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詳解linux電源管理驅(qū)動(dòng)編寫

更新時(shí)間：2018年04月13日 09:36:31 作者：feixiaoxing

這篇文章主要介紹了詳解linux電源管理驅(qū)動(dòng)編寫，小編覺(jué)得挺不錯(cuò)的，現(xiàn)在分享給大家，也給大家做個(gè)參考。一起跟隨小編過(guò)來(lái)看看吧

對(duì)于嵌入式設(shè)備來(lái)說(shuō)，合適的電源管理，不僅可以延長(zhǎng)電池的壽命，而且可以省電，延長(zhǎng)設(shè)備運(yùn)行時(shí)間，在提高用戶體驗(yàn)方面有很大的好處。所以，各個(gè)soc廠家在這方面花了很多的功夫。下面，我們可以看看linux是如何處理電源管理驅(qū)動(dòng)的。

1、代碼目錄

drivers/regulator

2、查看目錄下的Kconfig文件

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.

3、閱讀文件，得知REGULATOR是最核心的模塊macro，那我們可以找一個(gè)設(shè)備的macro看看

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.

4、沒(méi)有找到s3c，可以看一下stm32芯片的依賴屬性，接著看Makefile

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

5、看的出來(lái)stm32只依賴于stm32-verfbuf.c文件，繼續(xù)查看

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);

6、確認(rèn)驅(qū)動(dòng)為platform驅(qū)動(dòng)，尋找regulator特有的數(shù)據(jù)結(jié)構(gòu)

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, 
};

7、由代碼得知，regulator_ops和regulator_desc才是特有的regulator數(shù)據(jù)結(jié)構(gòu)，當(dāng)然也少不了注冊(cè)函數(shù)

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);

8、進(jìn)一步確認(rèn)of_device_id是不是真實(shí)存在，可以在arch/arm/boot/dts/stm32h743.dtsi找到對(duì)應(yīng)內(nèi)容

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

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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