diff options
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/dmaengine/client.rst | 14 | ||||
| -rw-r--r-- | Documentation/driver-api/dmaengine/provider.rst | 12 | ||||
| -rw-r--r-- | Documentation/driver-api/firmware/efi/index.rst | 11 | ||||
| -rw-r--r-- | Documentation/driver-api/firmware/fallback-mechanisms.rst | 103 | ||||
| -rw-r--r-- | Documentation/driver-api/firmware/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/driver-api/firmware/lookup-order.rst | 2 | ||||
| -rw-r--r-- | Documentation/driver-api/firmware/request_firmware.rst | 5 | ||||
| -rw-r--r-- | Documentation/driver-api/gpio/driver.rst | 4 | ||||
| -rw-r--r-- | Documentation/driver-api/ipmb.rst | 4 | ||||
| -rw-r--r-- | Documentation/driver-api/libata.rst | 2 | ||||
| -rw-r--r-- | Documentation/driver-api/soundwire/stream.rst | 61 | ||||
| -rw-r--r-- | Documentation/driver-api/thermal/cpu-idle-cooling.rst | 4 | ||||
| -rw-r--r-- | Documentation/driver-api/usb/typec_bus.rst | 22 |
13 files changed, 196 insertions, 49 deletions
diff --git a/Documentation/driver-api/dmaengine/client.rst b/Documentation/driver-api/dmaengine/client.rst index e5953e7e4bf4..2104830a99ae 100644 --- a/Documentation/driver-api/dmaengine/client.rst +++ b/Documentation/driver-api/dmaengine/client.rst @@ -151,8 +151,8 @@ The details of these operations are: Note that callbacks will always be invoked from the DMA engines tasklet, never from interrupt context. -Optional: per descriptor metadata ---------------------------------- + **Optional: per descriptor metadata** + DMAengine provides two ways for metadata support. DESC_METADATA_CLIENT @@ -199,12 +199,15 @@ Optional: per descriptor metadata DESC_METADATA_CLIENT - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM: + 1. prepare the descriptor (dmaengine_prep_*) construct the metadata in the client's buffer 2. use dmaengine_desc_attach_metadata() to attach the buffer to the descriptor 3. submit the transfer + - DMA_DEV_TO_MEM: + 1. prepare the descriptor (dmaengine_prep_*) 2. use dmaengine_desc_attach_metadata() to attach the buffer to the descriptor @@ -215,6 +218,7 @@ Optional: per descriptor metadata DESC_METADATA_ENGINE - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM: + 1. prepare the descriptor (dmaengine_prep_*) 2. use dmaengine_desc_get_metadata_ptr() to get the pointer to the engine's metadata area @@ -222,7 +226,9 @@ Optional: per descriptor metadata 4. use dmaengine_desc_set_metadata_len() to tell the DMA engine the amount of data the client has placed into the metadata buffer 5. submit the transfer + - DMA_DEV_TO_MEM: + 1. prepare the descriptor (dmaengine_prep_*) 2. submit the transfer 3. on transfer completion, use dmaengine_desc_get_metadata_ptr() to get @@ -278,8 +284,8 @@ Optional: per descriptor metadata void dma_async_issue_pending(struct dma_chan *chan); -Further APIs: -------------- +Further APIs +------------ 1. Terminate APIs diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst index 790a15089f1f..56e5833e8a07 100644 --- a/Documentation/driver-api/dmaengine/provider.rst +++ b/Documentation/driver-api/dmaengine/provider.rst @@ -266,11 +266,15 @@ to use. attached (via the dmaengine_desc_attach_metadata() helper to the descriptor. From the DMA driver the following is expected for this mode: + - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM + The data from the provided metadata buffer should be prepared for the DMA controller to be sent alongside of the payload data. Either by copying to a hardware descriptor, or highly coupled packet. + - DMA_DEV_TO_MEM + On transfer completion the DMA driver must copy the metadata to the client provided metadata buffer before notifying the client about the completion. After the transfer completion, DMA drivers must not touch the metadata @@ -284,10 +288,14 @@ to use. and dmaengine_desc_set_metadata_len() is provided as helper functions. From the DMA driver the following is expected for this mode: - - get_metadata_ptr + + - get_metadata_ptr() + Should return a pointer for the metadata buffer, the maximum size of the metadata buffer and the currently used / valid (if any) bytes in the buffer. - - set_metadata_len + + - set_metadata_len() + It is called by the clients after it have placed the metadata to the buffer to let the DMA driver know the number of valid bytes provided. diff --git a/Documentation/driver-api/firmware/efi/index.rst b/Documentation/driver-api/firmware/efi/index.rst new file mode 100644 index 000000000000..4fe8abba9fc6 --- /dev/null +++ b/Documentation/driver-api/firmware/efi/index.rst @@ -0,0 +1,11 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============ +UEFI Support +============ + +UEFI stub library functions +=========================== + +.. kernel-doc:: drivers/firmware/efi/libstub/mem.c + :internal: diff --git a/Documentation/driver-api/firmware/fallback-mechanisms.rst b/Documentation/driver-api/firmware/fallback-mechanisms.rst index 8b041d0ab426..036383dad6d6 100644 --- a/Documentation/driver-api/firmware/fallback-mechanisms.rst +++ b/Documentation/driver-api/firmware/fallback-mechanisms.rst @@ -202,3 +202,106 @@ the following file: If you echo 0 into it means MAX_JIFFY_OFFSET will be used. The data type for the timeout is an int. + +EFI embedded firmware fallback mechanism +======================================== + +On some devices the system's EFI code / ROM may contain an embedded copy +of firmware for some of the system's integrated peripheral devices and +the peripheral's Linux device-driver needs to access this firmware. + +Device drivers which need such firmware can use the +firmware_request_platform() function for this, note that this is a +separate fallback mechanism from the other fallback mechanisms and +this does not use the sysfs interface. + +A device driver which needs this can describe the firmware it needs +using an efi_embedded_fw_desc struct: + +.. kernel-doc:: include/linux/efi_embedded_fw.h + :functions: efi_embedded_fw_desc + +The EFI embedded-fw code works by scanning all EFI_BOOT_SERVICES_CODE memory +segments for an eight byte sequence matching prefix; if the prefix is found it +then does a sha256 over length bytes and if that matches makes a copy of length +bytes and adds that to its list with found firmwares. + +To avoid doing this somewhat expensive scan on all systems, dmi matching is +used. Drivers are expected to export a dmi_system_id array, with each entries' +driver_data pointing to an efi_embedded_fw_desc. + +To register this array with the efi-embedded-fw code, a driver needs to: + +1. Always be builtin to the kernel or store the dmi_system_id array in a + separate object file which always gets builtin. + +2. Add an extern declaration for the dmi_system_id array to + include/linux/efi_embedded_fw.h. + +3. Add the dmi_system_id array to the embedded_fw_table in + drivers/firmware/efi/embedded-firmware.c wrapped in a #ifdef testing that + the driver is being builtin. + +4. Add "select EFI_EMBEDDED_FIRMWARE if EFI_STUB" to its Kconfig entry. + +The firmware_request_platform() function will always first try to load firmware +with the specified name directly from the disk, so the EFI embedded-fw can +always be overridden by placing a file under /lib/firmware. + +Note that: + +1. The code scanning for EFI embedded-firmware runs near the end + of start_kernel(), just before calling rest_init(). For normal drivers and + subsystems using subsys_initcall() to register themselves this does not + matter. This means that code running earlier cannot use EFI + embedded-firmware. + +2. At the moment the EFI embedded-fw code assumes that firmwares always start at + an offset which is a multiple of 8 bytes, if this is not true for your case + send in a patch to fix this. + +3. At the moment the EFI embedded-fw code only works on x86 because other archs + free EFI_BOOT_SERVICES_CODE before the EFI embedded-fw code gets a chance to + scan it. + +4. The current brute-force scanning of EFI_BOOT_SERVICES_CODE is an ad-hoc + brute-force solution. There has been discussion to use the UEFI Platform + Initialization (PI) spec's Firmware Volume protocol. This has been rejected + because the FV Protocol relies on *internal* interfaces of the PI spec, and: + 1. The PI spec does not define peripheral firmware at all + 2. The internal interfaces of the PI spec