[RFC PATCH 3/3] usb: typec: Expose Product Type VDOs via sysfs

From: Heikki Krogerus
Date: Wed Nov 18 2020 - 10:01:30 EST


From: Prashant Malani <pmalani@xxxxxxxxxxxx>

Interim. ABI doc missing.

A PD-capable device can return up to 3 Product Type VDOs as part of its
DiscoverIdentity Response (USB PD Spec, Rev 3.0, Version 2.0, Section
6.4.4.3.1). Add sysfs attribute to expose these to userspace.

Signed-off-by: Prashant Malani <pmalani@xxxxxxxxxxxx>
[ heikki: Only one instead of three attribute files ]
Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>'
---
drivers/usb/typec/class.c | 41 +++++++++++++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)

diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
index 303f054181ff7..5e135678f5952 100644
--- a/drivers/usb/typec/class.c
+++ b/drivers/usb/typec/class.c
@@ -165,15 +165,55 @@ static ssize_t product_show(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR_RO(product);

+static ssize_t
+product_type_vdo_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct usb_pd_identity *id = get_pd_identity(dev);
+ size_t len = 0;
+ int i;
+
+ for (i = 0; i < 3; i++) {
+ if (!id->vdo[i])
+ break;
+ len += sysfs_emit(buf, "%08x ", id->vdo[i]);
+ }
+
+ buf[len - 1] = '\n';
+
+ return len;
+}
+
+static struct device_attribute dev_attr_product_type_vdo = {
+ .attr = {
+ .name = "product_type",
+ .mode = 0444,
+ },
+ .show = product_type_vdo_show,
+};
+
+static umode_t
+typec_identity_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n)
+{
+ struct usb_pd_identity *id = get_pd_identity(kobj_to_dev(kobj));
+
+ if (attr == &dev_attr_product_type_vdo.attr &&
+ !id->vdo[0])
+ return 0;
+
+ return attr->mode;
+}
+
static struct attribute *usb_pd_id_attrs[] = {
&dev_attr_id_header.attr,
&dev_attr_cert_stat.attr,
&dev_attr_product.attr,
+ &dev_attr_product_type_vdo.attr,
NULL
};

static const struct attribute_group usb_pd_id_group = {
.name = "identity",
+ .is_visible = typec_identity_attr_is_visible,
.attrs = usb_pd_id_attrs,
};

@@ -191,6 +231,7 @@ static void typec_product_type_notify(struct device *dev)
if (!ptype)
return;

+ sysfs_notify(&dev->kobj, "identity", "product_type");
sysfs_notify(&dev->kobj, NULL, "product_type");

envp[0] = kasprintf(GFP_KERNEL, "PRODUCT_TYPE=%s", ptype);
--
2.29.2