drivers/regulator 

menuconfig REGULATOR 
  bool "Voltage and Current Regulator Support" 
  help 
   Generic Voltage and Current Regulator support. 
 
   This framework is designed to provide a generic interface to voltage 
   and current regulators within the Linux kernel. It's intended to 
   provide voltage and current control to client or consumer drivers and 
   also provide status information to user space applications through a 
   sysfs interface. 
 
   The intention is to allow systems to dynamically control regulator 
   output in order to save power and prolong battery life. This applies 
   to both voltage regulators (where voltage output is controllable) and 
   current sinks (where current output is controllable). 
 
   This framework safely compiles out if not selected so that client 
   drivers can still be used in systems with no software controllable 
   regulators. 
 
   If unsure, say no. 

config REGULATOR_STM32_VREFBUF 
  tristate "STMicroelectronics STM32 VREFBUF" 
  depends on ARCH_STM32 || COMPILE_TEST 
  help 
   This driver supports STMicroelectronics STM32 VREFBUF (voltage 
   reference buffer) which can be used as voltage reference for 
   internal ADCs, DACs and also for external components through 
   dedicated Vref+ pin. 
 
   This driver can also be built as a module. If so, the module 
   will be called stm32-vrefbuf. 

obj-$(CONFIG_REGULATOR) += core.o dummy.o fixed-helper.o helpers.o devres.o 
obj-$(CONFIG_OF) += of_regulator.o 
obj-$(CONFIG_REGULATOR_FIXED_VOLTAGE) += fixed.o 
obj-$(CONFIG_REGULATOR_VIRTUAL_CONSUMER) += virtual.o 
obj-$(CONFIG_REGULATOR_USERSPACE_CONSUMER) += userspace-consumer.o 
 
obj-$(CONFIG_REGULATOR_STM32_VREFBUF) += stm32-vrefbuf.o 

static const struct of_device_id stm32_vrefbuf_of_match[] = { 
  { .compatible = "st,stm32-vrefbuf", }, 
  {}, 
}; 
MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match); 
 
static struct platform_driver stm32_vrefbuf_driver = { 
  .probe = stm32_vrefbuf_probe, 
  .remove = stm32_vrefbuf_remove, 
  .driver = { 
    .name = "stm32-vrefbuf", 
    .of_match_table = of_match_ptr(stm32_vrefbuf_of_match), 
  }, 
}; 
module_platform_driver(stm32_vrefbuf_driver); 

static const struct regulator_ops stm32_vrefbuf_volt_ops = { 
  .enable   = stm32_vrefbuf_enable, 
  .disable  = stm32_vrefbuf_disable, 
  .is_enabled = stm32_vrefbuf_is_enabled, 
  .get_voltage_sel = stm32_vrefbuf_get_voltage_sel, 
  .set_voltage_sel = stm32_vrefbuf_set_voltage_sel, 
  .list_voltage  = regulator_list_voltage_table, 
}; 
 
static const struct regulator_desc stm32_vrefbuf_regu = { 
  .name = "vref", 
  .supply_name = "vdda", 
  .volt_table = stm32_vrefbuf_voltages, 
  .n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages), 
  .ops = &stm32_vrefbuf_volt_ops, 
  .type = REGULATOR_VOLTAGE, 
  .owner = THIS_MODULE, 
}; 

rdev = regulator_register(&stm32_vrefbuf_regu, &config); 
if (IS_ERR(rdev)) { 
  ret = PTR_ERR(rdev); 
  dev_err(&pdev->dev, "register failed with error %d\n", ret); 
  goto err_clk_dis; 
} 
platform_set_drvdata(pdev, rdev); 

vrefbuf: regulator@58003C00 { 
  compatible = "st,stm32-vrefbuf"; 
  reg = <0x58003C00 0x8>; 
  clocks = <&rcc VREF_CK>; 
  regulator-min-microvolt = <1500000>; 
  regulator-max-microvolt = <2500000>; 
  status = "disabled"; 
};