Re: [PATCH v5] usb: typec: Add a sysfs node to manage port type

Guenter Roeck Sat, 27 May 2017 14:05:20 -0700

On 05/27/2017 01:52 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 <bad...@google.com>


Reviewed-by: Guenter Roeck <li...@roeck-us.net>

---
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

Changelog since v4:
- Corrected return value and moved moved one more line of code
   outside log in the port_type_store function as suggested


not that it matters: s/log/lock/

   by Geunter Roeck


and s/Geunter/Guenter/ ;-)

  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..63644785ce31 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;
+
+       type = ret;
+       mutex_lock(&port->port_type_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 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. */

Re: [PATCH v5] usb: typec: Add a sysfs node to manage port type

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