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| -rw-r--r-- | Documentation/power/regulator/machine.txt | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/Documentation/power/regulator/machine.txt b/Documentation/power/regulator/machine.txt new file mode 100644 index 000000000000..c9a35665cf70 --- /dev/null +++ b/Documentation/power/regulator/machine.txt @@ -0,0 +1,101 @@ +Regulator Machine Driver Interface +=================================== + +The regulator machine driver interface is intended for board/machine specific +initialisation code to configure the regulator subsystem. Typical things that +machine drivers would do are :- + + 1. Regulator -> Device mapping. + 2. Regulator supply configuration. + 3. Power Domain constraint setting. + + + +1. Regulator -> device mapping +============================== +Consider the following machine :- + + Regulator-1 -+-> Regulator-2 --> [Consumer A @ 1.8 - 2.0V] + | + +-> [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 +initialisation code by calling :- + +int regulator_set_device_supply(const char *regulator, struct device *dev, + const char *supply); + +and is shown with the following code :- + +regulator_set_device_supply("Regulator-1", devB, "Vcc"); +regulator_set_device_supply("Regulator-2", devA, "Vcc"); + +This maps Regulator-1 to the 'Vcc' supply for Consumer B and maps Regulator-2 +to the 'Vcc' supply for Consumer A. + + +2. Regulator supply configuration. +================================== +Consider the following machine (again) :- + + Regulator-1 -+-> Regulator-2 --> [Consumer A @ 1.8 - 2.0V] + | + +-> [Consumer B @ 3.3V] + +Regulator-1 supplies power to Regulator-2. This relationship must be registered +with the core so that Regulator-1 is also enabled when Consumer A enables it's +supply (Regulator-2). + +This relationship can be register with the core via :- + +int regulator_set_supply(const char *regulator, const char *regulator_supply); + +In this example we would use the following code :- + +regulator_set_supply("Regulator-2", "Regulator-1"); + +Relationships can be queried by calling :- + +const char *regulator_get_supply(const char *regulator); + + +3. Power Domain constraint setting. +=================================== +Each power domain within a system has physical constraints on voltage and +current. This must be defined in software so that the power domain is always +operated within specifications. + +Consider the following machine (again) :- + + Regulator-1 -+-> Regulator-2 --> [Consumer A @ 1.8 - 2.0V] + | + +-> [Consumer B @ 3.3V] + +This gives us two regulators and two power domains: + + Domain 1: Regulator-2, Consumer B. + Domain 2: Consumer A. + +Constraints can be registered by calling :- + +int regulator_set_platform_constraints(const char *regulator, + struct regulation_constraints *constraints); + +The example is defined as follows :- + +struct regulation_constraints domain_1 = { + .min_uV = 3300000, + .max_uV = 3300000, + .valid_modes_mask = REGULATOR_MODE_NORMAL, +}; + +struct regulation_constraints domain_2 = { + .min_uV = 1800000, + .max_uV = 2000000, + .valid_ops_mask = REGULATOR_CHANGE_VOLTAGE, + .valid_modes_mask = REGULATOR_MODE_NORMAL, +}; + +regulator_set_platform_constraints("Regulator-1", &domain_1); +regulator_set_platform_constraints("Regulator-2", &domain_2); |