你的位置:首页 > 操作系统

[操作系统]设备模型(device


关于关于驱动设备模型相关概念请参考《Linux Device Drivers》等相关书籍,和内核源码目录...\Documentation\driver-model

简单来说总线(bus),驱动(driver),设备(device)这三者之间的关系就是:驱动开发者可以通过总线(bus)来将驱动(driver)和设备(device)进行隔离,这样的好处就是开发者可以将相对稳定不变的驱动(driver)独立起来,可以通过总线(bus)来桥接与之匹配的设备(device)。设备(device)只需要提供与硬件相关的底层硬件的配置,如io,中断等。

platform.c 提供了一个平台总线(platform_bus),和注册平台设备(platform_device)和平台驱动(platform_driver)的相关接口,其中平台总线(platform_bus)已经编进内核,开发者只需要提供平台设备(platform_device)和平台驱动(platform_driver)的相关代码就行了。

在linux源码目录\drivers\input\keyboard下,提供了一个gpio_keys.c的平台驱动(platform_driver),这个就是一个简单地按键驱动,检测到按键状态,上报给输入子系统。

因此,开发者需要做的就是提供一个平台设备(platform_device),以向平台驱动(platform_driver)提供相关的硬件配置,如按键IO,中断号,按键码等等。

 

gpio_keys.c (不用任何改动)

