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add w1_ds28e17 driver for the DS28E17 Onewire to I2C master bridge

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This subpatch adds a driver for the DS28E17 Onewire to I2C master bridge.

Signed-off-by: Jan Kandziora <jjj@gmx.de>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jan Kandziora 2017-09-20 23:52:46 +02:00 committed by Greg Kroah-Hartman
parent eb8470db8b
commit ebc4768ac4
6 changed files with 878 additions and 0 deletions
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21
Documentation/ABI/testing/sysfs-driver-w1_ds28e17 Normal file
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@ -0,0 +1,21 @@
What: /sys/bus/w1/devices/19-<id>/speed
Date: Sep 2017
KernelVersion: 4.14
Contact: Jan Kandziora <jjj@gmx.de>
Description: When written, this file sets the I2C speed on the connected
DS28E17 chip. When read, it reads the current setting from
the DS28E17 chip.
Valid values: 100, 400, 900 [kBaud].
Default 100, can be set by w1_ds28e17.speed= module parameter.
Users: w1_ds28e17 driver
What: /sys/bus/w1/devices/19-<id>/stretch
Date: Sep 2017
KernelVersion: 4.14
Contact: Jan Kandziora <jjj@gmx.de>
Description: When written, this file sets the multiplier used to calculate
the busy timeout for I2C operations on the connected DS28E17
chip. When read, returns the current setting.
Valid values: 1 to 9.
Default 1, can be set by w1_ds28e17.stretch= module parameter.
Users: w1_ds28e17 driver

2
Documentation/w1/slaves/00-INDEX
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@ -10,3 +10,5 @@ w1_ds2438
- The Maxim/Dallas Semiconductor ds2438 smart battery monitor.
w1_ds28e04
- The Maxim/Dallas Semiconductor ds28e04 eeprom.
w1_ds28e17
- The Maxim/Dallas Semiconductor ds28e17 1-Wire-to-I2C Master Bridge.

68
Documentation/w1/slaves/w1_ds28e17 Normal file
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@ -0,0 +1,68 @@
Kernel driver w1_ds28e17
========================
Supported chips:
* Maxim DS28E17 1-Wire-to-I2C Master Bridge
supported family codes:
W1_FAMILY_DS28E17 0x19
Author: Jan Kandziora <jjj@gmx.de>
Description
-----------
The DS28E17 is a Onewire slave device which acts as an I2C bus master.
This driver creates a new I2C bus for any DS28E17 device detected. I2C buses
come and go as the DS28E17 devices come and go. I2C slave devices connected to
a DS28E17 can be accessed by the kernel or userspace tools as if they were
connected to a "native" I2C bus master.
An udev rule like the following
-------------------------------------------------------------------------------
SUBSYSTEM=="i2c-dev", KERNEL=="i2c-[0-9]*", ATTRS{name}=="w1-19-*", \
SYMLINK+="i2c-$attr{name}"
-------------------------------------------------------------------------------
may be used to create stable /dev/i2c- entries based on the unique id of the
DS28E17 chip.
Driver parameters are:
speed:
This sets up the default I2C speed a DS28E17 get configured for as soon
it is connected. The power-on default of the DS28E17 is 400kBaud, but
chips may come and go on the Onewire bus without being de-powered and
as soon the "w1_ds28e17" driver notices a freshly connected, or
reconnected DS28E17 device on the Onewire bus, it will re-apply this
setting.
Valid values are 100, 400, 900 [kBaud]. Any other value means to leave
alone the current DS28E17 setting on detect. The default value is 100.
stretch:
This sets up the default stretch value used for freshly connected
DS28E17 devices. It is a multiplier used on the calculation of the busy
wait time for an I2C transfer. This is to account for I2C slave devices
which make heavy use of the I2C clock stretching feature and thus, the
needed timeout cannot be pre-calculated correctly. As the w1_ds28e17
driver checks the DS28E17's busy flag in a loop after the precalculated
wait time, it should be hardly needed to tweak this setting.
Leave it at 1 unless you get ETIMEDOUT errors and a "w1_slave_driver
19-00000002dbd8: busy timeout" in the kernel log.
