Created
May 13, 2015 09:54
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a simple linux driver code to demo the GPIO-LED blinking by timer
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| /* | |
| * DESCRIPTION: | |
| * The example of using the timer to perform the blinking LED . | |
| * */ | |
| #include <linux/module.h> | |
| #include <linux/string.h> | |
| #include <linux/init.h> | |
| #include <linux/cdev.h> | |
| #include <linux/device.h> | |
| #include <linux/kernel.h> | |
| #include <linux/errno.h> | |
| #include <linux/io.h> | |
| #include <linux/sched.h> | |
| #include <linux/interrupt.h> | |
| #include <linux/list.h> | |
| #include <linux/irq.h> | |
| #include <linux/slab.h> | |
| #include <linux/gpio.h> | |
| #include <linux/time.h> | |
| #include <linux/delay.h> | |
| #include <linux/timer.h> | |
| #define LED0 22 | |
| #define LED1 27 | |
| // below is optional, used in more complex code, in our case, this could be | |
| // NULL | |
| #define MY_DEVICE_NAME "myLED_timer" | |
| MODULE_LICENSE("GPL"); | |
| MODULE_AUTHOR("ITtraining.com.tw"); | |
| MODULE_DESCRIPTION("A Simple GPIO Device Driver module for RaspPi"); | |
| struct timer_list my_timer; | |
| int my_flag = 0; | |
| /* | |
| * TIMER FUNCTION | |
| * */ | |
| static void timer_function(unsigned long data){ | |
| gpio_set_value(LED0, my_flag == 1); | |
| gpio_set_value(LED1, my_flag == 0); | |
| my_flag = my_flag ? (0):(1); | |
| // modify the timer for next time | |
| mod_timer(&my_timer, jiffies + HZ / 2); | |
| } | |
| /* | |
| * INIT MODULE | |
| * */ | |
| int init_module(void) | |
| { | |
| printk("moudle: LED blinking ...\n"); | |
| printk("*****LED GPIO Init ******************\n"); | |
| if(gpio_request(LED0,"LED0") ) return -1; | |
| if(gpio_request(LED1,"LED1") ) return -1; | |
| gpio_direction_output(LED0, 0); | |
| gpio_direction_output(LED1, 0); | |
| // -- initialize the timer | |
| init_timer(&my_timer); | |
| my_timer.expires = jiffies + HZ ; | |
| my_timer.function = timer_function; | |
| my_timer.data = NULL; | |
| // -- TIMER START | |
| add_timer(&my_timer); | |
| return 0; | |
| } | |
| /* | |
| * CLEANUP MODULE | |
| * */ | |
| void cleanup_module(void) | |
| { | |
| del_timer(&my_timer); | |
| printk("module : LED blinking END\n"); | |
| gpio_set_value(LED0, 0); | |
| gpio_set_value(LED1, 0); | |
| gpio_free(LED0); | |
| gpio_free(LED1); | |
| } |
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