Re: [PATCH 06/12] i2c: riic: Add suspend/resume support

[claudiu beznea <claudiu.beznea@tuxon.dev>]

On 21.06.2024 15:30, Biju Das wrote:
> Hi Claudiu,
> 
> Thanks for the patch
> 
>> -----Original Message-----
>> From: Claudiu <claudiu.beznea@tuxon.dev>
>> Sent: Friday, June 21, 2024 12:23 PM
>> Subject: [PATCH 06/12] i2c: riic: Add suspend/resume support
>>
>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>
>> Add suspend/resume support for the RIIC driver. This is necessary for the Renesas RZ/G3S SoC which
>> support suspend to deep sleep state where power to most of the SoC components is turned off. As a
>> result the I2C controller needs to be reconfigured after suspend/resume. For this, the reset line
>> was stored in the driver private data structure as well as i2c timings.
>> The reset line and I2C timings are necessary to re-initialize the controller after resume.
>>
>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>> ---
>>  drivers/i2c/busses/i2c-riic.c | 66 +++++++++++++++++++++++++++++------
>>  1 file changed, 55 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-riic.c b/drivers/i2c/busses/i2c-riic.c index
>> 00fb09786e48..f9b9e92570d8 100644
>> --- a/drivers/i2c/busses/i2c-riic.c
>> +++ b/drivers/i2c/busses/i2c-riic.c
>> @@ -105,6 +105,8 @@ struct riic_dev {
>>  	struct completion msg_done;
>>  	struct i2c_adapter adapter;
>>  	struct clk *clk;
>> +	struct reset_control *rstc;
>> +	struct i2c_timings i2c_t;
>>  };
>>
>>  struct riic_irq_desc {
>> @@ -306,11 +308,12 @@ static const struct i2c_algorithm riic_algo = {
>>  	.functionality	= riic_func,
>>  };
>>
>> -static int riic_init_hw(struct riic_dev *riic, struct i2c_timings *t)
>> +static int riic_init_hw(struct riic_dev *riic)
>>  {
>>  	int ret;
>>  	unsigned long rate;
>>  	int total_ticks, cks, brl, brh;
>> +	struct i2c_timings *t = &riic->i2c_t;
>>  	struct device *dev = riic->adapter.dev.parent;
>>
>>  	if (t->bus_freq_hz > I2C_MAX_FAST_MODE_FREQ) { @@ -429,8 +432,6 @@ static int
>> riic_i2c_probe(struct platform_device *pdev)
>>  	struct device *dev = &pdev->dev;
>>  	struct riic_dev *riic;
>>  	struct i2c_adapter *adap;
>> -	struct i2c_timings i2c_t;
>> -	struct reset_control *rstc;
>>  	int i, ret;
>>
>>  	riic = devm_kzalloc(dev, sizeof(*riic), GFP_KERNEL); @@ -447,16 +448,16 @@ static int
>> riic_i2c_probe(struct platform_device *pdev)
>>  		return PTR_ERR(riic->clk);
>>  	}
>>
>> -	rstc = devm_reset_control_get_optional_exclusive(dev, NULL);
>> -	if (IS_ERR(rstc))
>> -		return dev_err_probe(dev, PTR_ERR(rstc),
>> +	riic->rstc = devm_reset_control_get_optional_exclusive(dev, NULL);
>> +	if (IS_ERR(riic->rstc))
>> +		return dev_err_probe(dev, PTR_ERR(riic->rstc),
>>  				     "Error: missing reset ctrl\n");
>>
>> -	ret = reset_control_deassert(rstc);
>> +	ret = reset_control_deassert(riic->rstc);
>>  	if (ret)
>>  		return ret;
>>
>> -	ret = devm_add_action_or_reset(dev, riic_reset_control_assert, rstc);
>> +	ret = devm_add_action_or_reset(dev, riic_reset_control_assert,
>> +riic->rstc);
>>  	if (ret)
>>  		return ret;
>>
>> @@ -485,13 +486,13 @@ static int riic_i2c_probe(struct platform_device *pdev)
>>
>>  	init_completion(&riic->msg_done);
>>
>> -	i2c_parse_fw_timings(dev, &i2c_t, true);
>> +	i2c_parse_fw_timings(dev, &riic->i2c_t, true);
>>
>>  	pm_runtime_set_autosuspend_delay(dev, 0);
>>  	pm_runtime_use_autosuspend(dev);
>>  	pm_runtime_enable(dev);
>>
>> -	ret = riic_init_hw(riic, &i2c_t);
>> +	ret = riic_init_hw(riic);
>>  	if (ret)
>>  		goto out;
>>
>> @@ -501,7 +502,7 @@ static int riic_i2c_probe(struct platform_device *pdev)
>>
>>  	platform_set_drvdata(pdev, riic);
>>
>> -	dev_info(dev, "registered with %dHz bus speed\n", i2c_t.bus_freq_hz);
>> +	dev_info(dev, "registered with %dHz bus speed\n",
>> +riic->i2c_t.bus_freq_hz);
>>  	return 0;
>>
>>  out:
>> @@ -561,6 +562,48 @@ static const struct riic_of_data riic_rz_v2h_info = {
>>  	},
>>  };
>>
>> +static int riic_i2c_suspend(struct device *dev) {
>> +	struct riic_dev *riic = dev_get_drvdata(dev);
>> +	int ret;
>> +
>> +	ret = pm_runtime_resume_and_get(dev);
>> +	if (ret)
>> +		return ret;
>> +
>> +	i2c_mark_adapter_suspended(&riic->adapter);
>> +
>> +	/* Disable output on SDA, SCL pins. */
>> +	riic_clear_set_bit(riic, ICCR1_ICE, 0, RIIC_ICCR1);
>> +
>> +	pm_runtime_mark_last_busy(dev);
>> +	pm_runtime_put_sync(dev);
>> +
>> +	return reset_control_assert(riic->rstc); }
>> +
>> +static int riic_i2c_resume(struct device *dev) {
>> +	struct riic_dev *riic = dev_get_drvdata(dev);
>> +	int ret;
>> +
>> +	ret = reset_control_deassert(riic->rstc);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = riic_init_hw(riic);
>> +	if (ret)
>> +		return ret;
> 
> On error case we need to assert back??

Yes, it would be better as we cannot recover though other paths anymore, if
that happens.

> 
> Cheers,
> Biju
> 
>> +
>> +	i2c_mark_adapter_resumed(&riic->adapter);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct dev_pm_ops riic_i2c_pm_ops = {
>> +	SYSTEM_SLEEP_PM_OPS(riic_i2c_suspend, riic_i2c_resume) };
>> +
>>  static const struct of_device_id riic_i2c_dt_ids[] = {
>>  	{ .compatible = "renesas,riic-rz", .data = &riic_rz_a_info },
>>  	{ .compatible = "renesas,riic-r9a09g057", .data = &riic_rz_v2h_info }, @@ -573,6 +616,7 @@
>> static struct platform_driver riic_i2c_driver = {
>>  	.driver		= {
>>  		.name	= "i2c-riic",
>>  		.of_match_table = riic_i2c_dt_ids,
>> +		.pm	= pm_ptr(&riic_i2c_pm_ops),
>>  	},
>>  };
>>
>> --
>> 2.39.2
>>
>