Valid values are 1 to 9. The default is 1.
The driver creates sysfs files /sys/bus/w1/devices/19-<id>/speed and
/sys/bus/w1/devices/19-<id>/stretch for each device, preloaded with the default
settings from the driver parameters. They may be changed anytime. In addition a
directory /sys/bus/w1/devices/19-<id>/i2c-<nnn> for the I2C bus master sysfs
structure is created.
See https://github.com/ianka/w1_ds28e17 for even more information.

15
drivers/w1/slaves/Kconfig
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@ -148,4 +148,19 @@ config W1_SLAVE_DS28E04
If you are unsure, say N.
config W1_SLAVE_DS28E17
tristate "1-wire-to-I2C master bridge (DS28E17)"
select CRC16
depends on I2C
help
Say Y here if you want to use the DS28E17 1-wire-to-I2C master bridge.
For each DS28E17 detected, a new I2C adapter is created within the
kernel. I2C devices on that bus can be configured to be used by the
kernel and userspace tools as on any other "native" I2C bus.
This driver is also available as a module. If so, the module
will be called w1_ds28e17.
If you are unsure, say N.
endmenu

1
drivers/w1/slaves/Makefile
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@ -17,3 +17,4 @@ obj-$(CONFIG_W1_SLAVE_DS2760) += w1_ds2760.o
obj-$(CONFIG_W1_SLAVE_DS2780) += w1_ds2780.o
obj-$(CONFIG_W1_SLAVE_DS2781) += w1_ds2781.o
obj-$(CONFIG_W1_SLAVE_DS28E04) += w1_ds28e04.o
obj-$(CONFIG_W1_SLAVE_DS28E17) += w1_ds28e17.o

771
drivers/w1/slaves/w1_ds28e17.c Normal file
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@ -0,0 +1,771 @@
/*
* w1_ds28e17.c - w1 family 19 (DS28E17) driver
*
* Copyright (c) 2016 Jan Kandziora <jjj@gmx.de>
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
#include <linux/crc16.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#define CRC16_INIT 0
#include <linux/w1.h>
#define W1_FAMILY_DS28E17 0x19
/* Module setup. */
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Jan Kandziora <jjj@gmx.de>");
MODULE_DESCRIPTION("w1 family 19 driver for DS28E17, 1-wire to I2C master bridge");
MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS28E17));
/* Default I2C speed to be set when a DS28E17 is detected. */
static int i2c_speed = 100;
module_param_named(speed, i2c_speed, int, (S_IRUSR | S_IWUSR));
MODULE_PARM_DESC(speed, "Default I2C speed to be set when a DS28E17 is detected");
/* Default I2C stretch value to be set when a DS28E17 is detected. */
static char i2c_stretch = 1;
module_param_named(stretch, i2c_stretch, byte, (S_IRUSR | S_IWUSR));
MODULE_PARM_DESC(stretch, "Default I2C stretch value to be set when a DS28E17 is detected");
/* DS28E17 device command codes. */
#define W1_F19_WRITE_DATA_WITH_STOP 0x4B
#define W1_F19_WRITE_DATA_NO_STOP 0x5A
#define W1_F19_WRITE_DATA_ONLY 0x69
#define W1_F19_WRITE_DATA_ONLY_WITH_STOP 0x78
#define W1_F19_READ_DATA_WITH_STOP 0x87
#define W1_F19_WRITE_READ_DATA_WITH_STOP 0x2D
#define W1_F19_WRITE_CONFIGURATION 0xD2
#define W1_F19_READ_CONFIGURATION 0xE1
#define W1_F19_ENABLE_SLEEP_MODE 0x1E
#define W1_F19_READ_DEVICE_REVISION 0xC4
/* DS28E17 status bits */
#define W1_F19_STATUS_CRC 0x01
#define W1_F19_STATUS_ADDRESS 0x02
#define W1_F19_STATUS_START 0x08
/*
* Maximum number of I2C bytes to transfer within one CRC16 protected onewire
* command.
