Re: [PATCH v2 08/26] soc: qcom: spm: add support for voltage regulator

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 26/06/2023 14:47, Konrad Dybcio wrote:
> On 25.06.2023 22:25, Dmitry Baryshkov wrote:
>> The SPM / SAW2 device also provides a voltage regulator functionality
>> with optional AVS (Adaptive Voltage Scaling) support. The exact register
>> sequence and voltage ranges differs from device to device.
>>
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>> ---
>>   drivers/soc/qcom/spm.c | 205 ++++++++++++++++++++++++++++++++++++++++-
>>   include/soc/qcom/spm.h |   9 ++
>>   2 files changed, 212 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/soc/qcom/spm.c b/drivers/soc/qcom/spm.c
>> index a6cbeb40831b..3c16a7e1710c 100644
>> --- a/drivers/soc/qcom/spm.c
>> +++ b/drivers/soc/qcom/spm.c
>> @@ -9,19 +9,31 @@
>>   #include <linux/kernel.h>
>>   #include <linux/init.h>
>>   #include <linux/io.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/linear_range.h>
>>   #include <linux/module.h>
>>   #include <linux/slab.h>
>>   #include <linux/of.h>
>>   #include <linux/of_address.h>
>>   #include <linux/of_device.h>
>> +#include <linux/bitfield.h>
> This addition is very out-of-order

The whole list is out of order. Proably I should sort it first

> 
>>   #include <linux/err.h>
>>   #include <linux/platform_device.h>
>> +#include <linux/regulator/driver.h>
>> +#include <linux/smp.h>
>>   #include <soc/qcom/spm.h>
>>   
>> +#define FIELD_SET(current, mask, val)	\
>> +	(((current) & ~(mask)) | FIELD_PREP((mask), (val)))
>> +
>>   #define SPM_CTL_INDEX		0x7f
>>   #define SPM_CTL_INDEX_SHIFT	4
>>   #define SPM_CTL_EN		BIT(0)
>>   
>> +#define SPM_1_1_AVS_CTL_AVS_ENABLED BIT(27)
>> +#define SPM_AVS_CTL_MIN_VLVL	(0x3f << 10)
>> +#define SPM_AVS_CTL_MAX_VLVL	(0x3f << 17)
> GENMASK