do not guarantee any backward + compatibility. Any implementation details in FV may be subject to change, + and may vary system to system. Supporting the FV Protocol would be + difficult as it is purposely ambiguous. + +Example how to check for and extract embedded firmware +------------------------------------------------------ + +To check for, for example Silead touchscreen controller embedded firmware, +do the following: + +1. Boot the system with efi=debug on the kernel commandline + +2. cp /sys/kernel/debug/efi/boot_services_code? to your home dir + +3. Open the boot_services_code? files in a hex-editor, search for the + magic prefix for Silead firmware: F0 00 00 00 02 00 00 00, this gives you + the beginning address of the firmware inside the boot_services_code? file. + +4. The firmware has a specific pattern, it starts with a 8 byte page-address, + typically F0 00 00 00 02 00 00 00 for the first page followed by 32-bit + word-address + 32-bit value pairs. With the word-address incrementing 4 + bytes (1 word) for each pair until a page is complete. A complete page is + followed by a new page-address, followed by more word + value pairs. This + leads to a very distinct pattern. Scroll down until this pattern stops, + this gives you the end of the firmware inside the boot_services_code? file. + +5. "dd if=boot_services_code? of=firmware bs=1 skip=<begin-addr> count=<len>" + will extract the firmware for you. Inspect the firmware file in a + hexeditor to make sure you got the dd parameters correct. + +6. Copy it to /lib/firmware under the expected name to test it. + +7. If the extracted firmware works, you can use the found info to fill an + efi_embedded_fw_desc struct to describe it, run "sha256sum firmware" + to get the sha256sum to put in the sha256 field. diff --git a/Documentation/driver-api/firmware/index.rst b/Documentation/driver-api/firmware/index.rst index 29da39ec4b8a..57415d657173 100644 --- a/Documentation/driver-api/firmware/index.rst +++ b/Documentation/driver-api/firmware/index.rst @@ -6,6 +6,7 @@ Linux Firmware API introduction core + efi/index request_firmware other_interfaces diff --git a/Documentation/driver-api/firmware/lookup-order.rst b/Documentation/driver-api/firmware/lookup-order.rst index 88c81739683c..6064672a782e 100644 --- a/Documentation/driver-api/firmware/lookup-order.rst +++ b/Documentation/driver-api/firmware/lookup-order.rst @@ -12,6 +12,8 @@ a driver issues a firmware API call. return it immediately * The ''Direct filesystem lookup'' is performed next, if found we return it immediately +* The ''Platform firmware fallback'' is performed next, but only when + firmware_request_platform() is used, if found we return it immediately * If no firmware has been found and the fallback mechanism was enabled the sysfs interface is created. After this either a kobject uevent is issued or the custom firmware loading is relied upon for firmware diff --git a/Documentation/driver-api/firmware/request_firmware.rst b/Documentation/driver-api/firmware/request_firmware.rst index f62bdcbfed5b..cd076462d235 100644 --- a/Documentation/driver-api/firmware/request_firmware.rst +++ b/Documentation/driver-api/firmware/request_firmware.rst @@ -25,6 +25,11 @@ firmware_request_nowarn .. kernel-doc:: drivers/base/firmware_loader/main.c :functions: firmware_request_nowarn +firmware_request_platform +------------------------- +.. kernel-doc:: drivers/base/firmware_loader/main.c + :functions: firmware_request_platform + request_firmware_direct ----------------------- .. kernel-doc:: drivers/base/firmware_loader/main.c diff --git a/Documentation/driver-api/gpio/driver.rst b/Documentation/driver-api/gpio/driver.rst index 871922529332..9809f593c0ab 100644 --- a/Documentation/driver-api/gpio/driver.rst +++ b/Documentation/driver-api/gpio/driver.rst @@ -416,7 +416,7 @@ The preferred way to set up the helpers is to fill in the struct gpio_irq_chip inside struct gpio_chip before adding the gpio_chip. If you do this, the additional irq_chip will be set up by gpiolib at the same time as setting up the rest of the GPIO functionality. The following -is a typical example of a cascaded interrupt