* */
#define W1_F19_WRITE_DATA_LIMIT 255
/* Maximum number of I2C bytes to read with one onewire command. */
#define W1_F19_READ_DATA_LIMIT 255
/* Constants for calculating the busy sleep. */
#define W1_F19_BUSY_TIMEBASES { 90, 23, 10 }
#define W1_F19_BUSY_GRATUITY 1000
/* Number of checks for the busy flag before timeout. */
#define W1_F19_BUSY_CHECKS 1000
/* Slave specific data. */
struct w1_f19_data {
u8 speed;
u8 stretch;
struct i2c_adapter adapter;
};
/* Wait a while until the busy flag clears. */
static int w1_f19_i2c_busy_wait(struct w1_slave *sl, size_t count)
{
const unsigned long timebases[3] = W1_F19_BUSY_TIMEBASES;
struct w1_f19_data *data = sl->family_data;
unsigned int checks;
/* Check the busy flag first in any case.*/
if (w1_touch_bit(sl->master, 1) == 0)
return 0;
/*
* Do a generously long sleep in the beginning,
* as we have to wait at least this time for all
* the I2C bytes at the given speed to be transferred.
*/
usleep_range(timebases[data->speed] * (data->stretch) * count,
timebases[data->speed] * (data->stretch) * count
+ W1_F19_BUSY_GRATUITY);
/* Now continusly check the busy flag sent by the DS28E17. */
checks = W1_F19_BUSY_CHECKS;
while ((checks--) > 0) {
/* Return success if the busy flag is cleared. */
if (w1_touch_bit(sl->master, 1) == 0)
return 0;
/* Wait one non-streched byte timeslot. */
udelay(timebases[data->speed]);
}
/* Timeout. */
dev_warn(&sl->dev, "busy timeout\n");
return -ETIMEDOUT;
}
/* Utility function: result. */
static size_t w1_f19_error(struct w1_slave *sl, u8 w1_buf[])
{
/* Warnings. */
if (w1_buf[0] & W1_F19_STATUS_CRC)
dev_warn(&sl->dev, "crc16 mismatch\n");
if (w1_buf[0] & W1_F19_STATUS_ADDRESS)
dev_warn(&sl->dev, "i2c device not responding\n");
if ((w1_buf[0] & (W1_F19_STATUS_CRC | W1_F19_STATUS_ADDRESS)) == 0
&& w1_buf[1] != 0) {
dev_warn(&sl->dev, "i2c short write, %d bytes not acknowledged\n",
w1_buf[1]);
}
/* Check error conditions. */
if (w1_buf[0] & W1_F19_STATUS_ADDRESS)
return -ENXIO;
if (w1_buf[0] & W1_F19_STATUS_START)
return -EAGAIN;
if (w1_buf[0] != 0 || w1_buf[1] != 0)
return -EIO;
/* All ok. */
return 0;
}
/* Utility function: write data to I2C slave, single chunk. */
static int __w1_f19_i2c_write(struct w1_slave *sl,
const u8 *command, size_t command_count,
const u8 *buffer, size_t count)
{
u16 crc;
int error;
u8 w1_buf[2];
/* Send command and I2C data to DS28E17. */
crc = crc16(CRC16_INIT, command, command_count);
w1_write_block(sl->master, command, command_count);
w1_buf[0] = count;
crc = crc16(crc, w1_buf, 1);
w1_write_8(sl->master, w1_buf[0]);
crc = crc16(crc, buffer, count);
w1_write_block(sl->master, buffer, count);
w1_buf[0] = ~(crc & 0xFF);
w1_buf[1] = ~((crc >> 8) & 0xFF);
w1_write_block(sl->master, w1_buf, 2);
/* Wait until busy flag clears (or timeout). */
if (w1_f19_i2c_busy_wait(sl, count + 1) < 0)
return -ETIMEDOUT;
/* Read status from DS28E17. */
w1_read_block(sl->master, w1_buf, 2);
/* Check error conditions. */
error = w1_f19_error(sl, w1_buf);
if (error < 0)
return error;
/* Return number of bytes written. */
return count;
}
/* Write data to I2C slave. */
static int w1_f19_i2c_write(struct w1_slave *sl, u16 i2c_address,
const u8 *buffer, size_t count, bool stop)
{
int result;
int remaining = count;
const u8 *p;
u8 command[2];
/* Check input. */
if (count == 0)
return -EOPNOTSUPP;
/* Check whether we need multiple commands. */
if (count <= W1_F19_WRITE_DATA_LIMIT) {
/*
* Small data amount. Data can be sent with
* a single onewire command.
