Liam Girdwood | 6392776 | 2008-04-30 17:19:02 +0100 | [diff] [blame] | 1 | Regulator Consumer Driver Interface |
| 2 | =================================== |
| 3 | |
| 4 | This text describes the regulator interface for consumer device drivers. |
| 5 | Please see overview.txt for a description of the terms used in this text. |
| 6 | |
| 7 | |
| 8 | 1. Consumer Regulator Access (static & dynamic drivers) |
| 9 | ======================================================= |
| 10 | |
Francis Galiegue | a33f322 | 2010-04-23 00:08:02 +0200 | [diff] [blame] | 11 | A consumer driver can get access to its supply regulator by calling :- |
Liam Girdwood | 6392776 | 2008-04-30 17:19:02 +0100 | [diff] [blame] | 12 | |
| 13 | regulator = regulator_get(dev, "Vcc"); |
| 14 | |
Francis Galiegue | a33f322 | 2010-04-23 00:08:02 +0200 | [diff] [blame] | 15 | The consumer passes in its struct device pointer and power supply ID. The core |
Liam Girdwood | 6392776 | 2008-04-30 17:19:02 +0100 | [diff] [blame] | 16 | then finds the correct regulator by consulting a machine specific lookup table. |
| 17 | If the lookup is successful then this call will return a pointer to the struct |
| 18 | regulator that supplies this consumer. |
| 19 | |
| 20 | To release the regulator the consumer driver should call :- |
| 21 | |
| 22 | regulator_put(regulator); |
| 23 | |
| 24 | Consumers can be supplied by more than one regulator e.g. codec consumer with |
| 25 | analog and digital supplies :- |
| 26 | |
| 27 | digital = regulator_get(dev, "Vcc"); /* digital core */ |
| 28 | analog = regulator_get(dev, "Avdd"); /* analog */ |
| 29 | |
| 30 | The regulator access functions regulator_get() and regulator_put() will |
| 31 | usually be called in your device drivers probe() and remove() respectively. |
| 32 | |
| 33 | |
| 34 | 2. Regulator Output Enable & Disable (static & dynamic drivers) |
| 35 | ==================================================================== |
| 36 | |
Francis Galiegue | a33f322 | 2010-04-23 00:08:02 +0200 | [diff] [blame] | 37 | A consumer can enable its power supply by calling:- |
Liam Girdwood | 6392776 | 2008-04-30 17:19:02 +0100 | [diff] [blame] | 38 | |
| 39 | int regulator_enable(regulator); |
| 40 | |
| 41 | NOTE: The supply may already be enabled before regulator_enabled() is called. |
| 42 | This may happen if the consumer shares the regulator or the regulator has been |
| 43 | previously enabled by bootloader or kernel board initialization code. |
| 44 | |
| 45 | A consumer can determine if a regulator is enabled by calling :- |
| 46 | |
| 47 | int regulator_is_enabled(regulator); |
| 48 | |
| 49 | This will return > zero when the regulator is enabled. |
| 50 | |
| 51 | |
Francis Galiegue | a33f322 | 2010-04-23 00:08:02 +0200 | [diff] [blame] | 52 | A consumer can disable its supply when no longer needed by calling :- |
Liam Girdwood | 6392776 | 2008-04-30 17:19:02 +0100 | [diff] [blame] | 53 | |
| 54 | int regulator_disable(regulator); |
| 55 | |
| 56 | NOTE: This may not disable the supply if it's shared with other consumers. The |
| 57 | regulator will only be disabled when the enabled reference count is zero. |
| 58 | |
| 59 | Finally, a regulator can be forcefully disabled in the case of an emergency :- |
| 60 | |
| 61 | int regulator_force_disable(regulator); |
| 62 | |
| 63 | NOTE: this will immediately and forcefully shutdown the regulator output. All |
| 64 | consumers will be powered off. |
| 65 | |
| 66 | |
| 67 | 3. Regulator Voltage Control & Status (dynamic drivers) |
| 68 | ====================================================== |
| 69 | |
| 70 | Some consumer drivers need to be able to dynamically change their supply |
| 71 | voltage to match system operating points. e.g. CPUfreq drivers can scale |
| 72 | voltage along with frequency to save power, SD drivers may need to select the |
| 73 | correct card voltage, etc. |
| 74 | |
