From: Evgeniy Polyakov <zbr@ioremap.net>
Envelope-From: drustafa@yandex.ru
To: Jan Kandziora <jjj@gmx.de>, LKML <linux-kernel@vger.kernel.org>,
        GregKH <greg@kroah.com>
Cc: Linux-I2C <linux-i2c@vger.kernel.org>
In-Reply-To: <20170719201409.5968-2-jjj@gmx.de>
References: <20170719201409.5968-1-jjj@gmx.de> <20170719201409.5968-2-jjj@gmx.de>
Subject: Re: [PATCH v4 2/2] add w1_ds28e17 driver for the DS28E17 Onewire to I2C master bridge
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Date: Tue, 05 Sep 2017 16:19:48 +0300
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Hi Jan, Greg

19.07.2017, 23:14, "Jan Kandziora" <jjj@gmx.de>:
> This subpatch adds a driver for the DS28E17 Onewire to I2C master bridge.
>
> Signed-off-by: Jan Kandziora <jjj@gmx.de>

Greg, please queue this driver into your tree, it is sitting outside quite for a while and failed to be merged previously
since I missed it.
 
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>

> ---
> Changes in v4 against v3 in this subpatch:
>   - adapted to linux-4.12.0
>
> Changes in v3 against v2 in this subpatch:
>   - fixed a bug in using the i2c_adapter_quirks structure
>
> Changes in v2 against v1 in this subpatch:
>   - added error handling in w1_f19_error()
>   - added struct i2c_adapter_quirks
>   - removed unnecessary checks of I2C address and read count
>   - cleaned up error codes
>     + EOPNOTSUPP for read/write count == 0
>     + ETIMEDOUT for busy timeout
>     + ENXIO for no reply of I2C slave
>     + EAGAIN for I2C invalid start condition
>     + EIO for all w1 errors
>   - devm_kzalloc() instead of kzalloc()
>   - i2c speed to be set as 100, 400, 900 instead of 0, 1, 2
>   - added driver parameter documentation
>   - added sysfs documentation
>   - Kconfig fixed
>
>  Documentation/ABI/testing/sysfs-driver-w1_ds28e17 | 21 +
>  Documentation/w1/slaves/00-INDEX | 2 +
>  Documentation/w1/slaves/w1_ds28e17 | 68 ++
>  drivers/w1/slaves/Kconfig | 15 +
>  drivers/w1/slaves/Makefile | 1 +
>  drivers/w1/slaves/w1_ds28e17.c | 772 ++++++++++++++++++++++
>  drivers/w1/w1_family.h | 1 +
>  7 files changed, 880 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-driver-w1_ds28e17
>  create mode 100644 Documentation/w1/slaves/w1_ds28e17
>  create mode 100644 drivers/w1/slaves/w1_ds28e17.c
>
> diff --git a/Documentation/ABI/testing/sysfs-driver-w1_ds28e17 b/Documentation/ABI/testing/sysfs-driver-w1_ds28e17
> new file mode 100644
> index 0000000..b97b101
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-driver-w1_ds28e17
> @@ -0,0 +1,21 @@
> +What: /sys/bus/w1/devices/19-<id>/speed
> +Date: Jul 2016
> +KernelVersion: 4.7
> +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: Jul 2016
> +KernelVersion: 4.7
> +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
> diff --git a/Documentation/w1/slaves/00-INDEX b/Documentation/w1/slaves/00-INDEX
> index 8d76718..68946f8 100644
> --- a/Documentation/w1/slaves/00-INDEX
> +++ b/Documentation/w1/slaves/00-INDEX
> @@ -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.
> diff --git a/Documentation/w1/slaves/w1_ds28e17 b/Documentation/w1/slaves/w1_ds28e17
> new file mode 100644
> index 0000000..e82e16e
> --- /dev/null
> +++ b/Documentation/w1/slaves/w1_ds28e17
> @@ -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.
> +
> diff --git a/drivers/w1/slaves/Kconfig b/drivers/w1/slaves/Kconfig
> index fb68465..b94c55c 100644
> --- a/drivers/w1/slaves/Kconfig
> +++ b/drivers/w1/slaves/Kconfig
> @@ -140,6 +140,21 @@ 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.
> +
>  config W1_SLAVE_BQ27000
>          tristate "BQ27000 slave support"
>          help
> diff --git a/drivers/w1/slaves/Makefile b/drivers/w1/slaves/Makefile
> index 54c63e4..5ec927b 100644
> --- a/drivers/w1/slaves/Makefile
> +++ b/drivers/w1/slaves/Makefile
> @@ -17,3 +17,4 @@ obj-$(CONFIG_W1_SLAVE_DS2780) += w1_ds2780.o
>  obj-$(CONFIG_W1_SLAVE_DS2781) += w1_ds2781.o
>  obj-$(CONFIG_W1_SLAVE_BQ27000) += w1_bq27000.o
>  obj-$(CONFIG_W1_SLAVE_DS28E04) += w1_ds28e04.o
> +obj-$(CONFIG_W1_SLAVE_DS28E17) += w1_ds28e17.o
> diff --git a/drivers/w1/slaves/w1_ds28e17.c b/drivers/w1/slaves/w1_ds28e17.c
> new file mode 100644
> index 0000000..3e217e9
> --- /dev/null
> +++ b/drivers/w1/slaves/w1_ds28e17.c
> @@ -0,0 +1,772 @@
> +/*
> + * 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 "../w1.h"
> +#include "../w1_int.h"
> +#include "../w1_family.h"
> +
> +
> +/* 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);
> +
> diff --git a/drivers/w1/w1_family.h b/drivers/w1/w1_family.h
> index 869a3ff..f675638 100644
> --- a/drivers/w1/w1_family.h
> +++ b/drivers/w1/w1_family.h
> @@ -25,6 +25,7 @@
>  #define W1_FAMILY_SMEM_81 0x81
>  #define W1_FAMILY_DS2405 0x05
>  #define W1_THERM_DS18S20 0x10
> +#define W1_FAMILY_DS28E17 0x19
>  #define W1_FAMILY_DS28E04 0x1C
>  #define W1_COUNTER_DS2423 0x1D
>  #define W1_THERM_DS1822 0x22
> --
> 2.13.2