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HID: surface-hid: Add support for legacy keyboard interface
Add support for the legacy keyboard (KBD/TC=0x08) HID transport layer of the Surface System Aggregator Module (SSAM) to the Surface HID driver. On Surface Laptops 1 and 2, this interface is used to connect the integrated keyboard. Note that this subsystem interface essentially provides a limited HID transport layer. In contrast to the generic HID interface (TC=0x15) used on newer Surface models, this interface only allows (as far as we know) for a single device to be connected and is otherwise severely limited in terms of support for feature- and output-reports. Specifically, only caps-lock-LED output-reports and a single read-only feature-report are supported. Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Maximilian Luz
Jiri Kosina
parent
b05ff1002a
commit
35a927f284
@ -21,6 +21,20 @@ config SURFACE_HID
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integrated touchpad and keyboard, on 7th generation Microsoft Surface
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models.
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config SURFACE_KBD
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tristate "HID keyboard transport driver for Surface System Aggregator Module"
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select SURFACE_HID_CORE
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help
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Driver to support HID keyboards on Surface Laptop 1 and 2 devices.
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This driver provides support for the HID transport protocol provided
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by the Surface Aggregator Module (i.e. the embedded controller) on
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Microsoft Surface Laptops 1 and 2. It is used to connect the
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integrated keyboard on those devices.
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Say M or Y here, if you want support for the integrated keyboard on
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Microsoft Surface Laptops 1 and 2.
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endmenu
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config SURFACE_HID_CORE
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@ -4,3 +4,4 @@
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#
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obj-$(CONFIG_SURFACE_HID_CORE) += surface_hid_core.o
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obj-$(CONFIG_SURFACE_HID) += surface_hid.o
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obj-$(CONFIG_SURFACE_KBD) += surface_kbd.o
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300
drivers/hid/surface-hid/surface_kbd.c
Normal file
300
drivers/hid/surface-hid/surface_kbd.c
Normal file
@ -0,0 +1,300 @@
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// SPDX-License-Identifier: GPL-2.0+
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/*
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* Surface System Aggregator Module (SSAM) HID transport driver for the legacy
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* keyboard interface (KBD/TC=0x08 subsystem). Provides support for the
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* integrated HID keyboard on Surface Laptops 1 and 2.
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*
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* Copyright (C) 2019-2021 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/platform_device.h>
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#include <linux/types.h>
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#include <linux/surface_aggregator/controller.h>
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#include "surface_hid_core.h"
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/* -- SAM interface (KBD). -------------------------------------------------- */
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#define KBD_FEATURE_REPORT_SIZE 7 /* 6 + report ID */
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enum surface_kbd_cid {
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SURFACE_KBD_CID_GET_DESCRIPTOR = 0x00,
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SURFACE_KBD_CID_SET_CAPSLOCK_LED = 0x01,
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SURFACE_KBD_CID_EVT_INPUT_GENERIC = 0x03,
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SURFACE_KBD_CID_EVT_INPUT_HOTKEYS = 0x04,
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SURFACE_KBD_CID_GET_FEATURE_REPORT = 0x0b,
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};
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static int ssam_kbd_get_descriptor(struct surface_hid_device *shid, u8 entry, 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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int status;
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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_KBD_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(entry);
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rqst.payload = &entry;
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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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status = ssam_retry(ssam_request_sync_onstack, shid->ctrl, &rqst, &rsp, sizeof(entry));
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if (status)
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return status;
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if (rsp.length != len) {
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dev_err(shid->dev, "invalid descriptor length: got %zu, expected, %zu\n",
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rsp.length, 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_kbd_set_caps_led(struct surface_hid_device *shid, bool value)
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{
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struct ssam_request rqst;
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u8 value_u8 = value;
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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_KBD_CID_SET_CAPSLOCK_LED;
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rqst.instance_id = shid->uid.instance;
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rqst.flags = 0;
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rqst.length = sizeof(value_u8);
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rqst.payload = &value_u8;
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return ssam_retry(ssam_request_sync_onstack, shid->ctrl, &rqst, NULL, sizeof(value_u8));
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}
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static int ssam_kbd_get_feature_report(struct surface_hid_device *shid, 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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u8 payload = 0;
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int status;
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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_KBD_CID_GET_FEATURE_REPORT;
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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(payload);
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rqst.payload = &payload;
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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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status = ssam_retry(ssam_request_sync_onstack, shid->ctrl, &rqst, &rsp, sizeof(payload));
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if (status)
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return status;
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if (rsp.length != len) {
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dev_err(shid->dev, "invalid feature report length: got %zu, expected, %zu\n",
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rsp.length, 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 bool ssam_kbd_is_input_event(const struct ssam_event *event)
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{
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if (event->command_id == SURFACE_KBD_CID_EVT_INPUT_GENERIC)
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return true;
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if (event->command_id == SURFACE_KBD_CID_EVT_INPUT_HOTKEYS)
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return true;
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return false;
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}
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static u32 ssam_kbd_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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/*
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* Check against device UID manually, as registry and device target
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* category doesn't line up.
