编写使用中断的按键驱动程序
从头写按键驱动，特别是如何使用中断，是休眠-唤醒，POLL机制，异步通知，定时器，中断的线程化处理。
编程思路
1.编写设备树提供硬件信息；查看原理图确定按键使用的引脚，再在设备树中添加节点，在节点里指定中断信息。
gpio_keys_100ask { compatible = "100ask,gpio_key"; gpios = <&gpio5 1 GPIO_ACTIVE_HIGH &gpio4 14 GPIO_ACTIVE_HIGH>; pinctrl-names = "default"; pinctrl-0 = <&key1_pinctrl &key2_pinctrl>; key1_100ask: key1_100ask { /*!< Function assigned for the core: Cortex-A7[ca7] */ fsl,pins = < MX6ULL_PAD_SNVS_TAMPER1__GPIO5_IO01 0x000110A0 >; }; }; key2_100ask: key2_100ask { /*!< Function assigned for the core: Cortex-A7[ca7] */ fsl,pins = < MX6UL_PAD_NAND_CE1_B__GPIO4_IO14 0x000010B0 >; };
上面指定引脚信息
gpio_key_drv.c
#include <linux/module.h> #include <linux/fs.h> #include <linux/errno.h> #include <linux/miscdevice.h> #include <linux/kernel.h> #include <linux/major.h> #include <linux/mutex.h> #include <linux/proc_fs.h> #include <linux/seq_file.h> #include <linux/stat.h> #include <linux/init.h> #include <linux/device.h> #include <linux/tty.h> #include <linux/kmod.h> #include <linux/gfp.h> #include <linux/gpio/consumer.h> #include <linux/platform_device.h> #include <linux/of_gpio.h> #include <linux/of_irq.h> #include <linux/interrupt.h> #include <linux/irq.h> #include <linux/slab.h> struct gpio_key{ int gpio; struct gpio_desc *gpiod; int flag; int irq; } ; static struct gpio_key *gpio_keys_100ask; static irqreturn_t gpio_key_isr(int irq, void *dev_id) { struct gpio_key *gpio_key = dev_id; int val; val = gpiod_get_value(gpio_key->gpiod); printk("key %d %d\n", gpio_key->gpio, val); return IRQ_HANDLED; } /* 1. 从platform_device获得GPIO * 2. gpio=>irq * 3. request_irq */ static int gpio_key_probe(struct platform_device *pdev) { int err; struct device_node *node = pdev->dev.of_node; int count; int i; enum of_gpio_flags flag; unsigned flags = GPIOF_IN; printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__); count = of_gpio_count(node); if (!count) { printk("%s %s line %d, there isn't any gpio available\n", __FILE__, __FUNCTION__, __LINE__); return -1; } gpio_keys_100ask = kzalloc(sizeof(struct gpio_key) * count, GFP_KERNEL); for (i = 0; i < count; i++) { gpio_keys_100ask[i].gpio = of_get_gpio_flags(node, i, &flag); if (gpio_keys_100ask[i].gpio < 0) { printk("%s %s line %d, of_get_gpio_flags fail\n", __FILE__, __FUNCTION__, __LINE__); return -1; } gpio_keys_100ask[i].gpiod = gpio_to_desc(gpio_keys_100ask[i].gpio); gpio_keys_100ask[i].flag = flag & OF_GPIO_ACTIVE_LOW; if (flag & OF_GPIO_ACTIVE_LOW) flags |= GPIOF_ACTIVE_LOW; err = devm_gpio_request_one(&pdev->dev, gpio_keys_100ask[i].gpio, flags, NULL); gpio_keys_100ask[i].irq = gpio_to_irq(gpio_keys_100ask[i].gpio); } for (i = 0; i < count; i++) { err = request_irq(gpio_keys_100ask[i].irq, gpio_key_isr, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "100ask_gpio_key", &gpio_keys_100ask[i]); } return 0; } static int gpio_key_remove(struct platform_device *pdev) { //int err; struct device_node *node = pdev->dev.of_node; int count; int i; count = of_gpio_count(node); for (i = 0; i < count; i++) { free_irq(gpio_keys_100ask[i].irq, &gpio_keys_100ask[i]); } kfree(gpio_keys_100ask); return 0; } static const struct of_device_id ask100_keys[] = { { .compatible = "100ask,gpio_key" }, { }, }; /* 1. 定义platform_driver */ static struct platform_driver gpio_keys_driver = { .probe = gpio_key_probe, .remove = gpio_key_remove, .driver = { .name = "100ask_gpio_key", .of_match_table = ask100_keys, }, }; /* 2. 在入口函数注册platform_driver */ static int __init gpio_key_init(void) { int err; printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__); err = platform_driver_register(&gpio_keys_driver); return err; } /* 3. 有入口函数就应该有出口函数：卸载驱动程序时，就会去调用这个出口函数 * 卸载platform_driver */ static void __exit gpio_key_exit(void) { printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__); platform_driver_unregister(&gpio_keys_driver); } /* 7. 其他完善：提供设备信息，自动创建设备节点 */ module_init(gpio_key_init); module_exit(gpio_key_exit); MODULE_LICENSE("GPL");
首先编写入口函数gpio_key_init（）并在里面进行设备注册。出口函数在卸载驱动程序。在入口函数会注册platform_driver 名为gpio_keys_driver结构体，并声明probe和remove，driver函数在driver函数里面指明那个设备名。在probe函数里面*
1.从platform_device获得GPIO
2.gpio=>irq
3.request_irq
1.从设备树获得GPIO
count = of_gpio_count(node); for (i = 0; i < count; i++) gpio_keys_100ask[i].gpio = of_get_gpio_flags(node, i, &flag);
2.从GPIO获得中断号
gpio_keys_100ask[i].irq = gpio_to_irq(gpio_keys_100ask[i].gpio);
3.申请中断
err = request_irq(gpio_keys_100ask[i].irq, gpio_key_isr, \ IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "100ask_gpio_key", &gpio_keys_100ask [i]);
4.中断函数
static irqreturn_t gpio_key_isr(int irq, void *dev_id) { struct gpio_key *gpio_key = dev_id; int val; val = gpiod_get_value(gpio_key->gpiod); printk("key %d %d\n", gpio_key->gpio, val); return IRQ_HANDLED; }
