LED device driver

@@ -0,0 +1,316 @@
+/*
+ * Device driver for controlling LEDs.  See linux/led.h for info on
+ * how to use this.
+ *
+ * This currently only supports mono and bicolor LEDs, but support for
+ * fancier LEDs (scrolling text or numeric LEDs, for instance) could
+ * easily be added.
+ *
+ * Corey Minyard <[email protected]>
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/version.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/miscdevice.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <linux/init.h>
+#include <linux/led.h>
+#include <linux/string.h>
+#include <linux/spinlock.h>
+
+#define VERSION "1.0"
+
+/* A lock that is held when manipulating LED info. */
+static spinlock_t led_lock;
+
+/* A linked list of all the LEDs registered. */
+static struct led_reg_info *leds;
+
+/* Register a new LED with the driver. */
+int register_led_info(struct led_reg_info *info)
+{
+	struct led_reg_info *led;
+	int		    rv = 0;
+
+	spin_lock(&led_lock);
+	info->next = NULL;
+	led = leds;
+	if (led == NULL)
+	{
+		leds = info;
+	}
+	else
+	{
+		while (led->next != NULL)
+		{
+			if (strcmp(led->info->name, info->info->name) == 0)
+			{
+				/* Registering a duplicate. */
+				rv = -1;
+				goto out;
+			}
+			led = led->next;
+		}
+		led->next = info;
+	}
+	MOD_INC_USE_COUNT;
+
+out:
+	spin_unlock(&led_lock);
+
+	return rv;
+}
+
+/* Unregister an LED from the driver. */
+int unregister_led_info(struct led_reg_info *info)
+{
+	int                 rv = -1;
+	struct led_reg_info *led;
+
+	if (info == NULL)
+	{
+		return -1;
+	}
+
+	spin_lock(&led_lock);
+	led = leds;
+	if (led == info)
+	{
+	        MOD_DEC_USE_COUNT;
+		leds = leds->next;
+	}
+	else
+	{
+		while (led->next != NULL)
+		{
+			if (led->next == info)
+			{
+				MOD_DEC_USE_COUNT;
+				led->next = info->next;
+				rv = 0;
+				goto out;
+			}
+			led = led->next;
+		}
+	}
+out:
+	spin_unlock(&led_lock);
+	return rv;
+}
+
+/* Return the number of LEDs registered. */
+static int count_leds(void)
+{
+	struct led_reg_info *led;
+	int                 count = 0;
+
+	spin_lock(&led_lock);
+	led = leds;
+	while (led != NULL)
+	{
+		count = count + 1;
+		led = led->next;
+	}
+	spin_unlock(&led_lock);
+
+	return count;
+}
+
+/* Find an LED by its number.  Must be called with the led spin lock
+   held. */
+static struct led_reg_info *get_led_by_num(int num)
+{
+	struct led_reg_info *led;
+	int                 count = num;
+
+	led = leds;
+	while (led != NULL)
+	{
+		if (count == 0)
+		{
+			led->info->led_num = num;
+			return led;
+		}
+		count = count - 1;
+		led = led->next;
+	}
+
+	return NULL;
+}
+
+/* Find an LED by its name.  Must be called with the led spin lock
+   held. */
+static struct led_reg_info *get_led_by_name(char *name)
+{
+	struct led_reg_info *led;
+	int                 count = 0;
+
+	led = leds;
+	while (led != NULL)
+	{
+		if (strcmp(name, led->info->name) == 0)
+		{
+			led->info->led_num = count;
+			return led;
+		}
+		count++;
+		led = led->next;
+	}
+
+	return NULL;
+}
+