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*/
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if (shid->uid.category != event->target_category)
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return 0;
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if (shid->uid.target != event->target_id)
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return 0;
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if (shid->uid.instance != event->instance_id)
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return 0;
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if (!ssam_kbd_is_input_event(event))
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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 (KBD). ----------------------------------------------- */
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static int skbd_get_caps_led_value(struct hid_device *hid, u8 rprt_id, u8 *buf, size_t len)
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{
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struct hid_field *field;
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unsigned int offset, size;
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int i;
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/* Get LED field. */
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field = hidinput_get_led_field(hid);
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if (!field)
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return -ENOENT;
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/* Check if we got the correct report. */
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if (len != hid_report_len(field->report))
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return -ENOENT;
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if (rprt_id != field->report->id)
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return -ENOENT;
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/* Get caps lock LED index. */
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for (i = 0; i < field->report_count; i++)
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if ((field->usage[i].hid & 0xffff) == 0x02)
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break;
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if (i == field->report_count)
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return -ENOENT;
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/* Extract value. */
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size = field->report_size;
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offset = field->report_offset + i * size;
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return !!hid_field_extract(hid, buf + 1, size, offset);
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}
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static int skbd_output_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)
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{
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int caps_led;
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int status;
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caps_led = skbd_get_caps_led_value(shid->hid, rprt_id, buf, len);
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if (caps_led < 0)
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return -EIO; /* Only caps LED output reports are supported. */
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status = ssam_kbd_set_caps_led(shid, caps_led);
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if (status < 0)
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return status;
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return len;
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}
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static int skbd_get_feature_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)
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{
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u8 report[KBD_FEATURE_REPORT_SIZE];
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int status;
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/*
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* The keyboard only has a single hard-coded read-only feature report
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* of size KBD_FEATURE_REPORT_SIZE. Try to load it and compare its
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* report ID against the requested one.
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*/
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if (len < ARRAY_SIZE(report))
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return -ENOSPC;
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status = ssam_kbd_get_feature_report(shid, report, ARRAY_SIZE(report));
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if (status < 0)
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return status;
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if (rprt_id != report[0])
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return -ENOENT;
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memcpy(buf, report, ARRAY_SIZE(report));
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return len;
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}
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static int skbd_set_feature_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)
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{
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/* Not supported. See skbd_get_feature_report() for details. */
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return -EIO;
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}
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/* -- Driver setup. --------------------------------------------------------- */
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static int surface_kbd_probe(struct platform_device *pdev)
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{
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struct ssam_controller *ctrl;
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struct surface_hid_device *shid;
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/* Add device link to EC. */
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ctrl = ssam_client_bind(&pdev->dev);
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if (IS_ERR(ctrl))
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return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl);
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shid = devm_kzalloc(&pdev->dev, sizeof(*shid), GFP_KERNEL);
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if (!shid)
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return -ENOMEM;
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shid->dev = &pdev->dev;
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shid->ctrl = ctrl;
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shid->uid.domain = SSAM_DOMAIN_SERIALHUB;
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shid->uid.category = SSAM_SSH_TC_KBD;
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shid->uid.target = 2;
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shid->uid.instance = 0;
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shid->uid.function = 0;
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shid->notif.base.priority = 1;
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shid->notif.base.fn = ssam_kbd_event_fn;
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shid->notif.event.reg = SSAM_EVENT_REGISTRY_SAM;
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shid->notif.event.id.target_category = shid->uid.category;
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shid->notif.event.id.instance = shid->uid.instance;
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shid->notif.event.mask = SSAM_EVENT_MASK_NONE;
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shid->notif.event.flags = 0;
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shid->ops.get_descriptor = ssam_kbd_get_descriptor;
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shid->ops.output_report = skbd_output_report;
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shid->ops.get_feature_report = skbd_get_feature_report;
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shid->ops.set_feature_report = skbd_set_feature_report;
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platform_set_drvdata(pdev, shid);
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return surface_hid_device_add(shid);
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}
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static int surface_kbd_remove(struct platform_device *pdev)
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{
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surface_hid_device_destroy(platform_get_drvdata(pdev));
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return 0;
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}
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static const struct acpi_device_id surface_kbd_match[] = {
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{ "MSHW0096" },
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{ },
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};
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MODULE_DEVICE_TABLE(acpi, surface_kbd_match);
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static struct platform_driver surface_kbd_driver = {
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.probe = surface_kbd_probe,
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.remove = surface_kbd_remove,
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.driver = {
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.name = "surface_keyboard",
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.acpi_match_table = surface_kbd_match,
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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_platform_driver(surface_kbd_driver);
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MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
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MODULE_DESCRIPTION("HID legacy transport driver for Surface System Aggregator Module");
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MODULE_LICENSE("GPL");
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