[PATCH v5 08/28] fpga: dfl: add dfl_fpga_cdev_find_port

[Wu Hao]

For feature devices, we need a method to find the port dedicated
to the device. This patch adds a function dfl_fpga_cdev_find_port
for this purpose. e.g FPGA Management Engine (FME) Partial
Reconfiguration sub feature, it uses this function to find
dedicated port on the device for PR function implementation.

Signed-off-by: Tim Whisonant <tim.whisonant@xxxxxxxxx>
Signed-off-by: Enno Luebbers <enno.luebbers@xxxxxxxxx>
Signed-off-by: Shiva Rao <shiva.rao@xxxxxxxxx>
Signed-off-by: Christopher Rauer <christopher.rauer@xxxxxxxxx>
Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
Signed-off-by: Wu Hao <hao.wu@xxxxxxxxx>
Acked-by: Alan Tull <atull@xxxxxxxxxx>
Acked-by: Moritz Fischer <mdf@xxxxxxxxxx>
---
v3: s/fpga_for_each_port/fpga_cdev_find_port/
    move fpga_cdev_find_port to fpga-dfl module.
v4: improve description in commit message.
    add comments to remind user to put_device after use this function.
v5: add "dfl_" prefix to functions.
    improve function comments per suggestion from Alan Tull.
    add Acked-by from Alan and Moritz.
---
 drivers/fpga/dfl.c | 32 ++++++++++++++++++++++++++++++++
 drivers/fpga/dfl.h | 21 +++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index 18aba02..1e06efb 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c
@@ -795,6 +795,38 @@ void dfl_fpga_remove_feature_devs(struct dfl_fpga_cdev *cdev)
 }
 EXPORT_SYMBOL_GPL(dfl_fpga_remove_feature_devs);
 
+/**
+ * __dfl_fpga_cdev_find_port - find a port under given container device
+ *
+ * @cdev: container device
+ * @data: data passed to match function
+ * @match: match function used to find specific port from the port device list
+ *
+ * Find a port device under container device. This function needs to be
+ * invoked with lock held.
+ *
+ * Return: pointer to port's platform device if successful, NULL otherwise.
+ *
+ * NOTE: you will need to drop the device reference with put_device() after use.
+ */
+struct platform_device *
+__dfl_fpga_cdev_find_port(struct dfl_fpga_cdev *cdev, void *data,
+			  int (*match)(struct platform_device *, void *))
+{
+	struct dfl_feature_platform_data *pdata;
+	struct platform_device *port_dev;
+
+	list_for_each_entry(pdata, &cdev->port_dev_list, node) {
+		port_dev = pdata->dev;
+
+		if (match(port_dev, data) && get_device(&port_dev->dev))
+			return port_dev;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(__dfl_fpga_cdev_find_port);
+
 static int __init dfl_fpga_init(void)
 {
 	int ret;
diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
index 5fcb1a1..2b6aaef 100644
--- a/drivers/fpga/dfl.h
+++ b/drivers/fpga/dfl.h
@@ -290,4 +290,25 @@ struct dfl_fpga_cdev *
 dfl_fpga_enumerate_feature_devs(struct dfl_fpga_enum_info *info);
 void dfl_fpga_remove_feature_devs(struct dfl_fpga_cdev *cdev);
 
+/*
+ * need to drop the device reference with put_device() after use port platform
+ * device returned by __dfl_fpga_cdev_find_port and dfl_fpga_cdev_find_port
+ * functions.
+ */
+struct platform_device *
+__dfl_fpga_cdev_find_port(struct dfl_fpga_cdev *cdev, void *data,
+			  int (*match)(struct platform_device *, void *));
+
+static inline struct platform_device *
+dfl_fpga_cdev_find_port(struct dfl_fpga_cdev *cdev, void *data,
+			int (*match)(struct platform_device *, void *))
+{
+	struct platform_device *pdev;
+
+	mutex_lock(&cdev->lock);
+	pdev = __dfl_fpga_cdev_find_port(cdev, data, match);
+	mutex_unlock(&cdev->lock);
+
+	return pdev;
+}
 #endif /* __FPGA_DFL_H */
-- 
1.8.3.1