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這篇文章主要介紹了SPI設(shè)備樹節(jié)點(diǎn)處理流程和I2C節(jié)點(diǎn)的解析流程,具有一定借鑒價(jià)值,需要的朋友可以參考下。如下資料是關(guān)于spi設(shè)備樹和i2c節(jié)點(diǎn)的內(nèi)容。
一、設(shè)備樹中I2C節(jié)點(diǎn)的解析流程
/* i2c 控制器節(jié)點(diǎn) */
i2c0: i2c@2180000 {
compatible = "fsl,vf610-i2c";
/*reg = <address1 length2 [address2 length3] [address3 length4]..>*/
#address-cells = <1>; /* address一個(gè)32位表示*/
#size-cells = <0>; /* length位空*/
reg = <0x0 0x2180000 0x0 0x10000>;
interrupts = <GIC_SPI 88 IRQ_TYPE_LEVEL_HIGH>;/*GIC_SPI SPI:shared processor interrupts 中斷號(hào) 32 ~32+224 88號(hào)中斷 IRQ_TYPE_LEVEL_HIGH觸發(fā)方式 */
clock-names = "i2c";
clocks = <&platform_clk 1>; /*使用的時(shí)鐘*/
status = "disabled";
};
reg = <0x0 0x2180000 0x0 0x10000>解析:
I2C地址0x2180000物理地址,映射長(zhǎng)度0x10000,要使用這個(gè)物理地址先要在驅(qū)動(dòng)中將其映射成虛擬地址。
/* i2c設(shè)備節(jié)點(diǎn) */
&i2c0 {/* 引用i2c控制器0相當(dāng)于它的子節(jié)點(diǎn) */
status = "okay";
lm75@49 {
compatible = "ti,lm75";
reg = <0x49>;
};
lm75@4a {
compatible = "ti,lm75";
reg = <0x4a>;
};
};
/i2c0節(jié)點(diǎn)一般表示i2c控制器, 它會(huì)被轉(zhuǎn)換為platform_device, 在內(nèi)核中有對(duì)應(yīng)的platform_driver;
/i2c0/lm75@49節(jié)點(diǎn)不會(huì)被轉(zhuǎn)換為platform_device, 它被如何處理完全由父節(jié)點(diǎn)的platform_driver決定, 一般是被創(chuàng)建為一個(gè)i2c_client。
設(shè)備樹的匹配流程:
platform_match:
1、match driver.of_match_table:of_driver_match_device //設(shè)備樹解析
2、match driver.acpi_match_table
3、match platform_driver.id_table
4、match 設(shè)備的name和driver.name
上面四個(gè)任意匹配成功就算匹配ok。
代碼流程:
static const struct of_device_id i2c_imx_dt_ids[] = { { .compatible = "fsl,imx1-i2c", .data = &imx1_i2c_hwdata, }, { .compatible = "fsl,imx21-i2c", .data = &imx21_i2c_hwdata, }, { .compatible = "fsl,vf610-i2c",/* 對(duì)應(yīng)設(shè)備樹compatible */ .data = &vf610_i2c_hwdata, }, { /* sentinel */ } }; static struct platform_driver i2c_imx_driver = { .probe = i2c_imx_probe, .remove = i2c_imx_remove, .driver = { .name = DRIVER_NAME, .pm = I2C_IMX_PM_OPS, .of_match_table = i2c_imx_dt_ids, }, .id_table = imx_i2c_devtype, }; /* 將設(shè)備樹轉(zhuǎn)換成platform_device后i2c_imx_probe函數(shù)被調(diào)用 */ i2c_imx_probe i2c_add_numbered_adapter /* 添加I2C控制器 */ __i2c_add_numbered_adapter i2c_register_adapter /* 注冊(cè)I2C控制器 */ device_register /* I2C控制器設(shè)備注冊(cè) */ of_i2c_register_devices /* 查找設(shè)備樹控制器下面的從設(shè)備 */ of_i2c_register_device i2c_new_device client->dev.bus = &i2c_bus_type; device_register /* 添加設(shè)備I2C從設(shè)備 */ i2c_scan_static_board_info /* 查找靜態(tài)表,有些I2C設(shè)備是在代碼中寫死的,不是通過(guò)設(shè)備樹的形式 */ i2c_new_device client->dev.bus = &i2c_bus_type; device_register /* 添加設(shè)備I2C從設(shè)備 */ /* 添加設(shè)備成功后lm75@49幾點(diǎn)的I2C設(shè)備將通過(guò)i2c_bus_type.i2c_device_match匹配驅(qū)動(dòng)程序。*/ static const struct of_device_id lm75_of_match[] = { { .compatible = "ti,tmp75", .data = (void *)tmp75 }, 。。。。 } static struct i2c_driver lm75_driver = { .class= I2C_CLASS_HWMON, .driver = { .name= "lm75", .of_match_table = of_match_ptr(lm75_of_match), .pm= LM75_DEV_PM_OPS, }, .probe= lm75_probe, .id_table= lm75_ids, .detect= lm75_detect, .address_list= normal_i2c, };
lm75_probe函數(shù)將被調(diào)用。
二、SPI設(shè)備樹節(jié)點(diǎn)處理流程
xx_spi_probe spi_bitbang_start spi_register_master->spi_register_master of_register_spi_devices of_register_spi_device spi_add_device /* 和i2c_new_device處理流程就一樣了匹配設(shè)備驅(qū)動(dòng) */
看完上述內(nèi)容,你們對(duì)SPI設(shè)備樹節(jié)點(diǎn)處理流程和I2C節(jié)點(diǎn)的解析流程大概了解了嗎?如果想了解更多相關(guān)文章內(nèi)容,歡迎關(guān)注億速云行業(yè)資訊頻道,感謝各位的閱讀!
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