[PATCH 2/4] w1: add missing DS2413 documentation

From: Mariusz Bialonczyk
Date: Thu Feb 16 2017 - 04:21:50 EST

Signed-off-by: Mariusz Bialonczyk <manio@xxxxxxxxxx>
Documentation/w1/slaves/00-INDEX | 2 ++
Documentation/w1/slaves/w1_ds2413 | 50 +++++++++++++++++++++++++++++++++++++++
2 files changed, 52 insertions(+)
create mode 100644 Documentation/w1/slaves/w1_ds2413

diff --git a/Documentation/w1/slaves/00-INDEX b/Documentation/w1/slaves/00-INDEX
index 6e18c70..cbcca1d 100644
--- a/Documentation/w1/slaves/00-INDEX
+++ b/Documentation/w1/slaves/00-INDEX
@@ -2,6 +2,8 @@
- This file
- The Maxim/Dallas Semiconductor ds18*20 temperature sensor.
+ - The Maxim/Dallas Semiconductor ds2413 dual channel addressable switch.
- The Maxim/Dallas Semiconductor ds2423 counter device.
diff --git a/Documentation/w1/slaves/w1_ds2413 b/Documentation/w1/slaves/w1_ds2413
new file mode 100644
index 0000000..936263a
--- /dev/null
+++ b/Documentation/w1/slaves/w1_ds2413
@@ -0,0 +1,50 @@
+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@xxxxxxxxxx>
+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.