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Subject: [PATCH 5/5] Documentation: i3c: Add I3C slave mode controller and function
Date:   Wed, 18 Oct 2023 17:58:09 -0400
Message-Id: <20231018215809.3477437-6-Frank.Li@nxp.com>
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Add I3C slave mode and tty over i3c func driver document.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
 Documentation/driver-api/i3c/index.rst        |   1 +
 .../driver-api/i3c/slave/i3c-slave-cfs.rst    | 109 ++++++++++
 .../driver-api/i3c/slave/i3c-slave.rst        | 189 ++++++++++++++++++
 .../driver-api/i3c/slave/i3c-tty-function.rst | 103 ++++++++++
 .../driver-api/i3c/slave/i3c-tty-howto.rst    | 109 ++++++++++
 Documentation/driver-api/i3c/slave/index.rst  |  13 ++
 6 files changed, 524 insertions(+)
 create mode 100644 Documentation/driver-api/i3c/slave/i3c-slave-cfs.rst
 create mode 100644 Documentation/driver-api/i3c/slave/i3c-slave.rst
 create mode 100644 Documentation/driver-api/i3c/slave/i3c-tty-function.rst
 create mode 100644 Documentation/driver-api/i3c/slave/i3c-tty-howto.rst
 create mode 100644 Documentation/driver-api/i3c/slave/index.rst

diff --git a/Documentation/driver-api/i3c/index.rst b/Documentation/driver-api/i3c/index.rst
index 783d6dad054b6..63fc51fc8bd58 100644
--- a/Documentation/driver-api/i3c/index.rst
+++ b/Documentation/driver-api/i3c/index.rst
@@ -9,3 +9,4 @@ I3C subsystem
    protocol
    device-driver-api
    master-driver-api
+   slave/index
diff --git a/Documentation/driver-api/i3c/slave/i3c-slave-cfs.rst b/Documentation/driver-api/i3c/slave/i3c-slave-cfs.rst
new file mode 100644
index 0000000000000..d78fcbc4e5587
--- /dev/null
+++ b/Documentation/driver-api/i3c/slave/i3c-slave-cfs.rst
@@ -0,0 +1,109 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================================
+Configuring I3C Slave Using CONFIGFS
+=======================================
+
+:Author: Frank Li <Frank.Li@nxp.com>
+
+The I3C Slave Core exposes configfs entry (i3c_slave) to configure the I3C
+slave function and to bind the slave function
+with the slave controller. (For introducing other mechanisms to
+configure the I3C Slave Function refer to [1]).
+
+Mounting configfs
+=================
+
+The I3C Slave Core layer creates i3c_slave directory in the mounted configfs
+directory. configfs can be mounted using the following command::
+
+	mount -t configfs none /sys/kernel/config
+
+Directory Structure
+===================
+
+The i3c_slave configfs has two directories at its root: controllers and
+functions. Every Controller device present in the system will have an entry in
+the *controllers* directory and every Function driver present in the system
+will have an entry in the *functions* directory.
+::
+
+	/sys/kernel/config/i3c_slave/
+		.. controllers/
+		.. functions/
+
+Creating Function Device
+===================
+
+Every registered Function driver will be listed in controllers directory. The
+entries corresponding to Function driver will be created by the Function core.
+::
+
+	/sys/kernel/config/i3c_slave/functions/
+		.. <Function Driver1>/
+			... <Function Device 11>/
+			... <Function Device 21>/
+			... <Function Device 31>/
+		.. <Function Driver2>/
+			... <Function Device 12>/
+			... <Function Device 22>/
+
+In order to create a <Function device> of the type probed by <Function Driver>,
+the user has to create a directory inside <Function DriverN>.
+
+Every <Function device> directory consists of the following entries that can be
+used to configure the standard configuration header of the slave function.
+(These entries are created by the framework when any new <Function Device> is
+created)
+::
+
+		.. <Function Driver1>/
+			... <Function Device 11>/
+				... vendor_id
+				... part_id
+				... bcr
+				... dcr
+				... ext_id
+				... instance_id
+				... max_read_len
+				... max_write_len
+				... vendor_info
+
+Controller Device
+==========
+
+Every registered Controller device will be listed in controllers directory. The
+entries corresponding to Controller device will be created by the Controller
+core.
