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Commit 8c64821a authored by Fenglin Wu's avatar Fenglin Wu
Browse files

regulator: fan53555: update slew rate according to voltage step 



Currently, the voltage transition slew rate setting for fan53555 is
based on 10 mV voltage scaling step. For regulator with a scaling step
other than 10 mV, the slew rate has a relationship between voltage
scaling step and the slew rate based on 10 mV voltage scaling step.

Change the slew rate setting according to the voltage scaling step, and
round it to a lower avaiable value if it is an itermediate one.

Change-Id: Iccb13ebcb4bac15d76420602363bdcdfe5fc0a2d
Signed-off-by: default avatarFenglin Wu <fenglinw@codeaurora.org>
parent 3fc0e794

Documentation/devicetree/bindings/regulator/fan53555.txt

+0 −2
Original line number Diff line number Diff line
@@ -20,8 +20,6 @@ Required Properties: 
- regulator-max-microvolt:	Maximum voltage in microvolts supported by this

				regulator.

- regulator-ramp-delay:		The slew rate of the regulator, in uV/us.

				Supported values are 64000, 32000, 16000,

				8000, 4000, 2000, 1000 and 500.



Optional Properties:

- fairchild,vsel-gpio:		Present: GPIO connects to the VSEL pin and set

drivers/regulator/fan53555.c

+29 −19
Original line number Diff line number Diff line
@@ -183,6 +183,30 @@ static struct regulator_ops fan53555_regulator_disable_suspend_ops = { 
	.get_mode = fan53555_get_mode,

};



/*

 * The formula for calculating the actual slew rate is:

 * actual_slew_rate = 10mv_based_slew_rate * scaling_step_size_mv / 10mV

 */

#define FAN53555_DVS_DEFAULT_STEP_SIZE_UV	10000

static u32 fan53555_get_slew_rate_reg_value(struct fan53555_device_info *di,

							u32 slew_rate)

{

	u32 index;

	int scaled_slew_rate = slew_rate * FAN53555_DVS_DEFAULT_STEP_SIZE_UV /

						di->vsel_step;



	for (index = 0; index < ARRAY_SIZE(slew_rate_plan); index++)

		if (scaled_slew_rate >= slew_rate_plan[index])

			break;



	if (index == ARRAY_SIZE(slew_rate_plan)) {

		dev_err(di->dev, "invalid slew rate.\n");

		index = FAN53555_SLEW_RATE_8MV;

	}



	return index;

}



/* For 00,01,03,05 options:

 * VOUT = 0.60V + NSELx * 10mV, from 0.60 to 1.23V.

 * For 04 option:
@@ -241,10 +265,14 @@ static int fan53555_device_setup(struct fan53555_device_info *di, 
		return -EINVAL;

	}

	/* Init slew rate */

	if (pdata->slew_rate & 0x7)

	if (di->dev->of_node)

		pdata->slew_rate = fan53555_get_slew_rate_reg_value(di,

			pdata->regulator->constraints.ramp_delay);

	else if (pdata->slew_rate & 0x7)

		di->slew_rate = pdata->slew_rate;

	else

		di->slew_rate = FAN53555_SLEW_RATE_64MV;



	reg = FAN53555_CONTROL;

	data = di->slew_rate << CTL_SLEW_SHIFT;

	mask = CTL_SLEW_MASK;
@@ -303,22 +331,6 @@ static int fan53555_parse_backup_reg(struct i2c_client *client, u32 *sleep_sel) 
	return rc;

}



static u32 fan53555_get_slew_rate_reg_value(struct i2c_client *client,

					u32 slew_rate)

{

	u32 index;



	for (index = 0; index < ARRAY_SIZE(slew_rate_plan); index++)

		if (slew_rate == slew_rate_plan[index])

			break;



	if (index == ARRAY_SIZE(slew_rate_plan)) {

		dev_err(&client->dev, "invalid slew rate.\n");

		index = FAN53555_SLEW_RATE_8MV;

	}



	return index;

}



static struct fan53555_platform_data *

	fan53555_get_of_platform_data(struct i2c_client *client)
@@ -355,8 +367,6 @@ static struct fan53555_platform_data * 
	init_data->constraints.initial_mode = REGULATOR_MODE_NORMAL;



	pdata->regulator = init_data;

	pdata->slew_rate = fan53555_get_slew_rate_reg_value(client,

				init_data->constraints.ramp_delay);

	pdata->sleep_vsel_id = sleep_sel;



	return pdata;

include/linux/regulator/fan53555.h

+6 −0
Original line number Diff line number Diff line
@@ -19,6 +19,12 @@ enum { 
};



/* Transition slew rate limiting from a low to high voltage.

 * The slew rate values listed in this table are based on

 * 10 mV voltage scaling step. The actual slew rate has a

 * relationship between the slew rate based on 10 mV as its

 * voltage scaling step size and the actual voltage step size.

 * The formula for calculating the actual slew rate is:

 * actual_slew_rate = 10mv_based_slew_rate * scaling_step_size_mv / 10mV.

 * -----------------------

 *   Bin |Slew Rate(mV/uS)

 * ------|----------------