 1 /* 2  * Driver for keys on GPIO lines capable of generating interrupts. 3  * 4  * Copyright 2005 Phil Blundell 5  * 6  * This program is free software; you can redistribute it and/or modify 7  * it under the terms of the GNU General Public License version 2 as 8  * published by the Free Software Foundation. 9 */ 10  11 #include <linux/module.h> 12 #include <linux/version.h> 13  14 #include <linux/init.h> 15 #include <linux/fs.h> 16 #include <linux/interrupt.h> 17 #include <linux/irq.h> 18 #include <linux/sched.h> 19 #include <linux/pm.h> 20 #include <linux/sysctl.h> 21 #include <linux/proc_fs.h> 22 #include <linux/delay.h> 23 #include <linux/platform_device.h> 24 #include <linux/input.h> 25 #include <linux/irq.h> 26 #include <linux/gpio_keys.h> 27  28 #include <asm/gpio.h> 29  30 static irqreturn_t gpio_keys_isr(int irq, void *dev_id) 31 { 32   int i; 33   /* [cgw]: 在gpio_keys_probe()中调用了request_irq(..., pdev), 34    * 因此dev_id指向了platform_device *pdev,通过dev_id间接传递 35    * platform_device *指针 36   */ 37   struct platform_device *pdev = dev_id; 38   /* [cgw]: 当platform_device 和 platform_driver匹配时,会通过 39    * probe()传递platform_device进来。在注册platform_device时, 40    * platform_device.dev.platform_data必须指向gpio_keys_platform_data * 41   */ 42   struct gpio_keys_platform_data *pdata = pdev->dev.platform_data; 43   /* [cgw]: probe()中已分配了一个struct input_dev,并通过platform_set_drvdata() 44    * 设置platform_device->dev->driver_data = input; 45   */ 46   struct input_dev *input = platform_get_drvdata(pdev); 47  48   /* [cgw]: 轮询pdata->nbuttons个按键 */ 49   for (i = 0; i < pdata->nbuttons; i++) { 50     struct gpio_keys_button *button = &pdata->buttons[i]; 51     int gpio = button->gpio; 52      53     /* [cgw]: 某个gpio发生了中断 */ 54     if (irq == gpio_to_irq(gpio)) { 55       /* [cgw]: 获得按键类型 */ 56       unsigned int type = button->type ?: EV_KEY; 57       /* [cgw]: 获取按键状态 */ 58       int state = (gpio_get_value(gpio) ? 1 : 0) ^ button->active_low; 59       /* [cgw]: 发送按键事件 */ 60       input_event(input, type, button->code, !!state); 61       /* [cgw]: 发送同步事件 */ 62       input_sync(input); 63     } 64   } 65  66   return IRQ_HANDLED; 67 } 68  69 static int __devinit gpio_keys_probe(struct platform_device *pdev) 70 { 71   /* [cgw]: 在gpio_keys_probe()中调用了request_irq(..., pdev), 72    * 因此dev_id指向了platform_device *pdev,通过dev_id间接传递 73    * platform_device *指针 74   */ 75   struct gpio_keys_platform_data *pdata = pdev->dev.platform_data; 76   struct input_dev *input; 77   int i, error; 78  79   /* [cgw]: 分配一个输入设备 */ 80   input = input_allocate_device(); 81   /* [cgw]: 分配失败 */ 82   if (!input) 83     return -ENOMEM; 84  85   /* [cgw]: 设置platform_device->dev->driver_data = input */ 86   platform_set_drvdata(pdev, input); 87  88   /* [cgw]: 设置evdev.c支持的事件类型 */ 89   input->evbit[0] = BIT(EV_KEY); 90   /* [cgw]: 设置输入设备名,同platform_device的名字 */ 91   input->name = pdev->name; 92   /* [cgw]: */ 93   input->phys = "gpio-keys/input0"; 94   /* [cgw]: 设置输入设备dev的父节点为platform_device->dev */ 95   input->dev.parent = &pdev->dev; 96    97   /* [cgw]: 设置输入设备总线类型,供应商,产品,版本 */ 98   input->id.bustype = BUS_HOST; 99   input->id.vendor = 0x0001;100   input->id.product = 0x0001;101   input->id.version = 0x0100;102 103   /* [cgw]: 为pdata->nbuttons个按键申请中断 */104   for (i = 0; i < pdata->nbuttons; i++) {105     struct gpio_keys_button *button = &pdata->buttons[i];106     /* [cgw]: 获得gpio对应的中断号 */107     int irq = gpio_to_irq(button->gpio);108     /* [cgw]: 获得按键类型 */109     unsigned int type = button->type ?: EV_KEY;110 111     /* [cgw]: 设置中断类型为边沿中断 */112     set_irq_type(irq, IRQ_TYPE_EDGE_BOTH);113     /* [cgw]: 申请中断,设置中断服务程序 */114     error = request_irq(irq, gpio_keys_isr, IRQF_SAMPLE_RANDOM,115           button->desc ? button->desc : "gpio_keys",116            pdev);117     if (error) {118       printk(KERN_ERR "gpio-keys: unable to claim irq %d; error %d\n",119         irq, error);120       goto fail;121     }122 123     /* [cgw]: 设置evdev.c支持的按键码 */124     input_set_capability(input, type, button->code);125   }126 127   /* [cgw]: 注册一个输入设备 */128   error = input_register_device(input);129   /* [cgw]: 注册失败 */130   if (error) {131     printk(KERN_ERR "Unable to register gpio-keys input device\n");132     goto fail;133   }134 135   return 0;136 137  fail:138   /* [cgw]: 释放中断 */139   for (i = i - 1; i >= 0; i--)140     free_irq(gpio_to_irq(pdata->buttons[i].gpio), pdev);141   /* [cgw]: 释放输入设备占用的内存 */142   input_free_device(input);143 144   return error;145 }146 147 static int __devexit gpio_keys_remove(struct platform_device *pdev)148 {149   /* [cgw]: 在gpio_keys_probe()中调用了request_irq(..., pdev),150    * 因此dev_id指向了platform_device *pdev,通过dev_id间接传递151    * platform_device *指针152   */153   struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;154   /* [cgw]: probe()中已分配了一个struct input_dev,并通过platform_set_drvdata()155    * 设置platform_device->dev->driver_data = input;156   */157   struct input_dev *input = platform_get_drvdata(pdev);158   int i;159 160   /* [cgw]: 释放中断 */161   for (i = 0; i < pdata->nbuttons; i++) {162     int irq = gpio_to_irq(pdata->buttons[i].gpio);163     free_irq(irq, pdev);164   }165 166   /* [cgw]: 注销输入设备 */167   input_unregister_device(input);168 169   return 0;170 }171 172 struct platform_driver gpio_keys_device_driver = {173   .probe    = gpio_keys_probe,174   .remove    = __devexit_p(gpio_keys_remove),175   .driver    = {176     .name  = "gpio-keys",177   }178 };179 180 static int __init gpio_keys_init(void)181 {182   /* [cgw]: 注册gpio_keys_device_driver平台驱动 */183   return platform_driver_register(&gpio_keys_device_driver);184 }185 186 static void __exit gpio_keys_exit(void)187 {188   /* [cgw]: 注销gpio_keys_device_driver平台驱动 */189   platform_driver_unregister(&gpio_keys_device_driver);190 }191 192 module_init(gpio_keys_init);193 module_exit(gpio_keys_exit);194 195 MODULE_LICENSE("GPL");196 MODULE_AUTHOR("Phil Blundell <pb@handhelds.org>");197 MODULE_DESCRIPTION("Keyboard driver for CPU GPIOs");

