Resguardo inicial

linux-7.2.3/Documentation/w1/index.rst

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+.. SPDX-License-Identifier: GPL-2.0
+
+================
+1-Wire Subsystem
+================
+
+.. toctree::
+   :maxdepth: 1
+
+
+   w1-generic.rst
+   w1-netlink.rst
+   masters/index
+   slaves/index

linux-7.2.3/Documentation/w1/masters/ds2482.rst

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+====================
+Kernel driver ds2482
+====================
+
+Supported chips:
+
+  * Maxim DS2482-100, Maxim DS2482-800
+
+    Prefix: 'ds2482'
+
+    Addresses scanned: None
+
+    Datasheets:
+
+        - http://datasheets.maxim-ic.com/en/ds/DS2482-100.pdf
+        - http://datasheets.maxim-ic.com/en/ds/DS2482-800.pdf
+
+Author: Ben Gardner <bgardner@wabtec.com>
+
+
+Description
+-----------
+
+The Maxim/Dallas Semiconductor DS2482 is a I2C device that provides
+one (DS2482-100) or eight (DS2482-800) 1-wire buses.
+
+
+General Remarks
+---------------
+
+Valid addresses are 0x18, 0x19, 0x1a, and 0x1b.
+
+However, the device cannot be detected without writing to the i2c bus, so no
+detection is done. You should instantiate the device explicitly.
+
+::
+
+  $ modprobe ds2482
+  $ echo ds2482 0x18 > /sys/bus/i2c/devices/i2c-0/new_device

linux-7.2.3/Documentation/w1/masters/ds2490.rst

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+====================
+Kernel driver ds2490
+====================
+
+Supported chips:
+
+  * Maxim DS2490 based
+
+Author: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
+
+
+Description
+-----------
+
+The Maxim/Dallas Semiconductor DS2490 is a chip
+which allows to build USB <-> W1 bridges.
+
+DS9490(R) is a USB <-> W1 bus master device
+which has 0x81 family ID integrated chip and DS2490
+low-level operational chip.
+
+Notes and limitations.
+
+- The weak pullup current is a minimum of 0.9mA and maximum of 6.0mA.
+- The 5V strong pullup is supported with a minimum of 5.9mA and a
+  maximum of 30.4 mA.  (From DS2490.pdf)
+- The hardware will detect when devices are attached to the bus on the
+  next bus (reset?) operation, however only a message is printed as
+  the core w1 code doesn't make use of the information.  Connecting
+  one device tends to give multiple new device notifications.
+- The number of USB bus transactions could be reduced if w1_reset_send
+  was added to the API.  The name is just a suggestion.  It would take
+  a write buffer and a read buffer (along with sizes) as arguments.
+  The ds2490 block I/O command supports reset, write buffer, read
+  buffer, and strong pullup all in one command, instead of the current
+  1 reset bus, 2 write the match rom command and slave rom id, 3 block
+  write and read data.  The write buffer needs to have the match rom
+  command and slave rom id prepended to the front of the requested
+  write buffer, both of which are known to the driver.
+- The hardware supports normal, flexible, and overdrive bus
+  communication speeds, but only the normal is supported.
+- The registered w1_bus_master functions don't define error
+  conditions.  If a bus search is in progress and the ds2490 is
+  removed it can produce a good amount of error output before the bus
+  search finishes.
+- The hardware supports detecting some error conditions, such as
+  short, alarming presence on reset, and no presence on reset, but the
+  driver doesn't query those values.
+- The ds2490 specification doesn't cover short bulk in reads in
+  detail, but my observation is if fewer bytes are requested than are
+  available, the bulk read will return an error and the hardware will
+  clear the entire bulk in buffer.  It would be possible to read the
+  maximum buffer size to not run into this error condition, only extra
+  bytes in the buffer is a logic error in the driver.  The code should
+  match reads and writes as well as data sizes.  Reads and
+  writes are serialized and the status verifies that the chip is idle
+  (and data is available) before the read is executed, so it should
+  not happen.
+- Running x86_64 2.6.24 UHCI under qemu 0.9.0 under x86_64 2.6.22-rc6
+  with a OHCI controller, ds2490 running in the guest would operate
+  normally the first time the module was loaded after qemu attached
+  the ds2490 hardware, but if the module was unloaded, then reloaded
+  most of the time one of the bulk out or in, and usually the bulk in
+  would fail.  qemu sets a 50ms timeout and the bulk in would timeout
+  even when the status shows data available.  A bulk out write would
+  show a successful completion, but the ds2490 status register would
+  show 0 bytes written.  Detaching qemu from the ds2490 hardware and
+  reattaching would clear the problem.  usbmon output in the guest and
+  host did not explain the problem.  My guess is a bug in either qemu
+  or the host OS and more likely the host OS.
+
+03-06-2008 David Fries <David@Fries.net>

linux-7.2.3/Documentation/w1/masters/index.rst

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+.. SPDX-License-Identifier: GPL-2.0
+
+=====================
+1-wire Master Drivers
+=====================
+
+.. toctree::
+   :maxdepth: 1
+
+   ds2482
+   ds2490
+   mxc-w1
+   omap-hdq
+   w1-gpio
+   w1-uart

