Platform 드라이버 작성 — probe·remove·of_match·DT 바인딩

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static const struct of_device_id my_of_match[] = {
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    { .compatible = "vendor,foo-v1" },
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    { .compatible = "vendor,foo-v2", .data = (void *)1 },
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    { }
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};
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MODULE_DEVICE_TABLE(of, my_of_match);
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static struct platform_driver my_driver = {
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    .probe  = my_probe,
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    .remove = my_remove,
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    .driver = {
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        .name           = "foo",
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        .of_match_table = my_of_match,
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    },
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};
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module_platform_driver(my_driver);

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// DT
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foo@40000000 {
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    compatible = "vendor,foo-v1";
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    reg        = <0x40000000 0x1000>;
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    interrupts = <GIC_SPI 42 IRQ_TYPE_LEVEL_HIGH>;
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    clocks     = <&clkc CLK_FOO>;
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};

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// driver probe
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static int my_probe(struct platform_device *pdev) {
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    struct device *dev = &pdev->dev;
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    struct my_data *d;
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    d = devm_kzalloc(dev, sizeof(*d), GFP_KERNEL);
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    if (!d) return -ENOMEM;
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    d->regs = devm_platform_ioremap_resource(pdev, 0);
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    if (IS_ERR(d->regs)) return PTR_ERR(d->regs);
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    d->irq = platform_get_irq(pdev, 0);
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    if (d->irq < 0) return d->irq;
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    d->clk = devm_clk_get(dev, NULL);
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    if (IS_ERR(d->clk)) return PTR_ERR(d->clk);
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    clk_prepare_enable(d->clk);
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    if (devm_request_irq(dev, d->irq, my_isr, 0, dev_name(dev), d))
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        return -EIO;
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    platform_set_drvdata(pdev, d);
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    return 0;
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}
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static int my_remove(struct platform_device *pdev) {
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    struct my_data *d = platform_get_drvdata(pdev);
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    clk_disable_unprepare(d->clk);
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    return 0;
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    /* devm_* 자원은 자동 해제 */
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}

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static const struct of_device_id my_of_match[] = {
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    { .compatible = "vendor,foo-v1", .data = &foo_v1_cfg },
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    { .compatible = "vendor,foo-v2", .data = &foo_v2_cfg },
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    { }
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};
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static int my_probe(struct platform_device *pdev) {
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    const struct foo_cfg *cfg = of_device_get_match_data(&pdev->dev);
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    if (!cfg) return -EINVAL;
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    write_init_regs(cfg->init_seq, cfg->init_len);
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    /* ... */
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}

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u32 freq, channels;
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const char *mode;
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of_property_read_u32(dev->of_node, "sample-rate", &freq);
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of_property_read_u32(dev->of_node, "num-channels", &channels);
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of_property_read_string(dev->of_node, "mode", &mode);
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if (of_property_read_bool(dev->of_node, "enable-foo"))
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    enable_foo();

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d->reset = devm_reset_control_get_optional(dev, NULL);
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if (!IS_ERR(d->reset))
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    reset_control_assert(d->reset);
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d->reg = devm_regulator_get(dev, "vdd");
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if (!IS_ERR(d->reg))
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    regulator_enable(d->reg);
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d->pinctrl = devm_pinctrl_get_select_default(dev);

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static int my_runtime_suspend(struct device *dev) {
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    struct my_data *d = dev_get_drvdata(dev);
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    clk_disable_unprepare(d->clk);
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    return 0;
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}
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static int my_runtime_resume(struct device *dev) {
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    struct my_data *d = dev_get_drvdata(dev);
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    return clk_prepare_enable(d->clk);
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}
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static const struct dev_pm_ops my_pm = {
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    SET_RUNTIME_PM_OPS(my_runtime_suspend, my_runtime_resume, NULL)
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};
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static struct platform_driver my_driver = {
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    ...
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    .driver = {
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        ...
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        .pm = &my_pm,
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    },
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};

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static int my_probe(struct platform_device *pdev) {
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    d->clk = devm_clk_get(dev, NULL);
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    if (PTR_ERR(d->clk) == -EPROBE_DEFER)
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        return -EPROBE_DEFER;
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    if (IS_ERR(d->clk))
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        return PTR_ERR(d->clk);
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    /* ... */
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}

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RAM 사용량
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platform driver                  ~수 KB (code + private data)
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devm allocations                 device 해제 시 자동 free

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compatible = "vendor,fooo";    /* 's' 누락 → driver match 실패 */

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static int my_probe(...) {
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    p = kmalloc(...);
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    if (err) return -EIO;   /* p leak */
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}

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if (IS_ERR(d->clk))
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    return -EIO;    /* -EPROBE_DEFER을 -EIO로 덮어씀 → 영구 실패 */

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static irqreturn_t my_isr(int irq, void *d) {
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    mutex_lock(&m);    /* ISR에서 sleep 함수 — BUG */
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}

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static int my_open(...) { d->ref++; }