Re: [PATCH v4] usb: typec: Add a sysfs node to manage port type
From: Guenter Roeck
Date: Fri May 26 2017 - 22:25:17 EST
On 05/26/2017 04:07 PM, Badhri Jagan Sridharan wrote:
User space applications in some cases have the need to enforce a
specific port type(DFP/UFP/DRP). This change allows userspace to
attempt setting the desired port type. Low level drivers can
however reject the request if the specific port type is not supported.
Signed-off-by: Badhri Jagan Sridharan <Badhri@xxxxxxxxxx>
---
Changelog since v1:
- introduced a new variable port_type in struct typec_port to track
the current port type instead of changing type member in
typec_capability to address Heikki Krogerus comments.
- changed the output format and strings that would be displayed as
suggested by Heikki Krogerus.
Changelog since v2:
- introduced a new mutex lock to protect port_type for addressing
the race conditions identified by Geunter Roeck
- added typec_port_types_drp for printing port_type when cap->type
is TYPE_PORT_DRP as suggested by Geunter Roeck
- Power role swap and data role swaps would be rejected unless
port port_type == TYPE_PORT_DRP
- port_type_store would return immediately if the current port_type
is same as the new port_type as suggested by Geunter Roeck
Changelog since v3:
- Moved as much as code outside port_type_lock as suggested by
Geunter Roeck
- Removed Change-Id line from commit message identified by
Greg Kroah-Hartman
drivers/usb/typec/typec.c | 106 +++++++++++++++++++++++++++++++++++++++++-----
include/linux/usb/typec.h | 4 ++
2 files changed, 100 insertions(+), 10 deletions(-)
diff --git a/drivers/usb/typec/typec.c b/drivers/usb/typec/typec.c
index 89e540bb7ff3..bf1eb11c6646 100644
--- a/drivers/usb/typec/typec.c
+++ b/drivers/usb/typec/typec.c
@@ -11,6 +11,7 @@
#include <linux/device.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/usb/typec.h>
@@ -69,6 +70,8 @@ struct typec_port {
enum typec_role pwr_role;
enum typec_role vconn_role;
enum typec_pwr_opmode pwr_opmode;
+ enum typec_port_type port_type;
+ struct mutex port_type_lock;
const struct typec_capability *cap;
};
@@ -789,6 +792,18 @@ static const char * const typec_data_roles[] = {
[TYPEC_HOST] = "host",
};
+static const char * const typec_port_types[] = {
+ [TYPEC_PORT_DFP] = "source",
+ [TYPEC_PORT_UFP] = "sink",
+ [TYPEC_PORT_DRP] = "dual",
+};
+
+static const char * const typec_port_types_drp[] = {
+ [TYPEC_PORT_DFP] = "dual [source] sink",
+ [TYPEC_PORT_UFP] = "dual source [sink]",
+ [TYPEC_PORT_DRP] = "[dual] source sink",
+};
+
static ssize_t
preferred_role_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t size)
@@ -846,11 +861,6 @@ static ssize_t data_role_store(struct device *dev,
struct typec_port *port = to_typec_port(dev);
int ret;
- if (port->cap->type != TYPEC_PORT_DRP) {
- dev_dbg(dev, "data role swap only supported with DRP ports\n");
- return -EOPNOTSUPP;
- }
-
if (!port->cap->dr_set) {
dev_dbg(dev, "data role swapping not supported\n");
return -EOPNOTSUPP;
@@ -860,11 +870,22 @@ static ssize_t data_role_store(struct device *dev,
if (ret < 0)
return ret;
+ mutex_lock(&port->port_type_lock);
+ if (port->port_type != TYPEC_PORT_DRP) {
+ dev_dbg(dev, "port type fixed at \"%s\"",
+ typec_port_types[port->port_type]);
+ ret = -EOPNOTSUPP;
+ goto unlock_and_ret;
+ }
+
ret = port->cap->dr_set(port->cap, ret);
if (ret)
- return ret;
+ goto unlock_and_ret;
- return size;
+ ret = size;
+unlock_and_ret:
