Re: [PATCH] usb: typec: Add num_altmodes partner attribute

Greg Kroah-Hartman
2020-07-01T12:01:49Z

On Tue, Jun 30, 2020 at 05:31:48PM -0700, Prashant Malani wrote:
> Add a user-visible attribute for the number of alt modes available in a
> partner. This allows userspace to determine whether there are any
> remaining alt modes left to be registered by the kernel driver. It can
> begin implementing any policy state machine after all available alt
> modes have been registered with the connector class framework.
>
> This value is set to "-1" initially, which is an invalid value,
> signifying that a valid number of alt modes haven't been set for the
> partner.
>
> Signed-off-by: Prashant Malani <pmalani@chromium.org>
> Cc: Benson Leung <bleung@chromium.org>
> ---
> drivers/usb/typec/class.c | 34 ++++++++++++++++++++++++++++++++++
> include/linux/usb/typec.h | 1 +
> 2 files changed, 35 insertions(+)
>
> diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
> index c9234748537a..680cbcfbd427 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 {
> @@ -532,9 +533,18 @@ static ssize_t supports_usb_power_delivery_show(struct device *dev,
> }
> static DEVICE_ATTR_RO(supports_usb_power_delivery);
>
> +static ssize_t num_altmodes_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + struct typec_partner *p = to_typec_partner(dev);
> +
> + return sprintf(buf, "%d\n", p->num_altmodes);
> +}
> +static DEVICE_ATTR_RO(num_altmodes);
> +
> static struct attribute *typec_partner_attrs[] = {
> &dev_attr_accessory_mode.attr,
> &dev_attr_supports_usb_power_delivery.attr,
> + &dev_attr_num_altmodes.attr,
> NULL
> };
> ATTRIBUTE_GROUPS(typec_partner);
> @@ -570,6 +580,29 @@ int typec_partner_set_identity(struct typec_partner *partner)
> }
> EXPORT_SYMBOL_GPL(typec_partner_set_identity);
>
> +/**
> + * typec_partner_set_num_altmodes - Update number of available 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 alt 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.
> + */
> +int typec_partner_set_num_altmodes(struct typec_partner *partner, int num_altmodes)
> +{
> + if (num_altmodes < 0)
> + return -EINVAL;
> +
> + partner->num_altmodes = num_altmodes;
> + sysfs_notify(&partner->dev.kobj, NULL, "num_altmodes");
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(typec_partner_set_num_altmodes);

Who is calling this? We need a user before we can add a newly exported
function.

thanks,

greg k-h