From 04eca28cde52cdf9eb91e127cc358ad79a8ec53b Mon Sep 17 00:00:00 2001 From: Tuomas Tynkkynen Date: Mon, 21 Jul 2014 18:38:48 +0300 Subject: [PATCH] regulator: Add helpers for low-level register access Add helper functions that allow regulator consumers to obtain low-level details about the regulator hardware, like the voltage selector register address and such. These details can be useful when configuring hardware or firmware that want to do low-level access to regulators, with no involvement from the kernel. The use-case for Tegra is a voltage-controlled oscillator clocksource which has control logic to change the supply voltage via I2C to achieve a desired output clock rate. Signed-off-by: Tuomas Tynkkynen Signed-off-by: Mark Brown --- Documentation/power/regulator/consumer.txt | 35 +++++++++++ drivers/regulator/core.c | 71 ++++++++++++++++++++++ include/linux/regulator/consumer.h | 26 ++++++++ 3 files changed, 132 insertions(+) diff --git a/Documentation/power/regulator/consumer.txt b/Documentation/power/regulator/consumer.txt index 55c4175d8099..81c0e2b49cd8 100644 --- a/Documentation/power/regulator/consumer.txt +++ b/Documentation/power/regulator/consumer.txt @@ -180,3 +180,38 @@ int regulator_unregister_notifier(struct regulator *regulator, Regulators use the kernel notifier framework to send event to their interested consumers. + +7. Regulator Direct Register Access +=================================== +Some kinds of power management hardware or firmware are designed such that +they need to do low-level hardware access to regulators, with no involvement +from the kernel. Examples of such devices are: + +- clocksource with a voltage-controlled oscillator and control logic to change + the supply voltage over I2C to achieve a desired output clock rate +- thermal management firmware that can issue an arbitrary I2C transaction to + perform system poweroff during overtemperature conditions + +To set up such a device/firmware, various parameters like I2C address of the +regulator, addresses of various regulator registers etc. need to be configured +to it. The regulator framework provides the following helpers for querying +these details. + +Bus-specific details, like I2C addresses or transfer rates are handled by the +regmap framework. To get the regulator's regmap (if supported), use :- + +struct regmap *regulator_get_regmap(struct regulator *regulator); + +To obtain the hardware register offset and bitmask for the regulator's voltage +selector register, use :- + +int regulator_get_hardware_vsel_register(struct regulator *regulator, + unsigned *vsel_reg, + unsigned *vsel_mask); + +To convert a regulator framework voltage selector code (used by +regulator_list_voltage) to a hardware-specific voltage selector that can be +directly written to the voltage selector register, use :- + +int regulator_list_hardware_vsel(struct regulator *regulator, + unsigned selector); diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 4c1f999041dd..486b5908469e 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -2221,6 +2221,77 @@ int regulator_list_voltage(struct regulator *regulator, unsigned selector) } EXPORT_SYMBOL_GPL(regulator_list_voltage); +/** + * regulator_get_regmap - get the regulator's register map + * @regulator: regulator source + * + * Returns the register map for the given regulator, or an ERR_PTR value + * if the regulator doesn't use regmap. + */ +struct regmap *regulator_get_regmap(struct regulator *regulator) +{ + struct regmap *map = regulator->rdev->regmap; + + return map ? map : ERR_PTR(-EOPNOTSUPP); +} + +/** + * regulator_get_hardware_vsel_register - get the HW voltage selector register + * @regulator: regulator source + * @vsel_reg: voltage selector register, output parameter + * @vsel_mask: mask for voltage selector bitfield, output parameter + * + * Returns the hardware register offset and bitmask used for setting the + * regulator voltage. This might be useful when configuring voltage-scaling + * hardware or firmware that can make I2C requests behind the kernel's back, + * for example. + * + * On success, the output parameters @vsel_reg and @vsel_mask are filled in + * and 0 is returned, otherwise a negative errno is returned. + */ +int regulator_get_hardware_vsel_register(struct regulator *regulator, + unsigned *vsel_reg, + unsigned *vsel_mask) +{ + struct regulator_dev *rdev = regulator->rdev; + struct regulator_ops *ops = rdev->desc->ops; + + if (ops->set_voltage_sel != regulator_set_voltage_sel_regmap) + return -EOPNOTSUPP; + + *vsel_reg = rdev->desc->vsel_reg; + *vsel_mask = rdev->desc->vsel_mask; + + return 0; +} +EXPORT_SYMBOL_GPL(regulator_get_hardware_vsel_register); + +/** + * regulator_list_hardware_vsel - get the HW-specific register value for a selector + * @regulator: regulator source + * @selector: identify voltage to list + * + * Converts the selector to a hardware-specific voltage selector that can be + * directly written to the regulator registers. The address of the voltage + * register can be determined by calling @regulator_get_hardware_vsel_register. + * + * On error a negative errno is returned. + */ +int regulator_list_hardware_vsel(struct regulator *regulator, + unsigned selector) +{ + struct regulator_dev *rdev = regulator->rdev; + struct regulator_ops *ops = rdev->desc->ops; + + if (selector >= rdev->desc->n_voltages) + return -EINVAL; + if (ops->set_voltage_sel != regulator_set_voltage_sel_regmap) + return -EOPNOTSUPP; + + return selector; +} +EXPORT_SYMBOL_GPL(regulator_list_hardware_vsel); + /** * regulator_get_linear_step - return the voltage step size between VSEL values * @regulator: regulator source diff --git a/include/linux/regulator/consumer.h b/include/linux/regulator/consumer.h index a2d9d81038d1..0b1c8d09a6b1 100644 --- a/include/linux/regulator/consumer.h +++ b/include/linux/regulator/consumer.h @@ -37,6 +37,7 @@ struct device; struct notifier_block; +struct regmap; /* * Regulator operating modes. @@ -215,6 +216,13 @@ int regulator_set_optimum_mode(struct regulator *regulator, int load_uA); int regulator_allow_bypass(struct regulator *regulator, bool allow); +struct regmap *regulator_get_regmap(struct regulator *regulator); +int regulator_get_hardware_vsel_register(struct regulator *regulator, + unsigned *vsel_reg, + unsigned *vsel_mask); +int regulator_list_hardware_vsel(struct regulator *regulator, + unsigned selector); + /* regulator notifier block */ int regulator_register_notifier(struct regulator *regulator, struct notifier_block *nb); @@ -452,6 +460,24 @@ static inline int regulator_allow_bypass(struct regulator *regulator, return 0; } +struct regmap *regulator_get_regmap(struct regulator *regulator) +{ + return ERR_PTR(-EOPNOTSUPP); +} + +int regulator_get_hardware_vsel_register(struct regulator *regulator, + unsigned *vsel_reg, + unsigned *vsel_mask) +{ + return -EOPNOTSUPP; +} + +int regulator_list_hardware_vsel(struct regulator *regulator, + unsigned selector) +{ + return -EOPNOTSUPP; +} + static inline int regulator_register_notifier(struct regulator *regulator, struct notifier_block *nb) { -- 2.30.2