+::
+
+	/sys/kernel/config/i3c_slave/controllers/
+		.. <Controller Device1>/
+			... <Symlink Function Device11>/
+		.. <Controller Device2>/
+			... <Symlink Function Device21>/
+
+The <Controller Device> directory will have a list of symbolic links to
+<Function Device>. These symbolic links should be created by the user to
+represent the functions present in the slave device. Only <Function Device>
+that represents a physical function can be linked to a Controller device.
+
+::
+
+			 | controllers/
+				| <Directory: Controller name>/
+					| <Symbolic Link: Function>
+			 | functions/
+				| <Directory: Function driver>/
+					| <Directory: Function device>/
+						| vendor_id
+						| part_id
+						| bcr
+						| dcr
+						| ext_id
+						| instance_id
+						| max_read_len
+						| max_write_len
+						| vendor_info
+
+[1] Documentation/I3C/slave/pci-slave.rst
diff --git a/Documentation/driver-api/i3c/slave/i3c-slave.rst b/Documentation/driver-api/i3c/slave/i3c-slave.rst
new file mode 100644
index 0000000000000..363421241b594
--- /dev/null
+++ b/Documentation/driver-api/i3c/slave/i3c-slave.rst
@@ -0,0 +1,189 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+:Author: Frank Li <Frank.Li@nxp.com>
+
+This document is a guide to use the I3C Slave Framework in order to create
+slave controller driver, slave function driver, and using configfs
+interface to bind the function driver to the controller driver.
+
+Introduction
+============
+
+Linux has a comprehensive I3C subsystem to support I3C controllers that
+operates in master mode. The subsystem has capability to scan I3C bus,assign
+i3c device address, load I3C driver (based on Manufacturer ID, part ID),
+support other services like hot-join, In-Band Interrupt(IBI).
+
+However the I3C controller IP integrated in some SoCs is capable of operating
+either in Master mode or Slave mode. I3C Slave Framework will add slave mode
+support in Linux. This will help to run Linux in an slave system which can
+have a wide variety of use cases from testing or validation, co-processor
+accelerator, etc.
+
+I3C Slave Core
+=================
+
+The I3C Slave Core layer comprises 3 components: the Slave Controller
+library, the Slave Function library, and the configfs layer to bind the
+slave function with the slave controller.
+
+I3C Slave Controller Library
+------------------------------------
+
+The Controller library provides APIs to be used by the controller that can
+operate in slave mode. It also provides APIs to be used by function
+driver/library in order to implement a particular slave function.
+
+APIs for the I3C Slave controller Driver
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This section lists the APIs that the I3C Slave core provides to be used
+by the I3C controller driver.
+
+* devm_i3c_slave_ctrl_create()/i3c_slave_ctrl_create()
+
+   The I3C controller driver should implement the following ops:
+
+	* set_config: ops to set i3c configuration
+	* enable: ops to enable controller
+	* disable: ops to disable controller
+	* raise_ibi: ops to raise IBI to master controller
+	* alloc_request: ops to alloc a transfer request
+	* free_request: ops to free a transfer request
+	* queue: ops to queue a request to transfer queue
+	* dequeue: ops to dequeue a request from transfer queue
+	* cancel_all_reqs: ops to cancel all request from transfer queue
+        * fifo_status: ops to get fifo status
+        * fifo_flush: ops to flush hardware fifo
+	* get_features: ops to get controller supported features
+
+   The I3C controller driver can then create a new Controller device by
+   invoking devm_i3c_slave_ctrl_create()/i3c_slave_ctrl_create().
+
+* devm_i3c_slave_ctrl_destroy()/i3c_slave_ctrl_destroy()
+
+   The I3C controller driver can destroy the Controller device created by
+   either devm_i3c_slave_ctrl_create() or i3c_slave_ctrl_create() using
+   devm_i3c_slave_ctrl_destroy() or i3c_slave_ctrl_destroy().