ack

> 
>> +
>>   enum spm_reg {
>>   	SPM_REG_CFG,
>>   	SPM_REG_SPM_CTL,
>> @@ -31,10 +43,12 @@ enum spm_reg {
>>   	SPM_REG_PMIC_DATA_1,
>>   	SPM_REG_VCTL,
>>   	SPM_REG_SEQ_ENTRY,
>> -	SPM_REG_SPM_STS,
>> +	SPM_REG_STS0,
>> +	SPM_REG_STS1,
>>   	SPM_REG_PMIC_STS,
>>   	SPM_REG_AVS_CTL,
>>   	SPM_REG_AVS_LIMIT,
>> +	SPM_REG_RST,
>>   	SPM_REG_NR,
>>   };
>>   
>> @@ -171,6 +185,10 @@ static const struct spm_reg_data spm_reg_8226_cpu  = {
>>   
>>   static const u16 spm_reg_offset_v1_1[SPM_REG_NR] = {
>>   	[SPM_REG_CFG]		= 0x08,
>> +	[SPM_REG_STS0]		= 0x0c,
>> +	[SPM_REG_STS1]		= 0x10,
>> +	[SPM_REG_VCTL]		= 0x14,
>> +	[SPM_REG_AVS_CTL]	= 0x18,
>>   	[SPM_REG_SPM_CTL]	= 0x20,
>>   	[SPM_REG_PMIC_DLY]	= 0x24,
>>   	[SPM_REG_PMIC_DATA_0]	= 0x28,
>> @@ -178,7 +196,12 @@ static const u16 spm_reg_offset_v1_1[SPM_REG_NR] = {
>>   	[SPM_REG_SEQ_ENTRY]	= 0x80,
>>   };
>>   
>> +static void smp_set_vdd_v1_1(void *data);
>> +
>>   /* SPM register data for 8064 */
>> +static struct linear_range spm_v1_1_regulator_range =
>> +	REGULATOR_LINEAR_RANGE(700000, 0, 56, 12500);
>> +
>>   static const struct spm_reg_data spm_reg_8064_cpu = {
>>   	.reg_offset = spm_reg_offset_v1_1,
>>   	.spm_cfg = 0x1F,
>> @@ -189,6 +212,10 @@ static const struct spm_reg_data spm_reg_8064_cpu = {
>>   		0x10, 0x54, 0x30, 0x0C, 0x24, 0x30, 0x0F },
>>   	.start_index[PM_SLEEP_MODE_STBY] = 0,
>>   	.start_index[PM_SLEEP_MODE_SPC] = 2,
>> +	.set_vdd = smp_set_vdd_v1_1,
>> +	.range = &spm_v1_1_regulator_range,
>> +	.init_uV = 1300000,
>> +	.ramp_delay = 1250,
>>   };
>>   
>>   static inline void spm_register_write(struct spm_driver_data *drv,
>> @@ -240,6 +267,179 @@ void spm_set_low_power_mode(struct spm_driver_data *drv,
>>   	spm_register_write_sync(drv, SPM_REG_SPM_CTL, ctl_val);
>>   }
>>   
>> +static int spm_set_voltage_sel(struct regulator_dev *rdev, unsigned int selector)
>> +{
>> +	struct spm_driver_data *drv = rdev_get_drvdata(rdev);
>> +
>> +	drv->volt_sel = selector;
>> +
>> +	/* Always do the SAW register writes on the corresponding CPU */
>> +	return smp_call_function_single(drv->reg_cpu, drv->reg_data->set_vdd, drv, true);
>> +}
>> +
>> +static int spm_get_voltage_sel(struct regulator_dev *rdev)
>> +{
>> +	struct spm_driver_data *drv = rdev_get_drvdata(rdev);
>> +
>> +	return drv->volt_sel;
>> +}
>> +
>> +static const struct regulator_ops spm_reg_ops = {
>> +	.set_voltage_sel	= spm_set_voltage_sel,
>> +	.get_voltage_sel	= spm_get_voltage_sel,
>> +	.list_voltage		= regulator_list_voltage_linear_range,
>> +	.set_voltage_time_sel	= regulator_set_voltage_time_sel,
>> +};
>> +
>> +static void smp_set_vdd_v1_1(void *data)
>> +{
>> +	struct spm_driver_data *drv = data;
>> +	unsigned int vlevel = drv->volt_sel;
>> +	unsigned int vctl, data0, data1, avs_ctl, sts;
>> +	bool avs_enabled;
> Reverse-Christmas-tree?
> 
>> +
>> +	vlevel |= 0x80; /* band */
> That's conveniently 1<<7.. do we know if it's a significant number
> or just a bit that does something within that field?

More like 2 << 6. A bit of the issue is that PMIC_DATA_n format is 
PMIC-specific. I'll see what I can do here.

> 
>> +
>> +	avs_ctl = spm_register_read(drv, SPM_REG_AVS_CTL);
>> +	vctl = spm_register_read(drv, SPM_REG_VCTL);
>> +	data0 = spm_register_read(drv, SPM_REG_PMIC_DATA_0);
>> +	data1 = spm_register_read(drv, SPM_REG_PMIC_DATA_1);
>> +
>> +	avs_enabled = avs_ctl & SPM_1_1_AVS_CTL_AVS_ENABLED;
>> +
>> +	/* If AVS is enabled, switch it off during the voltage change */
>> +	if (avs_enabled) {
>> +		avs_ctl &= ~SPM_1_1_AVS_CTL_AVS_ENABLED;
>> +		spm_register_write(drv, SPM_REG_AVS_CTL, avs_ctl);
>> +	}
>> +
>> +	/* Kick the state machine back to idle */
>> +	spm_register_write(drv, SPM_REG_RST, 1);
>> +
>> +	vctl = FIELD_SET(vctl, 0xff, vlevel);
>> +	data0 = FIELD_SET(data0, 0xff, vlevel);
>> +	data1 = FIELD_SET(data1, 0x3f, vlevel);
>> +	data1 = FIELD_SET(data1, 0x3f << 16, vlevel);
> GENMASK
> 
>> +
>> +	spm_register_write(drv, SPM_REG_VCTL, vctl);
>> +	spm_register_write(drv, SPM_REG_PMIC_DATA_0, data0);
>> +	spm_register_write(drv, SPM_REG_PMIC_DATA_1, data1);
>> +
>> +	if (read_poll_timeout_atomic(spm_register_read,
>> +				      sts, sts == vlevel,
>> +				      1, 200, false,
>> +				      drv, SPM_REG_STS1)) {
> Not sure if misaligned or thunderfox is acting up again

off-by-one, I'll fix it.

