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// SPDX-License-Identifier: GPL-2.0+
/*
* Surface System Aggregator Module (SSAM) HID transport driver for the legacy
* keyboard interface (KBD/TC=0x08 subsystem). Provides support for the
* integrated HID keyboard on Surface Laptops 1 and 2.
*
* Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
*/
#include <asm/unaligned.h>
#include <linux/hid.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/surface_aggregator/controller.h>
#include "surface_hid_core.h"
/* -- SAM interface (KBD). -------------------------------------------------- */
#define KBD_FEATURE_REPORT_SIZE 7 /* 6 + report ID */
enum surface_kbd_cid {
SURFACE_KBD_CID_GET_DESCRIPTOR = 0x00,
SURFACE_KBD_CID_SET_CAPSLOCK_LED = 0x01,
SURFACE_KBD_CID_EVT_INPUT_GENERIC = 0x03,
SURFACE_KBD_CID_EVT_INPUT_HOTKEYS = 0x04,
SURFACE_KBD_CID_GET_FEATURE_REPORT = 0x0b,
};
static int ssam_kbd_get_descriptor(struct surface_hid_device *shid, u8 entry, u8 *buf, size_t len)
{
struct ssam_request rqst;
struct ssam_response rsp;
int status;
rqst.target_category = shid->uid.category;
rqst.target_id = shid->uid.target;
rqst.command_id = SURFACE_KBD_CID_GET_DESCRIPTOR;
rqst.instance_id = shid->uid.instance;
rqst.flags = SSAM_REQUEST_HAS_RESPONSE;
rqst.length = sizeof(entry);
rqst.payload = &entry;
rsp.capacity = len;
rsp.length = 0;
rsp.pointer = buf;
status = ssam_retry(ssam_request_do_sync_onstack, shid->ctrl, &rqst, &rsp, sizeof(entry));
if (status)
return status;
if (rsp.length != len) {
dev_err(shid->dev, "invalid descriptor length: got %zu, expected, %zu\n",
rsp.length, len);
return -EPROTO;
}
return 0;
}
static int ssam_kbd_set_caps_led(struct surface_hid_device *shid, bool value)
{
struct ssam_request rqst;
u8 value_u8 = value;
rqst.target_category = shid->uid.category;
rqst.target_id = shid->uid.target;
rqst.command_id = SURFACE_KBD_CID_SET_CAPSLOCK_LED;
rqst.instance_id = shid->uid.instance;
rqst.flags = 0;
rqst.length = sizeof(value_u8);
rqst.payload = &value_u8;
return ssam_retry(ssam_request_do_sync_onstack, shid->ctrl, &rqst, NULL, sizeof(value_u8));
}
static int ssam_kbd_get_feature_report(struct surface_hid_device *shid, u8 *buf, size_t len)
{
struct ssam_request rqst;
struct ssam_response rsp;
u8 payload = 0;
int status;
rqst.target_category = shid->uid.category;
rqst.target_id = shid->uid.target;
rqst.command_id = SURFACE_KBD_CID_GET_FEATURE_REPORT;
rqst.instance_id = shid->uid.instance;
rqst.flags = SSAM_REQUEST_HAS_RESPONSE;
rqst.length = sizeof(payload);
rqst.payload = &payload;
rsp.capacity = len;
rsp.length = 0;
rsp.pointer = buf;
status = ssam_retry(ssam_request_do_sync_onstack, shid->ctrl, &rqst, &rsp, sizeof(payload));
if (status)
return status;
if (rsp.length != len) {
dev_err(shid->dev, "invalid feature report length: got %zu, expected, %zu\n",
rsp.length, len);
return -EPROTO;
}
return 0;
}
static bool ssam_kbd_is_input_event(const struct ssam_event *event)
{
if (event->command_id == SURFACE_KBD_CID_EVT_INPUT_GENERIC)
return true;
if (event->command_id == SURFACE_KBD_CID_EVT_INPUT_HOTKEYS)
return true;
return false;
}
static u32 ssam_kbd_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);
/*
* Check against device UID manually, as registry and device target
* category doesn't line up.
