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Date: Fri, 30 Oct 2020 11:34:47 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Benson Leung <bleung@...omium.org>
Cc: heikki.krogerus@...ux.intel.com, bleung@...nel.org,
linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
pmalani@...omium.org, bleung@...gle.com
Subject: Re: [PATCH] typec: Provide USB PD Specification Revision for cable
and partner
On Thu, Oct 29, 2020 at 09:42:24PM -0700, Benson Leung wrote:
> The USB Power Delivery specification Section 6.2.1.1.5 outlines
> revision backward compatibility requirements starting from Revision 3.0.
>
> The Port, the Cable Plug, and the Port Partner may support either revision
> 2 or revision 3 individually, and communication between ports, partners,
> and cables of different revisions are allowed under rules that the parties
> agree to communicate between each other using the lowest common operating
> revision.
>
> This may mean that Port-to-Port operating revision comms may be different
> than Port-to-CablePlug operating revision comms. For example, it is
> possible for a R3.0 port to communicate with a R3.0 cable using R3.0
> messages, while the R3.0 port (in the same session) must communicate with
> a R2.0 partner using PD R2.0 messages only.
>
> This change will introduce individual revision number tracking for cable
> and port partner so that the port can track them independently.
>
> This will also enable future changes which change cable identifier
> decoding and visible sysfs nodes based on revision 2 or 3.
>
> Signed-off-by: Benson Leung <bleung@...omium.org>
> ---
> Documentation/ABI/testing/sysfs-class-typec | 8 +++++
> drivers/usb/typec/class.c | 38 +++++++++++++++------
> include/linux/usb/typec.h | 10 ++++++
> 3 files changed, 46 insertions(+), 10 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-typec b/Documentation/ABI/testing/sysfs-class-typec
> index b834671522d6..740b226bb80e 100644
> --- a/Documentation/ABI/testing/sysfs-class-typec
> +++ b/Documentation/ABI/testing/sysfs-class-typec
> @@ -102,6 +102,14 @@ Description:
> Revision number of the supported USB Power Delivery
> specification, or 0 when USB Power Delivery is not supported.
>
> +What: /sys/class/typec/<port>-{partner|cable}/usb_power_delivery_revision
> +Date: October 2020
> +Contact: Benson Leung <bleung@...omium.org>
> +Description:
> + Revision number of the supported USB Power Delivery
> + specification of the port partner or cable, or 0 when USB Power
> + Delivery is not supported.
> +
> What: /sys/class/typec/<port>/usb_typec_revision
> Date: April 2017
> Contact: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
> index 35eec707cb51..abae4cbe66d5 100644
> --- a/drivers/usb/typec/class.c
> +++ b/drivers/usb/typec/class.c
> @@ -25,6 +25,7 @@ struct typec_cable {
> enum typec_plug_type type;
> struct usb_pd_identity *identity;
> unsigned int active:1;
> + u16 pd_revision; /* 0300H = "3.0" */
> };
>
> struct typec_partner {
> @@ -33,6 +34,7 @@ struct typec_partner {
> struct usb_pd_identity *identity;
> enum typec_accessory accessory;
> struct ida mode_ids;
> + u16 pd_revision; /* 0300H = "3.0" */
> };
>
> struct typec_port {
> @@ -146,6 +148,28 @@ static void typec_report_identity(struct device *dev)
> sysfs_notify(&dev->kobj, "identity", "product");
> }
>
> +static ssize_t usb_power_delivery_revision_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + if (is_typec_partner(dev)) {
> + struct typec_partner *partner = to_typec_partner(dev);
> +
> + return sprintf(buf, "%d\n", (partner->pd_revision >> 8) & 0xff);
> + } else if (is_typec_cable(dev)) {
> + struct typec_cable *cable = to_typec_cable(dev);
> +
> + return sprintf(buf, "%d\n", (cable->pd_revision >> 8) & 0xff);
> + } else if (is_typec_port(dev)) {
> + struct typec_port *p = to_typec_port(dev);
> +
> + return sprintf(buf, "%d\n", (p->cap->pd_revision >> 8) & 0xff);
nit, you can use sysfs_emit() for the sprintf() calls in sysfs
attributes now.
