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Date: Tue, 10 Nov 2020 12:49:21 +0200
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: Prashant Malani <pmalani@...omium.org>
Cc: linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
gregkh@...uxfoundation.org, Benson Leung <bleung@...omium.org>,
Enric Balletbo i Serra <enric.balletbo@...labora.com>,
Guenter Roeck <groeck@...omium.org>
Subject: Re: [PATCH v2 1/2] usb: typec: Add number of altmodes partner attr
On Mon, Nov 09, 2020 at 10:15:34PM -0800, Prashant Malani wrote:
> Add a user-visible attribute for the number of alternate modes available
> in a partner. This allows userspace to determine whether there are any
> remaining alternate modes left to be registered by the kernel driver. It
> can begin executing any policy state machine after all available
> alternate modes have been registered with the connector class framework.
>
> This value is set to "-1" initially, signifying that a valid number of
> alternate modes haven't been set for the partner.
>
> Also add a sysfs file which exposes this attribute. The file remains
> hidden as long as the attribute value is -1.
>
> Cc: Benson Leung <bleung@...omium.org>
> Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> Signed-off-by: Prashant Malani <pmalani@...omium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> ---
>
> Changes in v2:
> - Added ABI/testing documentation entry for added sysfs file.
> - Changed name of the sysfs file to "number_of_alternate_modes" based on
> review comments.
> - Added is_visible() logic suggested by Heikki in the comments of v1.
> - Updated commit message.
>
> v1:
> https://lore.kernel.org/lkml/20200701003149.3101219-1-pmalani@chromium.org/
>
> Documentation/ABI/testing/sysfs-class-typec | 8 +++
> drivers/usb/typec/class.c | 66 ++++++++++++++++++++-
> include/linux/usb/typec.h | 1 +
> 3 files changed, 74 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-typec b/Documentation/ABI/testing/sysfs-class-typec
> index b834671522d6..73ac7b461ae5 100644
> --- a/Documentation/ABI/testing/sysfs-class-typec
> +++ b/Documentation/ABI/testing/sysfs-class-typec
> @@ -134,6 +134,14 @@ Description:
> Shows if the partner supports USB Power Delivery communication:
> Valid values: yes, no
>
> +What: /sys/class/typec/<port>-partner/number_of_alternate_modes
> +Date: November 2020
> +Contact: Prashant Malani <pmalani@...omium.org>
> +Description:
> + Shows the number of alternate modes which are advertised by the partner
> + during Power Delivery discovery. This file remains hidden until a value
> + greater than or equal to 0 is set by Type C port driver.
> +
> What: /sys/class/typec/<port>-partner>/identity/
> 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..c7412ddbd311 100644
> --- a/drivers/usb/typec/class.c
> +++ b/drivers/usb/typec/class.c
> @@ -33,6 +33,7 @@ struct typec_partner {
> struct usb_pd_identity *identity;
> enum typec_accessory accessory;
> struct ida mode_ids;
> + int num_altmodes;
> };
>
> struct typec_port {
> @@ -532,12 +533,43 @@ static ssize_t supports_usb_power_delivery_show(struct device *dev,
> }
> static DEVICE_ATTR_RO(supports_usb_power_delivery);
>
> +static ssize_t number_of_alternate_modes_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct typec_partner *p = to_typec_partner(dev);
> +
> + return sysfs_emit(buf, "%d\n", p->num_altmodes);
> +}
> +static DEVICE_ATTR_RO(number_of_alternate_modes);
> +
> static struct attribute *typec_partner_attrs[] = {
> &dev_attr_accessory_mode.attr,
> &dev_attr_supports_usb_power_delivery.attr,
> + &dev_attr_number_of_alternate_modes.attr,
> + NULL
> +};
> +
> +static umode_t typec_partner_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n)
> +{
> + struct typec_partner *partner = to_typec_partner(kobj_to_dev(kobj));
> +
> + if (attr == &dev_attr_number_of_alternate_modes.attr) {
> + if (partner->num_altmodes < 0)
> + return 0;
> + }
> +
> + return attr->mode;
> +}
> +
> +static struct attribute_group typec_partner_group = {
> + .is_visible = typec_partner_attr_is_visible,
> + .attrs = typec_partner_attrs
> +};
> +
> +static const struct attribute_group *typec_partner_groups[] = {
> + &typec_partner_group,
> NULL
> };
> -ATTRIBUTE_GROUPS(typec_partner);
>
> static void typec_partner_release(struct device *dev)
> {
> @@ -570,6 +602,37 @@ int typec_partner_set_identity(struct typec_partner *partner)
> }
> EXPORT_SYMBOL_GPL(typec_partner_set_identity);
>
> +/**
> + * typec_partner_set_num_altmodes - Set the number of available partner altmodes
> + * @partner: The partner to be updated.
> + * @num_alt_modes: The number of altmodes we want to specify as available.
> + *
> + * This routine is used to report the number of alternate modes supported by the
> + * partner. This value is *not* enforced in alternate mode registration routines.
> + *
> + * @partner.num_altmodes is set to -1 on partner registration, denoting that
> + * a valid value has not been set for it yet.
> + *
> + * Returns 0 on success or negative error number on failure.
> + */
> +int typec_partner_set_num_altmodes(struct typec_partner *partner, int num_altmodes)
> +{
> + int ret;
> +
> + if (num_altmodes < 0)
> + return -EINVAL;
> +
> + partner->num_altmodes = num_altmodes;
> + ret = sysfs_update_group(&partner->dev.kobj, &typec_partner_group);
> + if (ret < 0)
> + return ret;
> +
> + sysfs_notify(&partner->dev.kobj, NULL, "number_of_alternate_modes");
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(typec_partner_set_num_altmodes);
> +
> /**
> * typec_partner_register_altmode - Register USB Type-C Partner Alternate Mode
> * @partner: USB Type-C Partner that supports the alternate mode
> @@ -612,6 +675,7 @@ 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->num_altmodes = -1;
>
> if (desc->identity) {
> /*
> diff --git a/include/linux/usb/typec.h b/include/linux/usb/typec.h
> index 6be558045942..bc6b1a71cb8a 100644
> --- a/include/linux/usb/typec.h
> +++ b/include/linux/usb/typec.h
> @@ -126,6 +126,7 @@ struct typec_altmode_desc {
> enum typec_port_data roles;
> };
>
> +int typec_partner_set_num_altmodes(struct typec_partner *partner, int num_altmodes);
> struct typec_altmode
> *typec_partner_register_altmode(struct typec_partner *partner,
> const struct typec_altmode_desc *desc);
> --
> 2.29.2.222.g5d2a92d10f8-goog
thanks,
--
heikki
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