+
+I3C Slave Controller APIs for the I3C Slave Function Driver
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This section lists the APIs that the I3C Slave core provides to be used
+by the I3C slave function driver.
+
+* i3c_slave_ctrl_set_config()
+
+   The I3C slave function driver should use i3c_slave_ctrl_set_config() to
+   write i3c configuration to the slave controller.
+
+* i3c_slave_ctrl_enable()/i3c_slave_ctrl_disable()
+
+   The I3C slave function driver should use i3c_slave_ctrl_enable()/
+   i3c_slave_ctrl_disable() to enable/disable i3c slave controller.
+
+* i3c_slave_ctrl_alloc_request()/i3c_slave_ctrl_free_request()
+
+   The I3C slave function driver should usei3c_slave_ctrl_alloc_request() /
+   i3c_slave_ctrl_free_request() to alloc/free a i3c request.
+
+* i3c_slave_ctrl_raise_ibi()
+
+   The I3C slave function driver should use i3c_slave_ctrl_raise_ibi() to
+   raise IBI.
+
+* i3c_slave_ctrl_queue()/i3c_slave_ctrl_dequeue()
+
+   The I3C slave function driver should use i3c_slave_ctrl_queue()/
+   i3c_slave_ctrl_dequeue(), to queue/dequeue I3C transfer to/from transfer
+   queue.
+
+* i3c_slave_ctrl_get_features()
+
+   The I3C slave function driver should use i3c_slave_ctrl_get_features()
+   to get I3C slave controller supported features.
+
+Other I3C Slave Controller APIs
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There are other APIs provided by the Controller library. These are used for
+binding the I3C Slave Function device with Controlller device. i3c-cfs.c can
+be used as reference for using these APIs.
+
+* i3c_slave_ctrl_get()
+
+   Get a reference to the I3C slave controller based on the device name of
+   the controller.
+
+* i3c_slave_ctrl_put()
+
+   Release the reference to the I3C slave controller obtained using
+   i3c_slave_ctrl_get()
+
+* i3c_slave_ctrl_add_func()
+
+   Add a I3C slave function to a I3C slave controller.
+
+* i3c_slave_ctrl_remove_func()
+
+   Remove the I3C slave function from I3C slave controller.
+
+I3C Slave Function Library
+----------------------------------
+
+The I3C Slave Function library provides APIs to be used by the function driver
+and the Controller library to provide slave mode functionality.
+
+I3C Slave Function APIs for the I3C Slave Function Driver
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This section lists the APIs that the I3C Slave core provides to be used
+by the I3C slave function driver.
+
+* i3c_slave_func_register_driver()
+
+   The I3C Slave Function driver should implement the following ops:
+	 * bind: ops to perform when a Controller device has been bound to
+	   Function device
+	 * unbind: ops to perform when a binding has been lost between a
+	   Controller device and Function device
+
+  The I3C Function driver can then register the I3C Function driver by using
+  i3c_slave_func_register_driver().
+
+* i3c_slave_func_unregister_driver()
+
+  The I3C Function driver can unregister the I3C Function driver by using
+  i3c_epf_unregister_driver().
+
+APIs for the I3C Slave Controller Library
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This section lists the APIs that the I3C Slave core provides to be used
+by the I3C slave controller library.
+
+Other I3C Slave APIs
+~~~~~~~~~~~~~~~~~~~~
+
+There are other APIs provided by the Function library. These are used to
+notify the function driver when the Function device is bound to the EPC device.
+i3c-cfs.c can be used as reference for using these APIs.
+
+* i3c_slave_func_create()
+
+   Create a new I3C Function device by passing the name of the I3C EPF device.
+   This name will be used to bind the Function device to a Function driver.
+
+* i3c_slave_func_destroy()
+
+   Destroy the created I3C Function device.
+
+* i3c_slave_func_bind()
+
+   i3c_slave_func_bind() should be invoked when the EPF device has been bound
+   to a Controller device.