linux-7.2.3/Documentation/w1/masters/mxc-w1.rst

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+====================
+Kernel driver mxc_w1
+====================
+
+Supported chips:
+
+  * Freescale MX27, MX31 and probably other i.MX SoCs
+
+    Datasheets:
+
+        - http://www.freescale.com/files/32bit/doc/data_sheet/MCIMX31.pdf?fpsp=1
+	- http://cache.freescale.com/files/dsp/doc/archive/MCIMX27.pdf?fsrch=1&WT_TYPE=Data%20Sheets&WT_VENDOR=FREESCALE&WT_FILE_FORMAT=pdf&WT_ASSET=Documentation
+
+Author:
+
+	Originally based on Freescale code, prepared for mainline by
+	Sascha Hauer <s.hauer@pengutronix.de>

linux-7.2.3/Documentation/w1/masters/omap-hdq.rst

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+========================================
+Kernel driver for omap HDQ/1-wire module
+========================================
+
+Supported chips:
+================
+HDQ/1-wire controller on the TI OMAP 2430/3430 platforms.
+
+A useful link about HDQ basics:
+===============================
+http://focus.ti.com/lit/an/slua408a/slua408a.pdf
+
+Description:
+============
+The HDQ/1-Wire module of TI OMAP2430/3430 platforms implement the hardware
+protocol of the master functions of the Benchmark HDQ and the Dallas
+Semiconductor 1-Wire protocols. These protocols use a single wire for
+communication between the master (HDQ/1-Wire controller) and the slave
+(HDQ/1-Wire external compliant device).
+
+A typical application of the HDQ/1-Wire module is the communication with battery
+monitor (gas gauge) integrated circuits.
+
+The controller supports operation in both HDQ and 1-wire mode. The essential
+difference between the HDQ and 1-wire mode is how the slave device responds to
+initialization pulse.In HDQ mode, the firmware does not require the host to
+create an initialization pulse to the slave.However, the slave can be reset by
+using an initialization pulse (also referred to as a break pulse).The slave
+does not respond with a presence pulse as it does in the 1-Wire protocol.
+
+Remarks:
+========
+The driver (drivers/w1/masters/omap_hdq.c) supports the HDQ mode of the
+controller. In this mode, as we can not read the ID which obeys the W1
+spec(family:id:crc), a module parameter can be passed to the driver which will
+be used to calculate the CRC and pass back an appropriate slave ID to the W1
+core.
+
+By default the master driver and the BQ slave i/f
+driver(drivers/w1/slaves/w1_bq27000.c) sets the ID to 1.
+Please note to load both the modules with a different ID if required, but note
+that the ID used should be same for both master and slave driver loading.
+
+e.g::
+
+  insmod omap_hdq.ko W1_ID=2
+  insmod w1_bq27000.ko F_ID=2
+
+The driver also supports 1-wire mode. In this mode, there is no need to
+pass slave ID as parameter. The driver will auto-detect slaves connected
+to the bus using SEARCH_ROM procedure. 1-wire mode can be selected by
+setting "ti,mode" property to "1w" in DT (see
+Documentation/devicetree/bindings/w1/omap-hdq.txt for more details).
+By default driver is in HDQ mode.

linux-7.2.3/Documentation/w1/masters/w1-gpio.rst

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+=====================
+Kernel driver w1-gpio
+=====================
+
+Author: Ville Syrjala <syrjala@sci.fi>
+
+
+Description
+-----------
+
+GPIO 1-wire bus master driver. The driver uses the GPIO API to control the
+wire and the GPIO pin can be specified using GPIO machine descriptor tables.
+It is also possible to define the master using device tree, see
+Documentation/devicetree/bindings/w1/w1-gpio.yaml
+
+
+Example (mach-at91)
+-------------------
+
+::
+
+  #include <linux/gpio/machine.h>
+  #include <linux/w1-gpio.h>
+
+  static struct gpiod_lookup_table foo_w1_gpiod_table = {
+	.dev_id = "w1-gpio",
+	.table = {
+		GPIO_LOOKUP_IDX("at91-gpio", AT91_PIN_PB20, NULL, 0,
+			GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN),
+	},
+  };
+
+  static struct w1_gpio_platform_data foo_w1_gpio_pdata = {
+	.ext_pullup_enable_pin	= -EINVAL,
+  };
+
+  static struct platform_device foo_w1_device = {
+	.name			= "w1-gpio",
+	.id			= -1,
+	.dev.platform_data	= &foo_w1_gpio_pdata,
+  };
+
+  ...
+	at91_set_GPIO_periph(foo_w1_gpio_pdata.pin, 1);
+	at91_set_multi_drive(foo_w1_gpio_pdata.pin, 1);
+	gpiod_add_lookup_table(&foo_w1_gpiod_table);
+	platform_device_register(&foo_w1_device);

