138 lines
3.7 KiB
C
138 lines
3.7 KiB
C
/*
|
||
* 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);
|