| 75 | Consumers can control their supply voltage by calling :- |
| 76 | |
| 77 | int regulator_set_voltage(regulator, min_uV, max_uV); |
| 78 | |
| 79 | Where min_uV and max_uV are the minimum and maximum acceptable voltages in |
| 80 | microvolts. |
| 81 | |
| 82 | NOTE: this can be called when the regulator is enabled or disabled. If called |
| 83 | when enabled, then the voltage changes instantly, otherwise the voltage |
| 84 | configuration changes and the voltage is physically set when the regulator is |
| 85 | next enabled. |
| 86 | |
| 87 | The regulators configured voltage output can be found by calling :- |
| 88 | |
| 89 | int regulator_get_voltage(regulator); |
| 90 | |
| 91 | NOTE: get_voltage() will return the configured output voltage whether the |
| 92 | regulator is enabled or disabled and should NOT be used to determine regulator |
| 93 | output state. However this can be used in conjunction with is_enabled() to |
| 94 | determine the regulator physical output voltage. |
| 95 | |
| 96 | |
| 97 | 4. Regulator Current Limit Control & Status (dynamic drivers) |
| 98 | =========================================================== |
| 99 | |
| 100 | Some consumer drivers need to be able to dynamically change their supply |
| 101 | current limit to match system operating points. e.g. LCD backlight driver can |
| 102 | change the current limit to vary the backlight brightness, USB drivers may want |
| 103 | to set the limit to 500mA when supplying power. |
| 104 | |
| 105 | Consumers can control their supply current limit by calling :- |
| 106 | |
Dr. David Alan Gilbert | 1b35eda | 2009-11-22 14:53:15 +0000 | [diff] [blame] | 107 | int regulator_set_current_limit(regulator, min_uA, max_uA); |
Liam Girdwood | 6392776 | 2008-04-30 17:19:02 +0100 | [diff] [blame] | 108 | |
| 109 | Where min_uA and max_uA are the minimum and maximum acceptable current limit in |
| 110 | microamps. |
| 111 | |
| 112 | NOTE: this can be called when the regulator is enabled or disabled. If called |
| 113 | when enabled, then the current limit changes instantly, otherwise the current |
| 114 | limit configuration changes and the current limit is physically set when the |
| 115 | regulator is next enabled. |
| 116 | |
| 117 | A regulators current limit can be found by calling :- |
| 118 | |
| 119 | int regulator_get_current_limit(regulator); |
| 120 | |
| 121 | NOTE: get_current_limit() will return the current limit whether the regulator |
| 122 | is enabled or disabled and should not be used to determine regulator current |
| 123 | load. |
| 124 | |
| 125 | |
| 126 | 5. Regulator Operating Mode Control & Status (dynamic drivers) |
| 127 | ============================================================= |
| 128 | |
| 129 | Some consumers can further save system power by changing the operating mode of |
| 130 | their supply regulator to be more efficient when the consumers operating state |
| 131 | changes. e.g. consumer driver is idle and subsequently draws less current |
| 132 | |
| 133 | Regulator operating mode can be changed indirectly or directly. |
| 134 | |
| 135 | Indirect operating mode control. |
| 136 | -------------------------------- |
| 137 | Consumer drivers can request a change in their supply regulator operating mode |
| 138 | by calling :- |
| 139 | |
| 140 | int regulator_set_optimum_mode(struct regulator *regulator, int load_uA); |
| 141 | |
| 142 | This will cause the core to recalculate the total load on the regulator (based |
Francis Galiegue | a33f322 | 2010-04-23 00:08:02 +0200 | [diff] [blame] | 143 | on all its consumers) and change operating mode (if necessary and permitted) |
Liam Girdwood | 6392776 | 2008-04-30 17:19:02 +0100 | [diff] [blame] | 144 | to best match the current operating load. |
| 145 | |
Geert Uytterhoeven | 3a4c695 | 2014-08-25 10:47:51 +0200 | [diff] [blame] | 146 | The load_uA value can be determined from the consumer's datasheet. e.g. most |
