实验平台:Tiny6410 + Linux Kernel 2.6.38
本问主要实践下总线设备驱动模型和输入子系统。功能上实现四个按键("l"、"s"、"Enter"、"Shift")控制下的LED等点亮和熄灭,并通过输入子系统向用户空间上报按键信息。用户空间程序打印按键信息。驱动测试可以参考USB那份总结。
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//平台驱动:platform_driver
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/errno.h>
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#include <linux/cdev.h>
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#include <linux/types.h>
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#include <linux/device.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include <linux/poll.h>
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#include <linux/ioctl.h>
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#include <linux/input.h>
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#include <linux/semaphore.h>
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#include <linux/platform_device.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/compiler.h>
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#include <asm/uaccess.h>
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#include <asm/irq.h>
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#include <asm/io.h>
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#include <asm/system.h>
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#include <mach/map.h>
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#include <mach/regs-gpio.h>
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#include <mach/gpio-bank-k.h>
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#include <mach/gpio-bank-n.h>
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#include <asm-generic/errno-base.h>
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static struct timer_list button_control_leds_timer;
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static struct input_dev *button_control_leds_dev;
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static int led_tmp;
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static int button_control_leds_open(struct input_dev *dev)
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{
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//all the leds went out
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led_tmp = readl(S3C64XX_GPKDAT);
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led_tmp |= 0x000000f0;
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writel(led_tmp, S3C64XX_GPKDAT);
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return 0;
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}
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static void button_control_leds_close(struct input_dev *dev)
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{
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//all the leds went out
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led_tmp = readl(S3C64XX_GPKDAT);
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led_tmp |= 0x000000f0;
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writel(led_tmp, S3C64XX_GPKDAT);
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}
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//4. 定时器中断处理函数 static void button_control_leds_timer_function(unsigned long data)
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{
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int button_value, invalid_keys;
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/* GPN[3:0] is connected to buttons */
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//4.1 读取按键值并上报给用户空间
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button_value = readl(S3C64XX_GPNDAT) & 0x0000000f;
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switch(~button_value & 0x0000000f) {
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case 0x00000001: //key "l"
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input_event(button_control_leds_dev, EV_KEY, KEY_L, 1);
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break;
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case 0x00000002: //key "s"
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input_event(button_control_leds_dev, EV_KEY, KEY_S, 1);
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break;
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case 0x00000004: //key "Enter"
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input_event(button_control_leds_dev, EV_KEY, KEY_ENTER, 1);
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break;
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case 0x00000009: //key "SHIFT" + key "l"
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input_event(button_control_leds_dev, EV_KEY, KEY_LEFTSHIFT, 1);
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input_event(button_control_leds_dev, EV_KEY, KEY_L, 1);
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break;
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case 0x0000000a: //key "SHIFT" + key "s"
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input_event(button_control_leds_dev, EV_KEY, KEY_LEFTSHIFT, 1);
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input_event(button_control_leds_dev, EV_KEY, KEY_S, 1);
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break;
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case 0x00000000: //no key is pressed
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input_event(button_control_leds_dev, EV_KEY, KEY_L, 0);
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input_event(button_control_leds_dev, EV_KEY, KEY_S, 0);
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input_event(button_control_leds_dev, EV_KEY, KEY_ENTER, 0);
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input_event(button_control_leds_dev, EV_KEY, KEY_LEFTSHIFT, 0);
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break;
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default: //invalid keys
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invalid_keys = 1;
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break;
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}
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//如果按键有效,就上报给用户空间
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if(!invalid_keys)
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input_sync(button_control_leds_dev);
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else
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invalid_keys = 0;
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/* GPK[7:4] is connected to LEDs */
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//4.2 根据按键值,点亮相应的LED灯
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led_tmp = readl(S3C64XX_GPKDAT);
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switch(button_value) {
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case 0x0000000e: //light led1
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led_tmp |= 0x000000f0;
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led_tmp &= 0xffffffef;
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break;
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case 0x0000000d: //light led2
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led_tmp |= 0x000000f0;
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led_tmp &= 0xffffffdf;
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break;
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case 0x0000000b: //light led3
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led_tmp |= 0x000000f0;
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led_tmp &= 0xffffffbf;
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break;
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case 0x00000007: //light led4
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led_tmp |= 0x000000f0;
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led_tmp &= 0xffffff7f;
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break;
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case 0x0000000f: //all the leds went out
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led_tmp |= 0x000000f0;
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break;
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default: //light all the leds
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led_tmp &= 0xffffff0f;
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break;
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}
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writel(led_tmp, S3C64XX_GPKDAT);
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}
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//3. 按键中断处理函数
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static irqreturn_t button_control_leds_irq(int irq, void *dev_id)
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{
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//3.1 修改定时器,10ms延时,防止按键抖动引起的多次处理
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mod_timer(&button_control_leds_timer, jiffies + HZ/100);
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return IRQ_RETVAL(IRQ_HANDLED);
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}
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//2. 当设备和驱动匹配时,probe函数会被调用 static int button_control_leds_probe(struct platform_device *pdev)
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{
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struct resource *res;
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int ret, i, j;
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//2.1 输入子系统input_dev结构体的分配、设置和注册
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//2.1.1 分配一个input_dev
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button_control_leds_dev = input_allocate_device();
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//2.1.2 设置input_dev参数
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set_bit(EV_KEY, button_control_leds_dev->evbit); //按键类型
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set_bit(EV_REP, button_control_leds_dev->evbit); //支持重复按键
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set_bit(KEY_L, button_control_leds_dev->keybit); //按键“l”
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set_bit(KEY_S, button_control_leds_dev->keybit); //按键“s”
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set_bit(KEY_ENTER, button_control_leds_dev->keybit); //按键“Enter”
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set_bit(KEY_LEFTSHIFT, button_control_leds_dev->keybit); //按键“Shift”
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button_control_leds_dev->open = button_control_leds_open; //open函数
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button_control_leds_dev->close = button_control_leds_close; //close函数
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//2.1.3 注册一个input_dev结构体
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ret = input_register_device(button_control_leds_dev);
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if(unlikely(ret))
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goto fail1;
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//2.2 定时器初始化、设置定时器中断处理函数、添加一个定时器
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init_timer(&button_control_leds_timer);
