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-rw-r--r--drivers/platform/surface/surface_aggregator_hub.c371
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 000000000..43061514b
--- /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 = 0x01,
+ .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 = 0x01,
+ .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, 0x01, SSAM_SSH_TC_KIP, 0x00), (unsigned long)&kip_hub },
+ { SSAM_VDEV(HUB, 0x02, 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");