/*
* w1_ds2805 - w1 family 0d (DS28E05) driver
*
* Copyright (c) 2016 Andrew Worsley amworsley@gmail.com
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/w1.h>
#define W1_EEPROM_DS2805 0x0D
#define W1_F0D_EEPROM_SIZE 128
#define W1_F0D_PAGE_BITS 3
#define W1_F0D_PAGE_SIZE (1<<W1_F0D_PAGE_BITS)
#define W1_F0D_PAGE_MASK 0x0F
#define W1_F0D_SCRATCH_BITS 1
#define W1_F0D_SCRATCH_SIZE (1<<W1_F0D_SCRATCH_BITS)
#define W1_F0D_SCRATCH_MASK (W1_F0D_SCRATCH_SIZE-1)
#define W1_F0D_READ_EEPROM 0xF0
#define W1_F0D_WRITE_EEPROM 0x55
#define W1_F0D_RELEASE 0xFF
#define W1_F0D_CS_OK 0xAA /* Chip Status Ok */
#define W1_F0D_TPROG_MS 16
#define W1_F0D_READ_RETRIES 10
#define W1_F0D_READ_MAXLEN W1_F0D_EEPROM_SIZE
/*
* Check the file size bounds and adjusts count as needed.
* This would not be needed if the file size didn't reset to 0 after a write.
*/
static inline size_t w1_f0d_fix_count(loff_t off, size_t count, size_t size)
{
if (off > size)
return 0;
if ((off + count) > size)
return size - off;
return count;
}
/*
* Read a block from W1 ROM two times and compares the results.
* If they are equal they are returned, otherwise the read
* is repeated W1_F0D_READ_RETRIES times.
*
* count must not exceed W1_F0D_READ_MAXLEN.
*/
static int w1_f0d_readblock(struct w1_slave *sl, int off, int count, char *buf)
{
u8 wrbuf[3];
u8 cmp[W1_F0D_READ_MAXLEN];
int tries = W1_F0D_READ_RETRIES;
do {
wrbuf[0] = W1_F0D_READ_EEPROM;
wrbuf[1] = off & 0x7f;
wrbuf[2] = 0;
if (w1_reset_select_slave(sl))
return -1;
w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
w1_read_block(sl->master, buf, count);
if (w1_reset_select_slave(sl))
return -1;
w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
w1_read_block(sl->master, cmp, count);
if (!memcmp(cmp, buf, count))
return 0;
} while (--tries);
dev_err(&sl->dev, "proof reading failed %d times\n",
W1_F0D_READ_RETRIES);
return -1;
}
static ssize_t w1_f0d_read_bin(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr,
char *buf, loff_t off, size_t count)
{
struct w1_slave *sl = kobj_to_w1_slave(kobj);
int todo = count;
count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
if (count == 0)
return 0;
mutex_lock(&sl->master->mutex);
/* read directly from the EEPROM in chunks of W1_F0D_READ_MAXLEN */
while (todo > 0) {
int block_read;
if (todo >= W1_F0D_READ_MAXLEN)
block_read = W1_F0D_READ_MAXLEN;
else
block_read = todo;
if (w1_f0d_readblock(sl, off, block_read, buf) < 0) {
count = -EIO;
break;
}
todo -= W1_F0D_READ_MAXLEN;
buf += W1_F0D_READ_MAXLEN;
off += W1_F0D_READ_MAXLEN;
}
mutex_unlock(&sl->master->mutex);
return count;
}
/*
* Writes to the scratchpad and reads it back for verification.
* Then copies the scratchpad to EEPROM.
* The data must be aligned at W1_F0D_SCRATCH_SIZE bytes and
* must be W1_F0D_SCRATCH_SIZE bytes long.
* The master must be locked.
