[U-Boot] [PATCH v3 1/3] doc: Add new doc for file system firmware loader driver model

[tien.fong.chee at intel.com]

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 | 129 ++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 doc/driver-model/fs_firmware_loader.txt

diff --git a/doc/driver-model/fs_firmware_loader.txt b/doc/driver-model/fs_firmware_loader.txt
new file mode 100644
index 0000000..102e14b
--- /dev/null
+++ b/doc/driver-model/fs_firmware_loader.txt
@@ -0,0 +1,129 @@
+# 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 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:
+
+	fs_loader0: fs_loader at 0 {
+		u-boot,dm-pre-reloc;
+		compatible = "fs_loader";
+		storage_device = "mmc";
+		devpart = "0:1";
+	};
+
+	Then, firmware_loader property would be set with the path of fs_loader
+	node under /chosen node such as:
+	/{
+		chosen {
+			firmware_loader = &fs_loader0;
+		};
+	};
+
+	Example of storage type and device partition search set for mmc, usb,
+	sata and ubi as shown in below:
+	Example for mmc:
+	fs_loader0: fs_loader at 0 {
+		u-boot,dm-pre-reloc;
+		compatible = "fs_loader";
+		storage_device = "mmc";
+		devpart = "0:1";
+	};
+
+	Example for usb:
+	fs_loader1: fs_loader at 1 {
+		u-boot,dm-pre-reloc;
+		compatible = "fs_loader";
+		storage_device = "usb";
+		devpart = "0:1";
+	};
+
+	Example for sata:
+	fs_loader2: fs_loader at 2 {
+		u-boot,dm-pre-reloc;
+		compatible = "fs_loader";
+		storage_device = "sata";
+		devpart = "0:1";
+	};
+
+	Example for ubi:
+	fs_loader3: fs_loader at 3 {
+		u-boot,dm-pre-reloc;
+		compatible = "fs_loader";
+		storage_device = "ubi";
+		mtdpart = "UBI",
+		ubivol = "ubi0";
+	};
+
+
+	However, the property of devpart, mtdpart, and ubivol values from
+	fs_loader node can be overwritten with value which is defined in the
+	environment variable "fw_dev_part", "fw_ubi_mtdpart", and
+	"fw_ubi_volume" respectively.
+	For example: env_set("fw_dev_part", "0:2");
+
+File system firmware Loader API
+-------------------------------
+
+int request_firmware_into_buf(struct device_platdata *plat,
+				 struct firmware **firmware_p,
+				 const char *name,
+				 void *buf, size_t size, u32 offset)
+--------------------------------------------------------------------
+Load firmware into a previously allocated buffer
+
+Parameters:
+
+1. struct device_platdata *plat
+	Platform data such as storage and partition firmware loading from
+
+2. struct firmware **firmware_p
+	pointer to firmware image
+
+3. const char *name
+	name of firmware file
+
+4. void *buf
+	address of buffer to load firmware into
+
+5. size_t size
+	size of buffer
+
+6. u32 offset
+	offset of a file for start reading into buffer
+
+return:
+	size of total read
+	-ve when error
+
+Description:
+	The firmware is loaded directly into the buffer pointed to by buf and
+	the @firmware_p data member is pointed at buf
+
+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, &fw, filename,
+			 buffer_location, buffer_size, offset_ofreading);
+	}
-- 
2.2.0