Re: [v4,3/4] reset-controller: ti: introduce a new reset handler

[Crystal Guo]

On Thu, 2020-09-03 at 07:40 +0800, Suman Anna wrote:
> Hi Crystal,
> 
> On 8/16/20 10:03 PM, Crystal Guo wrote:
> > Introduce ti_syscon_reset() to integrate assert and deassert together.
> > If some modules need do serialized assert and deassert operations
> > to reset itself, reset_control_reset can be called for convenience.
> 
> There are multiple changes in this same patch. I think you should split this
> functionality away from the change for the regmap_update_bits() to
> regmap_write_bits(), similar to what you have done in your v2 Patch 4.
> 

Thanks for your suggestion.
I will split this patch in the next version.

> > 
> > Such as reset-qcom-aoss.c, it integrates assert and deassert together
> > by 'reset' method. MTK Socs also need this method to perform reset.
> > 
> > Signed-off-by: Crystal Guo <crystal.guo@xxxxxxxxxxxx>
> > ---
> >  drivers/reset/reset-ti-syscon.c | 26 ++++++++++++++++++++++++--
> >  1 file changed, 24 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/reset/reset-ti-syscon.c b/drivers/reset/reset-ti-syscon.c
> > index a2635c21db7f..08289342f9af 100644
> > --- a/drivers/reset/reset-ti-syscon.c
> > +++ b/drivers/reset/reset-ti-syscon.c
> > @@ -15,6 +15,7 @@
> >   * GNU General Public License for more details.
> >   */
> >  
> > +#include <linux/delay.h>
> >  #include <linux/mfd/syscon.h>
> >  #include <linux/module.h>
> >  #include <linux/of.h>
> > @@ -56,6 +57,7 @@ struct ti_syscon_reset_data {
> >  	struct regmap *regmap;
> >  	struct ti_syscon_reset_control *controls;
> >  	unsigned int nr_controls;
> > +	unsigned int reset_duration_us;
> >  };
> >  
> >  #define to_ti_syscon_reset_data(rcdev)	\
> > @@ -89,7 +91,7 @@ static int ti_syscon_reset_assert(struct reset_controller_dev *rcdev,
> >  	mask = BIT(control->assert_bit);
> >  	value = (control->flags & ASSERT_SET) ? mask : 0x0;
> >  
> > -	return regmap_update_bits(data->regmap, control->assert_offset, mask, value);
> > +	return regmap_write_bits(data->regmap, control->assert_offset, mask, value);
> >  }
> >  
> >  /**
> > @@ -120,7 +122,7 @@ static int ti_syscon_reset_deassert(struct reset_controller_dev *rcdev,
> >  	mask = BIT(control->deassert_bit);
> >  	value = (control->flags & DEASSERT_SET) ? mask : 0x0;
> >  
> > -	return regmap_update_bits(data->regmap, control->deassert_offset, mask, value);
> > +	return regmap_write_bits(data->regmap, control->deassert_offset, mask, value);
> >  }
> >  
> >  /**
> > @@ -158,9 +160,26 @@ static int ti_syscon_reset_status(struct reset_controller_dev *rcdev,
> >  		!(control->flags & STATUS_SET);
> >  }
> >  
> > +static int ti_syscon_reset(struct reset_controller_dev *rcdev,
> > +				  unsigned long id)
> > +{
> > +	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
> > +	int ret;
> > +
> > +	ret = ti_syscon_reset_assert(rcdev, id);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (data->reset_duration_us)
> > +		usleep_range(data->reset_duration_us, data->reset_duration_us * 2);
> > +
> > +	return ti_syscon_reset_deassert(rcdev, id);
> 
> I echo Philipp's comments [1] from your original v1 series about this. We don't
> need a property to distinguish this, but you could add a flag using match data
> and Mediatek compatible, and use that within this function, or optionally set
> this ops based on compatible (whatever is preferred by Philipp).
> 
> regards
> Suman
> 
> [1] https://patchwork.kernel.org/comment/23519193/
> 
Hi Suman, Philipp

Which method would you recommend more?
1. like v2 patch, but assign the flag "data->assert_deassert_together"
directly (maybe rename "assert_deassert_together" to
"reset_op_available")

2. use Mediatek compatible to decide the reset handler available or not.

Thanks
Crystal

> > +}
> > +
> >  static const struct reset_control_ops ti_syscon_reset_ops = {
> >  	.assert		= ti_syscon_reset_assert,
> >  	.deassert	= ti_syscon_reset_deassert,
> > +	.reset		= ti_syscon_reset,
> >  	.status		= ti_syscon_reset_status,
> >  };
> >  
> > @@ -204,6 +223,9 @@ static int ti_syscon_reset_probe(struct platform_device *pdev)
> >  		controls[i].flags = be32_to_cpup(list++);
> >  	}
> >  
> > +	of_property_read_u32(pdev->dev.of_node,	"reset-duration-us",
> > +				&data->reset_duration_us);
> > +
> >  	data->rcdev.ops = &ti_syscon_reset_ops;
> >  	data->rcdev.owner = THIS_MODULE;
> >  	data->rcdev.of_node = np;
> > 
>