Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

18 files changed, 1146 insertions, 0 deletions

diff --git a/Documentation/w1/index.rst b/Documentation/w1/index.rst
new file mode 100644
index 000000000..2e7bd8afe
--- /dev/null
+++ b/Documentation/w1/index.rst
@@ -0,0 +1,14 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+1-Wire Subsystem
+================
+
+.. toctree::
+   :maxdepth: 1
+
+
+   w1-generic.rst
+   w1-netlink.rst
+   masters/index
+   slaves/index
diff --git a/Documentation/w1/masters/ds2482.rst b/Documentation/w1/masters/ds2482.rst
new file mode 100644
index 000000000..5862024e4
--- /dev/null
+++ b/Documentation/w1/masters/ds2482.rst
@@ -0,0 +1,39 @@
+====================
+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
diff --git a/Documentation/w1/masters/ds2490.rst b/Documentation/w1/masters/ds2490.rst
new file mode 100644
index 000000000..842e7ae80
--- /dev/null
+++ b/Documentation/w1/masters/ds2490.rst
@@ -0,0 +1,72 @@
+====================
+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>
diff --git a/Documentation/w1/masters/index.rst b/Documentation/w1/masters/index.rst
new file mode 100644
index 000000000..871442c7f
--- /dev/null
+++ b/Documentation/w1/masters/index.rst
@@ -0,0 +1,15 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================
+1-wire Master Drivers
+=====================
+
+.. toctree::
+   :maxdepth: 1
+
+   ds2482
+   ds2490
+   mxc-w1
+   omap-hdq
+   w1-gpio
+   w1-uart
diff --git a/Documentation/w1/masters/mxc-w1.rst b/Documentation/w1/masters/mxc-w1.rst
new file mode 100644
index 000000000..334f98931
--- /dev/null
+++ b/Documentation/w1/masters/mxc-w1.rst
@@ -0,0 +1,17 @@
+====================
+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>
diff --git a/Documentation/w1/masters/omap-hdq.rst b/Documentation/w1/masters/omap-hdq.rst
new file mode 100644
index 000000000..2ecf572be
--- /dev/null
+++ b/Documentation/w1/masters/omap-hdq.rst
@@ -0,0 +1,54 @@
+========================================
+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/ti,hdq.yaml for more details).
+By default driver is in HDQ mode.
diff --git a/Documentation/w1/masters/w1-gpio.rst b/Documentation/w1/masters/w1-gpio.rst
new file mode 100644
index 000000000..152366055
--- /dev/null
+++ b/Documentation/w1/masters/w1-gpio.rst
@@ -0,0 +1,47 @@
+=====================
+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);
diff --git a/Documentation/w1/masters/w1-uart.rst b/Documentation/w1/masters/w1-uart.rst
new file mode 100644
index 000000000..8d0f12217
--- /dev/null
+++ b/Documentation/w1/masters/w1-uart.rst
@@ -0,0 +1,54 @@
+.. 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";
+    };
+  };
diff --git a/Documentation/w1/slaves/index.rst b/Documentation/w1/slaves/index.rst
new file mode 100644
index 000000000..a210f38c8
--- /dev/null
+++ b/Documentation/w1/slaves/index.rst
@@ -0,0 +1,16 @@
+.. 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
diff --git a/Documentation/w1/slaves/w1_ds2406.rst b/Documentation/w1/slaves/w1_ds2406.rst
new file mode 100644
index 000000000..d3e682660
--- /dev/null
+++ b/Documentation/w1/slaves/w1_ds2406.rst
@@ -0,0 +1,27 @@
+=======================
+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.
diff --git a/Documentation/w1/slaves/w1_ds2413.rst b/Documentation/w1/slaves/w1_ds2413.rst
new file mode 100644
index 000000000..c15bb5b91
--- /dev/null
+++ b/Documentation/w1/slaves/w1_ds2413.rst
@@ -0,0 +1,59 @@
+=======================
+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.
diff --git a/Documentation/w1/slaves/w1_ds2423.rst b/Documentation/w1/slaves/w1_ds2423.rst
new file mode 100644
index 000000000..755d659ad
--- /dev/null
+++ b/Documentation/w1/slaves/w1_ds2423.rst
@@ -0,0 +1,54 @@
+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
diff --git a/Documentation/w1/slaves/w1_ds2438.rst b/Documentation/w1/slaves/w1_ds2438.rst
new file mode 100644
index 000000000..4fa671fbc
--- /dev/null
+++ b/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.
diff --git a/Documentation/w1/slaves/w1_ds28e04.rst b/Documentation/w1/slaves/w1_ds28e04.rst
new file mode 100644
index 000000000..b12b11889
--- /dev/null
+++ b/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.
diff --git a/Documentation/w1/slaves/w1_ds28e17.rst b/Documentation/w1/slaves/w1_ds28e17.rst
new file mode 100644
index 000000000..e2d9f96d8
--- /dev/null
+++ b/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.
diff --git a/Documentation/w1/slaves/w1_therm.rst b/Documentation/w1/slaves/w1_therm.rst
new file mode 100644
index 000000000..6aec04dd0
--- /dev/null
+++ b/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.
diff --git a/Documentation/w1/w1-generic.rst b/Documentation/w1/w1-generic.rst
new file mode 100644
index 000000000..96a042585
--- /dev/null
+++ b/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.
+=================== ============================================================
diff --git a/Documentation/w1/w1-netlink.rst b/Documentation/w1/w1-netlink.rst
new file mode 100644
index 000000000..ff281713e
--- /dev/null
+++ b/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.