drivers: add fpga bridge framework

Import the fpga bridge framework from linux v4.10-rc2.

Description from the initial commit adding this to linux:
21aeda950c5f84a8351b862816d832120b217a9b

    fpga: add fpga bridge framework

    This framework adds API functions for enabling/
    disabling FPGA bridges under kernel control.

    This allows the Linux kernel to disable FPGA bridges
    during FPGA reprogramming and to enable FPGA bridges
    when FPGA reprogramming is done.  This framework is
    be manufacturer-agnostic, allowing it to be used in
    interfaces that use the FPGA Manager Framework to
    reprogram FPGA's.

    The functions are:
    * of_fpga_bridge_get
    * fpga_bridge_put
       Get/put an exclusive reference to a FPGA bridge.

    * fpga_bridge_enable
    * fpga_bridge_disable
       Enable/Disable traffic through a bridge.

    * fpga_bridge_register
    * fpga_bridge_unregister
       Register/unregister a device-specific low level FPGA
       Bridge driver.

    Get an exclusive reference to a bridge and add it to a list:
    * fpga_bridge_get_to_list

    To enable/disable/put a set of bridges that are on a list:
    * fpga_bridges_enable
    * fpga_bridges_disable
    * fpga_bridges_put

    Signed-off-by: Alan Tull <atull@opensource.altera.com>

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Link: https://lore.barebox.org/20210616063246.14900-2-s.trumtrar@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 74 insertions, 0 deletions

diff --git a/include/fpga-bridge.h b/include/fpga-bridge.h
new file mode 100644
index 0000000000..fef2a9ccbb
--- /dev/null
+++ b/include/fpga-bridge.h
@@ -0,0 +1,74 @@
+#include <common.h>
+
+#ifndef _LINUX_FPGA_BRIDGE_H
+#define _LINUX_FPGA_BRIDGE_H
+
+struct fpga_bridge;
+
+/**
+ * struct fpga_bridge_ops - ops for low level FPGA bridge drivers
+ * @enable_show: returns the FPGA bridge's status
+ * @enable_set: set a FPGA bridge as enabled or disabled
+ * @fpga_bridge_remove: set FPGA into a specific state during driver remove
+ */
+struct fpga_bridge_ops {
+	int (*enable_show)(struct fpga_bridge *bridge);
+	int (*enable_set)(struct fpga_bridge *bridge, bool enable);
+	void (*fpga_bridge_remove)(struct fpga_bridge *bridge);
+};
+
+/**
+ * struct fpga_bridge - FPGA bridge structure
+ * @name: name of low level FPGA bridge
+ * @dev: FPGA bridge device
+ * @mutex: enforces exclusive reference to bridge
+ * @br_ops: pointer to struct of FPGA bridge ops
+ * @info: fpga image specific information
+ * @node: FPGA bridge list node
+ * @priv: low level driver private date
+ */
+struct fpga_bridge {
+	struct device_d dev;
+	const struct fpga_bridge_ops *br_ops;
+	struct list_head node;
+	unsigned int enable;
+	void *priv;
+};
+
+#define to_fpga_bridge(d) container_of(d, struct fpga_bridge, dev)
+
+struct fpga_bridge *of_fpga_bridge_get(struct device_node *node);
+void fpga_bridge_put(struct fpga_bridge *bridge);
+int fpga_bridge_enable(struct fpga_bridge *bridge);
+int fpga_bridge_disable(struct fpga_bridge *bridge);
+
+#ifdef CONFIG_FPGA_BRIDGE
+int fpga_bridges_enable(struct list_head *bridge_list);
+int fpga_bridges_disable(struct list_head *bridge_list);
+int fpga_bridge_get_to_list(struct device_node *np,
+			    struct list_head *bridge_list);
+void fpga_bridges_put(struct list_head *bridge_list);
+#else
+static inline int fpga_bridges_enable(struct list_head *bridge_list)
+{
+	return -ENOSYS;
+};
+static inline int fpga_bridges_disable(struct list_head *bridge_list)
+{
+	return -ENOSYS;
+};
+static inline int fpga_bridge_get_to_list(struct device_node *np,
+			    struct list_head *bridge_list)
+{
+	return -ENOSYS;
+};
+static inline void fpga_bridges_put(struct list_head *bridge_list)
+{
+	return;
+};
+#endif
+
+int fpga_bridge_register(struct device_d *dev, const char *name,
+			 const struct fpga_bridge_ops *br_ops, void *priv);
+
+#endif /* _LINUX_FPGA_BRIDGE_H */