*/
/* Send all data to DS28E17. */
command[0] = (stop ? W1_F19_WRITE_DATA_WITH_STOP
: W1_F19_WRITE_DATA_NO_STOP);
command[1] = i2c_address << 1;
result = __w1_f19_i2c_write(sl, command, 2, buffer, count);
} else {
/* Large data amount. Data has to be sent in multiple chunks. */
/* Send first chunk to DS28E17. */
p = buffer;
command[0] = W1_F19_WRITE_DATA_NO_STOP;
command[1] = i2c_address << 1;
result = __w1_f19_i2c_write(sl, command, 2, p,
W1_F19_WRITE_DATA_LIMIT);
if (result < 0)
return result;
/* Resume to same DS28E17. */
if (w1_reset_resume_command(sl->master))
return -EIO;
/* Next data chunk. */
p += W1_F19_WRITE_DATA_LIMIT;
remaining -= W1_F19_WRITE_DATA_LIMIT;
while (remaining > W1_F19_WRITE_DATA_LIMIT) {
/* Send intermediate chunk to DS28E17. */
command[0] = W1_F19_WRITE_DATA_ONLY;
result = __w1_f19_i2c_write(sl, command, 1, p,
W1_F19_WRITE_DATA_LIMIT);
if (result < 0)
return result;
/* Resume to same DS28E17. */
if (w1_reset_resume_command(sl->master))
return -EIO;
/* Next data chunk. */
p += W1_F19_WRITE_DATA_LIMIT;
remaining -= W1_F19_WRITE_DATA_LIMIT;
}
/* Send final chunk to DS28E17. */
command[0] = (stop ? W1_F19_WRITE_DATA_ONLY_WITH_STOP
: W1_F19_WRITE_DATA_ONLY);
result = __w1_f19_i2c_write(sl, command, 1, p, remaining);
}
return result;
}
/* Read data from I2C slave. */
static int w1_f19_i2c_read(struct w1_slave *sl, u16 i2c_address,
u8 *buffer, size_t count)
{
u16 crc;
int error;
u8 w1_buf[5];
/* Check input. */
if (count == 0)
return -EOPNOTSUPP;
/* Send command to DS28E17. */
w1_buf[0] = W1_F19_READ_DATA_WITH_STOP;
w1_buf[1] = i2c_address << 1 | 0x01;
w1_buf[2] = count;
crc = crc16(CRC16_INIT, w1_buf, 3);
w1_buf[3] = ~(crc & 0xFF);
w1_buf[4] = ~((crc >> 8) & 0xFF);
w1_write_block(sl->master, w1_buf, 5);
/* Wait until busy flag clears (or timeout). */
if (w1_f19_i2c_busy_wait(sl, count + 1) < 0)
return -ETIMEDOUT;
/* Read status from DS28E17. */
w1_buf[0] = w1_read_8(sl->master);
w1_buf[1] = 0;
/* Check error conditions. */
error = w1_f19_error(sl, w1_buf);
if (error < 0)
return error;
/* Read received I2C data from DS28E17. */
return w1_read_block(sl->master, buffer, count);
}
/* Write to, then read data from I2C slave. */
static int w1_f19_i2c_write_read(struct w1_slave *sl, u16 i2c_address,
const u8 *wbuffer, size_t wcount, u8 *rbuffer, size_t rcount)
{
u16 crc;
int error;
u8 w1_buf[3];
/* Check input. */
if (wcount == 0 || rcount == 0)
return -EOPNOTSUPP;
/* Send command and I2C data to DS28E17. */
w1_buf[0] = W1_F19_WRITE_READ_DATA_WITH_STOP;
w1_buf[1] = i2c_address << 1;
w1_buf[2] = wcount;
crc = crc16(CRC16_INIT, w1_buf, 3);
w1_write_block(sl->master, w1_buf, 3);
crc = crc16(crc, wbuffer, wcount);
w1_write_block(sl->master, wbuffer, wcount);
w1_buf[0] = rcount;
crc = crc16(crc, w1_buf, 1);
w1_buf[1] = ~(crc & 0xFF);
w1_buf[2] = ~((crc >> 8) & 0xFF);
w1_write_block(sl->master, w1_buf, 3);
