GK SDK 源码库: XMIPCLinuxV100R005C00SPC030 (kernel/tools/open_source excluded)

2026-09-06 03:52:57 +08:00
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+.. SPDX-License-Identifier: GPL-2.0+
+.. (C) Copyright 2015
+.. Texas Instruments Incorporated - http://www.ti.com/
+
+Remote Processor Framework
+==========================
+
+Introduction
+------------
+
+This is an introduction to driver-model for Remote Processors found
+on various System on Chip(SoCs). The term remote processor is used to
+indicate that this is not the processor on which U-Boot is operating
+on, instead is yet another processing entity that may be controlled by
+the processor on which we are functional.
+
+The simplified model depends on a single UCLASS - UCLASS_REMOTEPROC
+
+UCLASS_REMOTEPROC:
+  - drivers/remoteproc/rproc-uclass.c
+  - include/remoteproc.h
+
+Commands:
+  - common/cmd_remoteproc.c
+
+Configuration:
+  - CONFIG_REMOTEPROC is selected by drivers as needed
+  - CONFIG_CMD_REMOTEPROC for the commands if required.
+
+How does it work - The driver
+-----------------------------
+
+Overall, the driver statemachine transitions are typically as follows::
+
+           (entry)
+           +-------+
+       +---+ init  |
+       |   |       | <---------------------+
+       |   +-------+                       |
+       |                                   |
+       |                                   |
+       |   +--------+                      |
+   Load|   |  reset |                      |
+       |   |        | <----------+         |
+       |   +--------+            |         |
+       |        |Load            |         |
+       |        |                |         |
+       |   +----v----+   reset   |         |
+       +-> |         |    (opt)  |         |
+           |  Loaded +-----------+         |
+           |         |                     |
+           +----+----+                     |
+                | Start                    |
+            +---v-----+        (opt)       |
+         +->| Running |        Stop        |
+   Ping  +- |         +--------------------+
+   (opt)    +---------+
+
+(is_running does not change state)
+opt: Optional state transition implemented by driver.
+
+NOTE: It depends on the remote processor as to the exact behavior
+of the statemachine, remoteproc core does not intent to implement
+statemachine logic. Certain processors may allow start/stop without
+reloading the image in the middle, certain other processors may only
+allow us to start the processor(image from a EEPROM/OTP) etc.
+
+It is hence the responsibility of the driver to handle the requisite
+state transitions of the device as necessary.
+
+Basic design assumptions:
+
+Remote processor can operate on a certain firmware that maybe loaded
+and released from reset.
+
+The driver follows a standard UCLASS DM.
+
+in the bare minimum form:
+
+.. code-block:: c
+
+	static const struct dm_rproc_ops sandbox_testproc_ops = {
+		.load = sandbox_testproc_load,
+		.start = sandbox_testproc_start,
+	};
+
+	static const struct udevice_id sandbox_ids[] = {
+		{.compatible = "sandbox,test-processor"},
+		{}
+	};
+
+	U_BOOT_DRIVER(sandbox_testproc) = {
+		.name = "sandbox_test_proc",
+		.of_match = sandbox_ids,
+		.id = UCLASS_REMOTEPROC,
+		.ops = &sandbox_testproc_ops,
+		.probe = sandbox_testproc_probe,
+	};
+
+This allows for the device to be probed as part of the "init" command
+or invocation of 'rproc_init()' function as the system dependencies define.
+
+The driver is expected to maintain it's own statemachine which is
+appropriate for the device it maintains. It must, at the very least
+provide a load and start function. We assume here that the device
+needs to be loaded and started, else, there is no real purpose of
+using the remoteproc framework.
+
+Describing the device using platform data
+-----------------------------------------
+
+*IMPORTANT* NOTE: THIS SUPPORT IS NOT MEANT FOR USE WITH NEWER PLATFORM
+SUPPORT. THIS IS ONLY FOR LEGACY DEVICES. THIS MODE OF INITIALIZATION
+*WILL* BE EVENTUALLY REMOVED ONCE ALL NECESSARY PLATFORMS HAVE MOVED
+TO DM/FDT.
+
+Considering that many platforms are yet to move to device-tree model,
+a simplified definition of a device is as follows:
+
+.. code-block:: c
+
+	struct dm_rproc_uclass_pdata proc_3_test = {
+		.name = "proc_3_legacy",
+		.mem_type = RPROC_INTERNAL_MEMORY_MAPPED,
+		.driver_plat_data = &mydriver_data;
+	};
+
+	U_BOOT_DEVICE(proc_3_demo) = {
+		.name = "sandbox_test_proc",
+		.platdata = &proc_3_test,
+	};
+
+There can be additional data that may be desired depending on the
+remoteproc driver specific needs (for example: SoC integration
+details such as clock handle or something similar). See appropriate
+documentation for specific remoteproc driver for further details.
+These are passed via driver_plat_data.
+
+Describing the device using device tree
+---------------------------------------
+
+.. code-block: none
+
+	/ {
+		...
+		aliases {
+			...
+			remoteproc0 = &rproc_1;
+			remoteproc1 = &rproc_2;
+
+		};
+		...
+
+		rproc_1: rproc@1 {
+			compatible = "sandbox,test-processor";
+			remoteproc-name = "remoteproc-test-dev1";
+		};
+
+		rproc_2: rproc@2 {
+			compatible = "sandbox,test-processor";
+			internal-memory-mapped;
+			remoteproc-name = "remoteproc-test-dev2";
+		};
+		...
+	};
+
+aliases usage is optional, but it is usually recommended to ensure the
+users have a consistent usage model for a platform.
+the compatible string used here is specific to the remoteproc driver involved.