linux-7.2.3/Documentation/w1/masters/w1-uart.rst

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+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+=====================
+Kernel driver w1-uart
+=====================
+
+Author: Christoph Winklhofer <cj.winklhofer@gmail.com>
+
+
+Description
+-----------
+
+UART 1-Wire bus driver. The driver utilizes the UART interface via the
+Serial Device Bus to create the 1-Wire timing patterns as described in
+the document `"Using a UART to Implement a 1-Wire Bus Master"`_.
+
+.. _"Using a UART to Implement a 1-Wire Bus Master": https://www.analog.com/en/technical-articles/using-a-uart-to-implement-a-1wire-bus-master.html
+
+In short, the UART peripheral must support full-duplex and operate in
+open-drain mode. The timing patterns are generated by a specific
+combination of baud-rate and transmitted byte, which corresponds to a
+1-Wire read bit, write bit or reset pulse.
+
+For instance the timing pattern for a 1-Wire reset and presence detect uses
+the baud-rate 9600, i.e. 104.2 us per bit. The transmitted byte 0xf0 over
+UART (least significant bit first, start-bit low) sets the reset low time
+for 1-Wire to 521 us. A present 1-Wire device changes the received byte by
+pulling the line low, which is used by the driver to evaluate the result of
+the 1-Wire operation.
+
+Similar for a 1-Wire read bit or write bit, which uses the baud-rate
+115200, i.e. 8.7 us per bit. The transmitted byte 0x80 is used for a
+Write-0 operation (low time 69.6us) and the byte 0xff for Read-0, Read-1
+and Write-1 (low time 8.7us).
+
+The default baud-rate for reset and presence detection is 9600 and for
+a 1-Wire read or write operation 115200. In case the actual baud-rate
+is different from the requested one, the transmitted byte is adapted
+to generate the 1-Wire timing patterns.
+
+
+Usage
+-----
+
+Specify the UART 1-wire bus in the device tree by adding the single child
+onewire to the serial node (e.g. uart0). For example:
+::
+
+  @uart0 {
+    ...
+    onewire {
+      compatible = "w1-uart";
+    };
+  };

linux-7.2.3/Documentation/w1/slaves/index.rst

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+.. SPDX-License-Identifier: GPL-2.0
+
+====================
+1-wire Slave Drivers
+====================
+
+.. toctree::
+   :maxdepth: 1
+
+   w1_ds2406
+   w1_ds2413
+   w1_ds2423
+   w1_ds2438
+   w1_ds28e04
+   w1_ds28e17
+   w1_therm

linux-7.2.3/Documentation/w1/slaves/w1_ds2406.rst

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+=======================
+w1_ds2406 kernel driver
+=======================
+
+Supported chips:
+
+  * Maxim DS2406 (and other family 0x12) addressable switches
+
+Author: Scott Alfter <scott@alfter.us>
+
+Description
+-----------
+
+The w1_ds2406 driver allows connected devices to be switched on and off.
+These chips also provide 128 bytes of OTP EPROM, but reading/writing it is
+not supported.  In TSOC-6 form, the DS2406 provides two switch outputs and
+can be provided with power on a dedicated input.  In TO-92 form, it provides
+one output and uses parasitic power only.
+
+The driver provides two sysfs files.  state is readable; it gives the
+current state of each switch, with PIO A in bit 0 and PIO B in bit 1.  The
+driver ORs this state with 0x30, so shell scripts get an ASCII 0/1/2/3 to
+work with.  output is writable; bits 0 and 1 control PIO A and B,
+respectively.  Bits 2-7 are ignored, so it's safe to write ASCII data.
+
+CRCs are checked on read and write.  Failed checks cause an I/O error to be
+returned.  On a failed write, the switch status is not changed.

linux-7.2.3/Documentation/w1/slaves/w1_ds2413.rst

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+=======================
+Kernel driver w1_ds2413
+=======================
+
+Supported chips:
+
+  * Maxim DS2413 1-Wire Dual Channel Addressable Switch
+
+supported family codes:
+
+        ================        ====
+        W1_FAMILY_DS2413        0x3A
+        ================        ====
+
+Author: Mariusz Bialonczyk <manio@skyboo.net>
+
+Description
+-----------
+
+The DS2413 chip has two open-drain outputs (PIO A and PIO B).
+Support is provided through the sysfs files "output" and "state".
+
+Reading state
+-------------
+The "state" file provides one-byte value which is in the same format as for
+the chip PIO_ACCESS_READ command (refer the datasheet for details):
+
+======== =============================================================
+Bit 0:   PIOA Pin State
+Bit 1:   PIOA Output Latch State
+Bit 2:   PIOB Pin State
+Bit 3:   PIOB Output Latch State
+Bit 4-7: Complement of Bit 3 to Bit 0 (verified by the kernel module)
+======== =============================================================
+
+This file is readonly.
+
+Writing output
+--------------
+You can set the PIO pins using the "output" file.
+It is writable, you can write one-byte value to this sysfs file.
+Similarly the byte format is the same as for the PIO_ACCESS_WRITE command:
+
+======== ======================================
+Bit 0:   PIOA
+Bit 1:   PIOB
+Bit 2-7: No matter (driver will set it to "1"s)
+======== ======================================
+
+
+The chip has some kind of basic protection against transmission errors.
+When reading the state, there is a four complement bits.
+The driver is checking this complement, and when it is wrong then it is
+returning I/O error.
+
+When writing output, the master must repeat the PIO Output Data byte in
+its inverted form and it is waiting for a confirmation.
+If the write is unsuccessful for three times, the write also returns
+I/O error.