> + }
> +}
> +static DEVICE_ATTR_RO(usb_power_delivery_revision);
> +
> +
> +
2 extra blank lines are not needed :(
> /* ------------------------------------------------------------------------- */
> /* Alternate Modes */
>
> @@ -535,6 +559,7 @@ static DEVICE_ATTR_RO(supports_usb_power_delivery);
> static struct attribute *typec_partner_attrs[] = {
> &dev_attr_accessory_mode.attr,
> &dev_attr_supports_usb_power_delivery.attr,
> + &dev_attr_usb_power_delivery_revision.attr,
> NULL
> };
> ATTRIBUTE_GROUPS(typec_partner);
> @@ -612,6 +637,7 @@ struct typec_partner *typec_register_partner(struct typec_port *port,
> ida_init(&partner->mode_ids);
> partner->usb_pd = desc->usb_pd;
> partner->accessory = desc->accessory;
> + partner->pd_revision = desc->pd_revision;
>
> if (desc->identity) {
> /*
> @@ -773,6 +799,7 @@ static DEVICE_ATTR_RO(plug_type);
> static struct attribute *typec_cable_attrs[] = {
> &dev_attr_type.attr,
> &dev_attr_plug_type.attr,
> + &dev_attr_usb_power_delivery_revision.attr,
> NULL
> };
> ATTRIBUTE_GROUPS(typec_cable);
> @@ -875,6 +902,7 @@ struct typec_cable *typec_register_cable(struct typec_port *port,
>
> cable->type = desc->type;
> cable->active = desc->active;
> + cable->pd_revision = desc->pd_revision;
>
> if (desc->identity) {
> /*
> @@ -1240,16 +1268,6 @@ static ssize_t usb_typec_revision_show(struct device *dev,
> }
> static DEVICE_ATTR_RO(usb_typec_revision);
>
> -static ssize_t usb_power_delivery_revision_show(struct device *dev,
> - struct device_attribute *attr,
> - char *buf)
> -{
> - struct typec_port *p = to_typec_port(dev);
> -
> - return sprintf(buf, "%d\n", (p->cap->pd_revision >> 8) & 0xff);
> -}
> -static DEVICE_ATTR_RO(usb_power_delivery_revision);
> -
> static ssize_t orientation_show(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> diff --git a/include/linux/usb/typec.h b/include/linux/usb/typec.h
> index 6be558045942..2306d40e18a1 100644
> --- a/include/linux/usb/typec.h
> +++ b/include/linux/usb/typec.h
> @@ -162,6 +162,7 @@ struct typec_plug_desc {
> * @type: The plug type from USB PD Cable VDO
> * @active: Is the cable active or passive
> * @identity: Result of Discover Identity command
> + * @pd_revision: USB Power Delivery Specification revision if supported
> *
> * Represents USB Type-C Cable attached to USB Type-C port.
> */
> @@ -169,6 +170,8 @@ struct typec_cable_desc {
> enum typec_plug_type type;
> unsigned int active:1;
> struct usb_pd_identity *identity;
> + u16 pd_revision; /* 0300H = "3.0" */
> +
> };
>
> /*
> @@ -176,15 +179,22 @@ struct typec_cable_desc {
> * @usb_pd: USB Power Delivery support
> * @accessory: Audio, Debug or none.
> * @identity: Discover Identity command data
> + * @pd_revision: USB Power Delivery Specification Revision if supported
> *
> * Details about a partner that is attached to USB Type-C port. If @identity
> * member exists when partner is registered, a directory named "identity" is
> * created to sysfs for the partner device.
> + *
> + * @pd_revision is based on the setting of the "Specification Revision" field
> + * in the message header on the initial "Source Capabilities" message receieved
> + * from the partner, or a "Request" message received from the partner, depending
> + * on whether our port is a Sink or a Source.
> */
> struct typec_partner_desc {
> unsigned int usb_pd:1;
> enum typec_accessory accessory;
> struct usb_pd_identity *identity;
> + u16 pd_revision; /* 0300H = "3.0" */
No endian issues? Where are you reading this data from? How is it in
"native cpu" endian already?
thanks,
greg k-h
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