I read some articles about this topic. but none of them describes the details.
What I know is:
declare "compatible" property in Device tree:
gpio0: gpio@44e07000 {
compatible = "ti,omap4-gpio";
...
};
and make the connection to platform driver by
static const struct of_device_id omap_gpio_match[] = {
{
.compatible = "ti,omap4-gpio",
},
{ },
};
...
static struct platform_driver omap_gpio_driver = {
.probe = omap_gpio_probe,
.driver = {
.name = "omap_gpio",
.pm = &gpio_pm_ops,
.of_match_table = of_match_ptr(omap_gpio_match),
},
};
and as a result, of_match_table will be used to match the compatible property declared in Device Tree.
and the match action performed in platform_match (drivers/base/platform.c
) function. I doubt this because the I greped reference of of_match_table and the only probable result located in of_device_get_match_data (drivers/of/device.c
) function.
~/wk/linux$ find . -name '*.c' | xargs grep '\<of_match_table\>' | grep -v -E 'of_match_table\s+='
./drivers/dma/sirf-dma.c: (of_match_device(op->dev.driver->of_match_table,
./drivers/macintosh/macio_asic.c: const struct of_device_id * matches = drv->of_match_table;
./drivers/macintosh/macio_asic.c: match = of_match_device(drv->driver.of_match_table, dev);
./drivers/nvmem/mxs-ocotp.c: match = of_match_device(dev->driver->of_match_table, dev);
./drivers/reset/sti/reset-syscfg.c: match = of_match_device(dev->driver->of_match_table, dev);
./drivers/mtd/devices/m25p80.c: * matching for .of_match_table
./drivers/soc/rockchip/pm_domains.c: match = of_match_device(dev->driver->of_match_table, dev);
./drivers/phy/phy-rockchip-usb.c: match = of_match_device(dev->driver->of_match_table, dev);
./drivers/acpi/bus.c: * @of_match_table: List of device IDs to match against.
./drivers/acpi/bus.c: const struct of_device_id *of_match_table)
./drivers/acpi/bus.c: if (!of_match_table || !of_compatible)
./drivers/acpi/bus.c: for (id = of_match_table; id->compatible[0]; id++)
./drivers/acpi/bus.c: drv->of_match_table);
./drivers/acpi/bus.c: drv->acpi_match_table, drv->of_match_table);
./drivers/pci/host/pcie-hisi.c: match = of_match_device(driver->of_match_table, &pdev->dev);
./drivers/pinctrl/stm32/pinctrl-stm32.c: match = of_match_device(dev->driver->of_match_table, dev);
./drivers/of/device.c: match = of_match_device(dev->driver->of_match_table, dev);
./drivers/mfd/axp20x.c: of_id = of_match_device(dev->driver->of_match_table, dev);
./drivers/gpu/drm/armada/armada_crtc.c: match = of_match_device(dev->driver->of_match_table, dev);
./arch/powerpc/kernel/ibmebus.c: ibmebus_create_devices(drv->driver.of_match_table);
./arch/powerpc/kernel/ibmebus.c: const struct of_device_id *matches = drv->of_match_table;
./sound/soc/qcom/lpass-cpu.c: match = of_match_device(dev->driver->of_match_table, dev);
But this function is not used in some common modules.
