[RESEND PATCH V8 1/2] serial/uart: Introduce device specific attribute group to uart_port structure

[Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>]

Current serial device driver has the common sysfs I/F for all serial
devices, but it does not have device specific sysfs I/F. To make device
specific sysfs I/F, this patch introduces device specific attribute group to
uart_port structure.

Changes in V8:
 - Divide this patch from V7's patch based on Greg's comment

Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
---
 drivers/tty/serial/serial_core.c |   18 +++++++++++-------
 include/linux/serial_core.h      |    4 ++++
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index fbf6c5a..ed6ec1c 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2559,15 +2559,16 @@ static struct attribute *tty_dev_attrs[] = {
 	NULL,
 	};
 
-static const struct attribute_group tty_dev_attr_group = {
+static 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
-	};
-
+static void make_uport_attr_grps(struct uart_port *uport)
+{
+	uport->attr_grps[0] = &tty_dev_attr_group;
+	if (uport->dev_spec_attr_group)
+		uport->attr_grps[1] = uport->dev_spec_attr_group;
+}
 
 /**
  *	uart_add_one_port - attach a driver-defined port structure
@@ -2618,12 +2619,15 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
 
 	uart_configure_port(drv, state, uport);
 
+	make_uport_attr_grps(uport);
+
 	/*
 	 * 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,
+			(const struct attribute_group **)uport->attr_grps);
 	if (likely(!IS_ERR(tty_dev))) {
 		device_set_wakeup_capable(tty_dev, 1);
 	} else {
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 5bbb809..3b20c17 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -113,6 +113,8 @@ struct uart_icount {
 
 typedef unsigned int __bitwise__ upf_t;
 
+#define MAX_ATTR_GRPS		3
+
 struct uart_port {
 	spinlock_t		lock;			/* port lock */
 	unsigned long		iobase;			/* in/out[bwl] */
@@ -195,6 +197,8 @@ struct uart_port {
 	unsigned int		line;			/* port index */
 	resource_size_t		mapbase;		/* for ioremap */
 	struct device		*dev;			/* parent device */
+	struct attribute_group	*dev_spec_attr_group;	/* specific attribute */
+	struct attribute_group	*attr_grps[MAX_ATTR_GRPS];/* all attr. groups */
 	unsigned char		hub6;			/* this should be in the 8250 driver */
 	unsigned char		suspended;
 	unsigned char		irq_wake;