linux-7.2.3/Documentation/w1/slaves/w1_ds2423.rst

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+Kernel driver w1_ds2423
+=======================
+
+Supported chips:
+
+  * Maxim DS2423 based counter devices.
+
+supported family codes:
+
+        ===============	====
+	W1_THERM_DS2423	0x1D
+        ===============	====
+
+Author: Mika Laitio <lamikr@pilppa.org>
+
+Description
+-----------
+
+Support is provided through the sysfs w1_slave file. Each opening and
+read sequence of w1_slave file initiates the read of counters and ram
+available in DS2423 pages 12 - 15.
+
+Result of each page is provided as an ASCII output where each counter
+value and associated ram buffer is outpputed to own line.
+
+Each lines will contain the values of 42 bytes read from the counter and
+memory page along the crc=YES or NO for indicating whether the read operation
+was successful and CRC matched.
+If the operation was successful, there is also in the end of each line
+a counter value expressed as an integer after c=
+
+Meaning of 42 bytes represented is following:
+
+ - 1 byte from ram page
+ - 4 bytes for the counter value
+ - 4 zero bytes
+ - 2 bytes for crc16 which was calculated from the data read since the previous crc bytes
+ - 31 remaining bytes from the ram page
+ - crc=YES/NO indicating whether read was ok and crc matched
+ - c=<int> current counter value
+
+example from the successful read::
+
+  00 02 00 00 00 00 00 00 00 6d 38 00 ff ff 00 00 fe ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=2
+  00 02 00 00 00 00 00 00 00 e0 1f 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=2
+  00 29 c6 5d 18 00 00 00 00 04 37 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=408798761
+  00 05 00 00 00 00 00 00 00 8d 39 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff crc=YES c=5
+
+example from the read with crc errors::
+
+  00 02 00 00 00 00 00 00 00 6d 38 00 ff ff 00 00 fe ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=2
+  00 02 00 00 22 00 00 00 00 e0 1f 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=NO
+  00 e1 61 5d 19 00 00 00 00 df 0b 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=NO
+  00 05 00 00 20 00 00 00 00 8d 39 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff crc=NO

linux-7.2.3/Documentation/w1/slaves/w1_ds2438.rst

@@ -0,0 +1,86 @@
+Kernel driver w1_ds2438
+=======================
+
+Supported chips:
+
+  * Maxim DS2438 Smart Battery Monitor
+
+supported family codes:
+        ================        ====
+        W1_FAMILY_DS2438        0x26
+        ================        ====
+
+Author: Mariusz Bialonczyk <manio@skyboo.net>
+
+Description
+-----------
+
+The DS2438 chip provides several functions that are desirable to carry in
+a battery pack. It also has a 40 bytes of nonvolatile EEPROM.
+Because the ability of temperature, current and voltage measurement, the chip
+is also often used in weather stations and applications such as: rain gauge,
+wind speed/direction measuring, humidity sensing, etc.
+
+Current support is provided through the following sysfs files (all files
+except "iad" and "offset" are readonly):
+
+"iad"
+-----
+This file controls the 'Current A/D Control Bit' (IAD) in the
+Status/Configuration Register.
+Writing a zero value will clear the IAD bit and disables the current
+measurements.
+Writing value "1" is setting the IAD bit (enables the measurements).
+The IAD bit is enabled by default in the DS2438.
+
+When writing to sysfs file bits 2-7 are ignored, so it's safe to write ASCII.
+An I/O error is returned when there is a problem setting the new value.
+
+"page0"
+-------
+This file provides full 8 bytes of the chip Page 0 (00h).
+This page contains the most frequently accessed information of the DS2438.
+Internally when this file is read, the additional CRC byte is also obtained
+from the slave device. If it is correct, the 8 bytes page data are passed
+to userspace, otherwise an I/O error is returned.
+
+"page1"
+-------
+This file provides full 8 bytes of the chip Page 1 (01h).
+This page contains the ICA, elapsed time meter and current offset data of the DS2438.
+Internally when this file is read, the additional CRC byte is also obtained
+from the slave device. If it is correct, the 8 bytes page data are passed
+to userspace, otherwise an I/O error is returned.
+
+"offset"
+--------
+This file controls the 2-byte Offset Register of the chip.
+Writing a 2-byte value will change the Offset Register, which changes the
+current measurement done by the chip. Changing this register to the two's complement
+of the current register while forcing zero current through the load will calibrate
+the chip, canceling offset errors in the current ADC.
+
+
+"temperature"
+-------------
+Opening and reading this file initiates the CONVERT_T (temperature conversion)
+command of the chip, afterwards the temperature is read from the device
+registers and provided as an ASCII decimal value.
+
+Important: The returned value has to be divided by 256 to get a real
+temperature in degrees Celsius.
+
+"vad", "vdd"
+------------
+Opening and reading this file initiates the CONVERT_V (voltage conversion)
+command of the chip.
+
+Depending on a sysfs filename a different input for the A/D will be selected:
+
+vad:
+    general purpose A/D input (VAD)
+vdd:
+    battery input (VDD)
+
+After the voltage conversion the value is returned as decimal ASCII.
+Note: To get a volts the value has to be divided by 100.

