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<head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/><meta name="viewport" content="width=device-width, initial-scale=1.0"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><meta name="description" content="源代码位于： drivers/pwm/pwm-artinchip.c drivers/pwm/epwm-artinchip.c EPWM 驱动设计与 PWM 驱动相同，本节仅以 PWM 驱动为例，详细描述 PWM 的设计思路。 模块架构 Linux 提供了一个 PWM 子系统，使得在用户空间可以通过 sysfs 节点来控制 Backlight 背光。 整个软件框架如下图： 图 1 . Linux ..."/><meta name="DC.rights.owner" content="(C) 版权 2025"/><meta name="copyright" content="(C) 版权 2025"/><meta name="generator" content="DITA-OT"/><meta name="DC.type" content="concept"/><meta name="DC.contributor" content="yan.wang"/><meta name="DC.date.modified" content="2024-12-18"/><meta name="DC.format" content="HTML5"/><meta name="DC.identifier" content="pwm_design_intro"/><meta name="DC.language" content="zh-CN"/><title>设计说明</title><!-- Build number 2023110923. --><meta name="wh-path2root" content="../../../"/><meta name="wh-toc-id" content=""/><meta name="wh-source-relpath" content="topics/sdk/pwm/pwm_design.dita"/><meta name="wh-out-relpath" content="topics/sdk/pwm/pwm_design.html"/>
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<div class=" wh_topic_content body "><main role="main"><article class="- topic/topic concept/concept topic concept" role="article" aria-labelledby="ariaid-title1"><span class="edit-link" style="font-size:12px; opacity:0.6; text-align:right; vertical-align:middle"><a target="_blank" href="http://172.16.35.88/tasks/jdssno1uvvbf2mltu9kb9v3if05d5gopuakboe8hlud18rma/edit/F:/aicdita/aicdita-cn/topics/sdk/pwm/pwm_design.dita">Edit online</a></span><h1 class="- topic/title title topictitle1" id="ariaid-title1">设计说明</h1><div class="date inPage">18 Dec 2024</div><div style="color: gray;">
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Read time: 4 minute(s)
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</div><div class="- topic/body concept/conbody body conbody"><p class="- topic/p p" data-ofbid="d333063e22__20250121171837">源代码位于：</p><ul class="- topic/ul ul" id="pwm_design_intro__ul_qyx_nks_21c" data-ofbid="pwm_design_intro__ul_qyx_nks_21c"><li class="- topic/li li" data-ofbid="d333063e25__20250121171837">
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<p class="- topic/p p" data-ofbid="d333063e27__20250121171837"><span class="+ topic/ph sw-d/filepath ph filepath">drivers/pwm/pwm-artinchip.c</span></p>
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</li><li class="- topic/li li" data-ofbid="d333063e31__20250121171837">
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<p class="- topic/p p" data-ofbid="d333063e33__20250121171837"><span class="+ topic/ph sw-d/filepath ph filepath">drivers/pwm/epwm-artinchip.c</span></p>
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</li></ul><p class="- topic/p p" data-ofbid="d333063e37__20250121171837">EPWM 驱动设计与 PWM 驱动相同，本节仅以 PWM 驱动为例，详细描述 PWM 的设计思路。</p><section class="- topic/section section" id="pwm_design_intro__section_ryx_nks_21c" data-ofbid="pwm_design_intro__section_ryx_nks_21c"><h2 class="- topic/title title sectiontitle">模块架构</h2>
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<p class="- topic/p p" data-ofbid="d333063e44__20250121171837">Linux 提供了一个 PWM 子系统，使得在用户空间可以通过 sysfs 节点来控制 Backlight 背光。 整个软件框架如下图：</p>
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<figure class="- topic/fig fig fignone" id="pwm_design_intro__fig_inh_qks_21c" data-ofbid="pwm_design_intro__fig_inh_qks_21c"><br/><div class="imagecenter"><img class="- topic/image image imagecenter" id="pwm_design_intro__image_syx_nks_21c" src="../../../images/pwm/sw_system18.png" width="480" alt="sw_system18"/></div><br/><figcaption data-caption-side="bottom" class="- topic/title title figcapcenter"><span class="figtitleprefix fig--title-label">图<span class="fig--title-label-number"> 1</span><span class="fig--title-label-punctuation">. </span></span><span class="fig--title">Linux PWM 子系统和 Backlight 子系统的软件关系</span></figcaption></figure>
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<p class="- topic/p p" data-ofbid="d333063e54__20250121171837">上图可以看到 PWM 子系统中有两个概念：</p>
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<ol class="- topic/ol ol" id="pwm_design_intro__ol_tyx_nks_21c" data-ofbid="pwm_design_intro__ol_tyx_nks_21c"><li class="- topic/li li" data-ofbid="d333063e58__20250121171837">PWM Chip<p class="- topic/p p" data-ofbid="d333063e60__20250121171837">和硬件的 PWM 控制器一一对应，内核中维护了一个 chip 的链表。</p></li><li class="- topic/li li" data-ofbid="d333063e62__20250121171837">PWM Device<p class="- topic/p p" data-ofbid="d333063e64__20250121171837">和硬件的多路 PWM 通道一一对应，一个 chip 可以包含多个 device。</p></li></ol>
