297 lines
6.8 KiB
C
297 lines
6.8 KiB
C
/*
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* w1_ds2431.c - w1 family 2d (DS2431) driver
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*
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* Copyright (c) 2008 Bernhard Weirich <bernhard.weirich@riedel.net>
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*
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* Heavily inspired by w1_DS2433 driver from Ben Gardner <bgardner@wabtec.com>
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/device.h>
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#include <linux/types.h>
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#include <linux/delay.h>
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#include <linux/w1.h>
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#define W1_EEPROM_DS2431 0x2D
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#define W1_F2D_EEPROM_SIZE 128
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#define W1_F2D_PAGE_COUNT 4
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#define W1_F2D_PAGE_BITS 5
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#define W1_F2D_PAGE_SIZE (1<<W1_F2D_PAGE_BITS)
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#define W1_F2D_PAGE_MASK 0x1F
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#define W1_F2D_SCRATCH_BITS 3
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#define W1_F2D_SCRATCH_SIZE (1<<W1_F2D_SCRATCH_BITS)
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#define W1_F2D_SCRATCH_MASK (W1_F2D_SCRATCH_SIZE-1)
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#define W1_F2D_READ_EEPROM 0xF0
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#define W1_F2D_WRITE_SCRATCH 0x0F
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#define W1_F2D_READ_SCRATCH 0xAA
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#define W1_F2D_COPY_SCRATCH 0x55
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#define W1_F2D_TPROG_MS 11
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#define W1_F2D_READ_RETRIES 10
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#define W1_F2D_READ_MAXLEN 8
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/*
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* Check the file size bounds and adjusts count as needed.
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* This would not be needed if the file size didn't reset to 0 after a write.
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*/
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static inline size_t w1_f2d_fix_count(loff_t off, size_t count, size_t size)
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{
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if (off > size)
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return 0;
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if ((off + count) > size)
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return size - off;
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return count;
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}
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/*
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* Read a block from W1 ROM two times and compares the results.
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* If they are equal they are returned, otherwise the read
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* is repeated W1_F2D_READ_RETRIES times.
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*
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* count must not exceed W1_F2D_READ_MAXLEN.
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*/
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static int w1_f2d_readblock(struct w1_slave *sl, int off, int count, char *buf)
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{
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u8 wrbuf[3];
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u8 cmp[W1_F2D_READ_MAXLEN];
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int tries = W1_F2D_READ_RETRIES;
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do {
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wrbuf[0] = W1_F2D_READ_EEPROM;
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wrbuf[1] = off & 0xff;
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wrbuf[2] = off >> 8;
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if (w1_reset_select_slave(sl))
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return -1;
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w1_write_block(sl->master, wrbuf, 3);
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w1_read_block(sl->master, buf, count);
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if (w1_reset_select_slave(sl))
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return -1;
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w1_write_block(sl->master, wrbuf, 3);
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w1_read_block(sl->master, cmp, count);
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if (!memcmp(cmp, buf, count))
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return 0;
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} while (--tries);
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dev_err(&sl->dev, "proof reading failed %d times\n",
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W1_F2D_READ_RETRIES);
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return -1;
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}
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static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr, char *buf,
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loff_t off, size_t count)
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{
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struct w1_slave *sl = kobj_to_w1_slave(kobj);
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int todo = count;
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count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
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if (count == 0)
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return 0;
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mutex_lock(&sl->master->bus_mutex);
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/* read directly from the EEPROM in chunks of W1_F2D_READ_MAXLEN */
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while (todo > 0) {
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int block_read;
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if (todo >= W1_F2D_READ_MAXLEN)
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block_read = W1_F2D_READ_MAXLEN;
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else
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block_read = todo;
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if (w1_f2d_readblock(sl, off, block_read, buf) < 0)
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count = -EIO;
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todo -= W1_F2D_READ_MAXLEN;
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buf += W1_F2D_READ_MAXLEN;
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off += W1_F2D_READ_MAXLEN;
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}
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mutex_unlock(&sl->master->bus_mutex);
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return count;
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}
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/*
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* Writes to the scratchpad and reads it back for verification.
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* Then copies the scratchpad to EEPROM.
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* The data must be aligned at W1_F2D_SCRATCH_SIZE bytes and
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* must be W1_F2D_SCRATCH_SIZE bytes long.
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* The master must be locked.