handler using gpio_irq_chip:: +is a typical example of a cascaded interrupt handler using gpio_irq_chip: .. code-block:: c @@ -453,7 +453,7 @@ is a typical example of a cascaded interrupt handler using gpio_irq_chip:: return devm_gpiochip_add_data(dev, &g->gc, g); The helper support using hierarchical interrupt controllers as well. -In this case the typical set-up will look like this:: +In this case the typical set-up will look like this: .. code-block:: c diff --git a/Documentation/driver-api/ipmb.rst b/Documentation/driver-api/ipmb.rst index 3ec3baed84c4..209c49e05116 100644 --- a/Documentation/driver-api/ipmb.rst +++ b/Documentation/driver-api/ipmb.rst @@ -71,9 +71,13 @@ b) Example for device tree:: ipmb@10 { compatible = "ipmb-dev"; reg = <0x10>; + i2c-protocol; }; }; +If xmit of data to be done using raw i2c block vs smbus +then "i2c-protocol" needs to be defined as above. + 2) Manually from Linux:: modprobe ipmb-dev-int diff --git a/Documentation/driver-api/libata.rst b/Documentation/driver-api/libata.rst index 207f0d24de69..e2f87b82b074 100644 --- a/Documentation/driver-api/libata.rst +++ b/Documentation/driver-api/libata.rst @@ -401,7 +401,7 @@ Error handling ============== This chapter describes how errors are handled under libata. Readers are -advised to read SCSI EH (Documentation/scsi/scsi_eh.txt) and ATA +advised to read SCSI EH (Documentation/scsi/scsi_eh.rst) and ATA exceptions doc first. Origins of commands diff --git a/Documentation/driver-api/soundwire/stream.rst b/Documentation/driver-api/soundwire/stream.rst index 5351bd2f34a8..8bceece51554 100644 --- a/Documentation/driver-api/soundwire/stream.rst +++ b/Documentation/driver-api/soundwire/stream.rst @@ -156,22 +156,27 @@ Below shows the SoundWire stream states and state transition diagram. :: +-----------+ +------------+ +----------+ +----------+ | ALLOCATED +---->| CONFIGURED +---->| PREPARED +---->| ENABLED | | STATE | | STATE | | STATE | | STATE | - +-----------+ +------------+ +----------+ +----+-----+ - ^ - | - | - v - +----------+ +------------+ +----+-----+ + +-----------+ +------------+ +---+--+---+ +----+-----+ + ^ ^ ^ + | | | + __| |___________ | + | | | + v | v + +----------+ +-----+------+ +-+--+-----+ | RELEASED |<----------+ DEPREPARED |<-------+ DISABLED | | STATE | | STATE | | STATE | +----------+ +------------+ +----------+ -NOTE: State transition between prepare and deprepare is supported in Spec -but not in the software (subsystem) +NOTE: State transitions between ``SDW_STREAM_ENABLED`` and +``SDW_STREAM_DISABLED`` are only relevant when then INFO_PAUSE flag is +supported at the ALSA/ASoC level. Likewise the transition between +``SDW_DISABLED_STATE`` and ``SDW_PREPARED_STATE`` depends on the +INFO_RESUME flag. -NOTE2: Stream state transition checks need to be handled by caller -framework, for example ALSA/ASoC. No checks for stream transition exist in -SoundWire subsystem. +NOTE2: The framework implements basic state transition checks, but +does not e.g. check if a transition from DISABLED to ENABLED is valid +on a specific platform. Such tests need to be added at the ALSA/ASoC +level. Stream State Operations ----------------------- @@ -246,6 +251,9 @@ SDW_STREAM_PREPARED Prepare state of stream. Operations performed before entering in this state: + (0) Steps 1 and 2 are omitted in the case of a resume operation, + where the bus bandwidth is known. + (1) Bus parameters such as bandwidth, frame shape, clock frequency, are computed based on current stream as well as already active stream(s) on Bus. Re-computation is required to accommodate current @@ -270,9 +278,11 @@ Prepare state of stream. Operations performed before entering in this state: After all above operations are successful, stream state is set to ``SDW_STREAM_PREPARED``. -Bus implements below API for PREPARE state which needs to be called once per -stream. From ASoC DPCM framework, this stream state is linked to -.prepare() operation. +Bus implements below API for PREPARE state which needs to be called +once per stream. From ASoC DPCM framework, this stream state is linked +to .prepare() operation. Since the .trigger() operations may not +follow the .prepare(), a direct transition from +``SDW_STREAM_PREPARED`` to ``SDW_STREAM_DEPREPARED`` is allowed. .. code-block:: c @@ -332,6 +342,14 @@ Bus implements below API for DISABLED state which needs to be called once per stream. From ASoC DPCM framework, this stream state is linked to .trigger() stop operation. +When the INFO_PAUSE flag is supported, a direct transition to +``SDW_STREAM_ENABLED`` is allowed. + +For resume operations where ASoC will use the .prepare() callback, the +stream can transition from ``SDW_STREAM_DISABLED`` to +``SDW_STREAM_PREPARED``, with all required settings restored but +without updating the bandwidth and bit allocation. + .. code-block:: c int sdw_disable_stream(struct sdw_stream_runtime * stream); @@ -353,9 +371,18 @@ state: After all above operations are successful, stream state is set to ``SDW_STREAM_DEPREPARED``. -Bus implements below API for DEPREPARED state which needs to be called once -per stream. From ASoC DPCM framework, this stream state is linked to -.trigger() stop operation. +Bus implements below API for DEPREPARED state which needs to be called +once per stream. ALSA/ASoC do not have a concept of 'deprepare', and +the mapping from this stream state to ALSA/ASoC operation may be +implementation specific. + +When the INFO_PAUSE flag is supported, the stream state is linked to +the .hw_free() operation - the stream is not deprepared on a +TRIGGER_STOP. + +Other implementations may transition to the ``SDW_STREAM_DEPREPARED`` +state on TRIGGER_STOP, should they require a transition through the +``SDW_STREAM_PREPARED`` state. .. code-block:: c diff --git a/Documentation/driver-api/thermal/cpu-idle-cooling.rst b/Documentation/driver-api/thermal/cpu-idle-cooling.rst index 9f0016ee4cfb..a1c3edecae00 100644 --- a/Documentation/driver-api/thermal/cpu-idle-cooling.rst +++ b/Documentation/driver-api/thermal/cpu-idle-cooling.rst @@ -105,8 +105,8 @@ and this variation will modulate the cooling effect. idle <--------------> running - <-----------------------------> - duty cycle 33% + <---------------------> + duty cycle 33% ^ diff --git a/Documentation/driver-api/usb/typec_bus.rst b/Documentation/driver-api/usb/typec_bus.rst index f47a69bff498..03dfa9c018b7 100644 --- a/Documentation/driver-api/usb/typec_bus.rst +++ b/Documentation/driver-api/usb/typec_bus.rst @@ -53,9 +53,7 @@ in need to reconfigure the pins on the connector, the alternate mode driver needs to notify the bus using :c:func:`typec_altmode_notify()`. The driver passes the negotiated SVID specific pin configuration value to the function as parameter. The bus driver will then configure the mux behind the connector using -that value as the state value for the mux, and also call blocking notification -chain to notify the external drivers about the state of the connector that need -to know it. +that value as the state value for the mux. NOTE: The SVID specific pin configuration values must always start from ``TYPEC_STATE_MODAL``. USB Type-C specification defines two default states for @@ -80,19 +78,6 @@ Helper macro ``TYPEC_MODAL_STATE()`` can also be used:: #define ALTMODEX_CONF_A = TYPEC_MODAL_STATE(0); #define ALTMODEX_CONF_B = TYPEC_MODAL_STATE(1); -Notification chain -~~~~~~~~~~~~~~~~~~ - -The drivers for the components that the alternate modes are designed for need to -get details regarding the results of the negotiation with the partner, and the -pin configuration of the connector. In case of DisplayPort alternate mode for -example, the GPU drivers will need to know those details. In case of -Thunderbolt alternate mode, the thunderbolt drivers will need to know them, and -so on. - -The notification chain is designed for this purpose. The drivers can register -notifiers with :c:func:`typec_altmode_register_notifier()`. - Cable plug alternate modes ~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -129,8 +114,3 @@ Cable Plug operations .. kernel-doc:: drivers/usb/typec/bus.c :functions: typec_altmode_get_plug typec_altmode_put_plug - -Notifications -~~~~~~~~~~~~~ -.. kernel-doc:: drivers/usb/typec/class.c - :functions: typec_altmode_register_notifier typec_altmode_unregister_notifier |