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</section><section class="- topic/section section" id="pwm_design_intro__section_os4_f14_4dc" data-ofbid="pwm_design_intro__section_os4_f14_4dc"><h2 class="- topic/title title sectiontitle">关键流程设计</h2>
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<div class="- topic/p p" data-ofbid="d333063e72__20250121171837">
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<ul class="- topic/ul ul" id="pwm_design_intro__ul_kc4_sks_21c" data-ofbid="pwm_design_intro__ul_kc4_sks_21c"><li class="- topic/li li" data-ofbid="d333063e75__20250121171837">初始化流程<p class="- topic/p p" data-ofbid="d333063e77__20250121171837">PWM 驱动的初始化过程见 aic_pwm_probe()函数，除了普通 platform 设备的处理过程（申请 regs
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资源、clk、reset）外，需要调用 PWM 子系统的接口 pwmchip_add()来注册一个 PWM
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控制器。</p><pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="pwm_design_intro__codeblock_txf_xks_21c" data-ofbid="pwm_design_intro__codeblock_txf_xks_21c"><strong class="hl-keyword">int</strong> pwmchip_add(<strong class="hl-keyword">struct</strong> pwm_chip *chip);</pre><p class="- topic/p p" data-ofbid="d333063e81__20250121171837">其中参数
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chip 中关键信息有：通道数目、PWM 控制器的 ops 等，aic_pwm_ops
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定义如下：</p><pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="pwm_design_intro__codeblock_zmd_xks_21c" data-ofbid="pwm_design_intro__codeblock_zmd_xks_21c"><strong class="hl-keyword">static</strong> <strong class="hl-keyword">const</strong> <strong class="hl-keyword">struct</strong> pwm_ops aic_pwm_ops = {
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.free = aic_pwm_free,
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.get_state = aic_pwm_get_state,
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.config = aic_pwm_config,
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.set_polarity = aic_pwm_set_polarity,
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.enable = aic_pwm_enable,
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.disable = aic_pwm_disable,
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.owner = THIS_MODULE,
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};</pre></li><li class="- topic/li li" data-ofbid="d333063e85__20250121171837">背光设备的初始化流程<p class="- topic/p p" data-ofbid="d333063e87__20250121171837">在 <a xml:lang="zh-CN" lang="zh-CN" class="- topic/xref xref" href="pwm_config.html#pwm_configuration__section_hqy_23s_21c">内核配置</a> 中，打开了
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“Generic PWM based Backlight Driver” 选项对应的白光设备，驱动代码详见
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<span class="+ topic/ph sw-d/filepath ph filepath">drivers/video/backlight/pwm_bl.c</span>。其中
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<span class="+ topic/keyword pr-d/apiname keyword apiname">probe()</span> 函数中会调用
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<span class="+ topic/keyword pr-d/apiname keyword apiname">devm_pwm_get()</span>来获取对应的 pwm
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设备。</p><pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="pwm_design_intro__codeblock_wgb_xks_21c" data-ofbid="pwm_design_intro__codeblock_wgb_xks_21c">pwm_bl.c, pwm_backlight_probe()
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-> pwm/core.c, devm_pwm_get()
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-> aic_pwm_get_state()
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-> pwm/core.c, pwm_apply_state()
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-> aic_pwm_config()
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-> aic_pwm_set_polarity()</pre></li><li class="- topic/li li" data-ofbid="d333063e104__20250121171837">中断处理流程<p class="- topic/p p" data-ofbid="d333063e106__20250121171837">PWM 的中断处理函数暂时为空，还不确定有哪些异常需要处理。</p></li></ul>
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</div>
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</section><section class="- topic/section section" id="pwm_design_intro__section_cpp_h14_4dc" data-ofbid="pwm_design_intro__section_cpp_h14_4dc"><h2 class="- topic/title title sectiontitle">数据结构设计</h2>
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<div class="- topic/p p" data-ofbid="d333063e115__20250121171837">
