Re: [PATCH V2 06/21] clk: tegra: dfll: CVB calculation alignment with the regulator

[Joseph Lo <josephl@nvidia.com>]

On 12/13/18 7:18 PM, Jon Hunter wrote:
> 
> On 13/12/2018 09:34, Joseph Lo wrote:
>> The CVB table contains calibration data for the CPU DFLL based on
>> process characterization. The regulator step and offset parameters depend
>> on the regulator supplying vdd-cpu, not on the specific Tegra SKU.
>>
>> When using a PWM controlled regulator, the voltage step and offset are
>> determined by the regulator type in use. This is specified in DT. When
>> using an I2C controlled regulator, we can retrieve them from CPU regulator
>> Then pass this information to the CVB table calculation function.
>>
>> Based on the work done of "Peter De Schrijver <pdeschrijver@nvidia.com>"
>> and "Alex Frid <afrid@nvidia.com>".
>>
>> Signed-off-by: Joseph Lo <josephl@nvidia.com>
>> ---
>> *V2:
>>   - use the updated DT binding string for parsing
>>   - update the mechanism for geting regulator data from DT (PWM mode) or
>>   regulator (I2C mode)
>> ---
>>   drivers/clk/tegra/clk-dfll.h               |  6 ++-
>>   drivers/clk/tegra/clk-tegra124-dfll-fcpu.c | 57 ++++++++++++++++++++--
>>   drivers/clk/tegra/cvb.c                    | 12 +++--
>>   drivers/clk/tegra/cvb.h                    |  6 +--
>>   4 files changed, 67 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/clk/tegra/clk-dfll.h b/drivers/clk/tegra/clk-dfll.h
>> index 83352c8078f2..ecc43cb9b6f1 100644
>> --- a/drivers/clk/tegra/clk-dfll.h
>> +++ b/drivers/clk/tegra/clk-dfll.h
>> @@ -1,6 +1,6 @@
>>   /*
>>    * clk-dfll.h - prototypes and macros for the Tegra DFLL clocksource driver
>> - * Copyright (C) 2013 NVIDIA Corporation.  All rights reserved.
>> + * Copyright (C) 2013-2018 NVIDIA Corporation.  All rights reserved.
>>    *
>>    * Aleksandr Frid <afrid@nvidia.com>
>>    * Paul Walmsley <pwalmsley@nvidia.com>
>> @@ -22,11 +22,14 @@
>>   #include <linux/reset.h>
>>   #include <linux/types.h>
>>   
>> +#include "cvb.h"
>> +
>>   /**
>>    * struct tegra_dfll_soc_data - SoC-specific hooks/integration for the DFLL driver
>>    * @dev: struct device * that holds the OPP table for the DFLL
>>    * @max_freq: maximum frequency supported on this SoC
>>    * @cvb: CPU frequency table for this SoC
>> + * @alignment: parameters of the regulator step and offset
>>    * @init_clock_trimmers: callback to initialize clock trimmers
>>    * @set_clock_trimmers_high: callback to tune clock trimmers for high voltage
>>    * @set_clock_trimmers_low: callback to tune clock trimmers for low voltage
>> @@ -35,6 +38,7 @@ struct tegra_dfll_soc_data {
>>   	struct device *dev;
>>   	unsigned long max_freq;
>>   	const struct cvb_table *cvb;
>> +	struct rail_alignment alignment;
>>   
>>   	void (*init_clock_trimmers)(void);
>>   	void (*set_clock_trimmers_high)(void);
>> diff --git a/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c b/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
>> index 1a2cc113e5c8..189b5e20ee4e 100644
>> --- a/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
>> +++ b/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
>> @@ -23,6 +23,7 @@
>>   #include <linux/init.h>
>>   #include <linux/of_device.h>
>>   #include <linux/platform_device.h>
>> +#include <linux/regulator/consumer.h>
>>   #include <soc/tegra/fuse.h>
>>   
>>   #include "clk.h"
>> @@ -50,9 +51,6 @@ static const struct cvb_table tegra124_cpu_cvb_tables[] = {
>>   		.process_id = -1,
>>   		.min_millivolts = 900,
>>   		.max_millivolts = 1260,
>> -		.alignment = {
>> -			.step_uv = 10000, /* 10mV */
>> -		},
>>   		.speedo_scale = 100,
>>   		.voltage_scale = 1000,
>>   		.entries = {
>> @@ -105,11 +103,45 @@ static const struct of_device_id tegra124_dfll_fcpu_of_match[] = {
>>   	{ },
>>   };
>>   
>> +static void get_alignment_from_dt(struct device *dev,
>> +				  struct rail_alignment *align)
>> +{
>> +	align->step_uv = 0;
>> +	align->offset_uv = 0;
>> +
>> +	if (of_property_read_u32(dev->of_node,
>> +				 "nvidia,pwm-voltage-step-microvolts",
>> +				 &align->step_uv))
>> +		align->step_uv = 0;
> 
> Not sure why it is necessary to initialise this again on failure.

Indeed, it's not necessary. Will remove two lines above.

> 
>> +
>> +	if (of_property_read_u32(dev->of_node,
>> +				 "nvidia,pwm-min-microvolts",
>> +				 &align->offset_uv))
>> +		align->offset_uv = 0;
> 
> Same here.
> 
>> +}
>> +
>> +static int get_alignment_from_regulator(struct device *dev,
>> +					 struct rail_alignment *align)
>> +{
>> +	struct regulator *reg = devm_regulator_get(dev, "vdd-cpu");
>> +
>> +	if (IS_ERR(reg))
>> +		return PTR_ERR(reg);
>> +
>> +	align->offset_uv = regulator_list_voltage(reg, 0);
>> +	align->step_uv = regulator_get_linear_step(reg);
>> +
>> +	devm_regulator_put(reg);
>> +
>> +	return 0;
>> +}
>> +
>>   static int tegra124_dfll_fcpu_probe(struct platform_device *pdev)
>>   {
>>   	int process_id, speedo_id, speedo_value, err;
>>   	struct tegra_dfll_soc_data *soc;
>>   	const struct dfll_fcpu_data *fcpu_data;
>> +	struct rail_alignment align;
>>   
>>   	fcpu_data = of_device_get_match_data(&pdev->dev);
>>   	if (!fcpu_data)
>> @@ -135,12 +167,27 @@ static int tegra124_dfll_fcpu_probe(struct platform_device *pdev)
>>   		return -ENODEV;
>>   	}
>>   
>> +	if (of_property_read_bool(pdev->dev.of_node, "nvidia,pwm-to-pmic")) {
>> +		get_alignment_from_dt(&pdev->dev, &align);
>> +	} else {
>> +		err = get_alignment_from_regulator(&pdev->dev, &align);
>> +		if (err == -EPROBE_DEFER)
>> +			return -EPROBE_DEFER;
> 
> Why not return any error here? The print below maybe misleading.

Okay, that should be fine. Will fix. Thanks.

Joseph

> 
>> +	}
>> +
>> +	if (!align.step_uv) {
>> +		dev_err(&pdev->dev, "missing step uv\n");
>> +		return -EINVAL;
>> +	}
>> +
> 
> Cheers
> Jon
>