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