*/
if (shid->uid.category != event->target_category)
return 0;
if (shid->uid.target != event->target_id)
return 0;
if (shid->uid.instance != event->instance_id)
return 0;
if (!ssam_kbd_is_input_event(event))
return 0;
hid_input_report(shid->hid, HID_INPUT_REPORT, (u8 *)&event->data[0], event->length, 0);
return SSAM_NOTIF_HANDLED;
}
/* -- Transport driver (KBD). ----------------------------------------------- */
static int skbd_get_caps_led_value(struct hid_device *hid, u8 rprt_id, u8 *buf, size_t len)
{
struct hid_field *field;
unsigned int offset, size;
int i;
/* Get LED field. */
field = hidinput_get_led_field(hid);
if (!field)
return -ENOENT;
/* Check if we got the correct report. */
if (len != hid_report_len(field->report))
return -ENOENT;
if (rprt_id != field->report->id)
return -ENOENT;
/* Get caps lock LED index. */
for (i = 0; i < field->report_count; i++)
if ((field->usage[i].hid & 0xffff) == 0x02)
break;
if (i == field->report_count)
return -ENOENT;
/* Extract value. */
size = field->report_size;
offset = field->report_offset + i * size;
return !!hid_field_extract(hid, buf + 1, size, offset);
}
static int skbd_output_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)
{
int caps_led;
int status;
caps_led = skbd_get_caps_led_value(shid->hid, rprt_id, buf, len);
if (caps_led < 0)
return -EIO; /* Only caps LED output reports are supported. */
status = ssam_kbd_set_caps_led(shid, caps_led);
if (status < 0)
return status;
return len;
}
static int skbd_get_feature_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)
{
u8 report[KBD_FEATURE_REPORT_SIZE];
int status;
/*
* The keyboard only has a single hard-coded read-only feature report
* of size KBD_FEATURE_REPORT_SIZE. Try to load it and compare its
* report ID against the requested one.
*/
if (len < ARRAY_SIZE(report))
return -ENOSPC;
status = ssam_kbd_get_feature_report(shid, report, ARRAY_SIZE(report));
if (status < 0)
return status;
if (rprt_id != report[0])
return -ENOENT;
memcpy(buf, report, ARRAY_SIZE(report));
return len;
}
static int skbd_set_feature_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)
{
/* Not supported. See skbd_get_feature_report() for details. */
return -EIO;
}
/* -- Driver setup. --------------------------------------------------------- */
static int surface_kbd_probe(struct platform_device *pdev)
{
struct ssam_controller *ctrl;
struct surface_hid_device *shid;
/* Add device link to EC. */
ctrl = ssam_client_bind(&pdev->dev);
if (IS_ERR(ctrl))
return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl);
shid = devm_kzalloc(&pdev->dev, sizeof(*shid), GFP_KERNEL);
if (!shid)
return -ENOMEM;
shid->dev = &pdev->dev;
shid->ctrl = ctrl;
shid->uid.domain = SSAM_DOMAIN_SERIALHUB;
shid->uid.category = SSAM_SSH_TC_KBD;
shid->uid.target = SSAM_SSH_TID_KIP;
shid->uid.instance = 0;
shid->uid.function = 0;
shid->notif.base.priority = 1;
shid->notif.base.fn = ssam_kbd_event_fn;
shid->notif.event.reg = SSAM_EVENT_REGISTRY_SAM;
shid->notif.event.id.target_category = shid->uid.category;
shid->notif.event.id.instance = shid->uid.instance;
shid->notif.event.mask = SSAM_EVENT_MASK_NONE;
shid->notif.event.flags = 0;
shid->ops.get_descriptor = ssam_kbd_get_descriptor;
shid->ops.output_report = skbd_output_report;
shid->ops.get_feature_report = skbd_get_feature_report;
shid->ops.set_feature_report = skbd_set_feature_report;
platform_set_drvdata(pdev, shid);
return surface_hid_device_add(shid);
}
static int surface_kbd_remove(struct platform_device *pdev)
{
surface_hid_device_destroy(platform_get_drvdata(pdev));
return 0;
}
static const struct acpi_device_id surface_kbd_match[] = {
{ "MSHW0096" },
{ },
};
MODULE_DEVICE_TABLE(acpi, surface_kbd_match);
static struct platform_driver surface_kbd_driver = {
.probe = surface_kbd_probe,
.remove = surface_kbd_remove,
.driver = {
.name = "surface_keyboard",
.acpi_match_table = surface_kbd_match,
.pm = &surface_hid_pm_ops,
.probe_type = PROBE_PREFER_ASYNCHRONOUS,
},
};
module_platform_driver(surface_kbd_driver);
MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
MODULE_DESCRIPTION("HID legacy transport driver for Surface System Aggregator Module");
MODULE_LICENSE("GPL");