+
+* i3c_slave_func_unbind()
+
+   i3c_slave_func_unbind() should be invoked when the binding between EPC
+   device and function device is lost.
diff --git a/Documentation/driver-api/i3c/slave/i3c-tty-function.rst b/Documentation/driver-api/i3c/slave/i3c-tty-function.rst
new file mode 100644
index 0000000000000..3c8521d7aa31a
--- /dev/null
+++ b/Documentation/driver-api/i3c/slave/i3c-tty-function.rst
@@ -0,0 +1,103 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+PCI Test Function
+=================
+
+:Author: Kishon Vijay Abraham I <kishon@ti.com>
+
+Traditionally PCI RC has always been validated by using standard
+PCI cards like ethernet PCI cards or USB PCI cards or SATA PCI cards.
+However with the addition of EP-core in linux kernel, it is possible
+to configure a PCI controller that can operate in EP mode to work as
+a test device.
+
+The PCI endpoint test device is a virtual device (defined in software)
+used to test the endpoint functionality and serve as a sample driver
+for other PCI endpoint devices (to use the EP framework).
+
+The PCI endpoint test device has the following registers:
+
+	1) PCI_ENDPOINT_TEST_MAGIC
+	2) PCI_ENDPOINT_TEST_COMMAND
+	3) PCI_ENDPOINT_TEST_STATUS
+	4) PCI_ENDPOINT_TEST_SRC_ADDR
+	5) PCI_ENDPOINT_TEST_DST_ADDR
+	6) PCI_ENDPOINT_TEST_SIZE
+	7) PCI_ENDPOINT_TEST_CHECKSUM
+	8) PCI_ENDPOINT_TEST_IRQ_TYPE
+	9) PCI_ENDPOINT_TEST_IRQ_NUMBER
+
+* PCI_ENDPOINT_TEST_MAGIC
+
+This register will be used to test BAR0. A known pattern will be written
+and read back from MAGIC register to verify BAR0.
+
+* PCI_ENDPOINT_TEST_COMMAND
+
+This register will be used by the host driver to indicate the function
+that the endpoint device must perform.
+
+========	================================================================
+Bitfield	Description
+========	================================================================
+Bit 0		raise legacy IRQ
+Bit 1		raise MSI IRQ
+Bit 2		raise MSI-X IRQ
+Bit 3		read command (read data from RC buffer)
+Bit 4		write command (write data to RC buffer)
+Bit 5		copy command (copy data from one RC buffer to another RC buffer)
+========	================================================================
+
+* PCI_ENDPOINT_TEST_STATUS
+
+This register reflects the status of the PCI endpoint device.
+
+========	==============================
+Bitfield	Description
+========	==============================
+Bit 0		read success
+Bit 1		read fail
+Bit 2		write success
+Bit 3		write fail
+Bit 4		copy success
+Bit 5		copy fail
+Bit 6		IRQ raised
+Bit 7		source address is invalid
+Bit 8		destination address is invalid
+========	==============================
+
+* PCI_ENDPOINT_TEST_SRC_ADDR
+
+This register contains the source address (RC buffer address) for the
+COPY/READ command.
+
+* PCI_ENDPOINT_TEST_DST_ADDR
+
+This register contains the destination address (RC buffer address) for
+the COPY/WRITE command.
+
+* PCI_ENDPOINT_TEST_IRQ_TYPE
+
+This register contains the interrupt type (Legacy/MSI) triggered
+for the READ/WRITE/COPY and raise IRQ (Legacy/MSI) commands.
+
+Possible types:
+
+======	==
+Legacy	0
+MSI	1
+MSI-X	2
+======	==
+
+* PCI_ENDPOINT_TEST_IRQ_NUMBER
+
+This register contains the triggered ID interrupt.
