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