1.. SPDX-License-Identifier: GPL-2.0
2
3===================
4Firmware Upload API
5===================
6
7A device driver that registers with the firmware loader will expose
8persistent sysfs nodes to enable users to initiate firmware updates for
9that device.  It is the responsibility of the device driver and/or the
10device itself to perform any validation on the data received. Firmware
11upload uses the same *loading* and *data* sysfs files described in the
12documentation for firmware fallback. It also adds additional sysfs files
13to provide status on the transfer of the firmware image to the device.
14
15Register for firmware upload
16============================
17
18A device driver registers for firmware upload by calling
19firmware_upload_register(). Among the parameter list is a name to
20identify the device under /sys/class/firmware. A user may initiate a
21firmware upload by echoing a 1 to the *loading* sysfs file for the target
22device. Next, the user writes the firmware image to the *data* sysfs
23file. After writing the firmware data, the user echos 0 to the *loading*
24sysfs file to signal completion. Echoing 0 to *loading* also triggers the
25transfer of the firmware to the lower-lever device driver in the context
26of a kernel worker thread.
27
28To use the firmware upload API, write a driver that implements a set of
29ops.  The probe function calls firmware_upload_register() and the remove
30function calls firmware_upload_unregister() such as::
31
32	static const struct fw_upload_ops m10bmc_ops = {
33		.prepare = m10bmc_sec_prepare,
34		.write = m10bmc_sec_write,
35		.poll_complete = m10bmc_sec_poll_complete,
36		.cancel = m10bmc_sec_cancel,
37		.cleanup = m10bmc_sec_cleanup,
38	};
39
40	static int m10bmc_sec_probe(struct platform_device *pdev)
41	{
42		const char *fw_name, *truncate;
43		struct m10bmc_sec *sec;
44		struct fw_upload *fwl;
45		unsigned int len;
46
47		sec = devm_kzalloc(&pdev->dev, sizeof(*sec), GFP_KERNEL);
48		if (!sec)
49			return -ENOMEM;
50
51		sec->dev = &pdev->dev;
52		sec->m10bmc = dev_get_drvdata(pdev->dev.parent);
53		dev_set_drvdata(&pdev->dev, sec);
54
55		fw_name = dev_name(sec->dev);
56		truncate = strstr(fw_name, ".auto");
57		len = (truncate) ? truncate - fw_name : strlen(fw_name);
58		sec->fw_name = kmemdup_nul(fw_name, len, GFP_KERNEL);
59
60		fwl = firmware_upload_register(THIS_MODULE, sec->dev, sec->fw_name,
61					       &m10bmc_ops, sec);
62		if (IS_ERR(fwl)) {
63			dev_err(sec->dev, "Firmware Upload driver failed to start\n");
64			kfree(sec->fw_name);
65			return PTR_ERR(fwl);
66		}
67
68		sec->fwl = fwl;
69		return 0;
70	}
71
72	static int m10bmc_sec_remove(struct platform_device *pdev)
73	{
74		struct m10bmc_sec *sec = dev_get_drvdata(&pdev->dev);
75
76		firmware_upload_unregister(sec->fwl);
77		kfree(sec->fw_name);
78		return 0;
79	}
80
81firmware_upload_register
82------------------------
83.. kernel-doc:: drivers/base/firmware_loader/sysfs_upload.c
84   :identifiers: firmware_upload_register
85
86firmware_upload_unregister
87--------------------------
88.. kernel-doc:: drivers/base/firmware_loader/sysfs_upload.c
89   :identifiers: firmware_upload_unregister
90
91Firmware Upload Ops
92-------------------
93.. kernel-doc:: include/linux/firmware.h
94   :identifiers: fw_upload_ops
95
96Firmware Upload Progress Codes
97------------------------------
98The following progress codes are used internally by the firmware loader.
99Corresponding strings are reported through the status sysfs node that
100is described below and are documented in the ABI documentation.
101
102.. kernel-doc:: drivers/base/firmware_loader/sysfs_upload.h
103   :identifiers: fw_upload_prog
104
105Firmware Upload Error Codes
106---------------------------
107The following error codes may be returned by the driver ops in case of
108failure:
109
110.. kernel-doc:: include/linux/firmware.h
111   :identifiers: fw_upload_err
112
113Sysfs Attributes
114================
115
116In addition to the *loading* and *data* sysfs files, there are additional
117sysfs files to monitor the status of the data transfer to the target
118device and to determine the final pass/fail status of the transfer.
119Depending on the device and the size of the firmware image, a firmware
120update could take milliseconds or minutes.
121
122The additional sysfs files are:
123
124* status - provides an indication of the progress of a firmware update
125* error - provides error information for a failed firmware update
126* remaining_size - tracks the data transfer portion of an update
127* cancel - echo 1 to this file to cancel the update
128