linux-kernel - Re: [PATCH 2/2] regulators: anatop: add set_voltage_time

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Message-ID: <51099107.3070705@boundarydevices.com>
Date:	Wed, 30 Jan 2013 14:30:47 -0700
From:	Troy Kisky <troy.kisky@...ndarydevices.com>
To:	Anson Huang <b20788@...escale.com>
CC:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	dong.aisheng@...aro.org, lrg@...com,
	broonie@...nsource.wolfsonmicro.com
Subject: Re: [PATCH 2/2] regulators: anatop: add set_voltage_time_sel interface

On 1/30/2013 3:37 PM, Anson Huang wrote:
> some of anatop's regulators(vppcpu, vddpu and vddsoc) have
> register settings about LDO's step time, which will impact
> the LDO ramp up speed, need to use set_voltage_time_sel
> interface to add necessary delay everytime LDOs' voltage
> is increased.
>
> offset 0x170:
> bit [24-25]: vddcpu
> bit [26-27]: vddpu
> bit [28-29]: vddsoc
>
> field definition:
> 0'b00: 64 cycles of 24M clock;
> 0'b01: 128 cycles of 24M clock;
> 0'b02: 256 cycles of 24M clock;
> 0'b03: 512 cycles of 24M clock;
>
> Signed-off-by: Anson Huang <b20788@...escale.com>
> ---
>   drivers/regulator/anatop-regulator.c |   42 ++++++++++++++++++++++++++++++++++
>   1 file changed, 42 insertions(+)
>
> diff --git a/drivers/regulator/anatop-regulator.c b/drivers/regulator/anatop-regulator.c
> index 8f39cac..a857b9c 100644
> --- a/drivers/regulator/anatop-regulator.c
> +++ b/drivers/regulator/anatop-regulator.c
> @@ -31,12 +31,18 @@
>   #include <linux/regulator/driver.h>
>   #include <linux/regulator/of_regulator.h>
>   
> +#define LDO_RAMP_UP_UNIT_IN_CYCLES      64 /* 64 cycles per step */
> +#define LDO_RAMP_UP_FREQ_IN_MHZ         24 /* cycle based on 24M OSC */
> +
>   struct anatop_regulator {
>   	const char *name;
>   	u32 control_reg;
>   	struct regmap *anatop;
>   	int vol_bit_shift;
>   	int vol_bit_width;
> +	u32 delay_reg;
> +	int delay_bit_shift;
> +	int delay_bit_width;
>   	int min_bit_val;
>   	int min_voltage;
>   	int max_voltage;
> @@ -55,6 +61,33 @@ static int anatop_regmap_set_voltage_sel(struct regulator_dev *reg,
>   	return regulator_set_voltage_sel_regmap(reg, selector);
>   }
>   
> +static int anatop_regmap_set_voltage_time_sel(struct regulator_dev *reg,
> +	unsigned int old_sel,
> +	unsigned int new_sel)
> +{
> +	struct anatop_regulator *anatop_reg = rdev_get_drvdata(reg);
> +	u32 val;
> +	int ret = 0;
> +
> +	/* check whether need to care about LDO ramp up speed */
> +	if (anatop_reg->delay_reg) {
> +		/*
> +		 * the delay for LDO ramp up time is
> +		 * based on the register setting, we need
> +		 * to calculate how many steps LDO need to
> +		 * ramp up, and how much delay needed. (us)
> +		 */
> +		regmap_read(anatop_reg->anatop, anatop_reg->delay_reg, &val);
> +		val = (val >> anatop_reg->delay_bit_shift) &
> +			((1 << anatop_reg->delay_bit_width) - 1);
> +		ret = new_sel > old_sel ? (new_sel - old_sel) *

The (new_sel > old_sel) could be part of the above if.

if (anatop_reg->delay_reg && new_sel > old_sel)

> +			((LDO_RAMP_UP_UNIT_IN_CYCLES << val) /
> +			LDO_RAMP_UP_FREQ_IN_MHZ + 1) : 0;
> +	}
> +
> +	return ret;
> +}
> +
>   static int anatop_regmap_get_voltage_sel(struct regulator_dev *reg)
>   {
>   	struct anatop_regulator *anatop_reg = rdev_get_drvdata(reg);
> @@ -67,6 +100,7 @@ static int anatop_regmap_get_voltage_sel(struct regulator_dev *reg)
>   
>   static struct regulator_ops anatop_rops = {
>   	.set_voltage_sel = anatop_regmap_set_voltage_sel,
> +	.set_voltage_time_sel = anatop_regmap_set_voltage_time_sel,
>   	.get_voltage_sel = anatop_regmap_get_voltage_sel,
>   	.list_voltage = regulator_list_voltage_linear,
>   	.map_voltage = regulator_map_voltage_linear,
> @@ -143,6 +177,14 @@ static int anatop_regulator_probe(struct platform_device *pdev)
>   		goto anatop_probe_end;
>   	}
>   
> +	/* read LDO ramp up setting, only for core reg */
> +	of_property_read_u32(np, "anatop-delay-reg-offset",
> +			     &sreg->delay_reg);
> +	of_property_read_u32(np, "anatop-delay-bit-width",
> +			     &sreg->delay_bit_width);
> +	of_property_read_u32(np, "anatop-delay-bit-shift",
> +			     &sreg->delay_bit_shift);
> +
>   	rdesc->n_voltages = (sreg->max_voltage - sreg->min_voltage) / 25000 + 1
>   			    + sreg->min_bit_val;
>   	rdesc->min_uV = sreg->min_voltage;

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