现在做的是RK平台的I2C驱动，不是说linux每个外设对应一个设备文件吗？可是找了一下一直没找到，今天特别搞了一下。I2C设备是注册为platform平台驱动的。
下面是我用adb命令查看的
linux的设备文件不一定只在dev/这个目录下面，像sys/ 目录下面也会有一些设备文件的
MID下面的I2C设备的设备文件
1|root@android:/ # ls sys/bus/i2c/drivers/RK610_CODEC/ gc0308/ir-kbd-i2c/sensors/tps65910/act8846/gc0328/nt99340/sp0838/wm831x/dummy/gc2035/rk610_ctl/sp2518/ft5x0x_touch/ gslX680/rk610_hdmi/sp2541/MID下面的I2C设备的I2C地址root@android:/ # ls sys/bus/i2c/devices/0-004c/ 1-002d/ 1-005a/ 2-0040/ 3-003c/ 4-0042/ 4-0060/ i2c-1/ i2c-3/ 1-0014/ 1-0034/ 2-0038/ 3-0021/ 4-0040/ 4-0046/ i2c-0/ i2c-2/ i2c-4/
在板级文件里面，我们可以看到我们的I2C设备地址是多少，代码如下，用i2c_register_board_info这个函数来注册i2c的device。每一个I2C的硬件接口对应一个i2cX_infostatic void __init rk30_i2c_register_board_info(void){#ifdef CONFIG_I2C0_RK30i2c_register_board_info(0, i2c0_info, ARRAY_SIZE(i2c0_info));#endif#ifdef CONFIG_I2C1_RK30i2c_register_board_info(1, i2c1_info, ARRAY_SIZE(i2c1_info));#endif#ifdef CONFIG_I2C2_RK30i2c_register_board_info(2, i2c2_info, ARRAY_SIZE(i2c2_info));#endif#ifdef CONFIG_I2C3_RK30i2c_register_board_info(3, i2c3_info, ARRAY_SIZE(i2c3_info));#endif#ifdef CONFIG_I2C4_RK30i2c_register_board_info(4, i2c4_info, ARRAY_SIZE(i2c4_info));#endif#ifdef CONFIG_I2C_GPIO_RK30i2c_register_board_info(5, i2c_gpio_info, ARRAY_SIZE(i2c_gpio_info));#endif}#if defined (CONFIG_TOUCHSCREEN_GSLX680){.type= "gslX680",.addr= 0x40,.flags= 0,.platform_data =&gslx680_info,},#endif然后看I2C的对应的设备驱动，下面给出一个TP的驱动的注册的地方，用i2c_add_driver这个函数去注册i2c的驱动driverstatic const struct i2c_device_id gsl_ts_id[] = {{GSLX680_I2C_NAME, 0},{}};MODULE_DEVICE_TABLE(i2c, gsl_ts_id);static struct i2c_driver gsl_ts_driver = {.driver = {.name = GSLX680_I2C_NAME,.owner = THIS_MODULE,},#ifndef CONFIG_HAS_EARLYSUSPEND.suspend= gsl_ts_suspend,.resume= gsl_ts_resume,#endif.probe= gsl_ts_probe,.remove= __devexit_p(gsl_ts_remove),.id_table= gsl_ts_id,};static int __init gsl_ts_init(void){int ret;printk("==gsl_ts_init==\n");ret = i2c_add_driver(&gsl_ts_driver);printk("ret=%d\n",ret);return ret;}static void __exit gsl_ts_exit(void){printk("==gsl_ts_exit==\n");i2c_del_driver(&gsl_ts_driver);return;}module_init(gsl_ts_init);module_exit(gsl_ts_exit);MODULE_LICENSE("GPL");MODULE_DESCRIPTION("GSLX680 touchscreen controller driver");MODULE_AUTHOR("Guan Yuwei, guanyuwei@basewin.com");MODULE_ALIAS("platform:gsl_ts");
好了。然后再看一下这里，可以看到 devices/和drivers/1|root@android:/ # ls sys/bus/i2c/devices/drivers_autoprobe ueventdrivers/drivers_probe
再看一下这个，就很清楚的知道这个设备挂载在哪个I2C接口下面了
root@android:/ # ll sys/bus/i2c/drivers/gslX680/lrwxrwxrwx rootroot2013-09-04 08:51 2-0040 -> ../../../../devices/platform/rk30_i2c.2/i2c-2/2-0040–w——- rootroot4096 2013-09-04 08:51 bind–w——- rootroot4096 2013-09-04 08:51 uevent–w——- rootroot4096 2013-09-04 08:51 unbindroot@android:/ # root@android:/ # ll sys/bus/i2c/devices/2-0040/lrwxrwxrwx rootroot2013-09-04 08:55 driver -> ../../../../../bus/i2c/drivers/gslX680drwxr-xr-x rootroot2013-09-04 08:55 input-r–r–r– rootroot4096 2013-09-04 08:55 modalias-r–r–r– rootroot4096 2013-09-04 08:55 namedrwxr-xr-x rootroot2013-09-04 08:55 powerlrwxrwxrwx rootroot2013-09-04 08:55 subsystem -> ../../../../../bus/i2c-rw-r–r– rootroot4096 2013-09-04 08:55 ueventroot@android:/ #
到这里已经能够很直接得去理解这个i2c驱动了。其他对于一些代码的理解，网上很多~
自己写了一个I2C的驱动。
/* * drivers/input/touchscreen/gslX680.c * * Copyright (c) 2012 Shanghai Basewin *Guan Yuwei<guanyuwei@basewin.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */#include <linux/module.h>#include <linux/delay.h>#include <linux/earlysuspend.h>#include <linux/hrtimer.h>#include <linux/i2c.h>#include <linux/input.h>#include <linux/interrupt.h>#include <linux/io.h>#include <linux/platform_device.h>#include <linux/async.h>#include <mach/gpio.h>#include <linux/irq.h>#include <mach/board.h>#include <linux/workqueue.h>#include <linux/proc_fs.h>#include <linux/input/mt.h>#define WQF_I2C_NAME "wfi2ctest"static const struct i2c_device_id gsl_ts_id[] = {{WQF_I2C_NAME, 0},{}};MODULE_DEVICE_TABLE(i2c, gsl_ts_id);static struct i2c_driver wftest_driver = {.driver = {.name = WQF_I2C_NAME,.owner = THIS_MODULE,},};static int __init wf_init(void){int ret;printk("==wftest_driver==\n");ret = i2c_add_driver(&wftest_driver);printk("ret=%d\n",ret);return ret;}static void __exit wf_exit(void){printk("==wftest_driver==\n");i2c_del_driver(&wftest_driver);return;}module_init(wf_init);module_exit(wf_exit);MODULE_LICENSE("GPL");MODULE_DESCRIPTION("wqf test i2c driver");MODULE_AUTHOR("wf , 329410527@qq.com");MODULE_ALIAS("platform:test");
都在努力为你驱逐烦恼焦躁，