~/wk/linux$ find . -name '*.c' | xargs grep of_device_get_match_data
./drivers/dma/sh/shdmac.c: pdata = of_device_get_match_data(&pdev->dev);
./drivers/dma/tegra210-adma.c: cdata = of_device_get_match_data(&pdev->dev);
./drivers/dma/tegra20-apb-dma.c: cdata = of_device_get_match_data(&pdev->dev);
./drivers/usb/host/xhci-tegra.c: tegra->soc = of_device_get_match_data(&pdev->dev);
./drivers/usb/phy/phy-msm-usb.c: pdata->phy_type = (enum msm_usb_phy_type)of_device_get_match_data(&pdev->dev);
./drivers/mtd/spi-nor/fsl-quadspi.c: q->devtype_data = of_device_get_match_data(dev);
./drivers/mtd/nand/qcom_nandc.c: dev_data = of_device_get_match_data(dev);
./drivers/mtd/nand/atmel_nand.c: of_device_get_match_data(host->dev);
./drivers/rtc/rtc-sunxi.c: chip->data_year = of_device_get_match_data(&pdev->dev);
./drivers/spi/spi-mpc512x-psc.c: mps->type = (int)of_device_get_match_data(dev);
./drivers/watchdog/mpc8xxx_wdt.c: wdt_type = of_device_get_match_data(&ofdev->dev);
./drivers/phy/phy-exynos-mipi-video.c: phy_dev = of_device_get_match_data(dev);
./drivers/phy/phy-sun4i-usb.c: data->cfg = of_device_get_match_data(dev);
./drivers/pci/host/pci-imx6.c: (enum imx6_pcie_variants)of_device_get_match_data(&pdev->dev);
./drivers/pci/host/pcie-qcom.c: pcie->ops = (struct qcom_pcie_ops *)of_device_get_match_data(dev);
./drivers/i2c/busses/i2c-rcar.c: priv->devtype = (enum rcar_i2c_type)of_device_get_match_data(dev);
./drivers/i2c/busses/i2c-tegra.c: i2c_dev->hw = of_device_get_match_data(&pdev->dev);
./drivers/tty/serial/imx.c: sport->devdata = of_device_get_match_data(&pdev->dev);
./drivers/gpio/gpio-mpc8xxx.c: of_device_get_match_data(&pdev->dev);
./drivers/gpio/gpio-tegra.c: config = of_device_get_match_data(&pdev->dev);
./drivers/clk/clk-palmas.c: match_data = of_device_get_match_data(&pdev->dev);
./drivers/input/misc/pmic8xxx-pwrkey.c: pwrkey->shutdown_fn = of_device_get_match_data(&pdev->dev);
./drivers/input/touchscreen/edt-ft5x06.c: chip_data = of_device_get_match_data(&client->dev);
./drivers/pinctrl/sh-pfc/core.c: info = of_device_get_match_data(&pdev->dev);
./drivers/thermal/rcar_thermal.c: unsigned long of_data = (unsigned long)of_device_get_match_data(dev);
./drivers/net/ethernet/stmicro/stmmac/dwmac-sti.c: data = of_device_get_match_data(&pdev->dev);
./drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c: data = of_device_get_match_data(&pdev->dev);
./drivers/net/ethernet/renesas/sh_eth.c: mdp->cd = (struct sh_eth_cpu_data *)of_device_get_match_data(&pdev->dev);
./drivers/net/ethernet/renesas/ravb_main.c: chip_id = (enum ravb_chip_id)of_device_get_match_data(&pdev->dev);
./drivers/of/device.c:const void *of_device_get_match_data(const struct device *dev)
./drivers/of/device.c:EXPORT_SYMBOL(of_device_get_match_data);
./drivers/gpu/drm/nouveau/nouveau_platform.c: func = of_device_get_match_data(&pdev->dev);
./drivers/gpu/drm/exynos/exynos_drm_rotator.c: of_device_get_match_data(dev);
./drivers/gpu/drm/exynos/exynos_mixer.c: drv = of_device_get_match_data(dev);
./drivers/gpu/drm/exynos/exynos5433_drm_decon.c: ctx->out_type = (unsigned long)of_device_get_match_data(dev);
./drivers/gpu/drm/exynos/exynos_drm_fimd.c: ctx->driver_data = of_device_get_match_data(dev);
./drivers/gpu/drm/exynos/exynos_hdmi.c: hdata->drv_data = of_device_get_match_data(dev);
./drivers/gpu/drm/exynos/exynos_drm_dsi.c: dsi->driver_data = of_device_get_match_data(dev);
./drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c: dc_ops = (struct kirin_dc_ops *)of_device_get_match_data(dev);
./drivers/gpu/drm/msm/hdmi/hdmi_phy.c: phy->cfg = (struct hdmi_phy_cfg *)of_device_get_match_data(dev);
./drivers/gpu/drm/msm/hdmi/hdmi.c: of_device_get_match_data(dev);
./drivers/gpu/drm/msm/msm_drv.c: return (int) (unsigned long) of_device_get_match_data(dev);
./drivers/gpu/drm/rockchip/rockchip_drm_vop.c: vop_data = of_device_get_match_data(dev);
./sound/soc/sh/rcar/core.c: priv->flags = (unsigned long)of_device_get_match_data(dev);
./sound/soc/sh/rcar/rsrc-card.c: of_data = of_device_get_match_data(dev);
./sound/soc/sh/rcar/rsrc-card.c: const struct rsrc_card_of_data *of_data = of_device_get_match_data(dev);
anyone can give some useful information?
The canonical answer to your question can be found at LWN: Platform Devices and Device Trees. What you need is the proper guidance on using it. A Tutorial on the Device Tree is a reasonable instruction guide. For background, you should read about Linux and the Device Tree. Also, elinux.org has a few wikis that should help, like Device Tree Linux and Device Tree Usage and Device Tree Reference.