254 lines
6.8 KiB
C
254 lines
6.8 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Surface System Aggregator Module (SSAM) HID transport driver for the
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* generic HID interface (HID/TC=0x15 subsystem). Provides support for
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* integrated HID devices on Surface Laptop 3, Book 3, and later.
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*
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* Copyright (C) 2019-2021 Blaž Hrastnik <blaz@mxxn.io>,
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* Maximilian Luz <luzmaximilian@gmail.com>
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*/
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#include <asm/unaligned.h>
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#include <linux/hid.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/surface_aggregator/controller.h>
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#include <linux/surface_aggregator/device.h>
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#include "surface_hid_core.h"
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/* -- SAM interface. -------------------------------------------------------- */
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struct surface_hid_buffer_slice {
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__u8 entry;
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__le32 offset;
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__le32 length;
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__u8 end;
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__u8 data[];
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} __packed;
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static_assert(sizeof(struct surface_hid_buffer_slice) == 10);
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enum surface_hid_cid {
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SURFACE_HID_CID_OUTPUT_REPORT = 0x01,
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SURFACE_HID_CID_GET_FEATURE_REPORT = 0x02,
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SURFACE_HID_CID_SET_FEATURE_REPORT = 0x03,
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SURFACE_HID_CID_GET_DESCRIPTOR = 0x04,
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};
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static int ssam_hid_get_descriptor(struct surface_hid_device *shid, u8 entry, u8 *buf, size_t len)
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{
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u8 buffer[sizeof(struct surface_hid_buffer_slice) + 0x76];
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struct surface_hid_buffer_slice *slice;
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struct ssam_request rqst;
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struct ssam_response rsp;
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u32 buffer_len, offset, length;
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int status;
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/*
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* Note: The 0x76 above has been chosen because that's what's used by
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* the Windows driver. Together with the header, this leads to a 128
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* byte payload in total.
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*/
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buffer_len = ARRAY_SIZE(buffer) - sizeof(struct surface_hid_buffer_slice);
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rqst.target_category = shid->uid.category;
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rqst.target_id = shid->uid.target;
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rqst.command_id = SURFACE_HID_CID_GET_DESCRIPTOR;
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rqst.instance_id = shid->uid.instance;
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rqst.flags = SSAM_REQUEST_HAS_RESPONSE;
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rqst.length = sizeof(struct surface_hid_buffer_slice);
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rqst.payload = buffer;
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rsp.capacity = ARRAY_SIZE(buffer);
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rsp.pointer = buffer;
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slice = (struct surface_hid_buffer_slice *)buffer;
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slice->entry = entry;
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slice->end = 0;
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offset = 0;
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length = buffer_len;
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while (!slice->end && offset < len) {
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put_unaligned_le32(offset, &slice->offset);
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put_unaligned_le32(length, &slice->length);
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rsp.length = 0;
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status = ssam_retry(ssam_request_sync_onstack, shid->ctrl, &rqst, &rsp,
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sizeof(*slice));
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if (status)
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return status;
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offset = get_unaligned_le32(&slice->offset);
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length = get_unaligned_le32(&slice->length);
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/* Don't mess stuff up in case we receive garbage. */
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if (length > buffer_len || offset > len)
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return -EPROTO;
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if (offset + length > len)
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length = len - offset;
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memcpy(buf + offset, &slice->data[0], length);
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offset += length;
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length = buffer_len;
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}
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if (offset != len) {
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dev_err(shid->dev, "unexpected descriptor length: got %u, expected %zu\n",
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offset, len);
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return -EPROTO;
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}
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return 0;
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}
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static int ssam_hid_set_raw_report(struct surface_hid_device *shid, u8 rprt_id, bool feature,
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u8 *buf, size_t len)
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{
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struct ssam_request rqst;
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u8 cid;
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if (feature)
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cid = SURFACE_HID_CID_SET_FEATURE_REPORT;
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else
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cid = SURFACE_HID_CID_OUTPUT_REPORT;
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rqst.target_category = shid->uid.category;
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rqst.target_id = shid->uid.target;
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rqst.instance_id = shid->uid.instance;
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rqst.command_id = cid;
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rqst.flags = 0;
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rqst.length = len;
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rqst.payload = buf;
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buf[0] = rprt_id;