linux-7.2.3/Documentation/w1/slaves/w1_ds28e04.rst

@@ -0,0 +1,41 @@
+========================
+Kernel driver w1_ds28e04
+========================
+
+Supported chips:
+
+  * Maxim DS28E04-100 4096-Bit Addressable 1-Wire EEPROM with PIO
+
+supported family codes:
+
+        =================	====
+	W1_FAMILY_DS28E04	0x1C
+        =================	====
+
+Author: Markus Franke, <franke.m@sebakmt.com> <franm@hrz.tu-chemnitz.de>
+
+Description
+-----------
+
+Support is provided through the sysfs files "eeprom" and "pio". CRC checking
+during memory accesses can optionally be enabled/disabled via the device
+attribute "crccheck". The strong pull-up can optionally be enabled/disabled
+via the module parameter "w1_strong_pullup".
+
+Memory Access
+
+	A read operation on the "eeprom" file reads the given amount of bytes
+	from the EEPROM of the DS28E04.
+
+	A write operation on the "eeprom" file writes the given byte sequence
+	to the EEPROM of the DS28E04. If CRC checking mode is enabled only
+	fully aligned blocks of 32 bytes with valid CRC16 values (in bytes 30
+	and 31) are allowed to be written.
+
+PIO Access
+
+	The 2 PIOs of the DS28E04-100 are accessible via the "pio" sysfs file.
+
+	The current status of the PIO's is returned as an 8 bit value. Bit 0/1
+	represent the state of PIO_0/PIO_1. Bits 2..7 do not care. The PIO's are
+	driven low-active, i.e. the driver delivers/expects low-active values.

linux-7.2.3/Documentation/w1/slaves/w1_ds28e17.rst

@@ -0,0 +1,72 @@
+========================
+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.

linux-7.2.3/Documentation/w1/slaves/w1_therm.rst

@@ -0,0 +1,144 @@
+======================
+Kernel driver w1_therm
+======================
+
+Supported chips:
+
+  * Maxim ds18*20 based temperature sensors.
+  * Maxim ds1825 based temperature sensors.
+  * GXCAS GX20MH01 temperature sensor.
+  * Maxim MAX31850 thermoelement interface.
+
+Author: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
+
+
+Description
+-----------
+
+w1_therm provides basic temperature conversion for ds18*20, ds28ea00, GX20MH01
+and MAX31850 devices.
+
+Supported family codes:
+
+====================	====
+W1_THERM_DS18S20	0x10
+W1_THERM_DS1822		0x22
+W1_THERM_DS18B20	0x28
+W1_THERM_DS1825		0x3B
+W1_THERM_DS28EA00	0x42
+====================	====
+
+Support is provided through the sysfs entry ``w1_slave``. Each open and
+read sequence will initiate a temperature conversion, then provide two
+lines of ASCII output. The first line contains the nine hex bytes
+read along with a calculated crc value and YES or NO if it matched.
+If the crc matched the returned values are retained. The second line
+displays the retained values along with a temperature in millidegrees
+Centigrade after t=.
+
+Alternatively, temperature can be read using ``temperature`` sysfs, it
+returns only the temperature in millidegrees Centigrade.
+
+A bulk read of all devices on the bus could be done writing ``trigger``
+to ``therm_bulk_read`` entry at w1_bus_master level. This will
+send the convert command to all devices on the bus, and if parasite
+powered devices are detected on the bus (and strong pullup is enabled
+in the module), it will drive the line high during the longer conversion
+time required by parasited powered device on the line. Reading
+``therm_bulk_read`` will return 0 if no bulk conversion pending,
+-1 if at least one sensor still in conversion, 1 if conversion is complete
+but at least one sensor value has not been read yet. Result temperature is
+then accessed by reading the ``temperature`` entry of each device, which
+may return empty if conversion is still in progress. Note that if a bulk
+read is sent but one sensor is not read immediately, the next access to
+``temperature`` on this device will return the temperature measured at the
+time of issue of the bulk read command (not the current temperature).
+
+A strong pullup will be applied during the conversion if required.
+
+``conv_time`` is used to get current conversion time (read), and
+adjust it (write). A temperature conversion time depends on the device type and
+its current resolution. Default conversion time is set by the driver according
+to the device datasheet. A conversion time for many original device clones
+deviate from datasheet specs. There are three options: 1) manually set the
+correct conversion time by writing a value in milliseconds to ``conv_time``; 2)
+auto measure and set a conversion time by writing ``1`` to
