drivers/hid/surface-hid/surface_hid_core.c

Source file repositories/reference/linux-study-clean/drivers/hid/surface-hid/surface_hid_core.c

File Facts

System
Linux kernel
Corpus path
drivers/hid/surface-hid/surface_hid_core.c
Extension
.c
Size
7839 bytes
Lines
294
Domain
Driver Families
Bucket
drivers/hid
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0+
/*
 * Common/core components for the Surface System Aggregator Module (SSAM) HID
 * transport driver. Provides support for integrated HID devices on Microsoft
 * Surface models.
 *
 * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
 */

#include <linux/unaligned.h>
#include <linux/hid.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/usb/ch9.h>

#include <linux/surface_aggregator/controller.h>

#include "surface_hid_core.h"


/* -- Utility functions. ---------------------------------------------------- */

static bool surface_hid_is_hot_removed(struct surface_hid_device *shid)
{
	/*
	 * Non-ssam client devices, i.e. platform client devices, cannot be
	 * hot-removed.
	 */
	if (!is_ssam_device(shid->dev))
		return false;

	return ssam_device_is_hot_removed(to_ssam_device(shid->dev));
}


/* -- Device descriptor access. --------------------------------------------- */

static int surface_hid_load_hid_descriptor(struct surface_hid_device *shid)
{
	int status;

	if (surface_hid_is_hot_removed(shid))
		return -ENODEV;

	status = shid->ops.get_descriptor(shid, SURFACE_HID_DESC_HID,
			(u8 *)&shid->hid_desc, sizeof(shid->hid_desc));
	if (status)
		return status;

	if (shid->hid_desc.desc_len != sizeof(shid->hid_desc)) {
		dev_err(shid->dev, "unexpected HID descriptor length: got %u, expected %zu\n",
			shid->hid_desc.desc_len, sizeof(shid->hid_desc));
		return -EPROTO;
	}

	if (shid->hid_desc.desc_type != HID_DT_HID) {
		dev_err(shid->dev, "unexpected HID descriptor type: got %#04x, expected %#04x\n",
			shid->hid_desc.desc_type, HID_DT_HID);
		return -EPROTO;
	}

	if (shid->hid_desc.num_descriptors != 1) {
		dev_err(shid->dev, "unexpected number of descriptors: got %u, expected 1\n",
			shid->hid_desc.num_descriptors);
		return -EPROTO;
	}

	if (shid->hid_desc.report_desc_type != HID_DT_REPORT) {
		dev_err(shid->dev, "unexpected report descriptor type: got %#04x, expected %#04x\n",
			shid->hid_desc.report_desc_type, HID_DT_REPORT);
		return -EPROTO;
	}

	return 0;
}

static int surface_hid_load_device_attributes(struct surface_hid_device *shid)
{
	int status;

	if (surface_hid_is_hot_removed(shid))
		return -ENODEV;

	status = shid->ops.get_descriptor(shid, SURFACE_HID_DESC_ATTRS,
			(u8 *)&shid->attrs, sizeof(shid->attrs));
	if (status)
		return status;

	if (get_unaligned_le32(&shid->attrs.length) != sizeof(shid->attrs)) {

Annotation

Implementation Notes