详解linux电源管理驱动编写

茶香淡雅 發表於 2023-6-5 00:00:00

<p>
对于嵌入式设备来说，合适的电源管理，不仅可以延长电池的寿命，而且可以省电，延长设备运行时间，在提高用户体验方面有很大的好处。所以，各个soc厂家在这方面花了很多的功夫。下面，我们可以看看linux是如何处理电源管理驱动的。</p>
<p>
1、代码目录</p>
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<code class="plain plain">drivers/regulator</code>
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2、查看目录下的Kconfig文件</p>
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<code class="plain plain">menuconfig REGULATOR </code>
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<code class="plain spaces">  </code><code class="plain plain">bool "Voltage and Current Regulator Support" </code>
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<code class="plain spaces">  </code><code class="plain plain">help </code>
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<code class="plain spaces">   </code><code class="plain plain">Generic Voltage and Current Regulator support. </code>
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<code class="plain spaces"> </code>
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<code class="plain spaces">   </code><code class="plain plain">This framework is designed to provide a generic interface to voltage </code>
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<code class="plain spaces">   </code><code class="plain plain">and current regulators within the Linux kernel. It's intended to </code>
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<code class="plain spaces">   </code><code class="plain plain">provide voltage and current control to client or consumer drivers and </code>
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<code class="plain spaces">   </code><code class="plain plain">also provide status information to user space applications through a </code>
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<code class="plain spaces">   </code><code class="plain plain">sysfs interface. </code>
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<code class="plain spaces"> </code>
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<code class="plain spaces">   </code><code class="plain plain">The intention is to allow systems to dynamically control regulator </code>
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<code class="plain spaces">   </code><code class="plain plain">output in order to save power and prolong battery life. This applies </code>
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<code class="plain spaces">   </code><code class="plain plain">to both voltage regulators (where voltage output is controllable) and </code>
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<code class="plain spaces">   </code><code class="plain plain">current sinks (where current output is controllable). </code>
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<code class="plain spaces"> </code>
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<code class="plain spaces">   </code><code class="plain plain">This framework safely compiles out if not selected so that client </code>
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<code class="plain spaces">   </code><code class="plain plain">drivers can still be used in systems with no software controllable </code>
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<code class="plain spaces">   </code><code class="plain plain">regulators. </code>
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<code class="plain spaces"> </code>
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<code class="plain spaces">   </code><code class="plain plain">If unsure, say no. </code>
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<p>
3、阅读文件，得知REGULATOR是最核心的模块macro，那我们可以找一个设备的macro看看 </p>
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<code class="plain plain">config REGULATOR_STM32_VREFBUF </code>
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<code class="plain spaces">  </code><code class="plain plain">tristate "STMicroelectronics STM32 VREFBUF" </code>
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<code class="plain spaces">  </code><code class="plain plain">depends on ARCH_STM32 || COMPILE_TEST </code>
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<code class="plain spaces">  </code><code class="plain plain">help </code>
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<code class="plain spaces">   </code><code class="plain plain">This driver supports STMicroelectronics STM32 VREFBUF (voltage </code>
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<code class="plain spaces">   </code><code class="plain plain">reference buffer) which can be used as voltage reference for </code>
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<code class="plain spaces">   </code><code class="plain plain">internal ADCs, DACs and also for external components through </code>
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<code class="plain spaces">   </code><code class="plain plain">dedicated Vref+ pin. </code>
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<code class="plain spaces"> </code>
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<code class="plain spaces">   </code><code class="plain plain">This driver can also be built as a module. If so, the module </code>
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<code class="plain spaces">   </code><code class="plain plain">will be called stm32-vrefbuf. </code>
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<p>
4、没有找到s3c，可以看一下stm32芯片的依赖属性，接着看Makefile</p>
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<code class="cpp plain">obj-$(CONFIG_REGULATOR) += core.o dummy.o fixed-helper.o helpers.o devres.o </code>
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<code class="cpp plain">obj-$(CONFIG_OF) += of_regulator.o </code>
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<code class="cpp plain">obj-$(CONFIG_REGULATOR_FIXED_VOLTAGE) += fixed.o </code>
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<code class="cpp plain">obj-$(CONFIG_REGULATOR_VIRTUAL_CONSUMER) += </code><code class="cpp keyword bold">virtual</code><code class="cpp plain">.o </code>
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<code class="cpp plain">obj-$(CONFIG_REGULATOR_USERSPACE_CONSUMER) += userspace-consumer.o </code>
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<code class="cpp spaces"> </code>
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<code class="cpp plain">obj-$(CONFIG_REGULATOR_STM32_VREFBUF) += stm32-vrefbuf.o</code>
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<p>
5、看的出来stm32只依赖于stm32-verfbuf.c文件，继续查看</p>
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<code class="cpp keyword bold">static</code> <code class="cpp keyword bold">const</code> <code class="cpp keyword bold">struct</code> <code class="cpp plain">of_device_id stm32_vrefbuf_of_match[] = { </code>
