NFC: RFKILL support

All NFC devices will now get proper RFKILL support as long as they provide
some dev_up and dev_down hooks. Rfkilling an NFC device will bring it down
while it is left to userspace to bring it back up when being rfkill unblocked.
This is very similar to what Bluetooth does.

Acked-by: Marcel Holtmann <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>

include/net/nfc/nfc.h

···
 
 	bool shutting_down;
 
+	struct rfkill *rfkill;
+
 	struct nfc_ops *ops;
 };
 #define to_nfc_dev(_dev) container_of(_dev, struct nfc_dev, dev)

net/nfc/core.c

···
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/rfkill.h>
 #include <linux/nfc.h>
 
 #include <net/genetlink.h>
···
 	pr_debug("dev_name=%s\n", dev_name(&dev->dev));
 
 	device_lock(&dev->dev);
+
+	if (dev->rfkill && rfkill_blocked(dev->rfkill)) {
+		rc = -ERFKILL;
+		goto error;
+	}
 
 	if (!device_is_registered(&dev->dev)) {
 		rc = -ENODEV;
···
 	device_unlock(&dev->dev);
 	return rc;
 }
+
+static int nfc_rfkill_set_block(void *data, bool blocked)
+{
+	struct nfc_dev *dev = data;
+
+	pr_debug("%s blocked %d", dev_name(&dev->dev), blocked);
+
+	if (!blocked)
+		return 0;
+
+	nfc_dev_down(dev);
+
+	return 0;
+}
+
+static const struct rfkill_ops nfc_rfkill_ops = {
+	.set_block = nfc_rfkill_set_block,
+};
 
 /**
  * nfc_start_poll - start polling for nfc targets
···
 		pr_debug("The userspace won't be notified that the device %s was added\n",
 			 dev_name(&dev->dev));
 
+	dev->rfkill = rfkill_alloc(dev_name(&dev->dev), &dev->dev,
+				   RFKILL_TYPE_NFC, &nfc_rfkill_ops, dev);
+	if (dev->rfkill) {
+		if (rfkill_register(dev->rfkill) < 0) {
+			rfkill_destroy(dev->rfkill);
+			dev->rfkill = NULL;
+		}
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL(nfc_register_device);
···
 	pr_debug("dev_name=%s\n", dev_name(&dev->dev));
 
 	id = dev->idx;
+
+	if (dev->rfkill) {
+		rfkill_unregister(dev->rfkill);
+		rfkill_destroy(dev->rfkill);
+	}
 
 	if (dev->ops->check_presence) {
 		device_lock(&dev->dev);