From 04eca28cde52cdf9eb91e127cc358ad79a8ec53b Mon Sep 17 00:00:00 2001 From: Tuomas Tynkkynen Date: Mon, 21 Jul 2014 18:38:48 +0300 Subject: 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 ++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'Documentation/power/regulator/consumer.txt') 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); -- cgit v1.2.3 From 3a4c695965cb1b3fd5b7e420eeab958af139328c Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Mon, 25 Aug 2014 10:47:51 +0200 Subject: regulator: Proofread documentation Signed-off-by: Geert Uytterhoeven Signed-off-by: Mark Brown --- Documentation/power/regulator/consumer.txt | 7 ++++--- Documentation/power/regulator/design.txt | 8 ++++---- Documentation/power/regulator/machine.txt | 4 ++-- Documentation/power/regulator/overview.txt | 6 +++--- Documentation/power/regulator/regulator.txt | 6 +++--- 5 files changed, 16 insertions(+), 15 deletions(-) (limited to 'Documentation/power/regulator/consumer.txt') diff --git a/Documentation/power/regulator/consumer.txt b/Documentation/power/regulator/consumer.txt index 81c0e2b49cd8..8afb236ca765 100644 --- a/Documentation/power/regulator/consumer.txt +++ b/Documentation/power/regulator/consumer.txt @@ -143,8 +143,9 @@ This will cause the core to recalculate the total load on the regulator (based on all its consumers) and change operating mode (if necessary and permitted) to best match the current operating load. -The load_uA value can be determined from the consumers datasheet. e.g.most -datasheets have tables showing the max current consumed in certain situations. +The load_uA value can be determined from the consumer's datasheet. e.g. most +datasheets have tables showing the maximum current consumed in certain +situations. Most consumers will use indirect operating mode control since they have no knowledge of the regulator or whether the regulator is shared with other @@ -173,7 +174,7 @@ Consumers can register interest in regulator events by calling :- int regulator_register_notifier(struct regulator *regulator, struct notifier_block *nb); -Consumers can uregister interest by calling :- +Consumers can unregister interest by calling :- int regulator_unregister_notifier(struct regulator *regulator, struct notifier_block *nb); diff --git a/Documentation/power/regulator/design.txt b/Documentation/power/regulator/design.txt index f9b56b72b782..fdd919b96830 100644 --- a/Documentation/power/regulator/design.txt +++ b/Documentation/power/regulator/design.txt @@ -9,14 +9,14 @@ Safety - Errors in regulator configuration can have very serious consequences for the system, potentially including lasting hardware damage. - - It is not possible to automatically determine the power confugration + - It is not possible to automatically determine the power configuration of the system - software-equivalent variants of the same chip may - have different power requirments, and not all components with power + have different power requirements, and not all components with power requirements are visible to software. => The API should make no changes to the hardware state unless it has - specific knowledge that these changes are safe to do perform on - this particular system. + specific knowledge that these changes are safe to perform on this + particular system. Consumer use cases ------------------ diff --git a/Documentation/power/regulator/machine.txt b/Documentation/power/regulator/machine.txt index ce63af0a8e35..757e3b53dc11 100644 --- a/Documentation/power/regulator/machine.txt +++ b/Documentation/power/regulator/machine.txt @@ -11,7 +11,7 @@ Consider the following machine :- +-> [Consumer B @ 3.3V] The drivers for consumers A & B must be mapped to the correct regulator in -order to control their power supply. This mapping can be achieved in machine +order to control their power supplies. This mapping can be achieved in machine initialisation code by creating a struct regulator_consumer_supply for each regulator. @@ -39,7 +39,7 @@ to the 'Vcc' supply for Consumer A. Constraints can now be registered by defining a struct regulator_init_data for each regulator power domain. This structure also maps the consumers -to their supply regulator :- +to their supply regulators :- static struct regulator_init_data regulator1_data = { .constraints = { diff --git a/Documentation/power/regulator/overview.txt b/Documentation/power/regulator/overview.txt index 8ed17587a74b..40ca2d6e2742 100644 --- a/Documentation/power/regulator/overview.txt +++ b/Documentation/power/regulator/overview.txt @@ -36,11 +36,11 @@ Some terms used in this document:- Consumers can be classified into two types:- Static: consumer does not change its supply voltage or - current limit. It only needs to enable or disable it's + current limit. It only needs to enable or disable its power supply. Its supply voltage is set by the hardware, bootloader, firmware or kernel board initialisation code. - Dynamic: consumer needs to change it's supply voltage or + Dynamic: consumer needs to change its supply voltage or current limit to meet operation demands. @@ -156,7 +156,7 @@ relevant to non SoC devices and is split into the following four interfaces:- This interface is for machine specific code and allows the creation of voltage/current domains (with constraints) for each regulator. It can provide regulator constraints that will prevent device damage through - overvoltage or over current caused by buggy client drivers. It also + overvoltage or overcurrent caused by buggy client drivers. It also allows the creation of a regulator tree whereby some regulators are supplied by others (similar to a clock tree). diff --git a/Documentation/power/regulator/regulator.txt b/Documentation/power/regulator/regulator.txt index 13902778ae44..b17e5833ce21 100644 --- a/Documentation/power/regulator/regulator.txt +++ b/Documentation/power/regulator/regulator.txt @@ -13,7 +13,7 @@ Drivers can register a regulator by calling :- struct regulator_dev *regulator_register(struct regulator_desc *regulator_desc, const struct regulator_config *config); -This will register the regulators capabilities and operations to the regulator +This will register the regulator's capabilities and operations to the regulator core. Regulators can be unregistered by calling :- @@ -23,8 +23,8 @@ void regulator_unregister(struct regulator_dev *rdev); Regulator Events ================ -Regulators can send events (e.g. over temp, under voltage, etc) to consumer -drivers by calling :- +Regulators can send events (e.g. overtemperature, undervoltage, etc) to +consumer drivers by calling :- int regulator_notifier_call_chain(struct regulator_dev *rdev, unsigned long event, void *data); -- cgit v1.2.3