/* Wait until busy flag clears (or timeout). */
if (w1_f19_i2c_busy_wait(sl, wcount + rcount + 2) < 0)
return -ETIMEDOUT;
/* Read status from DS28E17. */
w1_read_block(sl->master, w1_buf, 2);
/* Check error conditions. */
error = w1_f19_error(sl, w1_buf);
if (error < 0)
return error;
/* Read received I2C data from DS28E17. */
return w1_read_block(sl->master, rbuffer, rcount);
}
/* Do an I2C master transfer. */
static int w1_f19_i2c_master_transfer(struct i2c_adapter *adapter,
struct i2c_msg *msgs, int num)
{
struct w1_slave *sl = (struct w1_slave *) adapter->algo_data;
int i = 0;
int result = 0;
/* Start onewire transaction. */
mutex_lock(&sl->master->bus_mutex);
/* Select DS28E17. */
if (w1_reset_select_slave(sl)) {
i = -EIO;
goto error;
}
/* Loop while there are still messages to transfer. */
while (i < num) {
/*
* Check for special case: Small write followed
* by read to same I2C device.
*/
if (i < (num-1)
&& msgs[i].addr == msgs[i+1].addr
&& !(msgs[i].flags & I2C_M_RD)
&& (msgs[i+1].flags & I2C_M_RD)
&& (msgs[i].len <= W1_F19_WRITE_DATA_LIMIT)) {
/*
* The DS28E17 has a combined transfer
* for small write+read.
*/
result = w1_f19_i2c_write_read(sl, msgs[i].addr,
msgs[i].buf, msgs[i].len,
msgs[i+1].buf, msgs[i+1].len);
if (result < 0) {
i = result;
goto error;
}
/*
* Check if we should interpret the read data
* as a length byte. The DS28E17 unfortunately
* has no read without stop, so we can just do
* another simple read in that case.
*/
if (msgs[i+1].flags & I2C_M_RECV_LEN) {
result = w1_f19_i2c_read(sl, msgs[i+1].addr,
&(msgs[i+1].buf[1]), msgs[i+1].buf[0]);
if (result < 0) {
i = result;
goto error;
}
}
/* Eat up read message, too. */
i++;
} else if (msgs[i].flags & I2C_M_RD) {
/* Read transfer. */
result = w1_f19_i2c_read(sl, msgs[i].addr,
msgs[i].buf, msgs[i].len);
if (result < 0) {
i = result;
goto error;
}
/*
* Check if we should interpret the read data
* as a length byte. The DS28E17 unfortunately
* has no read without stop, so we can just do
* another simple read in that case.
*/
if (msgs[i].flags & I2C_M_RECV_LEN) {
result = w1_f19_i2c_read(sl,
msgs[i].addr,
&(msgs[i].buf[1]),
msgs[i].buf[0]);
if (result < 0) {
i = result;
goto error;
}
}
} else {
/*
* Write transfer.
* Stop condition only for last
* transfer.
*/
result = w1_f19_i2c_write(sl,
msgs[i].addr,
msgs[i].buf,
msgs[i].len,
i == (num-1));
if (result < 0) {
i = result;
goto error;
}
}
/* Next message. */
i++;
/* Are there still messages to send/receive? */
if (i < num) {
/* Yes. Resume to same DS28E17. */
if (w1_reset_resume_command(sl->master)) {
i = -EIO;
goto error;
}
}
}
error:
/* End onewire transaction. */
mutex_unlock(&sl->master->bus_mutex);
/* Return number of messages processed or error. */
return i;
}
/* Get I2C adapter functionality. */
static u32 w1_f19_i2c_functionality(struct i2c_adapter *adapter)
{
/*
* Plain I2C functions only.
