Serial: allow port drivers to have a default attribute group

Some serial drivers (like 8250), want to add sysfs files.  We need to do
so in a race-free way, so allow any port to be able to specify an
attribute group that should be added at device creation time.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 19 insertions, 7 deletions

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index b70095e55df6..61529a84c3fc 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2564,12 +2564,6 @@ static const struct attribute_group tty_dev_attr_group = {
         .attrs = tty_dev_attrs,
         };
 
-static const struct attribute_group *tty_dev_attr_groups[] = {
-        &tty_dev_attr_group,
-        NULL
-        };
-
-
 /**
  *      uart_add_one_port - attach a driver-defined port structure
  *      @drv: pointer to the uart low level driver structure for this port
@@ -2586,6 +2580,7 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
         struct tty_port *port;
         int ret = 0;
         struct device *tty_dev;
+        int num_groups;
 
         BUG_ON(in_interrupt());
 
@@ -2619,12 +2614,26 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
 
         uart_configure_port(drv, state, uport);
 
+        num_groups = 2;
+        if (uport->attr_group)
+                num_groups++;
+
+        uport->tty_groups = kcalloc(num_groups, sizeof(**uport->tty_groups),
+                                    GFP_KERNEL);
+        if (!uport->tty_groups) {
+                ret = -ENOMEM;
+                goto out;
+        }
+        uport->tty_groups[0] = &tty_dev_attr_group;
+        if (uport->attr_group)
+                uport->tty_groups[1] = uport->attr_group;
+
         /*
          * Register the port whether it's detected or not.  This allows
          * setserial to be used to alter this port's parameters.
          */
         tty_dev = tty_port_register_device_attr(port, drv->tty_driver,
-                        uport->line, uport->dev, port, tty_dev_attr_groups);
+                        uport->line, uport->dev, port, uport->tty_groups);
         if (likely(!IS_ERR(tty_dev))) {
                 device_set_wakeup_capable(tty_dev, 1);
         } else {
@@ -2703,6 +2712,7 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
          */
         if (uport->type != PORT_UNKNOWN)
                 uport->ops->release_port(uport);
+        kfree(uport->tty_groups);
 
         /*
          * Indicate that there isn't a port here anymore.
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 5bbb809ee197..cf3a1e789bf5 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -199,6 +199,8 @@ struct uart_port {
         unsigned char           suspended;
         unsigned char           irq_wake;
         unsigned char           unused[2];
+        struct attribute_group  *attr_group;            /* port specific attributes */
+        const struct attribute_group **tty_groups;      /* all attributes (serial core use only) */
         void                    *private_data;          /* generic platform data pointer */
 };