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<ul class="- topic/ul ul" id="pwm_design_intro__ul_hwg_vks_21c" data-ofbid="pwm_design_intro__ul_hwg_vks_21c"><li class="- topic/li li" data-ofbid="d333063e118__20250121171837">struct aic_pwm_arg：记录每一个 PWM
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通道的配置信息<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="pwm_design_intro__codeblock_qfw_wks_21c" data-ofbid="pwm_design_intro__codeblock_qfw_wks_21c"><strong class="hl-keyword">struct</strong> aic_pwm_arg {
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bool available;
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<strong class="hl-keyword">enum</strong> aic_pwm_mode mode;
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u32 tb_clk_rate;
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u32 freq;
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u32 db_red; <em class="hl-comment">/* Rising edge delay count of Dead-band */</em>
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u32 db_fed; <em class="hl-comment">/* Failing edge delay count of Dead-band */</em>
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<strong class="hl-keyword">struct</strong> aic_pwm_action action0;
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<strong class="hl-keyword">struct</strong> aic_pwm_action action1;
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u32 period;
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bool def_level;
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<strong class="hl-keyword">enum</strong> pwm_polarity polarity;
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};</pre></li><li class="- topic/li li" data-ofbid="d333063e122__20250121171837">struct
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aic_pwm_chip<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="pwm_design_intro__codeblock_ffz_fls_21c" data-ofbid="pwm_design_intro__codeblock_ffz_fls_21c"><strong class="hl-keyword">struct</strong> aic_pwm_chip {
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<strong class="hl-keyword">struct</strong> pwm_chip chip;
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<strong class="hl-keyword">struct</strong> attribute_group attrs;
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<strong class="hl-keyword">struct</strong> aic_pwm_arg args[AIC_PWM_CH_NUM];
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<strong class="hl-keyword">unsigned</strong> <strong class="hl-keyword">long</strong> pll_rate;
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<strong class="hl-keyword">unsigned</strong> <strong class="hl-keyword">long</strong> clk_rate;
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<strong class="hl-keyword">void</strong> __iomem *regs;
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<strong class="hl-keyword">struct</strong> clk *clk;
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<strong class="hl-keyword">struct</strong> reset_control *rst;
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u32 irq;
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};</pre></li><li class="- topic/li li" data-ofbid="d333063e126__20250121171837">struct aic_pwm_action：属于 HAL 层接口，记录一组 Action
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的配置信息<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="pwm_design_intro__codeblock_dns_d2p_g1c" data-ofbid="pwm_design_intro__codeblock_dns_d2p_g1c"><strong class="hl-keyword">struct</strong> aic_pwm_action {
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<strong class="hl-keyword">enum</strong> aic_pwm_action_type CBD;
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<strong class="hl-keyword">enum</strong> aic_pwm_action_type CBU;
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<strong class="hl-keyword">enum</strong> aic_pwm_action_type CAD;
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<strong class="hl-keyword">enum</strong> aic_pwm_action_type CAU;
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<strong class="hl-keyword">enum</strong> aic_pwm_action_type PRD;
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<strong class="hl-keyword">enum</strong> aic_pwm_action_type ZRO;
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};</pre></li></ul>
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</div>
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</section><section class="- topic/section section" id="pwm_design_intro__section_bh1_314_4dc" data-ofbid="pwm_design_intro__section_bh1_314_4dc"><h2 class="- topic/title title sectiontitle">接口设计</h2>