* SMBus is emulated by the kernel's I2C layer.
* No "I2C_FUNC_SMBUS_QUICK"
* No "I2C_FUNC_SMBUS_READ_BLOCK_DATA"
* No "I2C_FUNC_SMBUS_BLOCK_PROC_CALL"
*/
return I2C_FUNC_I2C |
I2C_FUNC_SMBUS_BYTE |
I2C_FUNC_SMBUS_BYTE_DATA |
I2C_FUNC_SMBUS_WORD_DATA |
I2C_FUNC_SMBUS_PROC_CALL |
I2C_FUNC_SMBUS_WRITE_BLOCK_DATA |
I2C_FUNC_SMBUS_I2C_BLOCK |
I2C_FUNC_SMBUS_PEC;
}
/* I2C adapter quirks. */
static const struct i2c_adapter_quirks w1_f19_i2c_adapter_quirks = {
.max_read_len = W1_F19_READ_DATA_LIMIT,
};
/* I2C algorithm. */
static const struct i2c_algorithm w1_f19_i2c_algorithm = {
.master_xfer = w1_f19_i2c_master_transfer,
.functionality = w1_f19_i2c_functionality,
};
/* Read I2C speed from DS28E17. */
static int w1_f19_get_i2c_speed(struct w1_slave *sl)
{
struct w1_f19_data *data = sl->family_data;
int result = -EIO;
/* Start onewire transaction. */
mutex_lock(&sl->master->bus_mutex);
/* Select slave. */
if (w1_reset_select_slave(sl))
goto error;
/* Read slave configuration byte. */
w1_write_8(sl->master, W1_F19_READ_CONFIGURATION);
result = w1_read_8(sl->master);
if (result < 0 || result > 2) {
result = -EIO;
goto error;
}
/* Update speed in slave specific data. */
data->speed = result;
error:
/* End onewire transaction. */
mutex_unlock(&sl->master->bus_mutex);
return result;
}
/* Set I2C speed on DS28E17. */
static int __w1_f19_set_i2c_speed(struct w1_slave *sl, u8 speed)
{
struct w1_f19_data *data = sl->family_data;
const int i2c_speeds[3] = { 100, 400, 900 };
u8 w1_buf[2];
/* Select slave. */
if (w1_reset_select_slave(sl))
return -EIO;
w1_buf[0] = W1_F19_WRITE_CONFIGURATION;
w1_buf[1] = speed;
w1_write_block(sl->master, w1_buf, 2);
/* Update speed in slave specific data. */
data->speed = speed;
dev_info(&sl->dev, "i2c speed set to %d kBaud\n", i2c_speeds[speed]);
return 0;
}
static int w1_f19_set_i2c_speed(struct w1_slave *sl, u8 speed)
{
int result;
/* Start onewire transaction. */
mutex_lock(&sl->master->bus_mutex);
/* Set I2C speed on DS28E17. */
result = __w1_f19_set_i2c_speed(sl, speed);
/* End onewire transaction. */
mutex_unlock(&sl->master->bus_mutex);
return result;
}
/* Sysfs attributes. */
/* I2C speed attribute for a single chip. */
static ssize_t speed_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct w1_slave *sl = dev_to_w1_slave(dev);
int result;
/* Read current speed from slave. Updates data->speed. */
result = w1_f19_get_i2c_speed(sl);
if (result < 0)
return result;
/* Return current speed value. */
return sprintf(buf, "%d\n", result);
}
static ssize_t speed_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct w1_slave *sl = dev_to_w1_slave(dev);
int error;
/* Valid values are: "100", "400", "900" */
if (count < 3 || count > 4 || !buf)
return -EINVAL;
if (count == 4 && buf[3] != '\n')
return -EINVAL;
if (buf[1] != '0' || buf[2] != '0')
return -EINVAL;
/* Set speed on slave. */
switch (buf[0]) {
case '1':
error = w1_f19_set_i2c_speed(sl, 0);
break;
case '4':
error = w1_f19_set_i2c_speed(sl, 1);
break;
case '9':
error = w1_f19_set_i2c_speed(sl, 2);
break;
default:
return -EINVAL;
