Re: [PATCH v7 4/4] input/power: Add driver for BD71837/BD71847 PMIC power button

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Matti,

On Thu, Jun 21, 2018 at 01:25:47PM +0300, Matti Vaittinen wrote:
> On Wed, Jun 20, 2018 at 09:43:16AM +0300, Matti Vaittinen wrote:
> > On Tue, Jun 19, 2018 at 10:50:28AM -0700, Dmitry Torokhov wrote:
> > > Hi Matti,
> > > 
> > > On Tue, Jun 19, 2018 at 01:57:09PM +0300, Matti Vaittinen wrote:
> > > > ROHM BD71837 PMIC power button driver providing power-key press
> > > > information to user-space.
> > > > 
> > > > Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
> > > > ---
> > > >  drivers/input/misc/Kconfig          | 10 +++++
> > > >  drivers/input/misc/Makefile         |  1 +
> > > >  drivers/input/misc/bd718xx-pwrkey.c | 90 +++++++++++++++++++++++++++++++++++++
> > > >  3 files changed, 101 insertions(+)
> > > >  create mode 100644 drivers/input/misc/bd718xx-pwrkey.c
> > > > 
> > > > +	platform_set_drvdata(pdev, pk);
> > > > +	err = regmap_update_bits(pk->mfd->regmap,
> > > > +				 BD71837_REG_PWRONCONFIG0,
> > > > +				 BD718XX_PWRBTN_SHORT_PRESS_MASK,
> > > > +				 BD718XX_PWRBTN_SHORT_PRESS_10MS);
> > > 
> > > This seems to be the only custom bit of set up in the driver, the rest I
> > > think can easily be handled by gpio-keys.c in interrupt-only mode. Maybe
> > > we could move this into MFD piece and drop this driver?
> 
> I did following in MFD driver - is this what you suggested:
> +static struct gpio_keys_button btns[] = {
> +       {
> +               .code = KEY_POWER,
> +               .gpio = -1,
> +               .type = EV_KEY,
> +       },
> +};
> +
> +static struct gpio_keys_platform_data bd718xx_powerkey_data = {
> +       .buttons = &btns[0],
> +       .nbuttons = ARRAY_SIZE(btns),
> +       .name = "bd718xx-pwrkey",
> +};
> +
> +/* bd71837 multi function cells */
> +
> +static struct mfd_cell bd71837_mfd_cells[] = {
> +       {
> +               .name = "bd71837-clk",
> +       }, {
> +               .name = "gpio-keys",
> +               .platform_data = &bd718xx_powerkey_data,
> +               .pdata_size = sizeof(bd718xx_powerkey_data),
> +       }, {

Yes, something like this should work. It will not expose the internal
kernel structure (the fact that we are using gpio-keys dirver) to handle
power button of this PMIC, which Rob would appreciate. And we can change
it later if you want to create a fancier driver.

> 
> //snip
> 
> +static int bd71837_i2c_probe(struct i2c_client *i2c,
> +                           const struct i2c_device_id *id)
> +{
> 
> // snip
> 
> +       ret = regmap_add_irq_chip(bd71837->regmap, bd71837->chip_irq,
> +               IRQF_ONESHOT, 0,
> +               &bd71837_irq_chip, &bd71837->irq_data);
> +       if (ret < 0) {
> +               dev_err(bd71837->dev, "Failed to add irq_chip %d\n", ret);
> +               goto err_out;
> +       }
> +       /* I think this should be done conditionally and only when pwrkey is used
> +        * What would be the correct way to decide if we want to touch rhw button
> +        * press detection times?
> +        */
> +       ret = regmap_update_bits(bd71837->regmap,
> +                                BD71837_REG_PWRONCONFIG0,
> +                                BD718XX_PWRBTN_PRESS_DURATION_MASK,
> +                                BD718XX_PWRBTN_SHORT_PRESS_10MS);
> +       if (ret < 0) {
> +               dev_err(bd71837->dev, "Failed to configure button short press timeout %d\n", ret);
> +               goto err_out;
> +       }
> +       /* According to BD71847 datasheet the HW default for long press detection
> +        * is 10ms. So letch change it to 10 sec so we can actually get the short
> +        * push and allow gracefull shut down
> +        */
> +       ret = regmap_update_bits(bd71837->regmap,
> +                                BD71837_REG_PWRONCONFIG1,
> +                                BD718XX_PWRBTN_PRESS_DURATION_MASK,
> +                                BD718XX_PWRBTN_LONG_PRESS_10S);
> +       if (ret < 0) {
> +               dev_err(bd71837->dev, "Failed to configure button long press timeout %d\n", ret);
> +               goto err_out;
> +       }
> +       btns[0].irq = regmap_irq_get_virq(bd71837->irq_data,
> +                                         BD71837_INT_PWRBTN_S);
> +
> +       if (btns[0].irq < 0) {
> +               ret = btns[0].irq;
> +               goto err_out;
> +       }
> +
> +       ret = mfd_add_devices(bd71837->dev, PLATFORM_DEVID_AUTO,
> +                             bd71837_mfd_cells, ARRAY_SIZE(bd71837_mfd_cells),
> +                             NULL, 0,
> +                             regmap_irq_get_domain(bd71837->irq_data));
> 
> If looks is Ok I will send new patch with this approach at next week -
> unless I get lost during the traditional midsummer festival here in
> Finland.
> 
> > Finally, there may be cases when power button is not attached to PMIC
> > or is needing different configuration for 'short push'. This is why I
> > would prefer having own Kconfig option for this power-key driver. I am
> > not sure if it is easily doable if we use gpio_keys?
> 
> What would be the preferred mechanism for skipping the button push duration
> configurations (time it takes for PMIC to detect short or long push)? Or
> setting the durations to values user(s) would prefer? To me this sounds again
> something we could configure from DT. Would adding propereties
> rohm,short-press-ms and rohm,long-press-ms sound reasonable? I will send
> the first version with no option to skip/specify the configuration
> (fixed 10ms for short press, 10 sec for long press) but I would like to add
> support for specifying the duration as next step.

This sounds OK to be but you'd need to get Rob's buy in here. The
properties should probably be in a sub-node of the PMIC device node.

Thanks.

-- 
Dmitry