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*
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* @param sl The slave structure
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* @param addr Address for the write
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* @param len length must be <= (W1_F2D_PAGE_SIZE - (addr & W1_F2D_PAGE_MASK))
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* @param data The data to write
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* @return 0=Success -1=failure
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*/
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static int w1_f2d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
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{
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int tries = W1_F2D_READ_RETRIES;
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u8 wrbuf[4];
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u8 rdbuf[W1_F2D_SCRATCH_SIZE + 3];
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u8 es = (addr + len - 1) % W1_F2D_SCRATCH_SIZE;
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retry:
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/* Write the data to the scratchpad */
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if (w1_reset_select_slave(sl))
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return -1;
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wrbuf[0] = W1_F2D_WRITE_SCRATCH;
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wrbuf[1] = addr & 0xff;
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wrbuf[2] = addr >> 8;
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w1_write_block(sl->master, wrbuf, 3);
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w1_write_block(sl->master, data, len);
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/* Read the scratchpad and verify */
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if (w1_reset_select_slave(sl))
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return -1;
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w1_write_8(sl->master, W1_F2D_READ_SCRATCH);
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w1_read_block(sl->master, rdbuf, len + 3);
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/* Compare what was read against the data written */
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if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
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(rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0)) {
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if (--tries)
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goto retry;
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dev_err(&sl->dev,
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"could not write to eeprom, scratchpad compare failed %d times\n",
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W1_F2D_READ_RETRIES);
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return -1;
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}
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/* Copy the scratchpad to EEPROM */
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if (w1_reset_select_slave(sl))
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return -1;
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wrbuf[0] = W1_F2D_COPY_SCRATCH;
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wrbuf[3] = es;
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w1_write_block(sl->master, wrbuf, 4);
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/* Sleep for tprog ms to wait for the write to complete */
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msleep(W1_F2D_TPROG_MS);
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/* Reset the bus to wake up the EEPROM */
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w1_reset_bus(sl->master);
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return 0;
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}
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static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr, char *buf,
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loff_t off, size_t count)
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{
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struct w1_slave *sl = kobj_to_w1_slave(kobj);
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int addr, len;
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int copy;
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count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
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if (count == 0)
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return 0;
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mutex_lock(&sl->master->bus_mutex);
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/* Can only write data in blocks of the size of the scratchpad */
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addr = off;
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len = count;
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while (len > 0) {
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/* if len too short or addr not aligned */
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if (len < W1_F2D_SCRATCH_SIZE || addr & W1_F2D_SCRATCH_MASK) {
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char tmp[W1_F2D_SCRATCH_SIZE];
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/* read the block and update the parts to be written */
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if (w1_f2d_readblock(sl, addr & ~W1_F2D_SCRATCH_MASK,
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W1_F2D_SCRATCH_SIZE, tmp)) {
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count = -EIO;
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goto out_up;
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}
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/* copy at most to the boundary of the PAGE or len */
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copy = W1_F2D_SCRATCH_SIZE -
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(addr & W1_F2D_SCRATCH_MASK);
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if (copy > len)
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copy = len;
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memcpy(&tmp[addr & W1_F2D_SCRATCH_MASK], buf, copy);
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if (w1_f2d_write(sl, addr & ~W1_F2D_SCRATCH_MASK,
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W1_F2D_SCRATCH_SIZE, tmp) < 0) {
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count = -EIO;
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goto out_up;
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}
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} else {
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copy = W1_F2D_SCRATCH_SIZE;
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if (w1_f2d_write(sl, addr, copy, buf) < 0) {
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count = -EIO;
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goto out_up;
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}
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}
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buf += copy;
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addr += copy;
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len -= copy;
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}
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out_up:
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mutex_unlock(&sl->master->bus_mutex);
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return count;
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}
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static BIN_ATTR_RW(eeprom, W1_F2D_EEPROM_SIZE);
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static struct bin_attribute *w1_f2d_bin_attrs[] = {
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&bin_attr_eeprom,
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NULL,
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};
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static const struct attribute_group w1_f2d_group = {
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.bin_attrs = w1_f2d_bin_attrs,
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};
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static const struct attribute_group *w1_f2d_groups[] = {
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&w1_f2d_group,
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NULL,
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};
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static struct w1_family_ops w1_f2d_fops = {
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.groups = w1_f2d_groups,
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};
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static struct w1_family w1_family_2d = {
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.fid = W1_EEPROM_DS2431,
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.fops = &w1_f2d_fops,
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};
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module_w1_family(w1_family_2d);
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MODULE_AUTHOR("Bernhard Weirich <bernhard.weirich@riedel.net>");
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MODULE_DESCRIPTION("w1 family 2d driver for DS2431, 1kb EEPROM");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2431));
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