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button_control_leds_timer.function = button_control_leds_timer_function;
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add_timer(&button_control_leds_timer);
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//2.3 获取平台设备资源、注册按键中断
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for(i = 0; i < pdev->num_resources; i++) {
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//2.3.1 获取平台设备资源:中断获取
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res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
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if(unlikely(res == NULL)) {
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printk("Button %d: get platform resource failed!\n", i);
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goto fail2;
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}
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//2.3.2 注册按键中断
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ret = request_irq(res->start, button_control_leds_irq, \
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IRQ_TYPE_EDGE_BOTH, res->name, pdev);
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if(unlikely(ret != 0)) {
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printk("Button %d: request_irq failed\n", i);
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goto fail3;
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}
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}
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return 0;
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fail1:
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input_unregister_device(button_control_leds_dev);
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input_free_device(button_control_leds_dev);
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return ret;
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fail2:
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del_timer(&button_control_leds_timer);
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input_unregister_device(button_control_leds_dev);
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input_free_device(button_control_leds_dev);
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return -ENXIO;
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fail3:
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for(j = 0; j <= i; j++) {
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res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
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free_irq(res->start, pdev);
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}
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del_timer(&button_control_leds_timer);
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input_unregister_device(button_control_leds_dev);
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input_free_device(button_control_leds_dev);
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return ret;
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}
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static int button_control_leds_remove(struct platform_device *pdev)
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{
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struct resource *res;
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int i;
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for(i = 0; i < pdev->num_resources; i++) {
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res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
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free_irq(res->start, pdev);
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}
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del_timer(&button_control_leds_timer);
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input_unregister_device(button_control_leds_dev);
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input_free_device(button_control_leds_dev);
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return 0;
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}
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//1. 平台总线platform_driver结构体及其注册
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struct platform_driver button_control_leds_drv = {
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.probe = button_control_leds_probe,
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.remove = button_control_leds_remove,
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.driver = {
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.name = "button_control_leds",
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.owner = THIS_MODULE,
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}
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};
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static int __init button_control_leds_init(void)
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{
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platform_driver_register(&button_control_leds_drv);
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return 0;
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}
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static void __exit button_control_leds_exit(void)
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{
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platform_driver_unregister(&button_control_leds_drv);
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}
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module_init(button_control_leds_init);
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module_exit(button_control_leds_exit);
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MODULE_AUTHOR("Jason Lu");
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MODULE_VERSION("0.1.0");
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MODULE_DESCRIPTION("Jason's blog: jason2012.blog.chinaunix.net");
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MODULE_LICENSE("Dual MPL/GPL");
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MODULE_ALIAS("Driver of button control leds");
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//平台设备:platform_device
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#include <linux/module.h>
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#include <linux/version.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/interrupt.h>
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#include <linux/list.h>
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#include <linux/timer.h>
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#include <linux/serial_core.h>
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#include <linux/platform_device.h>
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#include <mach/gpio.h>
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#include <mach/irqs.h>
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//1. 平台设备资源
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static struct resource button_control_leds_resource[] = {
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[0] = {
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.name = "button 1",
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.start = IRQ_EINT(0),
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.end = IRQ_EINT(0),
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.flags = IORESOURCE_IRQ,
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},
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[1] = {
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.name = "button 2",
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.start = IRQ_EINT(1),
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.end = IRQ_EINT(1),
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.flags = IORESOURCE_IRQ,
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},
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[2] = {
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.name = "button 3",
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.start = IRQ_EINT(2),
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.end = IRQ_EINT(2),
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.flags = IORESOURCE_IRQ,
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},
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[3] = {
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.name = "button 4",
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.start = IRQ_EINT(3),
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.end = IRQ_EINT(3),
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.flags = IORESOURCE_IRQ,
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},
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};
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static void button_control_leds_release(struct device * dev)
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{
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}
//平台设备platform_device结构体
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static struct platform_device button_control_leds_dev = {
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.name = "button_control_leds",
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.id = -1,
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.num_resources = ARRAY_SIZE(button_control_leds_resource),
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.resource = button_control_leds_resource,
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.dev = {
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.release = button_control_leds_release,
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},
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};
//3. 注册一个平台设备
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static int button_control_leds_dev_init(void)
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{
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platform_device_register(&button_control_leds_dev);
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return 0;
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}
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static void button_control_leds_dev_exit(void)
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{
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platform_device_unregister(&button_control_leds_dev);
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}
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module_init(button_control_leds_dev_init);
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module_exit(button_control_leds_dev_exit);
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MODULE_AUTHOR("Jason Lu");
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MODULE_VERSION("0.1.0");
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MODULE_DESCRIPTION("Jason's blog: jason2012.blog.chinaunix.net");
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MODULE_LICENSE("Dual MPL/GPL");
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MODULE_ALIAS("Device of button control leds");
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