+/* The IOCTL handler for the LED driver. */
+static int led_ioctl(struct inode  *inode,
+		     struct file   *file,
+		     unsigned int  cmd,
+		     unsigned long arg)
+{
+	int i;
+	struct led_reg_info *led;
+	struct led_info     info;
+	struct led_op       op;
+
+	switch(cmd)
+	{
+	case LEDIOC_GETCOUNT:
+		return count_leds();
+
+	case LEDIOC_GETINFO_BY_NUM:
+	case LEDIOC_GETINFO_BY_NAME:
+		i = copy_from_user(&info, (void*)arg, sizeof(info));
+		if (i)
+		{
+			return -EFAULT;
+		}
+
+		spin_lock(&led_lock);
+		if (cmd == LEDIOC_GETINFO_BY_NUM)
+			led = get_led_by_num(info.led_num);
+		else
+			led = get_led_by_name(info.name);
+		if (led == NULL)
+		{
+			spin_unlock(&led_lock);
+			return -EINVAL;
+		}
+
+		info.type = led->info->type;
+		info.led_num = led->info->led_num;
+		strcpy(info.name, led->info->name);
+		info.info = led->info->info;
+		i = copy_to_user((void *)arg, &info, sizeof(info));
+
+		spin_unlock(&led_lock);
+
+		if (i)
+		{
+			return -EFAULT;
+		}
+		return 0;
+
+	case LEDIOC_OP:
+		i = copy_from_user(&op, (void*)arg, sizeof(op));
+		if (i)
+		{
+			return -EFAULT;
+		}
+
+		spin_lock(&led_lock);
+		led = get_led_by_name(op.name);
+		if (led == NULL)
+		{
+			spin_unlock(&led_lock);
+			return -EINVAL;
+		}
+
+		i = led->handle_led_op(led, &op);
+		if (!i)
+		{
+		    i = copy_to_user((void *)arg, &op, sizeof(op));
+		    if (i)
+		    {
+			i = -EFAULT;
+		    }
+		}
+		spin_unlock(&led_lock);
+
+		return i;
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+
+/* Not much to do for opening. */ 
+static int led_open(struct inode *inode, struct file *file)
+{
+	switch(MINOR(inode->i_rdev))
+	{
+		case LED_MINOR:
+			return 0;
+
+		default:
+			return -ENODEV;
+	}
+}
+
+/* Closing is really easy. */ 
+static int led_close(struct inode *inode, struct file *file)
+{
+	return 0;
+}
+
+ 
+static struct file_operations led_fops = {
+	owner:		THIS_MODULE,
+	llseek:		NULL,
+	read:		NULL,
+	write:		NULL,
+	ioctl:		led_ioctl,
+	open:		led_open,
+	release:	led_close,
+};
+
+static struct miscdevice led_miscdev=
+{
+	LED_MINOR,
+	"led",
+	&led_fops
+};
+
+
+/* Remove the LED driver. */
+static void __exit led_exit(void)
+{
+	misc_deregister(&led_miscdev);
+}
+
+/* Set up the LED device driver. */
+static int __init led_init(void)
+{
+	int ret;
+
+	printk("generic LED driver: v%s Corey Minyard ([email protected])\n",
+	       VERSION);
+
+	leds = NULL;
+	ret = misc_register(&led_miscdev);
+	if (ret) {
+		printk(KERN_ERR "led: can't misc_register on minor=%d\n",
+		       LED_MINOR);
+		return -1;
+	}
+	return 0;
+}
+
+module_init(led_init);
+module_exit(led_exit);
+
+EXPORT_SYMBOL(register_led_info);
+EXPORT_SYMBOL(unregister_led_info);

130 lines not on this page · raw message

@@ -15,6 +15,7 @@
 #define ADB_MOUSE_MINOR 10
 #define WATCHDOG_MINOR		130	/* Watchdog timer     */
 #define TEMP_MINOR		131	/* Temperature Sensor */
+#define LED_MINOR		132	/* LED device driver */
 #define RTC_MINOR 135
 #define EFI_RTC_MINOR		136	/* EFI Time services */
 #define SUN_OPENPROM_MINOR 139