> 
>> +		dev_err_ratelimited(drv->dev, "timeout setting the voltage (%x %x)!\n", sts, vlevel);
>> +		goto enable_avs;
>> +	}
>> +
>> +	if (avs_enabled) {
>> +		unsigned int max_avs = vlevel & 0x3f;
> GENMASK
> 
>> +		unsigned int min_avs = max(max_avs, 4U) - 4;
> So it's 0 or >= (1<<31 - 4)?
> 
>> +		avs_ctl = FIELD_SET(avs_ctl, SPM_AVS_CTL_MIN_VLVL, min_avs);
>> +		avs_ctl = FIELD_SET(avs_ctl, SPM_AVS_CTL_MAX_VLVL, max_avs);
>> +		spm_register_write(drv, SPM_REG_AVS_CTL, avs_ctl);
>> +	}
>> +
>> +enable_avs:
>> +	if (avs_enabled) {
>> +		avs_ctl |= SPM_1_1_AVS_CTL_AVS_ENABLED;
>> +		spm_register_write(drv, SPM_REG_AVS_CTL, avs_ctl);
>> +	}
>> +}
>> +
>> +static int spm_get_cpu(struct device *dev)
>> +{
>> +	int cpu;
>> +	bool found;
> Reverse-Christmas-tree?
> 
>> +
>> +	for_each_possible_cpu(cpu) {
>> +		struct device_node *cpu_node, *saw_node;
> As long as Linux is running, there should be at least one CPU up,
> so this always gets entered, perhaps the definitions could be moved
> to the main function body

Huh, I'm not sure that I got you correct here. Do you mean movign 
cpu_node and saw_node to the top of spm_get_cpu()?

> 
>> +
>> +		cpu_node = of_cpu_device_node_get(cpu);
>> +		if (!cpu_node)
>> +			continue;
>> +
>> +		saw_node = of_parse_phandle(cpu_node, "qcom,saw", 0);
>> +		found = (saw_node == dev->of_node);
> The error checking here works out, but it's a bit cryptic.. Though
> I'm not opposed to saving 3 cycles on slow and old CPUs :D

It's not the error checking per se. We have to put both nodes before 
returning.

So an alternative might me:

saw_node = ...
if (saw_node == cpu_node) {
     of_node_put(saw_node);
     of_node_put(cpu_node);
     return cpu;
}

of_node_put(saw_node);
of_node_put(cpu_node);

But it looks worse to me. Did you mean this kind of code or was 
something else on your mind?

