Merge branch 'i2c/for-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux

Pull i2c updates from Wolfram Sang:

 - if a host can be a client, too, the I2C core can now use it to
   emulate SMBus HostNotify support (STM32 and R-Car added this so far)

 - also for client mode, a testunit has been added. It can create rare
   situations on the bus, so host controllers can be tested

 - a binding has been added to mark the bus as "single-master". This
   allows for better timeout detections

 - new driver for Mellanox Bluefield

 - massive refactoring of the Tegra driver

 - EEPROMs recognized by the at24 driver can now have custom names

 - rest is driver updates

* 'i2c/for-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (80 commits)
  Documentation: i2c: add testunit docs to index
  i2c: tegra: Improve driver module description
  i2c: tegra: Clean up whitespaces, newlines and indentation
  i2c: tegra: Clean up and improve comments
  i2c: tegra: Clean up printk messages
  i2c: tegra: Clean up variable names
  i2c: tegra: Improve formatting of variables
  i2c: tegra: Check errors for both positive and negative values
  i2c: tegra: Factor out hardware initialization into separate function
  i2c: tegra: Factor out register polling into separate function
  i2c: tegra: Factor out packet header setup from tegra_i2c_xfer_msg()
  i2c: tegra: Factor out error recovery from tegra_i2c_xfer_msg()
  i2c: tegra: Rename wait/poll functions
  i2c: tegra: Remove "dma" variable from tegra_i2c_xfer_msg()
  i2c: tegra: Remove redundant check in tegra_i2c_issue_bus_clear()
  i2c: tegra: Remove likely/unlikely from the code
  i2c: tegra: Remove outdated barrier()
  i2c: tegra: Clean up variable types
  i2c: tegra: Reorder location of functions in the code
  i2c: tegra: Clean up probe function
  ...

3 files changed, 71 insertions, 0 deletions

diff --git a/Documentation/i2c/busses/i2c-i801.rst b/Documentation/i2c/busses/i2c-i801.rst
index faf32330c335..42bbdd6e7fd8 100644
--- a/Documentation/i2c/busses/i2c-i801.rst
+++ b/Documentation/i2c/busses/i2c-i801.rst
@@ -44,6 +44,7 @@ Supported adapters:
   * Intel Tiger Lake (PCH)
   * Intel Jasper Lake (SOC)
   * Intel Emmitsburg (PCH)
+  * Intel Alder Lake (PCH)
 
    Datasheets: Publicly available at the Intel website
 
diff --git a/Documentation/i2c/index.rst b/Documentation/i2c/index.rst
index 8a2ad3845191..8b76217e370a 100644
--- a/Documentation/i2c/index.rst
+++ b/Documentation/i2c/index.rst
@@ -47,6 +47,7 @@ Slave I2C
 
    slave-interface
    slave-eeprom-backend
+   slave-testunit-backend
 
 Advanced topics
 ===============
diff --git a/Documentation/i2c/slave-testunit-backend.rst b/Documentation/i2c/slave-testunit-backend.rst
new file mode 100644
index 000000000000..2c38e64f0bac
--- /dev/null
+++ b/Documentation/i2c/slave-testunit-backend.rst
@@ -0,0 +1,69 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================================
+Linux I2C slave testunit backend
+================================
+
+by Wolfram Sang <wsa@sang-engineering.com> in 2020
+
+This backend can be used to trigger test cases for I2C bus masters which
+require a remote device with certain capabilities (and which are usually not so
+easy to obtain). Examples include multi-master testing, and SMBus Host Notify
+testing. For some tests, the I2C slave controller must be able to switch
+between master and slave mode because it needs to send data, too.
+
+Note that this is a device for testing and debugging. It should not be enabled
+in a production build. And while there is some versioning and we try hard to
+keep backward compatibility, there is no stable ABI guaranteed!
+
+Instantiating the device is regular. Example for bus 0, address 0x30:
+
+# echo "slave-testunit 0x1030" > /sys/bus/i2c/devices/i2c-0/new_device
+
+After that, you will have a write-only device listening. Reads will just return
+an 8-bit version number of the testunit. When writing, the device consists of 4
+8-bit registers and all must be written to start a testcase, i.e. you must
+always write 4 bytes to the device. The registers are:
+
+0x00 CMD   - which test to trigger
+0x01 DATAL - configuration byte 1 for the test
+0x02 DATAH - configuration byte 2 for the test
+0x03 DELAY - delay in n * 10ms until test is started
+
+Using 'i2cset' from the i2c-tools package, the generic command looks like:
+
+# i2cset -y <bus_num> <testunit_address> <CMD> <DATAL> <DATAH> <DELAY> i
+
+DELAY is a generic parameter which will delay the execution of the test in CMD.
+While a command is running (including the delay), new commands will not be
+acknowledged. You need to wait until the old one is completed.
+
+The commands are described in the following section. An invalid command will
+result in the transfer not being acknowledged.
+
+Commands
+--------
+
+0x00 NOOP (reserved for future use)
+
+0x01 READ_BYTES (also needs master mode)
+   DATAL - address to read data from (lower 7 bits, highest bit currently unused)
+   DATAH - number of bytes to read
+
+This is useful to test if your bus master driver is handling multi-master
+correctly. You can trigger the testunit to read bytes from another device on
+the bus. If the bus master under test also wants to access the bus at the same
+time, the bus will be busy. Example to read 128 bytes from device 0x50 after
+50ms of delay:
+
+# i2cset -y 0 0x30 0x01 0x50 0x80 0x05 i
+
+0x02 SMBUS_HOST_NOTIFY (also needs master mode)
+   DATAL - low byte of the status word to send
+   DATAH - high byte of the status word to send
+
+This test will send an SMBUS_HOST_NOTIFY message to the host. Note that the
+status word is currently ignored in the Linux Kernel. Example to send a
+notification after 10ms:
+
+# i2cset -y 0 0x30 0x02 0x42 0x64 0x01 i