Re: [PATCH v2 03/12] usb: typec: API for controlling USB Type-C Multiplexers

[Randy Dunlap <rdunlap@infradead.org>]

On 02/25/2018 07:25 AM, Hans de Goede wrote:
> From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> 
> ---
>  Documentation/driver-api/usb/typec.rst |  73 +++++++++++--
>  drivers/usb/typec/Makefile             |   1 +
>  drivers/usb/typec/{typec.c => class.c} |  70 ++++++++++++
>  drivers/usb/typec/mux.c                | 188 +++++++++++++++++++++++++++++++++
>  include/linux/usb/typec.h              |  14 +++
>  include/linux/usb/typec_mux.h          |  55 ++++++++++
>  6 files changed, 390 insertions(+), 11 deletions(-)
>  rename drivers/usb/typec/{typec.c => class.c} (95%)
>  create mode 100644 drivers/usb/typec/mux.c
>  create mode 100644 include/linux/usb/typec_mux.h
> 
> diff --git a/Documentation/driver-api/usb/typec.rst b/Documentation/driver-api/usb/typec.rst
> index 8a7249f2ff04..091e4def3a39 100644
> --- a/Documentation/driver-api/usb/typec.rst
> +++ b/Documentation/driver-api/usb/typec.rst
> +
> +Multiplexer/DeMultiplexer Switches
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +USB Type-C connectors may have one or more mux/demux switches behind them. Since
> +the plugs can be inserted right-side-up or upside-down, a switch is needed to
> +route the correct data pairs from the connector to the USB controllers. If
> +Alternate or Accessory Modes are supported, an other switch is needed that can

                                               another

> +route the pins on the connector to some other component besides USB. USB Type-C
> +Connector Class supplies an API for registering those switches.
> +
> +.. kernel-doc:: drivers/usb/typec/mux.c
> +   :functions: typec_switch_register typec_switch_unregister typec_mux_register typec_mux_unregister
> +
> +In most cases the same physical mux will handle both the orientation and mode.
> +However, as the port drivers will be responsible of the orientation, and the

                                                    for the orientation,

> +alternate mode drivers of the mode, the two are always separated into their own

                          for the mode,

> +logical components: "mux" for the mode and "switch" for the orientation.
> +
> +When a port is registered, USB Type-C Connector Class requests both the mux and
> +the switch for the port. The drivers can then use the following API for
> +controlling them:
> +
> +.. kernel-doc:: drivers/usb/typec/class.c
> +   :functions: typec_set_orientation typec_set_mode
> +
> +If the connector is dual-role capable, there may also be a switch for the data
> +role. USB Type-C Connector Class does not supply separate API for them. The
> +port drivers can use USB Role Class API with those.
> +
> +Illustration of the muxes behind a connector that supports an alternate mode:
> +
> +                     ------------------------
> +                     |       Connector      |
> +                     ------------------------
> +                            |         |
> +                     ------------------------
> +                      \     Orientation    /
> +                       --------------------
> +                                |
> +                       --------------------
> +                      /        Mode        \
> +                     ------------------------
> +                         /              \
> +      ------------------------        --------------------
> +      |       Alt Mode       |       /      USB Role      \
> +      ------------------------      ------------------------
> +                                         /            \
> +                     ------------------------      ------------------------
> +                     |       USB Host       |      |       USB Device     |
> +                     ------------------------      ------------------------

> diff --git a/drivers/usb/typec/mux.c b/drivers/usb/typec/mux.c
> new file mode 100644
> index 000000000000..3102238366ed
> --- /dev/null
> +++ b/drivers/usb/typec/mux.c
> @@ -0,0 +1,188 @@
> +// 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/connection.h>
> +#include <linux/usb/typec_mux.h>

Needs: <linux/mutex.h> <linux/list.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 devcon *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.

	                          show up.

> +	 */
> +	return ERR_PTR(-EPROBE_DEFER);
> +}
> +


> +static void *typec_mux_match(struct devcon *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.

	                          show up.

> +	 */
> +	return ERR_PTR(-EPROBE_DEFER);
> +}

> diff --git a/include/linux/usb/typec_mux.h b/include/linux/usb/typec_mux.h
> new file mode 100644
> index 000000000000..0ddaaa8b0ac1
> --- /dev/null
> +++ b/include/linux/usb/typec_mux.h
> @@ -0,0 +1,55 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#ifndef __USB_TYPEC_MUX
> +#define __USB_TYPEC_MUX
> +
> +#include <linux/list.h>
> +#include <linux/usb/typec.h>
> +
> +struct device;
> +
> +/**
> + * typec_switch - USB Type-C cable orientation switch

    * struct typec_switch - USB Type-C cable orientation switch

> + * @dev: Switch device
> + * @entry: List entry
> + * @set: Callback to the driver for setting the orientation
> + *
> + * USB Type-C pin flipper switch routing the correct data pairs from the
> + * connector to the USB controller depending on the orientation of the cable
> + * plug.
> + */
> +struct typec_switch {
> +	struct device *dev;
> +	struct list_head entry;
> +
> +	int (*set)(struct typec_switch *sw, enum typec_orientation orientation);
> +};
> +
> +/**
> + * typec_switch - USB Type-C connector pin mux

    * struct typec_mux - USB Type-C connector pin mux

> + * @dev: Mux device
> + * @entry: List entry
> + * @set: Callback to the driver for setting the state of the mux
> + *
> + * Pin Multiplexer/DeMultiplexer switch routing the USB Type-C connector pins to
> + * different components depending on the requested mode of operation. Used with
> + * Accessory/Alternate modes.
> + */
> +struct typec_mux {
> +	struct device *dev;
> +	struct list_head entry;
> +
> +	int (*set)(struct typec_mux *mux, int state);
> +};

ta.
-- 
~Randy