- 根目录:
- drivers
- w1
- w1_io.c
/*
* w1_io.c
*
* Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <asm/io.h>
#include <linux/delay.h>
#include <linux/moduleparam.h>
#include <linux/module.h>
#include "w1.h"
#include "w1_log.h"
static int w1_delay_parm = 1;
module_param_named(delay_coef, w1_delay_parm, int, 0);
static int w1_disable_irqs = 0;
module_param_named(disable_irqs, w1_disable_irqs, int, 0);
static u8 w1_crc8_table[] = {
0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205,
17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80,
175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238,
50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53
};
static void w1_delay(unsigned long tm)
{
udelay(tm * w1_delay_parm);
}
static void w1_write_bit(struct w1_master *dev, int bit);
static u8 w1_read_bit(struct w1_master *dev);
/**
* Generates a write-0 or write-1 cycle and samples the level.
*/
static u8 w1_touch_bit(struct w1_master *dev, int bit)
{
if (dev->bus_master->touch_bit)
return dev->bus_master->touch_bit(dev->bus_master->data, bit);
else if (bit)
return w1_read_bit(dev);
else {
w1_write_bit(dev, 0);
return 0;
}
}
/**
* Generates a write-0 or write-1 cycle.
* Only call if dev->bus_master->touch_bit is NULL
*/
static void w1_write_bit(struct w1_master *dev, int bit)
{
unsigned long flags = 0;
if(w1_disable_irqs) local_irq_save(flags);
if (bit) {
dev->bus_master->write_bit(dev->bus_master->data, 0);
w1_delay(6);
dev->bus_master->write_bit(dev->bus_master->data, 1);
w1_delay(64);
} else {
dev->bus_master->write_bit(dev->bus_master->data, 0);
w1_delay(60);
dev->bus_master->write_bit(dev->bus_master->data, 1);
w1_delay(10);
}
if(w1_disable_irqs) local_irq_restore(flags);
}
/**
* Pre-write operation, currently only supporting strong pullups.
* Program the hardware for a strong pullup, if one has been requested and
* the hardware supports it.
*
* @param dev the master device
*/
static void w1_pre_write(struct w1_master *dev)
{
if (dev->pullup_duration &&
dev->enable_pullup && dev->bus_master->set_pullup) {
dev->bus_master->set_pullup(dev->bus_master->data,
dev->pullup_duration);
}
}
/**
* Post-write operation, currently only supporting strong pullups.
* If a strong pullup was requested, clear it if the hardware supports
* them, or execute the delay otherwise, in either case clear the request.
*
* @param dev the master device
*/
static void w1_post_write(struct w1_master *dev)
{
if (dev->pullup_duration) {
if (dev->enable_pullup && dev->bus_master->set_pullup)
dev->bus_master->set_pullup(dev->bus_master->data, 0);
else
msleep(dev->pullup_duration);
dev->pullup_duration = 0;
}
}
/**
* Writes 8 bits.
*
* @param dev the master device
* @param byte the byte to write
*/
void w1_write_8(struct w1_master *dev, u8 byte)
{
int i;
if (dev->bus_master->write_byte) {
w1_pre_write(dev);
dev->bus_master->write_byte(dev->bus_master->data, byte);
}
else
for (i = 0; i < 8; ++i) {
if (i == 7)
w1_pre_write(dev);
w1_touch_bit(dev, (byte >> i) & 0x1);
}
w1_post_write(dev);
}
EXPORT_SYMBOL_GPL(w1_write_8);
/**
* Generates a write-1 cycle and samples the level.
* Only call if dev->bus_master->touch_bit is NULL
*/
static u8 w1_read_bit(struct w1_master *dev)
{
int result;
unsigned long flags = 0;
/* sample timing is critical here */
local_irq_save(flags);
dev->bus_master->write_bit(dev->bus_master->data, 0);
w1_delay(6);
dev->bus_master->write_bit(dev->bus_master->data, 1);
w1_delay(9);
result = dev->bus_master->read_bit(dev->bus_master->data);
local_irq_restore(flags);
w1_delay(55);
return result & 0x1;
}
/**
* Does a triplet - used for searching ROM addresses.
* Return bits:
* bit 0 = id_bit
* bit 1 = comp_bit
* bit 2 = dir_taken
* If both bits 0 & 1 are set, the search should be restarted.
*
* @param dev the master device
* @param bdir the bit to write if both id_bit and comp_bit are 0
* @return bit fields - see above
*/
u8 w1_triplet(struct w1_master *dev, int bdir)
{
if (dev->bus_master->triplet)
return dev->bus_master->triplet(dev->bus_master->data, bdir);
else {
u8 id_bit = w1_touch_bit(dev, 1);
u8 comp_bit = w1_touch_bit(dev, 1);
u8 retval;
if (id_bit && comp_bit)
return 0x03; /* error */
if (!id_bit && !comp_bit) {
/* Both bits are valid, take the direction given */
retval = bdir ? 0x04 : 0;
} else {
/* Only one bit is valid, take that direction */
bdir = id_bit;
retval = id_bit ? 0x05 : 0x02;
}
if (dev->bus_master->touch_bit)
w1_touch_bit(dev, bdir);
else
w1_write_bit(dev, bdir);
return retval;
}
}
/**
* Reads 8 bits.
*
* @param dev the master device
* @return the byte read
*/
u8 w1_read_8(struct w1_master *dev)
{
int i;
u8 res = 0;
if (dev->bus_master->read_byte)
res = dev->bus_master->read_byte(dev->bus_master->data);
else
for (i = 0; i < 8; ++i)
res |= (w1_touch_bit(dev,1) << i);
return res;
}
EXPORT_SYMBOL_GPL(w1_read_8);
/**
* Writes a series of bytes.
