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

[Crystal Guo <crystal.guo@mediatek.com>]

On Fri, 2020-09-11 at 10:52 +0800, Suman Anna wrote:
> On 9/10/20 9:42 PM, Crystal Guo wrote:
> > On Wed, 2020-09-09 at 23:39 +0800, Suman Anna wrote:
> >> On 9/8/20 9:57 PM, Crystal Guo wrote:
> >>> 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@mediatek.com>
> >>>>> ---
> >>>>>  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.
> >>
> >> I would go with this option. Anyway, I think you might have to add the reset SoC
> >> data as well, based on Rob's comment on the binding.
> >>
> >> regards
> >> Suman
> > 
> > 
> > Thanks for your suggestions
> > I will add the following changes in the next version, 
> > please correct me if there is any misunderstanding.
> > 1). revert ti-syscon-reset.txt add a new mediatek reset binding doc.
> > 2). split the patch [v4,3/4] with the change for the
> > regmap_update_bits() to regmap_write_bits() and the change to integrate
> > assert and deassert together.
> > 3). add the reset SoC data, which contains the flag "reset_op_available"
> > to decide the reset handler available or not.
> 
> You would also need to add your SoC-specific data equivalent of the current
> ti,reset-bits in your infra node. Please see Rob's comments on patch 2. Also,
> your new Mediatek binding should be in YAML format.
> 
> regards
> Suman
> 

Should I add the SoC-specific data as follows?
This may also modify the ti original code, is it OK?

+       data->reset_data = of_device_get_match_data(&pdev->dev);
+
+       list = of_get_property(np, data->reset_data->reset_bits, &size);

+static const struct common_reset_data ti_reset_data = {
+       .reset_op_available = false,
+       .reset_bits = "ti, reset-bits",
+};
+
+static const struct common_reset_data mediatek_reset_data = {
+       .reset_op_available = true,
+       .reset_bits = "mediatek, reset-bits",
+};
+
 static const struct of_device_id ti_syscon_reset_of_match[] = {
-       { .compatible = "ti,syscon-reset", },
+       { .compatible = "ti,syscon-reset", .data = &ti_reset_data},
+       { .compatible = "mediatek,syscon-reset", .data =
&mediatek_reset_data},
        { /* sentinel */ },
 };

Thanks
Crystal

> > 4). separate the dts patch from this patch sets
> > 
> >>>
> >>> 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;
> >>>>>
> >>>>
> >>>
> >>
> > 
>