push driver

groupdvr.c

+#include <linux/init.h> 
+#include <linux/module.h> 
+#include <linux/device.h> 
+#include <linux/kernel.h>
+#include <linux/fs.h>   
+#include <asm/uaccess.h> 
+#include <alsa/asoundlib.h>
+#include <alsa/mixer.h>
+
+#define  DEVICE_NAME "grpdrv"    // /dev/<value>
+#define  CLASS_NAME  "grp"          // The device class
+
+MODULE_LICENSE("GPL");            
+MODULE_AUTHOR("Rayhan Muzakki");    
+MODULE_DESCRIPTION("My Linux char driver");
+MODULE_VERSION("0.1");        
+static int    majorNumber;                  
+static char   message[256] = {0};           
+static short  size_of_message;         
+static int    numberOpens = 0;              
+static struct class*  classptr  = NULL;     
+static struct device* dvcptr = NULL;        
+
+// The prototype functions for the character driver
+static int     dev_open(struct inode *, struct file *);
+static int     dev_release(struct inode *, struct file *);
+static ssize_t dev_read(struct file *, char *, size_t, loff_t *);
+static ssize_t dev_write(struct file *, const char *, size_t, loff_t *);
+
+static struct file_operations fops =
+{
+   .open = dev_open,
+   .read = dev_read,
+   .write = dev_write,
+   .release = dev_release,
+   .set = dev_set,
+   .mute = dev_mute,
+   .unmute = dev_unmute,
+};
+
+
+static int dev_open(struct inode *inodep, struct file *filep){
+   numberOpens++;
+   printk(KERN_INFO "GRPdrv: Device has been opened %d time(s)\n", numberOpens);
+   return 0;
+}
+
+static int dev_release(struct inode *inodep, struct file *filep){
+   printk(KERN_INFO "GRPdrv: Device successfully closed\n");
+   return 0;
+}
+
+
+static int __init rdchardrv_init(void){
+   majorNumber = register_chrdev(0, DEVICE_NAME, &fops);
+   if (majorNumber<0) return majorNumber;
+   // Register the device class
+   classptr = class_create(THIS_MODULE, CLASS_NAME);
+   if (IS_ERR(classptr)){
+           unregister_chrdev(majorNumber, DEVICE_NAME);
+           return PTR_ERR(classptr);
+   }
+
+
+   // Register the device driver
+   dvcptr = device_create(classptr, NULL, MKDEV(majorNumber, 0), NULL, DEVICE_NAME);
+   if (IS_ERR(dvcptr)){
+          class_destroy(classptr);
+          unregister_chrdev(majorNumber, DEVICE_NAME);
+          return PTR_ERR(dvcptr);
+   }
+   printk(KERN_INFO "GRPdrv: device class created correctly\n");
+   return 0;
+}
+
+
+static void __exit rdchardrv_exit(void){
+    device_destroy(classptr, MKDEV(majorNumber, 0));      
+    class_unregister(classptr);                          
+    class_destroy(classptr);                              
+    unregister_chrdev(majorNumber, DEVICE_NAME);              
+    printk(KERN_INFO "GRPdrv: Goodbye from the LKM!\n");
+}
+
+static ssize_t dev_read(struct file *filep, char *buffer, size_t len, loff_t *offset){
+    // precaution
+    size_t bytesToCopy = len >= size_of_message ? size_of_message: len;
+    size_t bytesNotCopied = 0;
+    if(!bytesToCopy) return 0;
+
+bytesNotCopied = raw_copy_to_user(buffer, message,
+bytesToCopy);
+    if(bytesNotCopied){
+         return -EFAULT;
+    }
+    size_of_message = 0;
+    return bytesToCopy;
+}
+
+
+static ssize_t dev_write(struct file *filep,
+const char *buffer, size_t len, loff_t *offset){
+
+    const size_t maxLen = 256 - 1;
+    size_t bytesToCopy = len >= maxLen ? maxLen: len;
+    size_t bytesNotCopied = 0;
+
+    bytesNotCopied = raw_copy_from_user(message, buffer,bytesToCopy);
+    size_of_message = bytesToCopy - bytesNotCopied;
+
+    if(bytesNotCopied)
+            return -EFAULT;
+    return bytesToCopy;
+}
+
+static int dev_set(long volume){
+
+    long min, max;
+    snd_mixer_t *handle;
+    snd_mixer_selem_id_t *sid;
+    const char *card = "default";
+    const char *selem_name = "Master";
+
+    snd_mixer_open(&handle, 0);
+    snd_mixer_attach(handle, card);
+    snd_mixer_selem_register(handle, NULL, NULL);
+    snd_mixer_load(handle);
+
+    snd_mixer_selem_id_alloca(&sid);
+    snd_mixer_selem_id_set_index(sid, 0);
+    snd_mixer_selem_id_set_name(sid, selem_name);
+    snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, sid);
+
+    snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
+    snd_mixer_selem_set_playback_volume_all(elem, volume * max / 100);
+
+    snd_mixer_close(handle);
+    
+    return 0;
+}
+
+static int dev_mute(){
+
+    long min, max;
+    snd_mixer_t *handle;
+    snd_mixer_selem_id_t *sid;
+    const char *card = "default";
+    const char *selem_name = "Master";
+
+    snd_mixer_open(&handle, 0);
+    snd_mixer_attach(handle, card);
+    snd_mixer_selem_register(handle, NULL, NULL);
+    snd_mixer_load(handle);
+
+    snd_mixer_selem_id_alloca(&sid);
+    snd_mixer_selem_id_set_index(sid, 0);
+    snd_mixer_selem_id_set_name(sid, selem_name);
+    snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, sid);
+
+    if (snd_mixer_selem_has_playback_switch(elem)) {
+        snd_mixer_selem_set_playback_switch_all(elem, 0);
+    }
+
+    snd_mixer_close(handle);
+    
+    return 0
+}
+
+static int dev_unmute(){
+
+    long min, max;
+    snd_mixer_t *handle;
+    snd_mixer_selem_id_t *sid;
+    const char *card = "default";
+    const char *selem_name = "Master";
+
+    snd_mixer_open(&handle, 0);
+    snd_mixer_attach(handle, card);
+    snd_mixer_selem_register(handle, NULL, NULL);
+    snd_mixer_load(handle);
+
+    snd_mixer_selem_id_alloca(&sid);
+    snd_mixer_selem_id_set_index(sid, 0);
+    snd_mixer_selem_id_set_name(sid, selem_name);
+    snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, sid);
+
+    if (snd_mixer_selem_has_playback_switch(elem)) {
+        snd_mixer_selem_set_playback_switch_all(elem, 1);
+    }
+
+    snd_mixer_close(handle);
+    
+    return 0
+}
+
+module_init(rdchardrv_init);
+module_exit(rdchardrv_exit);