[U-Boot] [PATCH v4 4/6] doc: Add new doc for file system firmware loader driver model
Simon Glass
sjg at chromium.org
Wed Jul 11 14:02:39 UTC 2018
Hi Tien,
On 6 July 2018 at 02:27, <tien.fong.chee at intel.com> wrote:
> From: Tien Fong Chee <tien.fong.chee at intel.com>
>
> Provide information about
>
> - overview of file system firmware loader driver model
> - describe storage device and partition in device tree source
> - describe fie system firmware loader API
>
> Signed-off-by: Tien Fong Chee <tien.fong.chee at intel.com>
> ---
> doc/driver-model/fs_firmware_loader.txt | 133 ++++++++++++++++++++++++++++++++
> 1 file changed, 133 insertions(+)
> create mode 100644 doc/driver-model/fs_firmware_loader.txt
Reviewed-by: Simon Glass <sjg at chromium.org>
A few comments below.
>
> diff --git a/doc/driver-model/fs_firmware_loader.txt b/doc/driver-model/fs_firmware_loader.txt
> new file mode 100644
> index 0000000..290915a
> --- /dev/null
> +++ b/doc/driver-model/fs_firmware_loader.txt
> @@ -0,0 +1,133 @@
> +# Copyright (C) 2018 Intel Corporation <www.intel.com>
> +#
> +# SPDX-License-Identifier: GPL-2.0
> +
> +Introduction
> +============
> +
> +This is file system firmware loader for U-Boot framework, which has very close
> +to some Linux Firmware API. For the details of Linux Firmware API, you can refer
> +to https://01.org/linuxgraphics/gfx-docs/drm/driver-api/firmware/index.html.
> +
> +File system firmware loader can be used to load whatever(firmware, image,
> +and binary) from the storage device in file system format into target location
> +such as memory, then consumer driver such as FPGA driver can program FPGA image
> +from the target location into FPGA.
> +
> +To enable firmware loader, CONFIG_FS_LOADER need to be set at
> +<board_name>_defconfig such as "CONFIG_FS_LOADER=y".
> +
> +Firmware Loader API core features
> +---------------------------------
> +
> +Firmware storage device described in device tree source
> +-------------------------------------------------------
> + For passing data like storage device phandle and partition where the
> + firmware loading from to the firmware loader driver, those data could be
> + defined in fs-loader node as shown in below:
> +
> + Example for block device:
> + fs_loader0: fs-loader at 0 {
> + u-boot,dm-pre-reloc;
> + compatible = "u-boot,fs-loader";
> + phandlepart = <&mmc 1>;
I don't like this name much. How about
source-partition = <&mmc 1>;
or something like that?
> + };
> +
> + <&mmc 1> means block storage device pointer and its partition.
> +
> + Above example is a description for block storage, but for UBI storage
> + device, it can be described in FDT as shown in below:
> +
> + Example for ubi:
> + fs_loader1: fs-loader at 1 {
> + u-boot,dm-pre-reloc;
> + compatible = "u-boot,fs-loader";
> + mtdpart = "UBI",
> + ubivol = "ubi0";
> + };
> +
> + Then, firmware_loader property would be set with the path of fs_loader
> + node under /chosen node such as:
> + /{
> + chosen {
> + firmware_loader = &fs_loader0;
> + };
> + };
> +
> + However, this driver is also designed to support U-boot environment
U-Boot
Please fix below also.
> + variables, so all these data from FDT can be overwritten
> + through the U-boot environment variable during run time.
> + For examples:
> + "storage_interface" - Storage interface, it can be "mmc", "usb", "sata"
> + or "ubi".
> + "fw_dev_part" - Block device number and its partition, it can be "0:1".
> + "fw_ubi_mtdpart" - UBI device mtd partition, it can be "UBI".
> + "fw_ubi_volume" - UBI volume, it can be "ubi0".
> +
> + When above environment variables are set, environment values would be
> + used instead of data from FDT.
> + The benefit of this design allows user to change storage attribute data
> + at run time through U-boot console and saving the setting as default
> + environment values in the storage for the next power cycle, so no
> + compilation is required for both driver and FDT.
> +
> +File system firmware Loader API
> +-------------------------------
> +
> +int request_firmware_into_buf(struct device_platdata *plat,
> + const char *name,
> + void *buf, size_t size, u32 offset,
> + struct firmware **firmwarep)
> +--------------------------------------------------------------------
> +Load firmware into a previously allocated buffer
> +
> +Parameters:
> +
> +1. struct device_platdata *plat
> + Platform data such as storage and partition firmware loading from
> +
> +2. const char *name
> + name of firmware file
> +
> +3. void *buf
> + address of buffer to load firmware into
> +
> +4. size_t size
> + size of buffer
> +
> +5. u32 offset
> + offset of a file for start reading into buffer
> +
> +6. struct firmware **firmwarep
> + pointer to firmware image
> +
> +return:
> + size of total read
> + -ve when error
> +
> +Description:
> + The firmware is loaded directly into the buffer pointed to by buf and
> + the @firmwarep data member is pointed at buf
> +
> +Note: Memory would be allocated for firmware image, hence user should
> + free() *firmwarep and *firmwarep->priv structs after usage of
> + request_firmware_into_buf(), otherwise it will always leak memory
> + while subsequent calls of request_firmware_into_buf() with the same
> + *firmwarep argument. Those arguments can be free through calling API
> + below release_firmware();
> +
> +Example of creating firmware loader instance and calling
> +request_firmware_into_buf API:
> + if (uclass_get_device(UCLASS_FS_FIRMWARE_LOADER, 0, &dev)) {
> + request_firmware_into_buf(dev->plat, filename, buffer_location,
> + buffer_size, offset_ofreading, &fw);
> + }
> +
> +void release_firmware(struct firmware *firmware)
> +------------------------------------------------
> +Release the resource associated with a firmware image
> +
> +Parameters:
> +
> +1. struct firmware *firmware
> + Firmware resource to release
> --
> 2.2.0
>
Regards,
Simon
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