> 
>> +		of_node_put(saw_node);
>> +		of_node_put(cpu_node);
>> +
>> +		if (found)
>> +			return cpu;
>> +	}
>> +
>> +	/* L2 SPM is not bound to any CPU, tie it to CPU0 */
>> +
>> +	return 0;
>> +}
>> +
>> +#ifdef CONFIG_REGULATOR
>> +static int spm_register_regulator(struct device *dev, struct spm_driver_data *drv)
>> +{
>> +	struct regulator_config config = {
>> +		.dev = dev,
>> +		.driver_data = drv,
>> +	};
>> +	struct regulator_desc *rdesc;
>> +	struct regulator_dev *rdev;
>> +	int ret;
>> +	bool found;
> Reverse-Christmas-tree?
> 
> Konrad
>> +
>> +	if (!drv->reg_data->set_vdd)
>> +		return 0;
>> +
>> +	rdesc = devm_kzalloc(dev, sizeof(*rdesc), GFP_KERNEL);
>> +	if (!rdesc)
>> +		return -ENOMEM;
>> +
>> +	rdesc->name = "spm";
>> +	rdesc->of_match = of_match_ptr("regulator");
>> +	rdesc->type = REGULATOR_VOLTAGE;
>> +	rdesc->owner = THIS_MODULE;
>> +	rdesc->ops = &spm_reg_ops;
>> +
>> +	rdesc->linear_ranges = drv->reg_data->range;
>> +	rdesc->n_linear_ranges = 1;
>> +	rdesc->n_voltages = rdesc->linear_ranges[rdesc->n_linear_ranges - 1].max_sel + 1;
>> +	rdesc->ramp_delay = drv->reg_data->ramp_delay;
>> +
>> +	drv->reg_cpu = spm_get_cpu(dev);
>> +	dev_dbg(dev, "SAW2 bound to CPU %d\n", drv->reg_cpu);
>> +
>> +	/*
>> +	 * Program initial voltage, otherwise registration will also try
>> +	 * setting the voltage, which might result in undervolting the CPU.
>> +	 */
>> +	drv->volt_sel = DIV_ROUND_UP(drv->reg_data->init_uV - rdesc->min_uV,
>> +				     rdesc->uV_step);
>> +	ret = linear_range_get_selector_high(drv->reg_data->range,
>> +					     drv->reg_data->init_uV,
>> +					     &drv->volt_sel,
>> +					     &found);
>> +	if (ret) {
>> +		dev_err(dev, "Initial uV value out of bounds\n");
>> +		return ret;
>> +	}
>> +
>> +	/* Always do the SAW register writes on the corresponding CPU */
>> +	smp_call_function_single(drv->reg_cpu, drv->reg_data->set_vdd, drv, true);
>> +
>> +	rdev = devm_regulator_register(dev, rdesc, &config);
>> +	if (IS_ERR(rdev)) {
>> +		dev_err(dev, "failed to register regulator\n");
>> +		return PTR_ERR(rdev);
>> +	}
>> +
>> +	return 0;
>> +}
>> +#else
>> +static int spm_register_regulator(struct device *dev, struct spm_driver_data *drv)
>> +{
>> +	return 0;
>> +}
>> +#endif
>> +
>>   static const struct of_device_id spm_match_table[] = {
>>   	{ .compatible = "qcom,sdm660-gold-saw2-v4.1-l2",
>>   	  .data = &spm_reg_660_gold_l2 },
>> @@ -292,6 +492,7 @@ static int spm_dev_probe(struct platform_device *pdev)
>>   		return -ENODEV;
>>   
>>   	drv->reg_data = match_id->data;
>> +	drv->dev = &pdev->dev;
>>   	platform_set_drvdata(pdev, drv);
>>   
>>   	/* Write the SPM sequences first.. */
>> @@ -319,7 +520,7 @@ static int spm_dev_probe(struct platform_device *pdev)
>>   	if (drv->reg_data->reg_offset[SPM_REG_SPM_CTL])
>>   		spm_set_low_power_mode(drv, PM_SLEEP_MODE_STBY);
>>   
>> -	return 0;
>> +	return spm_register_regulator(&pdev->dev, drv);
>>   }
>>   
>>   static struct platform_driver spm_driver = {
>> diff --git a/include/soc/qcom/spm.h b/include/soc/qcom/spm.h
>> index 4951f9d8b0bd..9859ebe42003 100644
>> --- a/include/soc/qcom/spm.h
>> +++ b/include/soc/qcom/spm.h
>> @@ -30,11 +30,20 @@ struct spm_reg_data {
>>   	u32 avs_limit;
>>   	u8 seq[MAX_SEQ_DATA];
>>   	u8 start_index[PM_SLEEP_MODE_NR];
>> +
>> +	smp_call_func_t set_vdd;
>> +	/* for now we support only a single range */
>> +	struct linear_range *range;
>> +	unsigned int ramp_delay;
>> +	unsigned int init_uV;
>>   };
>>   
>>   struct spm_driver_data {
>>   	void __iomem *reg_base;
>>   	const struct spm_reg_data *reg_data;
>> +	struct device *dev;
>> +	unsigned int volt_sel;
>> +	int reg_cpu;
>>   };
>>   
>>   void spm_set_low_power_mode(struct spm_driver_data *drv,

-- 
With best wishes
Dmitry