+ mutex_unlock(&port->port_type_lock);
+ return ret;
}
static ssize_t data_role_show(struct device *dev,
@@ -885,7 +906,7 @@ static ssize_t power_role_store(struct device *dev,
const char *buf, size_t size)
{
struct typec_port *port = to_typec_port(dev);
- int ret = size;
+ int ret;
if (!port->cap->pd_revision) {
dev_dbg(dev, "USB Power Delivery not supported\n");
@@ -906,11 +927,22 @@ static ssize_t power_role_store(struct device *dev,
if (ret < 0)
return ret;
+ mutex_lock(&port->port_type_lock);
+ if (port->port_type != TYPEC_PORT_DRP) {
+ dev_dbg(dev, "port type fixed at \"%s\"",
+ typec_port_types[port->port_type]);
+ ret = -EOPNOTSUPP;
+ goto unlock_and_ret;
+ }
+
ret = port->cap->pr_set(port->cap, ret);
if (ret)
- return ret;
+ goto unlock_and_ret;
- return size;
+ ret = size;
+unlock_and_ret:
+ mutex_unlock(&port->port_type_lock);
+ return ret;
}
static ssize_t power_role_show(struct device *dev,
@@ -926,6 +958,57 @@ static ssize_t power_role_show(struct device *dev,
}
static DEVICE_ATTR_RW(power_role);
+static ssize_t
+port_type_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct typec_port *port = to_typec_port(dev);
+ int ret;
+ enum typec_port_type type;
+
+ if (!port->cap->port_type_set || port->cap->type != TYPEC_PORT_DRP) {
+ dev_dbg(dev, "changing port type not supported\n");
+ return -EOPNOTSUPP;
+ }
+
+ ret = sysfs_match_string(typec_port_types, buf);
+ if (ret < 0)
+ return ret;
+
+ mutex_lock(&port->port_type_lock);
+ type = ret;
+
Can be outside lock.
+ if (port->port_type == type) {
+ ret = size;
+ goto unlock_and_ret;
+ }
+
+ ret = port->cap->port_type_set(port->cap, type);
+ if (ret)
+ goto unlock_and_ret;
+
+ port->port_type = type;
+ ret = size;
+
+unlock_and_ret:
+ mutex_unlock(&port->port_type_lock);
+ return size;
return ret;
+}
+
+static ssize_t
+port_type_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct typec_port *port = to_typec_port(dev);
+
+ if (port->cap->type == TYPEC_PORT_DRP)
+ return sprintf(buf, "%s\n",
+ typec_port_types_drp[port->port_type]);
+
+ return sprintf(buf, "[%s]\n", typec_port_types[port->cap->type]);
+}
+static DEVICE_ATTR_RW(port_type);
+
static const char * const typec_pwr_opmodes[] = {
[TYPEC_PWR_MODE_USB] = "default",
[TYPEC_PWR_MODE_1_5A] = "1.5A",
@@ -1035,6 +1118,7 @@ static struct attribute *typec_attrs[] = {
&dev_attr_usb_power_delivery_revision.attr,
&dev_attr_usb_typec_revision.attr,
&dev_attr_vconn_source.attr,
+ &dev_attr_port_type.attr,
NULL,
};
ATTRIBUTE_GROUPS(typec);
@@ -1211,6 +1295,8 @@ struct typec_port *typec_register_port(struct device *parent,
port->id = id;
port->cap = cap;
+ port->port_type = cap->type;
+ mutex_init(&port->port_type_lock);
port->prefer_role = cap->prefer_role;
port->dev.class = typec_class;
diff --git a/include/linux/usb/typec.h b/include/linux/usb/typec.h
index ec78204964ab..b174248af7c9 100644
--- a/include/linux/usb/typec.h
+++ b/include/linux/usb/typec.h
@@ -190,6 +190,7 @@ struct typec_partner_desc {
* @pr_set: Set Power Role
* @vconn_set: Set VCONN Role
* @activate_mode: Enter/exit given Alternate Mode
+ * @port_type_set: Set port type
*
* Static capabilities of a single USB Type-C port.
*/
@@ -214,6 +215,9 @@ struct typec_capability {
int (*activate_mode)(const struct typec_capability *,
int mode, int activate);
+ int (*port_type_set)(const struct typec_capability *,
+ enum typec_port_type);
+
};
/* Specific to try_role(). Indicates the user want's to clear the preference. */