}
if (error < 0)
return error;
/* Return bytes written. */
return count;
}
static DEVICE_ATTR_RW(speed);
/* Busy stretch attribute for a single chip. */
static ssize_t stretch_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct w1_slave *sl = dev_to_w1_slave(dev);
struct w1_f19_data *data = sl->family_data;
/* Return current stretch value. */
return sprintf(buf, "%d\n", data->stretch);
}
static ssize_t stretch_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct w1_slave *sl = dev_to_w1_slave(dev);
struct w1_f19_data *data = sl->family_data;
/* Valid values are '1' to '9' */
if (count < 1 || count > 2 || !buf)
return -EINVAL;
if (count == 2 && buf[1] != '\n')
return -EINVAL;
if (buf[0] < '1' || buf[0] > '9')
return -EINVAL;
/* Set busy stretch value. */
data->stretch = buf[0] & 0x0F;
/* Return bytes written. */
return count;
}
static DEVICE_ATTR_RW(stretch);
/* All attributes. */
static struct attribute *w1_f19_attrs[] = {
&dev_attr_speed.attr,
&dev_attr_stretch.attr,
NULL,
};
static const struct attribute_group w1_f19_group = {
.attrs = w1_f19_attrs,
};
static const struct attribute_group *w1_f19_groups[] = {
&w1_f19_group,
NULL,
};
/* Slave add and remove functions. */
static int w1_f19_add_slave(struct w1_slave *sl)
{
struct w1_f19_data *data = NULL;
/* Allocate memory for slave specific data. */
data = devm_kzalloc(&sl->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
sl->family_data = data;
/* Setup default I2C speed on slave. */
switch (i2c_speed) {
case 100:
__w1_f19_set_i2c_speed(sl, 0);
break;
case 400:
__w1_f19_set_i2c_speed(sl, 1);
break;
case 900:
__w1_f19_set_i2c_speed(sl, 2);
break;
default:
/*
* A i2c_speed module parameter of anything else
* than 100, 400, 900 means not to touch the
* speed of the DS28E17.
* We assume 400kBaud, the power-on value.
*/
data->speed = 1;
}
/*
* Setup default busy stretch
* configuration for the DS28E17.
*/
data->stretch = i2c_stretch;
/* Setup I2C adapter. */
data->adapter.owner = THIS_MODULE;
data->adapter.algo = &w1_f19_i2c_algorithm;
data->adapter.algo_data = sl;
strcpy(data->adapter.name, "w1-");
strcat(data->adapter.name, sl->name);
data->adapter.dev.parent = &sl->dev;
data->adapter.quirks = &w1_f19_i2c_adapter_quirks;
return i2c_add_adapter(&data->adapter);
}
static void w1_f19_remove_slave(struct w1_slave *sl)
{
struct w1_f19_data *family_data = sl->family_data;
/* Delete I2C adapter. */
i2c_del_adapter(&family_data->adapter);
/* Free slave specific data. */
devm_kfree(&sl->dev, family_data);
sl->family_data = NULL;
}
/* Declarations within the w1 subsystem. */
static struct w1_family_ops w1_f19_fops = {
.add_slave = w1_f19_add_slave,
.remove_slave = w1_f19_remove_slave,
.groups = w1_f19_groups,
};
static struct w1_family w1_family_19 = {
.fid = W1_FAMILY_DS28E17,
.fops = &w1_f19_fops,
};
/* Module init and remove functions. */
static int __init w1_f19_init(void)
{
return w1_register_family(&w1_family_19);
}
static void __exit w1_f19_fini(void)
{
w1_unregister_family(&w1_family_19);
}
module_init(w1_f19_init);
module_exit(w1_f19_fini);