linux-kernel - [PATCH V2 5/5] virtio: Bind virtio device to device-tree node

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Date:   Thu, 22 Jul 2021 15:26:43 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Jason Wang <jasowang@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Arnd Bergmann <arnd@...nel.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Bill Mills <bill.mills@...aro.org>,
        Alex Bennée <alex.bennee@...aro.org>,
        "Enrico Weigelt, metux IT consult" <info@...ux.net>,
        Jie Deng <jie.deng@...el.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Subject: [PATCH V2 5/5] virtio: Bind virtio device to device-tree node

Bind the virtio devices with their of_node. This will help users of the
virtio devices to mention their dependencies on the device in the DT
itself. Like GPIO pin users can use the phandle of the device node, or
the node may contain more subnodes to add i2c or spi eeproms and other
users.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/virtio/virtio.c | 67 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 64 insertions(+), 3 deletions(-)

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 4b15c00c0a0a..87bee5b966c3 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -4,6 +4,7 @@
 #include <linux/virtio_config.h>
 #include <linux/module.h>
 #include <linux/idr.h>
+#include <linux/of.h>
 #include <uapi/linux/virtio_ids.h>
 
 /* Unique numbering for virtio devices. */
@@ -292,6 +293,9 @@ static int virtio_dev_remove(struct device *_d)
 
 	/* Acknowledge the device's existence again. */
 	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+
+	of_node_put(dev->dev.of_node);
+
 	return 0;
 }
 
@@ -319,6 +323,53 @@ void unregister_virtio_driver(struct virtio_driver *driver)
 }
 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 
+/* Virtio device compatibles and IDs */
+static const struct of_device_id of_virtio_devices[] = {
+	{ .compatible = "virtio,22", .data = (void *)VIRTIO_ID_I2C_ADAPTER },
+	{ .compatible = "virtio,29", .data = (void *)VIRTIO_ID_GPIO },
+	{ }
+};
+
+static int virtio_device_of_init(struct virtio_device *dev)
+{
+	struct device_node *np, *pnode = dev->dev.parent->of_node;
+	const struct of_device_id *match;
+	int ret, count;
+
+	if (!pnode)
+		return 0;
+
+	count = of_get_available_child_count(pnode);
+	if (!count)
+		return 0;
+
+	/* There can be only 1 child node */
+	if (WARN_ON(count > 1))
+		return -EINVAL;
+
+	np = of_get_next_available_child(pnode, NULL);
+	if (WARN_ON(!np))
+		return -ENODEV;
+
+	match = of_match_node(of_virtio_devices, np);
+	if (!match) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	if ((unsigned long)match->data != dev->id.device) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	dev->dev.of_node = np;
+	return 0;
+
+out:
+	of_node_put(np);
+	return ret;
+}
+
 /**
  * register_virtio_device - register virtio device
  * @dev        : virtio device to be registered
@@ -343,6 +394,10 @@ int register_virtio_device(struct virtio_device *dev)
 	dev->index = err;
 	dev_set_name(&dev->dev, "virtio%u", dev->index);
 
+	err = virtio_device_of_init(dev);
+	if (err)
+		goto out_ida_remove;
+
 	spin_lock_init(&dev->config_lock);
 	dev->config_enabled = false;
 	dev->config_change_pending = false;
@@ -362,10 +417,16 @@ int register_virtio_device(struct virtio_device *dev)
 	 */
 	err = device_add(&dev->dev);
 	if (err)
-		ida_simple_remove(&virtio_index_ida, dev->index);
+		goto out_of_node_put;
+
+	return 0;
+
+out_of_node_put:
+	of_node_put(dev->dev.of_node);
+out_ida_remove:
+	ida_simple_remove(&virtio_index_ida, dev->index);
 out:
-	if (err)
-		virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
+	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
 	return err;
 }
 EXPORT_SYMBOL_GPL(register_virtio_device);
-- 
2.31.1.272.g89b43f80a514