+
+Admissible values:
+
+======	===========
+Legacy	0
+MSI	[1 .. 32]
+MSI-X	[1 .. 2048]
+======	===========
diff --git a/Documentation/driver-api/i3c/slave/i3c-tty-howto.rst b/Documentation/driver-api/i3c/slave/i3c-tty-howto.rst
new file mode 100644
index 0000000000000..11c8900fd16f3
--- /dev/null
+++ b/Documentation/driver-api/i3c/slave/i3c-tty-howto.rst
@@ -0,0 +1,109 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===================
+I3C TTY User Guide
+===================
+
+:Author: Frank Li <Frank.Li@nxp.com>
+
+This document is a guide to help users use i3c-slave-tty function driver
+and i3ctty master driver for testing I3C. The list of steps to be followed in the
+master side and slave side is given below.
+
+Endpoint Device
+===============
+
+Endpoint Controller Devices
+---------------------------
+
+To find the list of slave controller devices in the system::
+
+	# ls  /sys/class/i3c_slave/
+	  44330000.i3c-slave
+
+If CONFIG_I3C_SLAVE_CONFIGFS is enabled::
+
+	# ls /sys/kernel/config/i3c_slave/controllers/
+	  44330000.i3c-slave
+
+
+Endpoint Function Drivers
+-------------------------
+
+To find the list of slave function drivers in the system::
+
+	# ls /sys/bus/i3c_slave_func/drivers
+	  tty
+
+If CONFIG_I3C_SLAVE_CONFIGFS is enabled::
+
+	# ls /sys/kernel/config/i3c_slave/functions
+	  tty
+
+
+Creating i3c-slave-tty Device
+----------------------------
+
+I3C slave function device can be created using the configfs. To create
+i3c-slave-tty device, the following commands can be used::
+
+	# mount -t configfs none /sys/kernel/config
+	# cd /sys/kernel/config/i3c_slave/
+	# mkdir functions/tty/func1
+
+The "mkdir func1" above creates the i3c-slave-tty function device that will
+be probed by i3c tty driver.
+
+The I3C slave framework populates the directory with the following
+configurable fields::
+
+	# ls functions/tty/func1
+	bcr  dcr  ext_id  instance_id  max_read_len  max_write_len
+	part_id  vendor_id  vendor_info
+
+The I3C slave function driver populates these entries with default values
+when the device is bound to the driver. The i3c-slave-tty driver populates
+vendorid with 0xffff and interrupt_pin with 0x0001::
+
+	# cat functions/tty/func1/vendor_id
+	  0x0
+
+Configuring i3c-slave-tty Device
+-------------------------------
+
+The user can configure the i3c-slave-tty device using configfs entry. In order
+to change the vendorid, the following commands can be used::
+
+	# echo 0x011b > functions/tty/func1/vendor_id
+	# echo 0x1000 > functions/tty/func1/part_id
+	# echo 0x6 > functions/tty/t/bcr
+
+Binding i3c-slave-tty Device to slave Controller
+------------------------------------------------
+
+In order for the slave function device to be useful, it has to be bound to
+a I3C slave controller driver. Use the configfs to bind the function
+device to one of the controller driver present in the system::
+
+	# ln -s functions/pci_epf_test/func1 controllers/44330000.i3c-slave/
+
+I3C Master Device
+================
+
+Check I3C tty device is probed
+
+	# ls /sys/bus/i3c/devices/0-23610000000
+	0-23610000000:0  bcr  dcr  driver  dynamic_address  hdrcap
+	modalias  pid  power  subsystem  tty  uevent
+
+Using Slave TTY function Device
+-----------------------------------
+
+Host side:
+	cat /dev/ttyI3C0
+Slave side
+	echo abc >/dev/ttyI3C0
+
+You will see "abc" show at console.
+
+You can use other tty tool to test I3C slave tty device.
diff --git a/Documentation/driver-api/i3c/slave/index.rst b/Documentation/driver-api/i3c/slave/index.rst
new file mode 100644
index 0000000000000..69727ccf985db
--- /dev/null
+++ b/Documentation/driver-api/i3c/slave/index.rst
@@ -0,0 +1,13 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================
+I3C Slave Framework
+======================
+
+.. toctree::
+   :maxdepth: 2
+
+   i3c-slave
+   i3c-slave-cfs
+   i3c-tty-howto
+
-- 
2.34.1