Created
January 5, 2016 09:57
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SI EpicClock
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| #include <linux/module.h> | |
| #include <linux/init.h> | |
| #include <linux/gpio.h> | |
| #include <linux/hrtimer.h> | |
| #include <linux/ktime.h> | |
| #include <linux/fs.h> | |
| #include <linux/kernel.h> | |
| #include <linux/uaccess.h> | |
| MODULE_DESCRIPTION("Epiclock Module"); | |
| MODULE_AUTHOR("SI"); | |
| MODULE_LICENSE("GPL"); | |
| static int open(struct inode *, struct file *); | |
| static int release(struct inode *, struct file *); | |
| static int read(struct file *file, char __user *user_buffer, size_t size, loff_t *offset); | |
| static int write(struct file *file, const char __user *user_buffer, size_t size, loff_t *offset); | |
| static struct file_operations fops = { | |
| .open = open, | |
| .release = release, | |
| .read = read, | |
| .write = write, | |
| }; | |
| static int major; // our assigned major number | |
| static atomic_t used; // 0 - led is available, 1 - led is already opened | |
| static int state; // 0 - led is off, 1 - led is on | |
| #define MS_TO_NS(x) (x * 1E6L) | |
| #define BLINK_DELAY 1 | |
| int digits[10][7] = | |
| { | |
| {1,1,1,1,1,1,0}, //0 | |
| {0,1,1,0,0,0,0}, //1 | |
| {1,1,0,1,1,0,1}, //2 | |
| {1,1,1,1,0,0,1}, //3 | |
| {0,1,1,0,0,1,1}, //4 | |
| {1,0,1,1,0,1,1}, //5 | |
| {1,0,1,1,1,1,1}, //6 | |
| {1,1,1,0,0,0,0}, //7 | |
| {1,1,1,1,1,1,1}, //8 | |
| {1,1,1,1,0,1,1}, //9 | |
| }; | |
| int seg[7] ={7,11,8,9,25,10,24};//25, 24, 23, 22, 27, 18, 17}; | |
| int en[8] = {22,23,27,18,17,2,14,4};//11, 10, 9, 8, 7, 4}; | |
| //saves the digit to display on the corresponding position | |
| //0-9 the digits to display, except the last 2 elements, were 1 means enable the dots, 0 disable | |
| //the last two elements control the dots | |
| static int saved_digit[8]={0}; | |
| static struct hrtimer hr_timer; | |
| static ktime_t ktime_period; | |
| /* Enables the correspondings segments of the digit | |
| * /param n The number to display | |
| */ | |
| void digit(int n) | |
| { | |
| /* sanity checks*/ | |
| //TODO 1 - read above; | |
| int i; | |
| for (i = 0; i < 7; i++) { | |
| gpio_set_value(seg[i], digits[n][i]); | |
| } | |
| } | |
| /* Enables the driver to turn on one of the digits | |
| * \param d Line of the driver to be enabled, -1 for none | |
| */ | |
| void enable(int d) | |
| { | |
| //TODO 1 - read above; | |
| int i; | |
| for (i = 0; i < 6; i++) { | |
| gpio_set_value(en[i], 0); | |
| } | |
| if (d == -1) { | |
| return; | |
| } | |
| gpio_set_value(en[d], 1); | |
| } | |
| /* Timer callback to update display | |
| */ | |
| enum hrtimer_restart epiclock_update(struct hrtimer* timer) | |
| { | |
| static unsigned pos = 0; | |
| ktime_t kt_now; | |
| int ret; | |
| //TODO 1 - increment pos and display the digit in the coresponding position | |
| enable(pos); | |
| digit(saved_digit[pos]); | |
| pos = (pos + 1) % 6; | |
| kt_now = hrtimer_cb_get_time(&hr_timer); | |
| ret = hrtimer_forward(&hr_timer, kt_now, ktime_period); | |
| return HRTIMER_RESTART; | |
| } | |
| static int __init epiclock_init(void) | |
| { | |
| int i; | |
| ktime_t ktime; | |
| printk(KERN_INFO "epiclock: loading\n"); | |
| /* initialize all signals to output, but off */ | |
| for(i = 0; i < 7; i++) | |
| { | |
| gpio_direction_output(seg[i], 0); | |
| } | |
| for(i = 0; i < 8; i++) | |
| { | |
| gpio_direction_output(en[i], 0); | |
| } | |
| /* set up the timer for the first time */ | |
| ktime_period = ktime_set(0, MS_TO_NS(BLINK_DELAY)); | |
| hrtimer_init(&hr_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
| hr_timer.function = epiclock_update; | |
| hrtimer_start(&hr_timer, ktime, HRTIMER_MODE_REL); | |
| // register as chardev and get our major number | |
| if((major = register_chrdev(0, "epic_clock", &fops)) < 0) | |
| return major; | |
| return 0; | |
| } | |
| static void __exit epiclock_cleanup(void) | |
| { | |
| printk(KERN_INFO "epiclock: unloading...\n"); | |
| /* disable timer */ | |
| hrtimer_cancel(&hr_timer); | |
| unregister_chrdev(major, "epic_clock"); | |
| /* disable all digits and points */ | |
| enable(-1); | |
| } | |
| static int open(struct inode *inode, struct file *file) | |
| { | |
| // led becomes used if it was previously unused, otherwise EPERM | |
| if(atomic_cmpxchg(&used, 0, 1) != 0) | |
| return -EPERM; | |
| return 0; | |
| } | |
| static int release(struct inode *inode, struct file *file) | |
| { | |
| int old_used; | |
| // led becomes unused | |
| if((old_used = atomic_cmpxchg(&used, 1, 0)) != 1) | |
| printk(KERN_ERR "closing device that was not opened; state is %d\n", old_used); | |
| return 0; | |
| } | |
| static int read(struct file *file, char __user *user_buffer, size_t size, loff_t *offset) | |
| { | |
| //DO NOT TOUCH THIS. | |
| return 0; | |
| } | |
| static int write(struct file *file, const char __user *user_buffer, size_t size, loff_t *offset) | |
| { | |
| // UGLY HACK - ignore concurrency issues | |
| // even if we allow only one process to open the device | |
| // we can still get concurrent accesses from a multithreaded process | |
| //TODO 2 - read data from userspace | |
| char buf[6]; | |
| if (size < 6) { | |
| return 0; | |
| } | |
| copy_from_user(buf, user_buffer, 6); | |
| int i; | |
| for (i = 0; i < 6; i++) { | |
| saved_digit[i] = buf[i] - '0'; | |
| } | |
| return 6; | |
| } | |
| module_init(epiclock_init); | |
| module_exit(epiclock_cleanup); |
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| obj-m = epicclock.o |
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| ARCH := arm | |
| CROSS_COMPILE := arm-linux-gnueabihf- | |
| KDIR := /opt/rpi/kernel | |
| PWD := $(shell pwd) | |
| obj-m := epicclock.o | |
| kbuild: | |
| make -C $(KDIR) M=`pwd` ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE) modules | |
| clean: | |
| make -C $(KDIR) M=`pwd` clean | |
| -rm -f *~ Module.symvers Module.markers modules.order | |
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| while [ true ]; do | |
| date +%H%M%S #> /dev/ec | |
| sleep 2 | |
| date +%d%m%y #> /dev/ec | |
| sleep 2 | |
| done |
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