diff options
Diffstat (limited to 'drivers/platform/surface/surface_aggregator_hub.c')
-rw-r--r-- | drivers/platform/surface/surface_aggregator_hub.c | 371 |
1 files changed, 371 insertions, 0 deletions
diff --git a/drivers/platform/surface/surface_aggregator_hub.c b/drivers/platform/surface/surface_aggregator_hub.c new file mode 100644 index 0000000000..8b8b80228c --- /dev/null +++ b/drivers/platform/surface/surface_aggregator_hub.c @@ -0,0 +1,371 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Driver for Surface System Aggregator Module (SSAM) subsystem device hubs. + * + * Provides a driver for SSAM subsystems device hubs. This driver performs + * instantiation of the devices managed by said hubs and takes care of + * (hot-)removal. + * + * Copyright (C) 2020-2022 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#include <linux/kernel.h> +#include <linux/limits.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/workqueue.h> + +#include <linux/surface_aggregator/device.h> + + +/* -- SSAM generic subsystem hub driver framework. -------------------------- */ + +enum ssam_hub_state { + SSAM_HUB_UNINITIALIZED, /* Only set during initialization. */ + SSAM_HUB_CONNECTED, + SSAM_HUB_DISCONNECTED, +}; + +enum ssam_hub_flags { + SSAM_HUB_HOT_REMOVED, +}; + +struct ssam_hub; + +struct ssam_hub_ops { + int (*get_state)(struct ssam_hub *hub, enum ssam_hub_state *state); +}; + +struct ssam_hub { + struct ssam_device *sdev; + + enum ssam_hub_state state; + unsigned long flags; + + struct delayed_work update_work; + unsigned long connect_delay; + + struct ssam_event_notifier notif; + struct ssam_hub_ops ops; +}; + +struct ssam_hub_desc { + struct { + struct ssam_event_registry reg; + struct ssam_event_id id; + enum ssam_event_mask mask; + } event; + + struct { + u32 (*notify)(struct ssam_event_notifier *nf, const struct ssam_event *event); + int (*get_state)(struct ssam_hub *hub, enum ssam_hub_state *state); + } ops; + + unsigned long connect_delay_ms; +}; + +static void ssam_hub_update_workfn(struct work_struct *work) +{ + struct ssam_hub *hub = container_of(work, struct ssam_hub, update_work.work); + enum ssam_hub_state state; + int status = 0; + + status = hub->ops.get_state(hub, &state); + if (status) + return; + + /* + * There is a small possibility that hub devices were hot-removed and + * re-added before we were able to remove them here. In that case, both + * the state returned by get_state() and the state of the hub will + * equal SSAM_HUB_CONNECTED and we would bail early below, which would + * leave child devices without proper (re-)initialization and the + * hot-remove flag set. + * + * Therefore, we check whether devices have been hot-removed via an + * additional flag on the hub and, in this case, override the returned + * hub state. In case of a missed disconnect (i.e. get_state returned + * "connected"), we further need to re-schedule this work (with the + * appropriate delay) as the actual connect work submission might have + * been merged with this one. + * + * This then leads to one of two cases: Either we submit an unnecessary + * work item (which will get ignored via either the queue or the state + * checks) or, in the unlikely case that the work is actually required, + * double the normal connect delay. + */ + if (test_and_clear_bit(SSAM_HUB_HOT_REMOVED, &hub->flags)) { + if (state == SSAM_HUB_CONNECTED) + schedule_delayed_work(&hub->update_work, hub->connect_delay); + + state = SSAM_HUB_DISCONNECTED; + } + + if (hub->state == state) + return; + hub->state = state; + + if (hub->state == SSAM_HUB_CONNECTED) + status = ssam_device_register_clients(hub->sdev); + else + ssam_remove_clients(&hub->sdev->dev); + + if (status) + dev_err(&hub->sdev->dev, "failed to update hub child devices: %d\n", status); +} + +static int ssam_hub_mark_hot_removed(struct device *dev, void *_data) +{ + struct ssam_device *sdev = to_ssam_device(dev); + + if (is_ssam_device(dev)) + ssam_device_mark_hot_removed(sdev); + + return 0; +} + +static void ssam_hub_update(struct ssam_hub *hub, bool connected) +{ + unsigned long delay; + + /* Mark devices as hot-removed before we remove any. */ + if (!connected) { + set_bit(SSAM_HUB_HOT_REMOVED, &hub->flags); + device_for_each_child_reverse(&hub->sdev->dev, NULL, ssam_hub_mark_hot_removed); + } + + /* + * Delay update when the base/keyboard cover is being connected to give + * devices/EC some time to set up. + */ + delay = connected ? hub->connect_delay : 0; + + schedule_delayed_work(&hub->update_work, delay); +} + +static int __maybe_unused ssam_hub_resume(struct device *dev) +{ + struct ssam_hub *hub = dev_get_drvdata(dev); + + schedule_delayed_work(&hub->update_work, 0); + return 0; +} +static SIMPLE_DEV_PM_OPS(ssam_hub_pm_ops, NULL, ssam_hub_resume); + +static