 

平台设备(platform_device):
keys_dev.c

 1 #include <linux/module.h> 2 #include <linux/version.h> 3  4 #include <linux/init.h> 5  6 #include <linux/kernel.h> 7 #include <linux/types.h> 8 #include <linux/interrupt.h> 9 #include <linux/list.h>10 #include <linux/timer.h>11 #include <linux/init.h>12 #include <linux/serial_core.h>13 #include <linux/platform_device.h>14 #include <linux/gpio_keys.h>15 #include <linux/input.h>16 #include <linux/irq.h>17 18 #include <asm/gpio.h>19 #include <asm/io.h>20 #include <asm/arch/regs-gpio.h>21 22 /* [cgw]: 设置四个按键的键码,按键io,激活状态,按键名,按键类型 */23 static struct gpio_keys_button keys_buff[4] = {24   {25     KEY_A,26     S3C2410_GPF0,27     1,28     "A",29     EV_KEY30   },31   32   {33     KEY_B,34     S3C2410_GPF2,35     1,36     "B",37     EV_KEY38   },39 40   {41     KEY_C,42     S3C2410_GPG3,43     1,44     "C",45     EV_KEY46   },47 48   {49     KEY_D,50     S3C2410_GPG11,51     1,52     "D",53     EV_KEY54   },55 };56 57 58 static struct gpio_keys_platform_data keys_dev = {59   .buttons = &keys_buff[0],60   .nbuttons = ARRAY_SIZE(keys_buff)61 };62 63 static void keys_dev_release(struct device * dev)64 {65   printk("keys_dev_release! \n");66 }67 68 /* [cgw]: 分配一个平台设备 */69 static struct platform_device keys_platform_dev = {70   .name     = "gpio-keys",71   .id      = -1,72   .dev = { 73     .release = keys_dev_release,74     .platform_data = (void *)&keys_dev,75   },76 };77 78 79 static int keys_dev_init(void)80 {81   /* [cgw]: 注册keys_platform_dev平台设备 */82   platform_device_register(&keys_platform_dev);83   return 0;84 }85 86 static void keys_dev_exit(void)87 {88   /* [cgw]: 注销keys_platform_dev平台设备 */89   platform_device_unregister(&keys_platform_dev);90 }91 92 module_init(keys_dev_init);93 module_exit(keys_dev_exit);94 95 MODULE_LICENSE("GPL");


