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author | Bingbu Cao <bingbu.cao@intel.com> | 2024-01-31 17:51:07 +0800 |
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committer | Hans Verkuil <hverkuil-cisco@xs4all.nl> | 2024-04-29 14:56:38 +0200 |
commit | d06fc8b6c3eb9f2ad034330dd833d5192e3f1016 (patch) | |
tree | 0bc156461712a97937c3f0a04c05ec95f77f973b | |
parent | ba124c8cf3b775c1575fc557203527e211d1fdc5 (diff) | |
download | linux-d06fc8b6c3eb9f2ad034330dd833d5192e3f1016.tar.gz linux-d06fc8b6c3eb9f2ad034330dd833d5192e3f1016.tar.bz2 linux-d06fc8b6c3eb9f2ad034330dd833d5192e3f1016.zip |
media: Documentation: add documentation of Intel IPU6 driver and hardware overview
Add a documentation for an overview of IPU6 hardware and describe the main
the components of IPU6 driver.
Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
-rw-r--r-- | Documentation/driver-api/media/drivers/index.rst | 1 | ||||
-rw-r--r-- | Documentation/driver-api/media/drivers/ipu6.rst | 205 |
2 files changed, 206 insertions, 0 deletions
diff --git a/Documentation/driver-api/media/drivers/index.rst b/Documentation/driver-api/media/drivers/index.rst index c4123a16b5f9..7f6f3dcd5c90 100644 --- a/Documentation/driver-api/media/drivers/index.rst +++ b/Documentation/driver-api/media/drivers/index.rst @@ -26,6 +26,7 @@ Video4Linux (V4L) drivers vimc-devel zoran ccs/ccs + ipu6 Digital TV drivers diff --git a/Documentation/driver-api/media/drivers/ipu6.rst b/Documentation/driver-api/media/drivers/ipu6.rst new file mode 100644 index 000000000000..6e1dd19b36fb --- /dev/null +++ b/Documentation/driver-api/media/drivers/ipu6.rst @@ -0,0 +1,205 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================== +Intel IPU6 Driver +================== + +Author: Bingbu Cao <bingbu.cao@intel.com> + +Overview +========= + +Intel IPU6 is the sixth generation of Intel Image Processing Unit used in some +Intel Chipsets such as Tiger Lake, Jasper Lake, Alder Lake, Raptor Lake and +Meteor Lake. IPU6 consists of two major systems: Input System (ISYS) and +Processing System (PSYS). IPU6 are visible on the PCI bus as a single device, it +can be found by ``lspci``: + +``0000:00:05.0 Multimedia controller: Intel Corporation Device xxxx (rev xx)`` + +IPU6 has a 16 MB BAR in PCI configuration Space for MMIO registers which is +visible for driver. + +Buttress +========= + +The IPU6 is connecting to the system fabric with Buttress which is enabling host +driver to control the IPU6, it also allows IPU6 access the system memory to +store and load frame pixel streams and any other metadata. + +Buttress mainly manages several system functionalities: power management, +interrupt handling, firmware authentication and global timer sync. + +ISYS and PSYS Power flow +------------------------ + +IPU6 driver initialize the ISYS and PSYS power up or down request by setting the +Buttress frequency control register for ISYS and PSYS +(``IPU6_BUTTRESS_REG_IS_FREQ_CTL`` and ``IPU6_BUTTRESS_REG_PS_FREQ_CTL``) in +function: + +.. c:function:: int ipu6_buttress_power(...) + +Buttress forwards the request to Punit, after Punit execute the power up flow, +Buttress indicates driver that ISYS or PSYS is powered up by updating the power +status registers. + +.. Note:: ISYS power up needs take place prior to PSYS power up, ISYS power down + needs take place after PSYS power down due to hardware limitation. + +Interrupt +--------- + +IPU6 interrupt can be generated as MSI or INTA, interrupt will be triggered when +ISYS, PSYS, Buttress event or error happen, driver can get the interrupt cause +by reading the interrupt status register ``BUTTRESS_REG_ISR_STATUS``, driver +clears the irq status and then calls specific ISYS or PSYS irq handler. + +.. c:function:: irqreturn_t ipu6_buttress_isr(int irq, ...) + +Security and firmware authentication +------------------------------------- + +To address the IPU6 firmware security concerns, the IPU6 firmware needs to +undergo an authentication process before it is allowed to executed on the IPU6 +internal processors. The IPU6 driver will work with Converged Security Engine +(CSE) to complete authentication process. The CSE is responsible of +authenticating the IPU6 firmware. The authenticated firmware binary is copied +into an isolated memory region. Firmware authentication process is implemented +by CSE following an IPC handshake with the IPU6 driver. There are some Buttress +registers used by the CSE and the IPU6 driver to communicate with each other via +IPC. + +.. c:function:: int ipu6_buttress_authenticate(...) + +Global timer sync +----------------- + +The IPU6 driver initiates a Hammock Harbor synchronization flow each time it +starts camera operation. The IPU6 will synchronizes an internal counter in the +Buttress with a copy of the SoC time, this counter maintains the up-to-date time +until camera operation is stopped. The IPU6 driver can use this time counter to +calibrate the timestamp based on the timestamp in response event from firmware. + +.. c:function:: int ipu6_buttress_start_tsc_sync(...) + +DMA and MMU +============ + +The IPU6 has its own scalar processor where the firmware run at and an internal +32-bit virtual address space. The IPU6 has MMU address translation hardware to +allow that scalar processors to access the internal memory and external system +memory through IPU6 virtual address. The address translation is based on two +levels of page lookup tables stored in system memory which are maintained by the +IPU6 driver. The IPU6 driver sets the level-1 page table base address to MMU +register and