| 147 | datasheets have tables showing the maximum current consumed in certain |
| 148 | situations. |
Liam Girdwood | 6392776 | 2008-04-30 17:19:02 +0100 | [diff] [blame] | 149 | |
| 150 | Most consumers will use indirect operating mode control since they have no |
| 151 | knowledge of the regulator or whether the regulator is shared with other |
| 152 | consumers. |
| 153 | |
| 154 | Direct operating mode control. |
| 155 | ------------------------------ |
| 156 | Bespoke or tightly coupled drivers may want to directly control regulator |
| 157 | operating mode depending on their operating point. This can be achieved by |
| 158 | calling :- |
| 159 | |
| 160 | int regulator_set_mode(struct regulator *regulator, unsigned int mode); |
| 161 | unsigned int regulator_get_mode(struct regulator *regulator); |
| 162 | |
| 163 | Direct mode will only be used by consumers that *know* about the regulator and |
| 164 | are not sharing the regulator with other consumers. |
| 165 | |
| 166 | |
| 167 | 6. Regulator Events |
| 168 | =================== |
| 169 | Regulators can notify consumers of external events. Events could be received by |
| 170 | consumers under regulator stress or failure conditions. |
| 171 | |
| 172 | Consumers can register interest in regulator events by calling :- |
| 173 | |
| 174 | int regulator_register_notifier(struct regulator *regulator, |
| 175 | struct notifier_block *nb); |
| 176 | |
Geert Uytterhoeven | 3a4c695 | 2014-08-25 10:47:51 +0200 | [diff] [blame] | 177 | Consumers can unregister interest by calling :- |
Liam Girdwood | 6392776 | 2008-04-30 17:19:02 +0100 | [diff] [blame] | 178 | |
| 179 | int regulator_unregister_notifier(struct regulator *regulator, |
| 180 | struct notifier_block *nb); |
| 181 | |
Matt LaPlante | 19f5946 | 2009-04-27 15:06:31 +0200 | [diff] [blame] | 182 | Regulators use the kernel notifier framework to send event to their interested |
Liam Girdwood | 6392776 | 2008-04-30 17:19:02 +0100 | [diff] [blame] | 183 | consumers. |
Tuomas Tynkkynen | 04eca28 | 2014-07-21 18:38:48 +0300 | [diff] [blame] | 184 | |
| 185 | 7. Regulator Direct Register Access |
| 186 | =================================== |
| 187 | Some kinds of power management hardware or firmware are designed such that |
| 188 | they need to do low-level hardware access to regulators, with no involvement |
| 189 | from the kernel. Examples of such devices are: |
| 190 | |
| 191 | - clocksource with a voltage-controlled oscillator and control logic to change |
| 192 | the supply voltage over I2C to achieve a desired output clock rate |
| 193 | - thermal management firmware that can issue an arbitrary I2C transaction to |
| 194 | perform system poweroff during overtemperature conditions |
| 195 | |
| 196 | To set up such a device/firmware, various parameters like I2C address of the |
| 197 | regulator, addresses of various regulator registers etc. need to be configured |
| 198 | to it. The regulator framework provides the following helpers for querying |
| 199 | these details. |
| 200 | |
| 201 | Bus-specific details, like I2C addresses or transfer rates are handled by the |
| 202 | regmap framework. To get the regulator's regmap (if supported), use :- |
| 203 | |
| 204 | struct regmap *regulator_get_regmap(struct regulator *regulator); |
| 205 | |
| 206 | To obtain the hardware register offset and bitmask for the regulator's voltage |
| 207 | selector register, use :- |
| 208 | |
| 209 | int regulator_get_hardware_vsel_register(struct regulator *regulator, |
| 210 | unsigned *vsel_reg, |
| 211 | unsigned *vsel_mask); |
| 212 | |
| 213 | To convert a regulator framework voltage selector code (used by |
| 214 | regulator_list_voltage) to a hardware-specific voltage selector that can be |
| 215 | directly written to the voltage selector register, use :- |
| 216 | |
| 217 | int regulator_list_hardware_vsel(struct regulator *regulator, |
| 218 | unsigned selector); |