+``conv_time``; 3) use ``features`` to enable poll for conversion
+completion. Options 2, 3 can't be used in parasite power mode. To get back to
+the default conversion time write ``0`` to ``conv_time``.
+
+Writing a resolution value (in bits) to ``w1_slave`` will change the
+precision of the sensor for the next readings. Allowed resolutions are defined by
+the sensor. Resolution is reset when the sensor gets power-cycled.
+
+To store the current resolution in EEPROM, write ``0`` to ``w1_slave``.
+Since the EEPROM has a limited amount of writes (>50k), this command should be
+used wisely.
+
+Alternatively, resolution can be read or written using the dedicated
+``resolution`` entry on each device, if supported by the sensor.
+
+Some non-genuine DS18B20 chips are fixed in 12-bit mode only, so the actual
+resolution is read back from the chip and verified.
+
+Note: Changing the resolution reverts the conversion time to default.
+
+The write-only sysfs entry ``eeprom_cmd`` is an alternative for EEPROM operations.
+Write ``save`` to save device RAM to EEPROM. Write ``restore`` to restore EEPROM
+data in device RAM.
+
+``ext_power`` entry allows checking the power state of each device. Reads
+``0`` if the device is parasite powered, ``1`` if the device is externally powered.
+
+Sysfs ``alarms`` allow read or write TH and TL (Temperature High an Low) alarms.
+Values shall be space separated and in the device range (typical -55 degC
+to 125 degC). Values are integer as they are store in a 8bit register in
+the device. Lowest value is automatically put to TL. Once set, alarms could
+be search at master level.
+
+The module parameter strong_pullup can be set to 0 to disable the
+strong pullup, 1 to enable autodetection or 2 to force strong pullup.
+In case of autodetection, the driver will use the "READ POWER SUPPLY"
+command to check if there are pariste powered devices on the bus.
+If so, it will activate the master's strong pullup.
+In case the detection of parasite devices using this command fails
+(seems to be the case with some DS18S20) the strong pullup can
+be force-enabled.
+
+If the strong pullup is enabled, the master's strong pullup will be
+driven when the conversion is taking place, provided the master driver
+does support the strong pullup (or it falls back to a pullup
+resistor).  The DS18b20 temperature sensor specification lists a
+maximum current draw of 1.5mA and that a 5k pullup resistor is not
+sufficient.  The strong pullup is designed to provide the additional
+current required.
+
+The DS28EA00 provides an additional two pins for implementing a sequence
+detection algorithm.  This feature allows you to determine the physical
+location of the chip in the 1-wire bus without needing pre-existing
+knowledge of the bus ordering.  Support is provided through the sysfs
+``w1_seq``. The file will contain a single line with an integer value
+representing the device index in the bus starting at 0.
+
+``features`` sysfs entry controls optional driver settings per device.
+Insufficient power in parasite mode, line noise and insufficient conversion
+time may lead to conversion failure. Original DS18B20 and some clones allow for
+detection of invalid conversion. Write bit mask ``1`` to ``features`` to enable
+checking the conversion success. If byte 6 of scratchpad memory is 0xC after
+conversion and temperature reads 85.00 (powerup value) or 127.94 (insufficient
+power), the driver returns a conversion error. Bit mask ``2`` enables poll for
+conversion completion (normal power only) by generating read cycles on the bus
+after conversion starts. In parasite power mode this feature is not available.
+Feature bit masks may be combined (OR). More details in
+Documentation/ABI/testing/sysfs-driver-w1_therm
+
+GX20MH01 device shares family number 0x28 with DS18*20. The device is generally
+compatible with DS18B20. Added are lowest 2\ :sup:`-5`, 2\ :sup:`-6` temperature
+bits in Config register; R2 bit in Config register enabling 13 and 14 bit
+resolutions. The device is powered up in 14-bit resolution mode. The conversion
+times specified in the datasheet are too low and have to be increased. The
+device supports driver features ``1`` and ``2``.
+
+MAX31850 device shares family number 0x3B with DS1825. The device is generally
+compatible with DS1825. The higher 4 bits of Config register read all 1,
+indicating 15, but the device is always operating in 14-bit resolution mode.

