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linux/drivers/hid/surface-hid/surface_hid.c
Maximilian Luz 2b2bcc76e2 HID: surface-hid: Fix get-report request 
Getting a report (e.g. feature report) from a device requires us to send
a request indicating which report we want to retrieve and then waiting
for the corresponding response containing that report. We already
provide the response structure to the request call, but the request
isn't marked as a request that expects a response. Thus the request
returns before we receive the response and the response buffer indicates
a zero length response due to that.

This essentially means that the get-report calls are broken and will
always indicate that a report of length zero has been read.

Fix this by appropriately marking the request.

Fixes: b05ff1002a ("HID: Add support for Surface Aggregator Module HID transport")
Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2021-06-15 10:54:51 +02:00

254 lines
6.8 KiB
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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 <blaz@mxxn.io>,
* Maximilian Luz <luzmaximilian@gmail.com>
*/
#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;
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, 0x02, 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 <blaz@mxxn.io>");
MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
MODULE_DESCRIPTION("HID transport driver for Surface System Aggregator Module");
MODULE_LICENSE("GPL");
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