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| -rw-r--r-- | Documentation/driver-api/firmware/fw_upload.rst | 126 |
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diff --git a/Documentation/driver-api/firmware/fw_upload.rst b/Documentation/driver-api/firmware/fw_upload.rst new file mode 100644 index 000000000000..76922591e446 --- /dev/null +++ b/Documentation/driver-api/firmware/fw_upload.rst @@ -0,0 +1,126 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=================== +Firmware Upload API +=================== + +A device driver that registers with the firmware loader will expose +persistent sysfs nodes to enable users to initiate firmware updates for +that device. It is the responsibility of the device driver and/or the +device itself to perform any validation on the data received. Firmware +upload uses the same *loading* and *data* sysfs files described in the +documentation for firmware fallback. It also adds additional sysfs files +to provide status on the transfer of the firmware image to the device. + +Register for firmware upload +============================ + +A device driver registers for firmware upload by calling +firmware_upload_register(). Among the parameter list is a name to +identify the device under /sys/class/firmware. A user may initiate a +firmware upload by echoing a 1 to the *loading* sysfs file for the target +device. Next, the user writes the firmware image to the *data* sysfs +file. After writing the firmware data, the user echos 0 to the *loading* +sysfs file to signal completion. Echoing 0 to *loading* also triggers the +transfer of the firmware to the lower-lever device driver in the context +of a kernel worker thread. + +To use the firmware upload API, write a driver that implements a set of +ops. The probe function calls firmware_upload_register() and the remove +function calls firmware_upload_unregister() such as:: + + static const struct fw_upload_ops m10bmc_ops = { + .prepare = m10bmc_sec_prepare, + .write = m10bmc_sec_write, + .poll_complete = m10bmc_sec_poll_complete, + .cancel = m10bmc_sec_cancel, + .cleanup = m10bmc_sec_cleanup, + }; + + static int m10bmc_sec_probe(struct platform_device *pdev) + { + const char *fw_name, *truncate; + struct m10bmc_sec *sec; + struct fw_upload *fwl; + unsigned int len; + + sec = devm_kzalloc(&pdev->dev, sizeof(*sec), GFP_KERNEL); + if (!sec) + return -ENOMEM; + + sec->dev = &pdev->dev; + sec->m10bmc = dev_get_drvdata(pdev->dev.parent); + dev_set_drvdata(&pdev->dev, sec); + + fw_name = dev_name(sec->dev); + truncate = strstr(fw_name, ".auto"); + len = (truncate) ? truncate - fw_name : strlen(fw_name); + sec->fw_name = kmemdup_nul(fw_name, len, GFP_KERNEL); + + fwl = firmware_upload_register(sec->dev, sec->fw_name, &m10bmc_ops, sec); + if (IS_ERR(fwl)) { + dev_err(sec->dev, "Firmware Upload driver failed to start\n"); + kfree(sec->fw_name); + return PTR_ERR(fwl); + } + + sec->fwl = fwl; + return 0; + } + + static int m10bmc_sec_remove(struct platform_device *pdev) + { + struct m10bmc_sec *sec = dev_get_drvdata(&pdev->dev); + + firmware_upload_unregister(sec->fwl); + kfree(sec->fw_name); + return 0; + } + +firmware_upload_register +------------------------ +.. kernel-doc:: drivers/base/firmware_loader/sysfs_upload.c + :identifiers: firmware_upload_register + +firmware_upload_unregister +-------------------------- +.. kernel-doc:: drivers/base/firmware_loader/sysfs_upload.c + :identifiers: firmware_upload_unregister + +Firmware Upload Ops +------------------- +.. kernel-doc:: include/linux/firmware.h + :identifiers: fw_upload_ops + +Firmware Upload Progress Codes +------------------------------ +The following progress codes are used internally by the firmware loader. +Corresponding strings are reported through the status sysfs node that +is described below and are documented in the ABI documentation. + +.. kernel-doc:: drivers/base/firmware_loader/sysfs_upload.h + :identifiers: fw_upload_prog + +Firmware Upload Error Codes +--------------------------- +The following error codes may be returned by the driver ops in case of +failure: + +.. kernel-doc:: include/linux/firmware.h + :identifiers: fw_upload_err + +Sysfs Attributes +================ + +In addition to the *loading* and *data* sysfs files, there are additional +sysfs files to monitor the status of the data transfer to the target +device and to determine the final pass/fail status of the transfer. +Depending on the device and the size of the firmware image, a firmware +update could take milliseconds or minutes. + +The additional sysfs files are: + +* status - provides an indication of the progress of a firmware update +* error - provides error information for a failed firmware update +* remaining_size - tracks the data transfer portion of an update +* cancel - echo 1 to this file to cancel the update |