*
* @param sl The slave structure
* @param addr Address for the write
* @param len length must be <= (W1_F0D_PAGE_SIZE - (addr & W1_F0D_PAGE_MASK))
* @param data The data to write
* @return 0=Success -1=failure
*/
static int w1_f0d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
{
int tries = W1_F0D_READ_RETRIES;
u8 wrbuf[3];
u8 rdbuf[W1_F0D_SCRATCH_SIZE];
u8 cs;
if ((addr & 1) || (len != 2)) {
dev_err(&sl->dev, "%s: bad addr/len - addr=%#x len=%d\n",
__func__, addr, len);
return -1;
}
retry:
/* Write the data to the scratchpad */
if (w1_reset_select_slave(sl))
return -1;
wrbuf[0] = W1_F0D_WRITE_EEPROM;
wrbuf[1] = addr & 0xff;
wrbuf[2] = 0xff; /* ?? from Example */
w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
w1_write_block(sl->master, data, len);
w1_read_block(sl->master, rdbuf, sizeof(rdbuf));
/* Compare what was read against the data written */
if ((rdbuf[0] != data[0]) || (rdbuf[1] != data[1])) {
if (--tries)
goto retry;
dev_err(&sl->dev,
"could not write to eeprom, scratchpad compare failed %d times\n",
W1_F0D_READ_RETRIES);
pr_info("%s: rdbuf = %#x %#x data = %#x %#x\n",
__func__, rdbuf[0], rdbuf[1], data[0], data[1]);
return -1;
}
/* Trigger write out to EEPROM */
w1_write_8(sl->master, W1_F0D_RELEASE);
/* Sleep for tprog ms to wait for the write to complete */
msleep(W1_F0D_TPROG_MS);
/* Check CS (Command Status) == 0xAA ? */
cs = w1_read_8(sl->master);
if (cs != W1_F0D_CS_OK) {
dev_err(&sl->dev, "save to eeprom failed = CS=%#x\n", cs);
return -1;
}
return 0;
}
static ssize_t w1_f0d_write_bin(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr,
char *buf, loff_t off, size_t count)
{
struct w1_slave *sl = kobj_to_w1_slave(kobj);
int addr, len;
int copy;
count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
if (count == 0)
return 0;
mutex_lock(&sl->master->mutex);
/* Can only write data in blocks of the size of the scratchpad */
addr = off;
len = count;
while (len > 0) {
/* if len too short or addr not aligned */
if (len < W1_F0D_SCRATCH_SIZE || addr & W1_F0D_SCRATCH_MASK) {
char tmp[W1_F0D_SCRATCH_SIZE];
/* read the block and update the parts to be written */
if (w1_f0d_readblock(sl, addr & ~W1_F0D_SCRATCH_MASK,
W1_F0D_SCRATCH_SIZE, tmp)) {
count = -EIO;
goto out_up;
}
/* copy at most to the boundary of the PAGE or len */
copy = W1_F0D_SCRATCH_SIZE -
(addr & W1_F0D_SCRATCH_MASK);
if (copy > len)
copy = len;
memcpy(&tmp[addr & W1_F0D_SCRATCH_MASK], buf, copy);
if (w1_f0d_write(sl, addr & ~W1_F0D_SCRATCH_MASK,
W1_F0D_SCRATCH_SIZE, tmp) < 0) {
count = -EIO;
goto out_up;
}
} else {
copy = W1_F0D_SCRATCH_SIZE;
if (w1_f0d_write(sl, addr, copy, buf) < 0) {
count = -EIO;
goto out_up;
}
}
buf += copy;
addr += copy;
len -= copy;
}
out_up:
mutex_unlock(&sl->master->mutex);
return count;
}
static struct bin_attribute w1_f0d_bin_attr = {
.attr = {
.name = "eeprom",
.mode = S_IRUGO | S_IWUSR,
},
.size = W1_F0D_EEPROM_SIZE,
.read = w1_f0d_read_bin,
.write = w1_f0d_write_bin,
};
static int w1_f0d_add_slave(struct w1_slave *sl)
{
return sysfs_create_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
}
static void w1_f0d_remove_slave(struct w1_slave *sl)
{
sysfs_remove_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
}
static struct w1_family_ops w1_f0d_fops = {
.add_slave = w1_f0d_add_slave,
.remove_slave = w1_f0d_remove_slave,
};
static struct w1_family w1_family_2d = {
.fid = W1_EEPROM_DS2805,
.fops = &w1_f0d_fops,
};
static int __init w1_f0d_init(void)
{
pr_info("%s()\n", __func__);
return w1_register_family(&w1_family_2d);
}
static void __exit w1_f0d_fini(void)
{
pr_info("%s()\n", __func__);
w1_unregister_family(&w1_family_2d);
}
module_init(w1_f0d_init);
module_exit(w1_f0d_fini);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Andrew Worsley amworsley@gmail.com");
MODULE_DESCRIPTION("w1 family 0d driver for DS2805, 1kb EEPROM");
