diff options
Diffstat (limited to 'drivers/usb/typec/mux.c')
| -rw-r--r-- | drivers/usb/typec/mux.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/drivers/usb/typec/mux.c b/drivers/usb/typec/mux.c new file mode 100644 index 000000000000..f89093bd7185 --- /dev/null +++ b/drivers/usb/typec/mux.c @@ -0,0 +1,191 @@ +// SPDX-License-Identifier: GPL-2.0 +/** + * USB Type-C Multiplexer/DeMultiplexer Switch support + * + * Copyright (C) 2018 Intel Corporation + * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com> + * Hans de Goede <hdegoede@redhat.com> + */ + +#include <linux/device.h> +#include <linux/list.h> +#include <linux/mutex.h> +#include <linux/usb/typec_mux.h> + +static DEFINE_MUTEX(switch_lock); +static DEFINE_MUTEX(mux_lock); +static LIST_HEAD(switch_list); +static LIST_HEAD(mux_list); + +static void *typec_switch_match(struct device_connection *con, int ep, + void *data) +{ + struct typec_switch *sw; + + list_for_each_entry(sw, &switch_list, entry) + if (!strcmp(con->endpoint[ep], dev_name(sw->dev))) + return sw; + + /* + * We only get called if a connection was found, tell the caller to + * wait for the switch to show up. + */ + return ERR_PTR(-EPROBE_DEFER); +} + +/** + * typec_switch_get - Find USB Type-C orientation switch + * @dev: The caller device + * + * Finds a switch linked with @dev. Returns a reference to the switch on + * success, NULL if no matching connection was found, or + * ERR_PTR(-EPROBE_DEFER) when a connection was found but the switch + * has not been enumerated yet. + */ +struct typec_switch *typec_switch_get(struct device *dev) +{ + struct typec_switch *sw; + + mutex_lock(&switch_lock); + sw = device_connection_find_match(dev, "typec-switch", NULL, + typec_switch_match); + if (!IS_ERR_OR_NULL(sw)) + get_device(sw->dev); + mutex_unlock(&switch_lock); + + return sw; +} +EXPORT_SYMBOL_GPL(typec_switch_get); + +/** + * typec_put_switch - Release USB Type-C orientation switch + * @sw: USB Type-C orientation switch + * + * Decrement reference count for @sw. + */ +void typec_switch_put(struct typec_switch *sw) +{ + if (!IS_ERR_OR_NULL(sw)) + put_device(sw->dev); +} +EXPORT_SYMBOL_GPL(typec_switch_put); + +/** + * typec_switch_register - Register USB Type-C orientation switch + * @sw: USB Type-C orientation switch + * + * This function registers a switch that can be used for routing the correct + * data pairs depending on the cable plug orientation from the USB Type-C + * connector to the USB controllers. USB Type-C plugs can be inserted + * right-side-up or upside-down. + */ +int typec_switch_register(struct typec_switch *sw) +{ + mutex_lock(&switch_lock); + list_add_tail(&sw->entry, &switch_list); + mutex_unlock(&switch_lock); + + return 0; +} +EXPORT_SYMBOL_GPL(typec_switch_register); + +/** + * typec_switch_unregister - Unregister USB Type-C orientation switch + * @sw: USB Type-C orientation switch + * + * Unregister switch that was registered with typec_switch_register(). + */ +void typec_switch_unregister(struct typec_switch *sw) +{ + mutex_lock(&switch_lock); + list_del(&sw->entry); + mutex_unlock(&switch_lock); +} +EXPORT_SYMBOL_GPL(typec_switch_unregister); + +/* ------------------------------------------------------------------------- */ + +static void *typec_mux_match(struct device_connection *con, int ep, void *data) +{ + struct typec_mux *mux; + + list_for_each_entry(mux, &mux_list, entry) + if (!strcmp(con->endpoint[ep], dev_name(mux->dev))) + return mux; + + /* + * We only get called if a connection was found, tell the caller to + * wait for the switch to show up. + */ + return ERR_PTR(-EPROBE_DEFER); +} + +/** + * typec_mux_get - Find USB Type-C Multiplexer + * @dev: The caller device + * + * Finds a mux linked to the caller. This function is primarily meant for the + * Type-C drivers. Returns a reference to the mux on success, NULL if no + * matching connection was found, or ERR_PTR(-EPROBE_DEFER) when a connection + * was found but the mux has not been enumerated yet. + */ +struct typec_mux *typec_mux_get(struct device *dev) +{ + struct typec_mux *mux; + + mutex_lock(&mux_lock); + mux = device_connection_find_match(dev, "typec-mux", NULL, + typec_mux_match); + if (!IS_ERR_OR_NULL(mux)) + get_device(mux->dev); + mutex_unlock(&mux_lock); + + return mux; +} +EXPORT_SYMBOL_GPL(typec_mux_get); + +/** + * typec_mux_put - Release handle to a Multiplexer + * @mux: USB Type-C Connector Multiplexer/DeMultiplexer + * + * Decrements reference count for @mux. + */ +void typec_mux_put(struct typec_mux *mux) +{ + if (!IS_ERR_OR_NULL(mux)) + put_device(mux->dev); +} +EXPORT_SYMBOL_GPL(typec_mux_put); + +/** + * typec_mux_register - Register Multiplexer routing USB Type-C pins + * @mux: USB Type-C Connector Multiplexer/DeMultiplexer + * + * USB Type-C connectors can be used for alternate modes of operation besides + * USB when Accessory/Alternate Modes are supported. With some of those modes, + * the pins on the connector need to be reconfigured. This function registers + * multiplexer switches routing the pins on the connector. + */ +int typec_mux_register(struct typec_mux *mux) +{ + mutex_lock(&mux_lock); + list_add_tail(&mux->entry, &mux_list); + mutex_unlock(&mux_lock); + + return 0; +} +EXPORT_SYMBOL_GPL(typec_mux_register); + +/** + * typec_mux_unregister - Unregister Multiplexer Switch + * @sw: USB Type-C Connector Multiplexer/DeMultiplexer + * + * Unregister mux that was registered with typec_mux_register(). + */ +void typec_mux_unregister(struct typec_mux *mux) +{ + mutex_lock(&mux_lock); + list_del(&mux->entry); + mutex_unlock(&mux_lock); +} +EXPORT_SYMBOL_GPL(typec_mux_unregister); |