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Date: Thu, 31 Jan 2013 11:07:12 +0800
From: Shawn Guo <shawn.guo@...aro.org>
To: Anson Huang <b20788@...escale.com>
CC: <devicetree-discuss@...ts.ozlabs.org>, <linux-doc@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <grant.likely@...retlab.ca>,
<rob.herring@...xeda.com>, <rob@...dley.net>,
<broonie@...nsource.wolfsonmicro.com>
Subject: Re: [PATCH V2] regulators: anatop: add set_voltage_time_sel interface
On Thu, Jan 31, 2013 at 10:57:06AM -0500, Anson Huang wrote:
> some of anatop's regulators(cpu, 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]: cpu
> 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>
> ---
> .../bindings/regulator/anatop-regulator.txt | 8 ++++
> drivers/regulator/anatop-regulator.c | 42 ++++++++++++++++++++
> 2 files changed, 50 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/regulator/anatop-regulator.txt b/Documentation/devicetree/bindings/regulator/anatop-regulator.txt
> index 357758c..758eae2 100644
> --- a/Documentation/devicetree/bindings/regulator/anatop-regulator.txt
> +++ b/Documentation/devicetree/bindings/regulator/anatop-regulator.txt
> @@ -9,6 +9,11 @@ Required properties:
> - anatop-min-voltage: Minimum voltage of this regulator
> - anatop-max-voltage: Maximum voltage of this regulator
>
> +Optional properties:
> +- anatop-delay-reg-offset: Anatop MFD step time register offset
> +- anatop-delay-bit-shift: Bit shift for the step time register
> +- anatop-delay-bit-width: Number of bits used in the step time register
> +
> Any property defined as part of the core regulator
> binding, defined in regulator.txt, can also be used.
>
> @@ -23,6 +28,9 @@ Example:
> anatop-reg-offset = <0x140>;
> anatop-vol-bit-shift = <9>;
> anatop-vol-bit-width = <5>;
> + anatop-delay-reg-offset = <0x170>;
> + anatop-delay-bit-shift = <24>;
> + anatop-delay-bit-width = <2>;
> anatop-min-bit-val = <1>;
> anatop-min-voltage = <725000>;
> anatop-max-voltage = <1300000>;
> diff --git a/drivers/regulator/anatop-regulator.c b/drivers/regulator/anatop-regulator.c
> index 8f39cac..fe79d24 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_bit_width) {
I would agree with Troy Kisky that the check of (new_sel > old_sel)
could be done in "if" statement, as the whole "if" block is only
needed in case that we are increasing the voltage.
Shawn
> + /*
> + * 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) *
> + ((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;
> --
> 1.7.9.5
>
>
--
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