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154 lines
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ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
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.. Copyright (C) 2018-2019 Intel Corporation <www.intel.com>
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File System Firmware Loader
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===========================
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This is file system firmware loader for U-Boot framework, which has very close
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to some Linux Firmware API. For the details of Linux Firmware API, you can refer
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to https://01.org/linuxgraphics/gfx-docs/drm/driver-api/firmware/index.html.
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File system firmware loader can be used to load whatever(firmware, image,
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and binary) from the storage device in file system format into target location
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such as memory, then consumer driver such as FPGA driver can program FPGA image
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from the target location into FPGA.
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To enable firmware loader, CONFIG_FS_LOADER need to be set at
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<board_name>_defconfig such as "CONFIG_FS_LOADER=y".
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Firmware Loader API core features
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---------------------------------
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Firmware storage device described in device tree source
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-------------------------------------------------------
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For passing data like storage device phandle and partition where the
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firmware loading from to the firmware loader driver, those data could be
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defined in fs-loader node as shown in below:
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Example for block device::
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fs_loader0: fs-loader {
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u-boot,dm-pre-reloc;
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compatible = "u-boot,fs-loader";
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phandlepart = <&mmc 1>;
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};
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<&mmc 1> means block storage device pointer and its partition.
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Above example is a description for block storage, but for UBI storage
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device, it can be described in FDT as shown in below:
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Example for ubi::
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fs_loader1: fs-loader {
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u-boot,dm-pre-reloc;
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compatible = "u-boot,fs-loader";
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mtdpart = "UBI",
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ubivol = "ubi0";
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};
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Then, firmware-loader property can be added with any device node, which
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driver would use the firmware loader for loading.
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The value of the firmware-loader property should be set with phandle
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of the fs-loader node. For example::
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firmware-loader = <&fs_loader0>;
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If there are majority of devices using the same fs-loader node, then
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firmware-loader property can be added under /chosen node instead of
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adding to each of device node.
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For example::
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/{
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chosen {
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firmware-loader = <&fs_loader0>;
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};
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};
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In each respective driver of devices using firmware loader, the firmware
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loaded instance should be created by DT phandle.
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For example of getting DT phandle from /chosen and creating instance:
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.. code-block:: c
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chosen_node = ofnode_path("/chosen");
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if (!ofnode_valid(chosen_node)) {
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debug("/chosen node was not found.\n");
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return -ENOENT;
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}
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phandle_p = ofnode_get_property(chosen_node, "firmware-loader", &size);
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if (!phandle_p) {
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debug("firmware-loader property was not found.\n");
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return -ENOENT;
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}
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phandle = fdt32_to_cpu(*phandle_p);
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ret = uclass_get_device_by_phandle_id(UCLASS_FS_FIRMWARE_LOADER,
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phandle, &dev);
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if (ret)
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return ret;
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Firmware loader driver is also designed to support U-boot environment
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variables, so all these data from FDT can be overwritten
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through the U-boot environment variable during run time.
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For examples:
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storage_interface:
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Storage interface, it can be "mmc", "usb", "sata" or "ubi".
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fw_dev_part:
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Block device number and its partition, it can be "0:1".
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fw_ubi_mtdpart:
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UBI device mtd partition, it can be "UBI".
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fw_ubi_volume:
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UBI volume, it can be "ubi0".
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When above environment variables are set, environment values would be
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used instead of data from FDT.
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The benefit of this design allows user to change storage attribute data
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at run time through U-boot console and saving the setting as default
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environment values in the storage for the next power cycle, so no
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compilation is required for both driver and FDT.
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File system firmware Loader API
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-------------------------------
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.. code-block:: c
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int request_firmware_into_buf(struct udevice *dev,
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const char *name,
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void *buf, size_t size, u32 offset)
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Load firmware into a previously allocated buffer
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Parameters:
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* struct udevice \*dev: An instance of a driver
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* const char \*name: name of firmware file
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* void \*buf: address of buffer to load firmware into
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* size_t size: size of buffer
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* u32 offset: offset of a file for start reading into buffer
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Returns:
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size of total read
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-ve when error
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Description:
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The firmware is loaded directly into the buffer pointed to by buf
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Example of calling request_firmware_into_buf API after creating firmware loader
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instance:
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.. code-block:: c
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ret = uclass_get_device_by_phandle_id(UCLASS_FS_FIRMWARE_LOADER,
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phandle, &dev);
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if (ret)
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return ret;
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request_firmware_into_buf(dev, filename, buffer_location, buffer_size,
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offset_ofreading);
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