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<p class="- topic/p p" data-ofbid="d333063e137__20250121171837">以下接口是 Linux PWM 子系统需要的标准接口。</p>
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<div class="table-container"><table class="- topic/table table frame-all" id="pwm_design_intro__table_gzx_nks_21c" data-ofbid="pwm_design_intro__table_gzx_nks_21c" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 1</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">aic_pwm_enable</span></caption><colgroup><col style="width:25%"/><col style="width:75%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="pwm_design_intro__table_gzx_nks_21c__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="pwm_design_intro__table_gzx_nks_21c__entry__2">static int aic_pwm_enable(struct pwm_chip *chip, struct
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pwm_device *pwm)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_gzx_nks_21c__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_gzx_nks_21c__entry__2">使能一个 pwm 通道（device）</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_gzx_nks_21c__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_gzx_nks_21c__entry__2">chip - 指向 chip 的指针 pwm - 指向 device 的指针</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_gzx_nks_21c__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_gzx_nks_21c__entry__2">0，成功。 < 0，失败</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="pwm_design_intro__table_gzx_nks_21c__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="pwm_design_intro__table_gzx_nks_21c__entry__2">-</td></tr></tbody></table></div>
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<div class="table-container"><table class="- topic/table table frame-all" id="pwm_design_intro__table_hzx_nks_21c" data-ofbid="pwm_design_intro__table_hzx_nks_21c" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 2</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">aic_pwm_disable</span></caption><colgroup><col style="width:25%"/><col style="width:75%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="pwm_design_intro__table_hzx_nks_21c__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="pwm_design_intro__table_hzx_nks_21c__entry__2">static void aic_pwm_disable(struct pwm_chip *chip, struct
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pwm_device *pwm)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_hzx_nks_21c__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_hzx_nks_21c__entry__2">关闭一个 pwm 通道（device）</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_hzx_nks_21c__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_hzx_nks_21c__entry__2">chip - 指向 chip 的指针 pwm - 指向 device 的指针</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_hzx_nks_21c__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_hzx_nks_21c__entry__2">-</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="pwm_design_intro__table_hzx_nks_21c__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="pwm_design_intro__table_hzx_nks_21c__entry__2">-</td></tr></tbody></table></div>
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<div class="table-container"><table class="- topic/table table frame-all" id="pwm_design_intro__table_izx_nks_21c" data-ofbid="pwm_design_intro__table_izx_nks_21c" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 3</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">aic_pwm_free</span></caption><colgroup><col style="width:25%"/><col style="width:75%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="pwm_design_intro__table_izx_nks_21c__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="pwm_design_intro__table_izx_nks_21c__entry__2">static void aic_pwm_free(struct pwm_chip *chip, struct pwm_device
|
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*pwm)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_izx_nks_21c__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_izx_nks_21c__entry__2">释放一个 pwm 通道（device），实际上是设置其 period 为 0（无效）</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_izx_nks_21c__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_izx_nks_21c__entry__2">chip - 指向 chip 的指针 pwm - 指向 device 的指针</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_izx_nks_21c__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_izx_nks_21c__entry__2">无</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="pwm_design_intro__table_izx_nks_21c__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="pwm_design_intro__table_izx_nks_21c__entry__2">需要先调用 aic_pwm_disable()，再调用此接口</td></tr></tbody></table></div>