应用测试程序:

platform_test.c

 1 #include <sys/types.h> 2 #include <sys/stat.h> 3 #include <fcntl.h> 4 #include <stdio.h> 5 #include <poll.h> 6 #include <signal.h> 7 #include <sys/types.h> 8 #include <unistd.h> 9 #include <fcntl.h>10 11 #include <linux/input.h>12 13 14 15 int fd;16 17 void my_signal_fun(int signum)18 {19   struct input_event buttons_event;20 21   /* [cgw]: 异步通知产生时返回的数据 */22   read(fd, &buttons_event, sizeof(struct input_event));23 24   /* [cgw]: 打印事件类型,事件码,事件值 */25   printf("type: 0x%x code: 0x%x value: 0x%x\n", 26       buttons_event.type,27       buttons_event.code, 28       buttons_event.value);29 }30 31 int main(int argc, char **argv)32 {33   int ret, arg;34   struct pollfd fds[1];35   unsigned long ver = 0;36 37   fd = open("/dev/event1", O_RDWR | O_NONBLOCK);38   39   if (fd < 0)40   {41     printf("can't open!\n");42   }43 44   ioctl(fd, EVIOCGVERSION, &ver);45   printf("Ver:0x%x \n", ver);46 47   /* [cgw]: 设置文件标识符 */48   fds[0].fd   = fd;49   /* [cgw]: 设置应用程序要响应的事件 */50   fds[0].events = POLLIN;51 52   while (1)53   {54     /* [cgw]: 休眠5S */55     ret = poll(fds, 1, 5000);56     57     /* [cgw]: 唤醒或超时 */58     //printf("wake up!\n");59     if (ret == 0)60     {61       printf("time out\n");62     }63     else64     {65       my_signal_fun(arg);66     }67   }68 69   close(fd);70   71   return 0;72 }

 

平台设备(platform_device) keys_platform_dev 是怎样找到与之匹配的平台驱动(platform_driver) gpio_keys_device_driver的呢?

因为他们都注册到了平台总线(platform_bus)上。平台驱动(platform_driver)和平台设备(platform_device)会相互查找彼此是否匹配,匹配的条件就是,

1 static int platform_match(struct device * dev, struct device_driver * drv)2 {3   struct platform_device *pdev = container_of(dev, struct platform_device, dev);4 5   return (strncmp(pdev->name, drv->name, BUS_ID_SIZE) == 0);6 }

platform_device->name == platform_driver->driver->name 即他们的名字就是:“gpio-keys”

一旦匹配,就会调用

1 static int platform_drv_probe(struct device *_dev)2 {3   struct platform_driver *drv = to_platform_driver(_dev->driver);4   struct platform_device *dev = to_platform_device(_dev);5 6   return drv->probe(dev);7 }

drv->probe() = platform_driver->probe() = gpio_keys_probe()

这样平台驱动(platform_driver)就可以获得平台设备(platform_device)的 struct platform_device结构的数据了,即keys_platform_dev,从这个结构就可以获得相关配置,以使能平台驱动(platform_driver) gpio_keys.c中相应的IO和中断。

实验现象:

# insmod gpio_keys.ko           //安装平台驱动(platform_driver)# insmod keys_dev.ko           //安装平台设备(platform_device)input: gpio-keys as /class/input/input1# ./platform_test             //运行应用测试程序Ver:0x10000                //用ioctl获取输入子系统的版本号type: 0x1 code: 0x2e value: 0x1      //按下"C"键type: 0x0 code: 0x0 value: 0x0      //因为调用了input_sync()type: 0x1 code: 0x2e value: 0x0      //松开(弹起)"C"键type: 0x0 code: 0x0 value: 0x0      //因为调用了input_sync()type: 0x1 code: 0x30 value: 0x1      //... ...type: 0x0 code: 0x0 value: 0x0type: 0x1 code: 0x30 value: 0x0type: 0x0 code: 0x0 value: 0x0type: 0x1 code: 0x1e value: 0x1type: 0x0 code: 0x0 value: 0x0type: 0x1 code: 0x1e value: 0x0type: 0x0 code: 0x0 value: 0x0type: 0x1 code: 0x20 value: 0x1type: 0x0 code: 0x0 value: 0x0type: 0x1 code: 0x20 value: 0x0type: 0x0 code: 0x0 value: 0x0time outtime outtime out