[media] media: lirc: Allow lirc dev to talk to rc device

The use case is simple, if any rc device has allowed protocols =
RC_TYPE_LIRC and map_name = RC_MAP_LIRC set, the driver open will be never
called. The reason for this is, all of the key maps except lirc have some
KEYS in there map, so during rc_register_device process these keys are
matched against the input drivers and open is performed, so for the case
of RC_MAP_EMPTY, a vt/keyboard is matched and the driver open is
performed.
In case of lirc, there is no match and result is that there is no open
performed, however the lirc-dev will go ahead and create a /dev/lirc0
node. Now when lircd/mode2 opens this device, no data is available
because the driver was never opened.
Other case pointed by Sean Young, As rc device gets opened via the
input interface. If the input device is never opened (e.g. embedded with
no console) then the rc open is never called and lirc will not work
either. So that's another case.
lirc_dev seems to have no link with actual rc device w.r.t open/close.
This patch adds rc_dev pointer to lirc_driver structure for cases like
this, so that it can do the open/close of the real driver in accordance
to lircd/mode2 open/close.
Without this patch its impossible to open a rc device which has
RC_TYPE_LIRC ad RC_MAP_LIRC set.

Signed-off-by: Srinivas Kandagatla <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/rc/ir-lirc-codec.c

···
 	drv->code_length = sizeof(struct ir_raw_event) * 8;
 	drv->fops = &lirc_fops;
 	drv->dev = &dev->dev;
+	drv->rdev = dev;
 	drv->owner = THIS_MODULE;
 
 	drv->minor = lirc_register_driver(drv);

drivers/media/rc/lirc_dev.c

···
 #include <linux/device.h>
 #include <linux/cdev.h>
 
+#include <media/rc-core.h>
 #include <media/lirc.h>
 #include <media/lirc_dev.h>
 
···
 		goto error;
 	}
 
+	if (ir->d.rdev) {
+		retval = rc_open(ir->d.rdev);
+		if (retval)
+			goto error;
+	}
+
 	cdev = ir->cdev;
 	if (try_module_get(cdev->owner)) {
 		ir->open++;
···
 	dev_dbg(ir->d.dev, LOGHEAD "close called\n", ir->d.name, ir->d.minor);
 
 	WARN_ON(mutex_lock_killable(&lirc_dev_lock));
+
+	if (ir->d.rdev)
+		rc_close(ir->d.rdev);
 
 	ir->open--;
 	if (ir->attached) {

include/media/lirc_dev.h

···
 	struct lirc_buffer *rbuf;
 	int (*set_use_inc) (void *data);
 	void (*set_use_dec) (void *data);
+	struct rc_dev *rdev;
 	const struct file_operations *fops;
 	struct device *dev;
 	struct module *owner;