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<div class="table-container"><table class="- topic/table table frame-all" id="pwm_design_intro__table_jzx_nks_21c" data-ofbid="pwm_design_intro__table_jzx_nks_21c" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 4</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">aic_pwm_get_state</span></caption><colgroup><col style="width:25%"/><col style="width:75%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="pwm_design_intro__table_jzx_nks_21c__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="pwm_design_intro__table_jzx_nks_21c__entry__2">static void aic_pwm_get_state(struct pwm_chip *chip, struct
|
||
pwm_device *pwm,struct pwm_state *state)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_jzx_nks_21c__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_jzx_nks_21c__entry__2">获取当前 PWM 控制器的配置信息。当使能 logo 功能时，U-Boot 中已经初始化过 PWM，所以 Linux 中需要从
|
||
PWM 控制器中同步一下当前状态</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_jzx_nks_21c__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_jzx_nks_21c__entry__2">chip - 指向 chip 的指针 pwm - 指向 device 的指针 state - 指向 state
|
||
的指针，用于返回当前 PWM 的状态信息</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_jzx_nks_21c__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_jzx_nks_21c__entry__2">无</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="pwm_design_intro__table_jzx_nks_21c__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="pwm_design_intro__table_jzx_nks_21c__entry__2">-</td></tr></tbody></table></div>
|
||
<div class="table-container"><table class="- topic/table table frame-all" id="pwm_design_intro__table_kzx_nks_21c" data-ofbid="pwm_design_intro__table_kzx_nks_21c" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 5</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">aic_pwm_config</span></caption><colgroup><col style="width:25%"/><col style="width:75%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="pwm_design_intro__table_kzx_nks_21c__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="pwm_design_intro__table_kzx_nks_21c__entry__2">static int aic_pwm_config(struct pwm_chip *chip, struct
|
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pwm_device *pwm,int duty_ns, int period_ns)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_kzx_nks_21c__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_kzx_nks_21c__entry__2">配置一个 pwm 通道（device）的占空比</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_kzx_nks_21c__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_kzx_nks_21c__entry__2">chip - 指向 chip 的指针 pwm - 指向 device 的指针 duty_ns - 一个 PWM 周期内的负载时长
|
||
period_ns - 一个 PWM 周期</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_kzx_nks_21c__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_kzx_nks_21c__entry__2">0，成功。< 0，失败</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="pwm_design_intro__table_kzx_nks_21c__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="pwm_design_intro__table_kzx_nks_21c__entry__2">-</td></tr></tbody></table></div>
|
||
<div class="table-container"><table class="- topic/table table frame-all" id="pwm_design_intro__table_lzx_nks_21c" data-ofbid="pwm_design_intro__table_lzx_nks_21c" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 6</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">aic_pwm_set_polarity</span></caption><colgroup><col style="width:25%"/><col style="width:75%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="pwm_design_intro__table_lzx_nks_21c__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="pwm_design_intro__table_lzx_nks_21c__entry__2">static int aic_pwm_set_polarity(struct pwm_chip *chip, struct
|
||
pwm_device *pwm,enum pwm_polarity polarity)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_lzx_nks_21c__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_lzx_nks_21c__entry__2">配置一个 pwm 通道（device）的极性（是否需要翻转）</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_lzx_nks_21c__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_lzx_nks_21c__entry__2">chip - 指向 chip 的指针 pwm - 指向 device 的指针 polarity - 指定的极性</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="pwm_design_intro__table_lzx_nks_21c__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="pwm_design_intro__table_lzx_nks_21c__entry__2">0，成功。< 0，失败</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="pwm_design_intro__table_lzx_nks_21c__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="pwm_design_intro__table_lzx_nks_21c__entry__2">-</td></tr></tbody></table></div>
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