Commit d4201854 authored by Maximilian Luz's avatar Maximilian Luz Committed by Hans de Goede
Browse files

platform/surface: aggregator_registry: Add KIP device hub 



Add a Surface System Aggregator Module (SSAM) client device hub for
hot-removable devices managed via the KIP subsystem.

The KIP subsystem (full name unknown, abbreviation has been obtained
through reverse engineering) is a subsystem that manages hot-removable
SSAM client devices. Specifically, it manages HID input devices
contained in the detachable keyboard cover of the Surface Pro 8 and
Surface Pro X.

The KIP subsystem handles a single group of devices (e.g. all devices
contained in the keyboard cover) and cannot handle devices individually.
Thus we model it as a client device hub, which (hot-)removes all devices
contained under it once removal of the hub (e.g. keyboard cover) has
been detected and (re-)adds all devices once the physical hub device has
been (re-)attached. To do this, use the previously generified SSAM
subsystem hub framework.

Signed-off-by: default avatarMaximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20220527023447.2460025-12-luzmaximilian@gmail.com


Reviewed-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
parent 58a4d884

drivers/platform/surface/surface_aggregator_registry.c

+101 −2
Original line number Diff line number Diff line
@@ -551,6 +551,93 @@ static struct ssam_device_driver ssam_base_hub_driver = { 
};





/* -- SSAM KIP-subsystem hub driver. ---------------------------------------- */



/*

 * Some devices may need a bit of time to be fully usable after being

 * (re-)connected. This delay has been determined via experimentation.

 */

#define SSAM_KIP_UPDATE_CONNECT_DELAY		msecs_to_jiffies(250)



#define SSAM_EVENT_KIP_CID_CONNECTION		0x2c



SSAM_DEFINE_SYNC_REQUEST_R(__ssam_kip_get_connection_state, u8, {

	.target_category = SSAM_SSH_TC_KIP,

	.target_id       = 0x01,

	.command_id      = 0x2c,

	.instance_id     = 0x00,

});



static int ssam_kip_get_connection_state(struct ssam_hub *hub, enum ssam_hub_state *state)

{

	int status;

	u8 connected;



	status = ssam_retry(__ssam_kip_get_connection_state, hub->sdev->ctrl, &connected);

	if (status < 0) {

		dev_err(&hub->sdev->dev, "failed to query KIP connection state: %d\n", status);

		return status;

	}



	*state = connected ? SSAM_HUB_CONNECTED : SSAM_HUB_DISCONNECTED;

	return 0;

}



static u32 ssam_kip_hub_notif(struct ssam_event_notifier *nf, const struct ssam_event *event)

{

	struct ssam_hub *hub = container_of(nf, struct ssam_hub, notif);



	if (event->command_id != SSAM_EVENT_KIP_CID_CONNECTION)

		return 0;	/* Return "unhandled". */



	if (event->length < 1) {

		dev_err(&hub->sdev->dev, "unexpected payload size: %u\n", event->length);

		return 0;

	}



	ssam_hub_update(hub, event->data[0]);

	return SSAM_NOTIF_HANDLED;

}



static int ssam_kip_hub_probe(struct ssam_device *sdev)

{

	struct ssam_hub *hub;



	hub = devm_kzalloc(&sdev->dev, sizeof(*hub), GFP_KERNEL);

	if (!hub)

		return -ENOMEM;



	hub->notif.base.priority = INT_MAX;  /* This notifier should run first. */

	hub->notif.base.fn = ssam_kip_hub_notif;

	hub->notif.event.reg = SSAM_EVENT_REGISTRY_SAM;

	hub->notif.event.id.target_category = SSAM_SSH_TC_KIP,

	hub->notif.event.id.instance = 0,

	hub->notif.event.mask = SSAM_EVENT_MASK_TARGET;

	hub->notif.event.flags = SSAM_EVENT_SEQUENCED;



	hub->connect_delay = SSAM_KIP_UPDATE_CONNECT_DELAY;

	hub->get_state = ssam_kip_get_connection_state;



	return ssam_hub_setup(sdev, hub);

}



static const struct ssam_device_id ssam_kip_hub_match[] = {

	{ SSAM_VDEV(HUB, 0x01, SSAM_SSH_TC_KIP, 0x00) },

	{ },

};



static struct ssam_device_driver ssam_kip_hub_driver = {

	.probe = ssam_kip_hub_probe,

	.remove = ssam_hub_remove,

	.match_table = ssam_kip_hub_match,

	.driver = {

		.name = "surface_kip_hub",

		.probe_type = PROBE_PREFER_ASYNCHRONOUS,

		.pm = &ssam_hub_pm_ops,

	},

};





/* -- SSAM platform/meta-hub driver. ---------------------------------------- */



static const struct acpi_device_id ssam_platform_hub_match[] = {
@@ -673,18 +760,30 @@ static int __init ssam_device_hub_init(void) 


	status = platform_driver_register(&ssam_platform_hub_driver);

	if (status)

		return status;

		goto err_platform;



	status = ssam_device_driver_register(&ssam_base_hub_driver);

	if (status)

		platform_driver_unregister(&ssam_platform_hub_driver);

		goto err_base;



	status = ssam_device_driver_register(&ssam_kip_hub_driver);

	if (status)

		goto err_kip;



	return 0;



err_kip:

	ssam_device_driver_unregister(&ssam_base_hub_driver);

err_base:

	platform_driver_unregister(&ssam_platform_hub_driver);

err_platform:

	return status;

}

module_init(ssam_device_hub_init);



static void __exit ssam_device_hub_exit(void)

{

	ssam_device_driver_unregister(&ssam_kip_hub_driver);

	ssam_device_driver_unregister(&ssam_base_hub_driver);

	platform_driver_unregister(&ssam_platform_hub_driver);

}