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#include <linux/init.h>
#include <linux/module.h>
#include <linux/gpio.h>
#include <linux/timer.h>
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/sched.h>
/*
* defines whether to access the gpios so other parts of the kernel module can
* be tested on systems w/o the prerequisite GPIOs
*/
#define USE_GPIO 1
/*
* Unsigned ints containing the BCM pin numbers for the pins used, __initdata
* helps with the loading and unloading of data in memory
*/
static __initdata unsigned int column_pins[10] = {10, 24, 23, 22, 27, 18, 17, 15, 14, 4};
static __initdata unsigned int row_pins[3] = {3, 6, 5};
/*
* GPIO labels
*/
static __initdata char * clabels[10] = {"C0", "C1", "C2", "C3", "C4", "C5", "C6", "C7", "C8", "C9",};
static __initdata char * rlabels[3] = {"R0", "R1", "R2"};
/*
* variables for setting up the thread
*/
static struct task_struct *update_task;
/*
*This function is called every timer-period to actually read the keyboard
*/
int skey_update_thread (void *data) {
printk(KERN_INFO "skey: starting update thread\n");
//thread stuff
const struct sched_param PARAM = { .sched_priority = 45};
sched_setscheduler(current, SCHED_FIFO, &PARAM);
printk(KERN_INFO "skey: started update thread\n");
if (!USE_GPIO) {
printk(KERN_ALERT "skey: currently in test mode with gpio use disabled\n");
}
while (1) {
if (USE_GPIO) {
//reads the keyboard
int row_index = 0;
int column_index = 0;
while (column_index < 10) {
//sets the column pin high for reading
gpio_set_value(column_pins[column_index], 1);
//reads with all the rows
row_index = 0;
while (row_index < 3) {
if (gpio_get_value(row_pins[row_index])) {
printk(KERN_INFO "skey: key pressed at column %d, row %d\n", column_index, row_index);
}
row_index++;
}
//sets the row pin low
gpio_set_value(column_pins[column_index], 0);
column_index++;
}
}
//sleep 2000us= 2ms = 0.002 seconds
usleep_range(2000, 2000);
//for when the thread has to stop
if (kthread_should_stop()) {
break;
}
}
return 0;
}
/*
* This function is called when the module is loaded
* __init functions similar to __initdata
*/
static int __init skey_init (void) {
printk(KERN_INFO "skey: module initiating...\n");
if (USE_GPIO) {
int i = 0;
//claims the column pins
while (i < 10) {
//checks to see if the gpios are valid
if (!gpio_is_valid(column_pins[i])) {
printk(KERN_ALERT "skey: column_pins[%d], BCM %d request invalid\n", i, column_pins[i]);
return -EINVAL;
}
//requests access of the GPIO
if (gpio_request_one(column_pins[i], GPIOF_OUT_INIT_LOW ,clabels[i])) {
printk(KERN_ALERT "skey: column_pins[%d], BCM %d request failed\n", i, column_pins[i]);
return -EINVAL;
}
if (gpio_direction_output(column_pins[i], 0)) {
printk(KERN_ALERT "skey: column_pins[%d], BCM %d, set output failed\n",i, column_pins[i]);
}
i++;
}
//ditto for row pins
int j = 0;
while (j < 3) {
//checks to see if the gpios are valid
if (!gpio_is_valid(row_pins[j])) {
printk(KERN_ALERT "skey: row_pins[%d], BCM %d request invalid\n", j, row_pins[j]);
return -EINVAL;
}
//requests access of the GPIO
if (gpio_request_one(row_pins[j], GPIOF_DIR_IN ,rlabels[j])) {
printk(KERN_ALERT "skey: row_pins[%d], BCM %d request failed\n", j, row_pins[j]);
return -EINVAL;
}
if (gpio_direction_input(row_pins[j])) {
printk(KERN_ALERT "skey: row_pins[%d], BCM %d, set output failed\n",j, row_pins[j]);
}
j++;
}
} else {
printk(KERN_ALERT "skey: currently in test mode with gpio use disabled\n");
}
//sets up update thread
printk("skey: setting up update thread...\n");
update_task = kthread_run(skey_update_thread, NULL, "skey_update_thread");
printk(KERN_INFO "skey: module finished initiating\n");
return 0;
}
/*
* This function is called when the module is unloaded
*
*/
static void __exit skey_exit (void) {
printk(KERN_INFO "skey: module exiting...\n");
if (USE_GPIO) {
//frees column and row pins
int i = 0;
while (i < 10) {
gpio_free(column_pins[i]);
i++;
}
int j = 0;
while (j < 3) {
gpio_free(row_pins[j]);
j++;
}
} else {
printk(KERN_ALERT "skey: currently in test mode with gpio use disabled\n");
}
//deletes the thread
kthread_stop(update_task);
printk(KERN_INFO "skey: module exited\n");
return;
}
/*
* Registers the init and exit functions
*/
module_init(skey_init);
module_exit(skey_exit);
/*
* registers module metadata
*/
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Haoran S. Diao <1339802534.kk@gmail.com>");
MODULE_DESCRIPTION("Driver for the omnicom switch keyboard");
/*
*this sets the name of device files used by this module, this is used
*when the kernel makes devices automatically
*/
MODULE_SUPPORTED_DEVICE("skeydev");
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