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<code class="cpp spaces">  </code><code class="cpp plain">{ .compatible = </code><code class="cpp string">"st,stm32-vrefbuf"</code><code class="cpp plain">, }, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">{}, </code>
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<code class="cpp plain">}; </code>
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<code class="cpp plain">MODULE_DEVICE_TABLE(of, stm32_vrefbuf_of_match); </code>
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<code class="cpp spaces"> </code>
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<code class="cpp keyword bold">static</code> <code class="cpp keyword bold">struct</code> <code class="cpp plain">platform_driver stm32_vrefbuf_driver = { </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.probe = stm32_vrefbuf_probe, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.</code><code class="cpp functions bold">remove</code> <code class="cpp plain">= stm32_vrefbuf_remove, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.driver = { </code>
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<code class="cpp spaces">    </code><code class="cpp plain">.name = </code><code class="cpp string">"stm32-vrefbuf"</code><code class="cpp plain">, </code>
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<code class="cpp spaces">    </code><code class="cpp plain">.of_match_table = of_match_ptr(stm32_vrefbuf_of_match), </code>
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<code class="cpp spaces">  </code><code class="cpp plain">}, </code>
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<code class="cpp plain">}; </code>
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<code class="cpp plain">module_platform_driver(stm32_vrefbuf_driver); </code>
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<p>
6、确认驱动为platform驱动，寻找regulator特有的数据结构</p>
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<code class="cpp keyword bold">static</code> <code class="cpp keyword bold">const</code> <code class="cpp keyword bold">struct</code> <code class="cpp plain">regulator_ops stm32_vrefbuf_volt_ops = { </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.enable   = stm32_vrefbuf_enable, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.disable = stm32_vrefbuf_disable, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.is_enabled = stm32_vrefbuf_is_enabled, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.get_voltage_sel = stm32_vrefbuf_get_voltage_sel, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.set_voltage_sel = stm32_vrefbuf_set_voltage_sel, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.list_voltage = regulator_list_voltage_table, </code>
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<code class="cpp plain">}; </code>
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<code class="cpp spaces"> </code>
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<code class="cpp keyword bold">static</code> <code class="cpp keyword bold">const</code> <code class="cpp keyword bold">struct</code> <code class="cpp plain">regulator_desc stm32_vrefbuf_regu = { </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.name = </code><code class="cpp string">"vref"</code><code class="cpp plain">, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.supply_name = </code><code class="cpp string">"vdda"</code><code class="cpp plain">, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.volt_table = stm32_vrefbuf_voltages, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.n_voltages = ARRAY_SIZE(stm32_vrefbuf_voltages), </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.ops = &stm32_vrefbuf_volt_ops, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.type = REGULATOR_VOLTAGE, </code>
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<code class="cpp spaces">  </code><code class="cpp plain">.owner = THIS_MODULE, </code>
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<code class="cpp plain">}; </code>
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<p>
7、由代码得知，regulator_ops和regulator_desc才是特有的regulator数据结构，当然也少不了注册函数</p>
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<code class="cpp plain">rdev = regulator_register(&stm32_vrefbuf_regu, &config); </code>
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<code class="cpp keyword bold">if</code> <code class="cpp plain">(IS_ERR(rdev)) { </code>
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<code class="cpp spaces">  </code><code class="cpp plain">ret = PTR_ERR(rdev); </code>
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<code class="cpp spaces">  </code><code class="cpp plain">dev_err(&pdev->dev, </code><code class="cpp string">"register failed with error %d\n"</code><code class="cpp plain">, ret); </code>
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<code class="cpp spaces">  </code><code class="cpp keyword bold">goto</code> <code class="cpp plain">err_clk_dis; </code>
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<code class="cpp plain">} </code>
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<code class="cpp plain">platform_set_drvdata(pdev, rdev); </code>
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<p>
8、进一步确认of_device_id是不是真实存在，可以在arch/arm/boot/dts/stm32h743.dtsi找到对应内容</p>
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<code class="cpp plain">vrefbuf: regulator@58003C00 { </code>
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<code class="cpp spaces">  </code><code class="cpp plain">compatible = </code><code class="cpp string">"st,stm32-vrefbuf"</code><code class="cpp plain">; </code>
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<code class="cpp spaces">  </code><code class="cpp plain">reg = <0x58003C00 0x8>; </code>
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<code class="cpp spaces">  </code><code class="cpp plain">clocks = <&rcc VREF_CK>; </code>
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<code class="cpp spaces">  </code><code class="cpp plain">regulator-min-microvolt = <1500000>; </code>
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<code class="cpp spaces">  </code><code class="cpp plain">regulator-max-microvolt = <2500000>; </code>
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<code class="cpp spaces">  </code><code class="cpp plain">status = </code><code class="cpp string">"disabled"</code><code class="cpp plain">; </code>
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<code class="cpp plain">};</code>
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以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。</p>
<p>
原文链接：https://blog.csdn.net/feixiaoxing/article/details/79874311</p>

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