linux-7.2.3/Documentation/w1/w1-generic.rst

@@ -0,0 +1,133 @@
+=========================================
+Introduction to the 1-wire (w1) subsystem
+=========================================
+
+The 1-wire bus is a simple master-slave bus that communicates via a single
+signal wire (plus ground, so two wires).
+
+Devices communicate on the bus by pulling the signal to ground via an open
+drain output and by sampling the logic level of the signal line.
+
+The w1 subsystem provides the framework for managing w1 masters and
+communication with slaves.
+
+All w1 slave devices must be connected to a w1 bus master device.
+
+Example w1 master devices:
+
+    - DS9490 usb device
+    - W1-over-GPIO
+    - DS2482 (i2c to w1 bridge)
+    - Emulated devices, such as a RS232 converter, parallel port adapter, etc
+
+
+What does the w1 subsystem do?
+------------------------------
+
+When a w1 master driver registers with the w1 subsystem, the following occurs:
+
+ - sysfs entries for that w1 master are created
+ - the w1 bus is periodically searched for new slave devices
+
+When a device is found on the bus, w1 core tries to load the driver for its family
+and check if it is loaded. If so, the family driver is attached to the slave.
+If there is no driver for the family, default one is assigned, which allows to perform
+almost any kind of operations. Each logical operation is a transaction
+in nature, which can contain several (two or one) low-level operations.
+Let's see how one can read EEPROM context:
+1. one must write control buffer, i.e. buffer containing command byte
+and two byte address. At this step bus is reset and appropriate device
+is selected using either W1_SKIP_ROM or W1_MATCH_ROM command.
+Then provided control buffer is being written to the wire.
+2. reading. This will issue reading eeprom response.
+
+It is possible that between 1. and 2. w1 master thread will reset bus for searching
+and slave device will be even removed, but in this case 0xff will
+be read, since no device was selected.
+
+
+W1 device families
+------------------
+
+Slave devices are handled by a driver written for a family of w1 devices.
+
+A family driver populates a struct w1_family_ops (see w1_family.h) and
+registers with the w1 subsystem.
+
+Current family drivers:
+
+w1_therm
+  - (ds18?20 thermal sensor family driver)
+    provides temperature reading function which is bound to ->rbin() method
+    of the above w1_family_ops structure.
+
+w1_smem
+  - driver for simple 64bit memory cell provides ID reading method.
+
+You can call above methods by reading appropriate sysfs files.
+
+
+What does a w1 master driver need to implement?
+-----------------------------------------------
+
+The driver for w1 bus master must provide at minimum two functions.
+
+Emulated devices must provide the ability to set the output signal level
+(write_bit) and sample the signal level (read_bit).
+
+Devices that support the 1-wire natively must provide the ability to write and
+sample a bit (touch_bit) and reset the bus (reset_bus).
+
+Most hardware provides higher-level functions that offload w1 handling.
+See struct w1_bus_master definition in w1.h for details.
+
+
+w1 master sysfs interface
+-------------------------
+
+========================= =====================================================
+<xx-xxxxxxxxxxxx>         A directory for a found device. The format is
+                          family-serial
+bus                       (standard) symlink to the w1 bus
+driver                    (standard) symlink to the w1 driver
+w1_master_add             (rw) manually register a slave device
+w1_master_attempts        (ro) the number of times a search was attempted
+w1_master_max_slave_count (rw) maximum number of slaves to search for at a time
+w1_master_name            (ro) the name of the device (w1_bus_masterX)
+w1_master_pullup          (rw) 5V strong pullup 0 enabled, 1 disabled
+w1_master_remove          (rw) manually remove a slave device
+w1_master_search          (rw) the number of searches left to do,
+                          -1=continual (default)
+w1_master_slave_count     (ro) the number of slaves found
+w1_master_slaves          (ro) the names of the slaves, one per line
+w1_master_timeout         (ro) the delay in seconds between searches
+w1_master_timeout_us      (ro) the delay in microseconds between searches
+========================= =====================================================
+
+If you have a w1 bus that never changes (you don't add or remove devices),
+you can set the module parameter search_count to a small positive number
+for an initially small number of bus searches.  Alternatively it could be
+set to zero, then manually add the slave device serial numbers by
+w1_master_add device file.  The w1_master_add and w1_master_remove files
+generally only make sense when searching is disabled, as a search will
+redetect manually removed devices that are present and timeout manually
+added devices that aren't on the bus.
+
+Bus searches occur at an interval, specified as a sum of timeout and
+timeout_us module parameters (either of which may be 0) for as long as
+w1_master_search remains greater than 0 or is -1.  Each search attempt
+decrements w1_master_search by 1 (down to 0) and increments
+w1_master_attempts by 1.
+
+w1 slave sysfs interface
+------------------------
+
+=================== ============================================================
+bus                 (standard) symlink to the w1 bus
+driver              (standard) symlink to the w1 driver
+name                the device name, usually the same as the directory name
+w1_slave            (optional) a binary file whose meaning depends on the
+                    family driver
+rw		    (optional) created for slave devices which do not have
+		    appropriate family driver. Allows to read/write binary data.
+=================== ============================================================