allows MMU to perform page table lookups. + +The IPU6 driver exports its own DMA operations. The IPU6 driver will update the +page table entries for each DMA operation and invalidate the MMU TLB after each +unmap and free. + +.. code-block:: none + + const struct dma_map_ops ipu6_dma_ops = { + .alloc = ipu6_dma_alloc, + .free = ipu6_dma_free, + .mmap = ipu6_dma_mmap, + .map_sg = ipu6_dma_map_sg, + .unmap_sg = ipu6_dma_unmap_sg, + ... + }; + +.. Note:: IPU6 MMU works behind IOMMU so for each IPU6 DMA ops, driver will call + generic PCI DMA ops to ask IOMMU to do the additional mapping if VT-d + enabled. + +Firmware file format +==================== + +The IPU6 firmware is in Code Partition Directory (CPD) file format. The CPD +firmware contains a CPD header, several CPD entries and components. The CPD +component includes 3 entries - manifest, metadata and module data. Manifest and +metadata are defined by CSE and used by CSE for authentication. Module data is +specific to IPU6 which holds the binary data of firmware called package +directory. The IPU6 driver (``ipu6-cpd.c`` in particular) parses and validates +the CPD firmware file and gets the package directory binary data of the IPU6 +firmware, copies it to specific DMA buffer and sets its base address to Buttress +``FW_SOURCE_BASE`` register. Finally the CSE will do authentication for this +firmware binary. + + +Syscom interface +================ + +The IPU6 driver communicates with firmware via the Syscom ABI. Syscom is an +inter-processor communication mechanism between the IPU scalar processors and +the CPU. There are a number of resources shared between firmware and software. +A system memory region where the message queues reside, firmware can access the +memory region via the IPU MMU. The Syscom queues are FIFO fixed depth queues +with a configurable number of tokens (messages). There are also common IPU6 MMIO +registers where the queue read and write indices reside. Software and firmware +function as producer and consumer of tokens in the queues and update the write +and read indices separately when sending or receiving each message. + +The IPU6 driver must prepare and configure the number of input and output +queues, configure the count of tokens per queue and the size of per token before +initiating and starting the communication with firmware. Firmware and software +must use same configurations. The IPU6 Buttress has a number of firmware boot +parameter registers which can be used to store the address of configuration and +initialise the Syscom state, then driver can request firmware to start and run via +setting the scalar processor control status register. + +Input System +============ + +IPU6 input system consists of MIPI D-PHY and several CSI-2 receivers. It can +capture image pixel data from camera sensors or other MIPI CSI-2 output devices. + +D-PHYs and CSI-2 ports lane mapping +----------------------------------- + +The IPU6 integrates different D-PHY IPs on different SoCs, on Tiger Lake and +Alder Lake, IPU6 integrates MCD10 D-PHY, IPU6SE on Jasper Lake integrates JSL +D-PHY and IPU6EP on Meteor Lake integrates a Synopsys DWC D-PHY. There is an +adaptional layer between D-PHY and CSI-2 receiver controller which includes port +configuration, PHY wrapper or private test interfaces for D-PHY. There are 3 +D-PHY drivers ``ipu6-isys-mcd-phy.c``, ``ipu6-isys-jsl-phy.c`` and +``ipu6-isys-dwc-phy.c`` program the above 3 D-PHYs in IPU6. + +Different IPU6 versions have different D-PHY lanes mappings, On Tiger Lake, +there are 12 data lanes and 8 clock lanes, IPU6 support maximum 8 CSI-2 ports, +see the PPI mmapping in ``ipu6-isys-mcd-phy.c`` for more information. On Jasper +Lake and Alder Lake, D-PHY has 8 data lanes and 4 clock lanes, the IPU6 supports +maximum 4 CSI-2 ports. For Meteor Lake, D-PHY has 12 data lanes and 6 clock +lanes so IPU6 support maximum 6 CSI-2 ports. + +.. Note:: Each pair of CSI-2 two ports is a single unit that can share the data + lanes. For example, for CSI-2 port 0 and 1, CSI-2 port 0 support + maximum 4 data lanes, CSI-2 port 1 support maximum 2 data lanes, CSI-2 + port 0 with 2 data lanes can work together with CSI-2 port 1 with 2 + data lanes. If trying to use CSI-2 port 0 with 4 lanes, CSI-2 port 1 + will not be available as the 4 data lanes are shared by CSI-2 port 0 + and 1. The same applies to CSI ports 2/3, 4/5 and 7/8. + +ISYS firmware ABIs +------------------ + +The IPU6 firmware implements a series of ABIs for software access. In general, +software firstly prepares the stream configuration ``struct +ipu6_fw_isys_stream_cfg_data_abi`` and sends the configuration to firmware via +sending ``STREAM_OPEN`` command. Stream configuration includes input pins and +output pins, input pin ``struct ipu6_fw_isys_input_pin_info_abi`` defines the +resolution and data type of input source, output pin ``struct +ipu6_fw_isys_output_pin_info_abi`` defines the output resolution, stride and +frame format, etc. + +Once the driver gets the interrupt from firmware that indicates stream open +successfully, the driver will send the ``STREAM_START`` and ``STREAM_CAPTURE`` +command to request firmware to start capturing image frames. ``STREAM_CAPTURE`` +command queues the buffers to firmware with ``struct +ipu6_fw_isys_frame_buff_set``, software then waits for the interrupt and +response from firmware, ``PIN_DATA_READY`` means a buffer is ready on a specific +output pin and then software can return the buffer to user. + +.. Note:: See :ref:`Examples<ipu6_isys_capture_examples>` about how to do + capture by IPU6 ISYS driver. |