linux-kernel - [RFC 2/2] drm/dsi: Get DSI host by DT device node

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Message-Id: <1435641851-27295-3-git-send-email-architt@codeaurora.org>
Date:	Tue, 30 Jun 2015 10:54:11 +0530
From:	Archit Taneja <architt@...eaurora.org>
To:	dri-devel@...ts.freedesktop.org
Cc:	linux-arm-msm@...r.kernel.org, treding@...dia.com,
	inki.dae@...sung.com, a.hajda@...sung.com,
	linux-kernel@...r.kernel.org, airlied@...ux.ie, daniel@...ll.ch,
	jani.nikula@...ux.intel.com, Archit Taneja <architt@...eaurora.org>
Subject: [RFC 2/2] drm/dsi: Get DSI host by DT device node

mipi_dsi_devices are inherently aware of their host because they
share a parent-child hierarchy in the device tree.

Non-dsi drivers that create a dummy dsi device don't have this data.
In order to get this information, they require to a phandle to the dsi
host in the device tree.

Maintain a list of all the hosts DSI that are currently registered.

This list will be used to find the mipi_dsi_host corresponding to the
device_node passed in of_find_mipi_dsi_host_by_node.

Signed-off-by: Archit Taneja <architt@...eaurora.org>
---
 drivers/gpu/drm/drm_mipi_dsi.c | 30 ++++++++++++++++++++++++++++++
 include/drm/drm_mipi_dsi.h     |  2 ++
 2 files changed, 32 insertions(+)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 9bfe215..81ddb73 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -239,6 +239,28 @@ struct mipi_dsi_device *mipi_dsi_new_dummy(struct mipi_dsi_host *host, u32 reg)
 	return dsi;
 }
 
+static DEFINE_MUTEX(host_lock);
+static LIST_HEAD(host_list);
+
+struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node)
+{
+	struct mipi_dsi_host *host;
+
+	mutex_lock(&host_lock);
+
+	list_for_each_entry(host, &host_list, list) {
+		if (host->dev->of_node == node) {
+			mutex_unlock(&host_lock);
+			return host;
+		}
+	}
+
+	mutex_unlock(&host_lock);
+
+	return NULL;
+}
+EXPORT_SYMBOL(of_find_mipi_dsi_host_by_node);
+
 int mipi_dsi_host_register(struct mipi_dsi_host *host)
 {
 	struct device_node *node;
@@ -250,6 +272,10 @@ int mipi_dsi_host_register(struct mipi_dsi_host *host)
 		of_mipi_dsi_device_add(host, node);
 	}
 
+	mutex_lock(&host_lock);
+	list_add_tail(&host->list, &host_list);
+	mutex_unlock(&host_lock);
+
 	return 0;
 }
 EXPORT_SYMBOL(mipi_dsi_host_register);
@@ -266,6 +292,10 @@ static int mipi_dsi_remove_device_fn(struct device *dev, void *priv)
 void mipi_dsi_host_unregister(struct mipi_dsi_host *host)
 {
 	device_for_each_child(host->dev, NULL, mipi_dsi_remove_device_fn);
+
+	mutex_lock(&host_lock);
+	list_del_init(&host->list);
+	mutex_unlock(&host_lock);
 }
 EXPORT_SYMBOL(mipi_dsi_host_unregister);
 
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index d06ba99..1684a0e 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -100,10 +100,12 @@ struct mipi_dsi_host_ops {
 struct mipi_dsi_host {
 	struct device *dev;
 	const struct mipi_dsi_host_ops *ops;
+	struct list_head list;
 };
 
 int mipi_dsi_host_register(struct mipi_dsi_host *host);
 void mipi_dsi_host_unregister(struct mipi_dsi_host *host);
+struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node);
 
 /* DSI mode flags */
 
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation

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