linux-7.2.3/Documentation/w1/w1-netlink.rst

@@ -0,0 +1,202 @@
+===============================================
+Userspace communication protocol over connector
+===============================================
+
+Message types
+=============
+
+There are three types of messages between w1 core and userspace:
+
+1. Events. They are generated each time a new master or slave device
+   is found either due to automatic or requested search.
+2. Userspace commands.
+3. Replies to userspace commands.
+
+
+Protocol
+========
+
+::
+
+  [struct cn_msg] - connector header.
+	Its length field is equal to size of the attached data
+  [struct w1_netlink_msg] - w1 netlink header.
+	__u8 type 	- message type.
+			W1_LIST_MASTERS
+				list current bus masters
+			W1_SLAVE_ADD/W1_SLAVE_REMOVE
+				slave add/remove events
+			W1_MASTER_ADD/W1_MASTER_REMOVE
+				master add/remove events
+			W1_MASTER_CMD
+				userspace command for bus master
+				device (search/alarm search)
+			W1_SLAVE_CMD
+				userspace command for slave device
+				(read/write/touch)
+	__u8 status	- error indication from kernel
+	__u16 len	- size of data attached to this header data
+	union {
+		__u8 id[8];			 - slave unique device id
+		struct w1_mst {
+			__u32		id;	 - master's id
+			__u32		res;	 - reserved
+		} mst;
+	} id;
+
+  [struct w1_netlink_cmd] - command for given master or slave device.
+	__u8 cmd	- command opcode.
+			W1_CMD_READ 	- read command
+			W1_CMD_WRITE	- write command
+			W1_CMD_SEARCH	- search command
+			W1_CMD_ALARM_SEARCH - alarm search command
+			W1_CMD_TOUCH	- touch command
+				(write and sample data back to userspace)
+			W1_CMD_RESET	- send bus reset
+			W1_CMD_SLAVE_ADD	- add slave to kernel list
+			W1_CMD_SLAVE_REMOVE	- remove slave from kernel list
+			W1_CMD_LIST_SLAVES	- get slaves list from kernel
+	__u8 res	- reserved
+	__u16 len	- length of data for this command
+		For read command data must be allocated like for write command
+	__u8 data[0]	- data for this command
+
+
+Each connector message can include one or more w1_netlink_msg with
+zero or more attached w1_netlink_cmd messages.
+
+For event messages there are no w1_netlink_cmd embedded structures,
+only connector header and w1_netlink_msg structure with "len" field
+being zero and filled type (one of event types) and id:
+either 8 bytes of slave unique id in host order,
+or master's id, which is assigned to bus master device
+when it is added to w1 core.
+
+Currently replies to userspace commands are only generated for read
+command request. One reply is generated exactly for one w1_netlink_cmd
+read request. Replies are not combined when sent - i.e. typical reply
+messages looks like the following::
+
+  [cn_msg][w1_netlink_msg][w1_netlink_cmd]
+  cn_msg.len = sizeof(struct w1_netlink_msg) +
+	     sizeof(struct w1_netlink_cmd) +
+	     cmd->len;
+  w1_netlink_msg.len = sizeof(struct w1_netlink_cmd) + cmd->len;
+  w1_netlink_cmd.len = cmd->len;
+
+Replies to W1_LIST_MASTERS should send a message back to the userspace
+which will contain list of all registered master ids in the following
+format::
+
+	cn_msg (CN_W1_IDX.CN_W1_VAL as id, len is equal to sizeof(struct
+	w1_netlink_msg) plus number of masters multiplied by 4)
+	w1_netlink_msg (type: W1_LIST_MASTERS, len is equal to
+		number of masters multiplied by 4 (u32 size))
+	id0 ... idN
+
+Each message is at most 4k in size, so if number of master devices
+exceeds this, it will be split into several messages.
+
+W1 search and alarm search commands.
+
+request::
+
+  [cn_msg]
+    [w1_netlink_msg type = W1_MASTER_CMD
+	id is equal to the bus master id to use for searching]
+    [w1_netlink_cmd cmd = W1_CMD_SEARCH or W1_CMD_ALARM_SEARCH]
+
+reply::
+
+  [cn_msg, ack = 1 and increasing, 0 means the last message,
+	seq is equal to the request seq]
+  [w1_netlink_msg type = W1_MASTER_CMD]
+  [w1_netlink_cmd cmd = W1_CMD_SEARCH or W1_CMD_ALARM_SEARCH
+	len is equal to number of IDs multiplied by 8]
+  [64bit-id0 ... 64bit-idN]
+
+Length in each header corresponds to the size of the data behind it, so
+w1_netlink_cmd->len = N * 8; where N is number of IDs in this message.
+Can be zero.
+
+::
+
+  w1_netlink_msg->len = sizeof(struct w1_netlink_cmd) + N * 8;
+  cn_msg->len = sizeof(struct w1_netlink_msg) +
+	      sizeof(struct w1_netlink_cmd) +
+	      N*8;
+
+W1 reset command::
+
+  [cn_msg]
+    [w1_netlink_msg type = W1_MASTER_CMD
+	id is equal to the bus master id to use for searching]
+    [w1_netlink_cmd cmd = W1_CMD_RESET]
+
+
+Command status replies
+======================
+
+Each command (either root, master or slave with or without w1_netlink_cmd
+structure) will be 'acked' by the w1 core. Format of the reply is the same
+as request message except that length parameters do not account for data
+requested by the user, i.e. read/write/touch IO requests will not contain
+data, so w1_netlink_cmd.len will be 0, w1_netlink_msg.len will be size
+of the w1_netlink_cmd structure and cn_msg.len will be equal to the sum
+of the sizeof(struct w1_netlink_msg) and sizeof(struct w1_netlink_cmd).
+If reply is generated for master or root command (which do not have
+w1_netlink_cmd attached), reply will contain only cn_msg and w1_netlink_msg
+structures.
+
+w1_netlink_msg.status field will carry positive error value
+(EINVAL for example) or zero in case of success.
+
+All other fields in every structure will mirror the same parameters in the
+request message (except lengths as described above).
+
+Status reply is generated for every w1_netlink_cmd embedded in the
+w1_netlink_msg, if there are no w1_netlink_cmd structures,
+reply will be generated for the w1_netlink_msg.
+
+All w1_netlink_cmd command structures are handled in every w1_netlink_msg,
+even if there were errors, only length mismatch interrupts message processing.
+
+
+Operation steps in w1 core when new command is received
+=======================================================
+
+When new message (w1_netlink_msg) is received w1 core detects if it is
+master or slave request, according to w1_netlink_msg.type field.
+Then master or slave device is searched for.
+When found, master device (requested or those one on where slave device
+is found) is locked. If slave command is requested, then reset/select
+procedure is started to select given device.
+
+Then all requested in w1_netlink_msg operations are performed one by one.
+If command requires reply (like read command) it is sent on command completion.
+
+When all commands (w1_netlink_cmd) are processed master device is unlocked
+and next w1_netlink_msg header processing started.
+
+
+Connector [1] specific documentation
+====================================
+
+Each connector message includes two u32 fields as "address".
+w1 uses CN_W1_IDX and CN_W1_VAL defined in include/linux/connector.h header.
+Each message also includes sequence and acknowledge numbers.
+Sequence number for event messages is appropriate bus master sequence number
+increased with each event message sent "through" this master.
+Sequence number for userspace requests is set by userspace application.
+Sequence number for reply is the same as was in request, and
+acknowledge number is set to seq+1.
+
+
+Additional documentation, source code examples
+==============================================
+
+1. Documentation/driver-api/connector.rst
+2. https://github.com/bioothod/w1
+
+   This archive includes userspace application w1d.c which uses
+   read/write/search commands for all master/slave devices found on the bus.