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