*
* @param dev the master device
* @param buf pointer to the data to write
* @param len the number of bytes to write
*/
void w1_write_block(struct w1_master *dev, const u8 *buf, int len)
{
int i;
if (dev->bus_master->write_block) {
w1_pre_write(dev);
dev->bus_master->write_block(dev->bus_master->data, buf, len);
}
else
for (i = 0; i < len; ++i)
w1_write_8(dev, buf[i]); /* calls w1_pre_write */
w1_post_write(dev);
}
EXPORT_SYMBOL_GPL(w1_write_block);
/**
* Touches a series of bytes.
*
* @param dev the master device
* @param buf pointer to the data to write
* @param len the number of bytes to write
*/
void w1_touch_block(struct w1_master *dev, u8 *buf, int len)
{
int i, j;
u8 tmp;
for (i = 0; i < len; ++i) {
tmp = 0;
for (j = 0; j < 8; ++j) {
if (j == 7)
w1_pre_write(dev);
tmp |= w1_touch_bit(dev, (buf[i] >> j) & 0x1) << j;
}
buf[i] = tmp;
}
}
EXPORT_SYMBOL_GPL(w1_touch_block);
/**
* Reads a series of bytes.
*
* @param dev the master device
* @param buf pointer to the buffer to fill
* @param len the number of bytes to read
* @return the number of bytes read
*/
u8 w1_read_block(struct w1_master *dev, u8 *buf, int len)
{
int i;
u8 ret;
if (dev->bus_master->read_block)
ret = dev->bus_master->read_block(dev->bus_master->data, buf, len);
else {
for (i = 0; i < len; ++i)
buf[i] = w1_read_8(dev);
ret = len;
}
return ret;
}
EXPORT_SYMBOL_GPL(w1_read_block);
/**
* Issues a reset bus sequence.
*
* @param dev The bus master pointer
* @return 0=Device present, 1=No device present or error
*/
int w1_reset_bus(struct w1_master *dev)
{
int result;
unsigned long flags = 0;
if(w1_disable_irqs) local_irq_save(flags);
if (dev->bus_master->reset_bus)
result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1;
else {
dev->bus_master->write_bit(dev->bus_master->data, 0);
/* minimum 480, max ? us
* be nice and sleep, except 18b20 spec lists 960us maximum,
* so until we can sleep with microsecond accuracy, spin.
* Feel free to come up with some other way to give up the
* cpu for such a short amount of time AND get it back in
* the maximum amount of time.
*/
w1_delay(500);
dev->bus_master->write_bit(dev->bus_master->data, 1);
w1_delay(70);
result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1;
/* minmum 70 (above) + 430 = 500 us
* There aren't any timing requirements between a reset and
* the following transactions. Sleeping is safe here.
*/
/* w1_delay(430); min required time */
msleep(1);
}
if(w1_disable_irqs) local_irq_restore(flags);
return result;
}
EXPORT_SYMBOL_GPL(w1_reset_bus);
u8 w1_calc_crc8(u8 * data, int len)
{
u8 crc = 0;
while (len--)
crc = w1_crc8_table[crc ^ *data++];
return crc;
}
EXPORT_SYMBOL_GPL(w1_calc_crc8);
void w1_search_devices(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
{
dev->attempts++;
if (dev->bus_master->search)
dev->bus_master->search(dev->bus_master->data, dev,
search_type, cb);
else
w1_search(dev, search_type, cb);
}
/**
* Resets the bus and then selects the slave by sending either a skip rom
* or a rom match.
* The w1 master lock must be held.
*
* @param sl the slave to select
* @return 0=success, anything else=error
*/
int w1_reset_select_slave(struct w1_slave *sl)
{
if (w1_reset_bus(sl->master))
return -1;
if (sl->master->slave_count == 1)
w1_write_8(sl->master, W1_SKIP_ROM);
else {
u8 match[9] = {W1_MATCH_ROM, };
u64 rn = le64_to_cpu(*((u64*)&sl->reg_num));
memcpy(&match[1], &rn, 8);
w1_write_block(sl->master, match, 9);
}
return 0;
}
EXPORT_SYMBOL_GPL(w1_reset_select_slave);
/**
* When the workflow with a slave amongst many requires several
* successive commands a reset between each, this function is similar
* to doing a reset then a match ROM for the last matched ROM. The
* advantage being that the matched ROM step is skipped in favor of the
* resume command. The slave must support the command of course.
*
* If the bus has only one slave, traditionnaly the match ROM is skipped
* and a "SKIP ROM" is done for efficiency. On multi-slave busses, this
* doesn't work of course, but the resume command is the next best thing.
*
* The w1 master lock must be held.
*
* @param dev the master device
*/
int w1_reset_resume_command(struct w1_master *dev)
{
if (w1_reset_bus(dev))
return -1;
/* This will make only the last matched slave perform a skip ROM. */
w1_write_8(dev, W1_RESUME_CMD);
return 0;
}
EXPORT_SYMBOL_GPL(w1_reset_resume_command);
/**
* Put out a strong pull-up of the specified duration after the next write
* operation. Not all hardware supports strong pullups. Hardware that
* doesn't support strong pullups will sleep for the given time after the
* write operation without a strong pullup. This is a one shot request for
* the next write, specifying zero will clear a previous request.
* The w1 master lock must be held.
*
* @param delay time in milliseconds
* @return 0=success, anything else=error
*/
void w1_next_pullup(struct w1_master *dev, int delay)
{
dev->pullup_duration = delay;
}
EXPORT_SYMBOL_GPL(w1_next_pullup);