int ssam_hub_probe(struct ssam_device *sdev) +{ + const struct ssam_hub_desc *desc; + struct ssam_hub *hub; + int status; + + desc = ssam_device_get_match_data(sdev); + if (!desc) { + WARN(1, "no driver match data specified"); + return -EINVAL; + } + + hub = devm_kzalloc(&sdev->dev, sizeof(*hub), GFP_KERNEL); + if (!hub) + return -ENOMEM; + + hub->sdev = sdev; + hub->state = SSAM_HUB_UNINITIALIZED; + + hub->notif.base.priority = INT_MAX; /* This notifier should run first. */ + hub->notif.base.fn = desc->ops.notify; + hub->notif.event.reg = desc->event.reg; + hub->notif.event.id = desc->event.id; + hub->notif.event.mask = desc->event.mask; + hub->notif.event.flags = SSAM_EVENT_SEQUENCED; + + hub->connect_delay = msecs_to_jiffies(desc->connect_delay_ms); + hub->ops.get_state = desc->ops.get_state; + + INIT_DELAYED_WORK(&hub->update_work, ssam_hub_update_workfn); + + ssam_device_set_drvdata(sdev, hub); + + status = ssam_device_notifier_register(sdev, &hub->notif); + if (status) + return status; + + schedule_delayed_work(&hub->update_work, 0); + return 0; +} + +static void ssam_hub_remove(struct ssam_device *sdev) +{ + struct ssam_hub *hub = ssam_device_get_drvdata(sdev); + + ssam_device_notifier_unregister(sdev, &hub->notif); + cancel_delayed_work_sync(&hub->update_work); + ssam_remove_clients(&sdev->dev); +} + + +/* -- SSAM base-subsystem hub driver. --------------------------------------- */ + +/* + * Some devices (especially battery) may need a bit of time to be fully usable + * after being (re-)connected. This delay has been determined via + * experimentation. + */ +#define SSAM_BASE_UPDATE_CONNECT_DELAY 2500 + +SSAM_DEFINE_SYNC_REQUEST_R(ssam_bas_query_opmode, u8, { + .target_category = SSAM_SSH_TC_BAS, + .target_id = SSAM_SSH_TID_SAM, + .command_id = 0x0d, + .instance_id = 0x00, +}); + +#define SSAM_BAS_OPMODE_TABLET 0x00 +#define SSAM_EVENT_BAS_CID_CONNECTION 0x0c + +static int ssam_base_hub_query_state(struct ssam_hub *hub, enum ssam_hub_state *state) +{ + u8 opmode; + int status; + + status = ssam_retry(ssam_bas_query_opmode, hub->sdev->ctrl, &opmode); + if (status < 0) { + dev_err(&hub->sdev->dev, "failed to query base state: %d\n", status); + return status; + } + + if (opmode != SSAM_BAS_OPMODE_TABLET) + *state = SSAM_HUB_CONNECTED; + else + *state = SSAM_HUB_DISCONNECTED; + + return 0; +} + +static u32 ssam_base_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_BAS_CID_CONNECTION) + return 0; + + 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]); + + /* + * Do not return SSAM_NOTIF_HANDLED: The event should be picked up and + * consumed by the detachment system driver. We're just a (more or less) + * silent observer. + */ + return 0; +} + +static const struct ssam_hub_desc base_hub = { + .event = { + .reg = SSAM_EVENT_REGISTRY_SAM, + .id = { + .target_category = SSAM_SSH_TC_BAS, + .instance = 0, + }, + .mask = SSAM_EVENT_MASK_NONE, + }, + .ops = { + .notify = ssam_base_hub_notif, + .get_state = ssam_base_hub_query_state, + }, + .connect_delay_ms = SSAM_BASE_UPDATE_CONNECT_DELAY, +}; + + +/* -- 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 250 + +#define SSAM_EVENT_KIP_CID_CONNECTION 0x2c + +SSAM_DEFINE_SYNC_REQUEST_R(__ssam_kip_query_state, u8, { + .target_category = SSAM_SSH_TC_KIP, + .target_id = SSAM_SSH_TID_SAM, + .command_id = 0x2c, + .instance_id = 0x00, +}); + +static int ssam_kip_hub_query_state(struct ssam_hub *hub, enum ssam_hub_state *state) +{ + int status; + u8 connected; + + status = ssam_retry(__ssam_kip_query_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 const struct ssam_hub_desc kip_hub = { + .event = { + .reg = SSAM_EVENT_REGISTRY_SAM, + .id = { + .target_category = SSAM_SSH_TC_KIP, + .instance = 0, + }, + .mask = SSAM_EVENT_MASK_TARGET, + }, + .ops = { + .notify = ssam_kip_hub_notif, + .get_state = ssam_kip_hub_query_state, + }, + .connect_delay_ms = SSAM_KIP_UPDATE_CONNECT_DELAY, +}; + + +/* -- Driver registration. -------------------------------------------------- */ + +static const struct ssam_device_id ssam_hub_match[] = { + { SSAM_VDEV(HUB, SAM, SSAM_SSH_TC_KIP, 0x00), (unsigned long)&kip_hub }, + { SSAM_VDEV(HUB, SAM, SSAM_SSH_TC_BAS, 0x00), (unsigned long)&base_hub }, + { } +}; +MODULE_DEVICE_TABLE(ssam, ssam_hub_match); + +static struct ssam_device_driver ssam_subsystem_hub_driver = { + .probe = ssam_hub_probe, + .remove = ssam_hub_remove, + .match_table = ssam_hub_match, + .driver = { + .name = "surface_aggregator_subsystem_hub", + .probe_type = PROBE_PREFER_ASYNCHRONOUS, + .pm = &ssam_hub_pm_ops, + }, +}; +module_ssam_device_driver(ssam_subsystem_hub_driver); + +MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>"); +MODULE_DESCRIPTION("Subsystem device hub driver for Surface System Aggregator Module"); +MODULE_LICENSE("GPL"); |