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

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Date:   Wed, 18 Nov 2020 18:00:59 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Prashant Malani <pmalani@...omium.org>
Cc:     Benson Leung <bleung@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: [RFC PATCH 3/3] usb: typec: Expose Product Type VDOs via sysfs

From: Prashant Malani <pmalani@...omium.org>

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@...omium.org>
[ heikki: Only one instead of three attribute files ]
Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>'
---
 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