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return ssam_retry(ssam_request_sync, shid->ctrl, &rqst, NULL);
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}
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static int ssam_hid_get_raw_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)
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{
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struct ssam_request rqst;
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struct ssam_response rsp;
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rqst.target_category = shid->uid.category;
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rqst.target_id = shid->uid.target;
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rqst.instance_id = shid->uid.instance;
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rqst.command_id = SURFACE_HID_CID_GET_FEATURE_REPORT;
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rqst.flags = 0;
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rqst.length = sizeof(rprt_id);
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rqst.payload = &rprt_id;
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rsp.capacity = len;
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rsp.length = 0;
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rsp.pointer = buf;
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return ssam_retry(ssam_request_sync_onstack, shid->ctrl, &rqst, &rsp, sizeof(rprt_id));
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}
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static u32 ssam_hid_event_fn(struct ssam_event_notifier *nf, const struct ssam_event *event)
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{
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struct surface_hid_device *shid = container_of(nf, struct surface_hid_device, notif);
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if (event->command_id != 0x00)
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return 0;
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hid_input_report(shid->hid, HID_INPUT_REPORT, (u8 *)&event->data[0], event->length, 0);
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return SSAM_NOTIF_HANDLED;
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}
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/* -- Transport driver. ----------------------------------------------------- */
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static int shid_output_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)
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{
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int status;
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status = ssam_hid_set_raw_report(shid, rprt_id, false, buf, len);
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return status >= 0 ? len : status;
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}
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static int shid_get_feature_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)
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{
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int status;
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status = ssam_hid_get_raw_report(shid, rprt_id, buf, len);
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return status >= 0 ? len : status;
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}
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static int shid_set_feature_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)
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{
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int status;
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status = ssam_hid_set_raw_report(shid, rprt_id, true, buf, len);
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return status >= 0 ? len : status;
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}
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/* -- Driver setup. --------------------------------------------------------- */
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static int surface_hid_probe(struct ssam_device *sdev)
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{
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struct surface_hid_device *shid;
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shid = devm_kzalloc(&sdev->dev, sizeof(*shid), GFP_KERNEL);
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if (!shid)
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return -ENOMEM;
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shid->dev = &sdev->dev;
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shid->ctrl = sdev->ctrl;
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shid->uid = sdev->uid;
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shid->notif.base.priority = 1;
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shid->notif.base.fn = ssam_hid_event_fn;
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shid->notif.event.reg = SSAM_EVENT_REGISTRY_REG;
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shid->notif.event.id.target_category = sdev->uid.category;
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shid->notif.event.id.instance = sdev->uid.instance;
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shid->notif.event.mask = SSAM_EVENT_MASK_STRICT;
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shid->notif.event.flags = 0;
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shid->ops.get_descriptor = ssam_hid_get_descriptor;
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shid->ops.output_report = shid_output_report;
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shid->ops.get_feature_report = shid_get_feature_report;
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shid->ops.set_feature_report = shid_set_feature_report;
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ssam_device_set_drvdata(sdev, shid);
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return surface_hid_device_add(shid);
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}
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static void surface_hid_remove(struct ssam_device *sdev)
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{
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surface_hid_device_destroy(ssam_device_get_drvdata(sdev));
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}
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static const struct ssam_device_id surface_hid_match[] = {
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{ SSAM_SDEV(HID, 0x02, SSAM_ANY_IID, 0x00) },
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{ },
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};
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MODULE_DEVICE_TABLE(ssam, surface_hid_match);
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static struct ssam_device_driver surface_hid_driver = {
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.probe = surface_hid_probe,
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.remove = surface_hid_remove,
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.match_table = surface_hid_match,
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.driver = {
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.name = "surface_hid",
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.pm = &surface_hid_pm_ops,
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.probe_type = PROBE_PREFER_ASYNCHRONOUS,
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},
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};
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module_ssam_device_driver(surface_hid_driver);
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MODULE_AUTHOR("Blaž Hrastnik <blaz@mxxn.io>");
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MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
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MODULE_DESCRIPTION("HID transport driver for Surface System Aggregator Module");
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MODULE_LICENSE("GPL");
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