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/*
* include/asm-v850/rte_cb_leds.c -- Midas lab RTE-CB board LED device support
*
* Copyright (C) 2002,03 NEC Electronics Corporation
* Copyright (C) 2002,03 Miles Bader <miles@gnu.org>
*
* This file is subject to the terms and conditions of the GNU General
* Public License. See the file COPYING in the main directory of this
* archive for more details.
*
* Written by Miles Bader <miles@gnu.org>
*/
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <asm/uaccess.h>
#define LEDS_MINOR 169 /* Minor device number, using misc major. */
/* The actual LED hardware is write-only, so we hold the contents here too. */
static unsigned char leds_image[LED_NUM_DIGITS] = { 0 };
/* Spinlock protecting the above leds. */
static DEFINE_SPINLOCK(leds_lock);
/* Common body of LED read/write functions, checks POS and LEN for
correctness, declares a variable using IMG_DECL, initialized pointing at
the POS position in the LED image buffer, and and iterates COPY_EXPR
until BUF is equal to the last buffer position; finally, sets LEN to be
the amount actually copied. IMG should be a variable declaration
(without an initializer or a terminating semicolon); POS, BUF, and LEN
should all be simple variables. */
#define DO_LED_COPY(img_decl, pos, buf, len, copy_expr) \
do { \
if (pos > LED_NUM_DIGITS) \
len = 0; \
else { \
if (pos + len > LED_NUM_DIGITS) \
len = LED_NUM_DIGITS - pos; \
\
if (len > 0) { \
int _flags; \
const char *_end = buf + len; \
img_decl = &leds_image[pos]; \
\
spin_lock_irqsave (leds_lock, _flags); \
do \
(copy_expr); \
while (buf != _end); \
spin_unlock_irqrestore (leds_lock, _flags); \
} \
} \
} while (0)
/* Read LEN bytes from LEDs at position POS, into BUF.
Returns actual amount read. */
unsigned read_leds (unsigned pos, char *buf, unsigned len)
{
DO_LED_COPY (const char *img, pos, buf, len, *buf++ = *img++);
return len;
}
/* Write LEN bytes to LEDs at position POS, from BUF.
Returns actual amount written. */
unsigned write_leds (unsigned pos, const char *buf, unsigned len)
{
/* We write the actual LED values backwards, because
increasing memory addresses reflect LEDs right-to-left. */
volatile char *led = &LED (LED_NUM_DIGITS - pos - 1);
/* We invert the value written to the hardware, because 1 = off,
and 0 = on. */
DO_LED_COPY (char *img, pos, buf, len,
*led-- = 0xFF ^ (*img++ = *buf++));
return len;
}
/* Device functions. */
static ssize_t leds_dev_read (struct file *file, char *buf, size_t len,
loff_t *pos)
{
char temp_buf[LED_NUM_DIGITS];
len = read_leds (*pos, temp_buf, len);
if (copy_to_user (buf, temp_buf, len))
return -EFAULT;
*pos += len;
return len;
}
static ssize_t leds_dev_write (struct file *file, const char *buf, size_t len,
loff_t *pos)
{
char temp_buf[LED_NUM_DIGITS];
if (copy_from_user (temp_buf, buf, min_t(size_t, len, LED_NUM_DIGITS)))
return -EFAULT;
len = write_leds (*pos, temp_buf, len);
*pos += len;
return len;
}
static loff_t leds_dev_lseek (struct file *file, loff_t offs, int whence)
{
if (whence == 1)
offs += file->f_pos; /* relative */
else if (whence == 2)
offs += LED_NUM_DIGITS; /* end-relative */
if (offs < 0 || offs > LED_NUM_DIGITS)
return -EINVAL;
file->f_pos = offs;
return 0;
}
static struct file_operations leds_fops = {
.read = leds_dev_read,
.write = leds_dev_write,
.llseek = leds_dev_lseek
};
static struct miscdevice leds_miscdev = {
.name = "leds",
.minor = LEDS_MINOR,
.fops = &leds_fops
};
int __init leds_dev_init (void)
{
return misc_register (&leds_miscdev);
}
__initcall (leds_dev_init);
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