_watchdog(priv);
> > +             if (err)
> > +                     return err;
> > +     }
> >
> >       if (client->irq > 0) {
> >               dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
> > @@ -649,7 +785,7 @@ static int abx80x_probe(struct i2c_client *client,
> >               return err;
> >       }
> >
> > -     err = rtc_register_device(rtc);
> > +     err = rtc_register_device(priv->rtc);
> >
> >       return err;
> >  }
> > --
> > 2.17.1
> >
>
> --
> Alexandre Belloni, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>

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