mfd: Versatile Express config infrastructure

Versatile Express platform has an elaborated configuration system,
consisting of microcontrollers residing on the mother- and
daughterboards known as Motherboard/Daughterboard Configuration
Controller (MCC and DCC). The controllers are responsible for
the platform initialization (reset generation, flash programming,
FPGA bitfiles loading etc.) but also control clock generators,
voltage regulators, gather environmental data like temperature,
power consumption etc. Even the video output switch (FPGA) is
controlled that way.

Those devices are _not_ visible in the main address space and
the usual communication channel uses some kind of a bridge in
the peripheral block sending commands (requests) to the
controllers and receiving responses. It can take up to
500 microseconds for a transaction to be completed, therefore
it is important to provide a non-blocking interface to it.

This patch adds an abstraction of this infrastructure. Bridge
drivers can register themselves with the framework. Then,
a driver of a device can request an abstract "function" - the
request will be redirected to a bridge referred by thedd
"arm,vexpress,config-bridge" property of the device tree node.

Signed-off-by: Pawel Moll <pawel.moll@arm.com>

1 files changed, 85 insertions, 0 deletions

diff --git a/include/linux/vexpress.h b/include/linux/vexpress.h
new file mode 100644
index 000000000000..c2d877a7b691
--- /dev/null
+++ b/include/linux/vexpress.h
@@ -0,0 +1,85 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Copyright (C) 2012 ARM Limited
+ */
+
+#ifndef _LINUX_VEXPRESS_H
+#define _LINUX_VEXPRESS_H
+
+#include <linux/device.h>
+
+#define VEXPRESS_SITE_MB                0
+#define VEXPRESS_SITE_DB1               1
+#define VEXPRESS_SITE_DB2               2
+#define VEXPRESS_SITE_MASTER            0xf
+
+#define VEXPRESS_CONFIG_STATUS_DONE     0
+#define VEXPRESS_CONFIG_STATUS_WAIT     1
+
+/* Config bridge API */
+
+/**
+ * struct vexpress_config_bridge_info - description of the platform
+ * configuration infrastructure bridge.
+ *
+ * @name:       Bridge name
+ *
+ * @func_get:   Obtains pointer to a configuration function for a given
+ *              device or a Device Tree node, to be used with @func_put
+ *              and @func_exec. The node pointer should take precedence
+ *              over device pointer when both are passed.
+ *
+ * @func_put:   Tells the bridge that the function will not be used any
+ *              more, so all allocated resources can be released.
+ *
+ * @func_exec:  Executes a configuration function read or write operation.
+ *              The offset selects a 32 bit word of the value accessed.
+ *              Must return VEXPRESS_CONFIG_STATUS_DONE when operation
+ *              is finished immediately, VEXPRESS_CONFIG_STATUS_WAIT when
+ *              will be completed in some time or negative value in case
+ *              of error.
+ */
+struct vexpress_config_bridge_info {
+        const char *name;
+        void *(*func_get)(struct device *dev, struct device_node *node);
+        void (*func_put)(void *func);
+        int (*func_exec)(void *func, int offset, bool write, u32 *data);
+};
+
+struct vexpress_config_bridge;
+
+struct vexpress_config_bridge *vexpress_config_bridge_register(
+                struct device_node *node,
+                struct vexpress_config_bridge_info *info);
+void vexpress_config_bridge_unregister(struct vexpress_config_bridge *bridge);
+
+void vexpress_config_complete(struct vexpress_config_bridge *bridge,
+                int status);
+
+/* Config function API */
+
+struct vexpress_config_func;
+
+struct vexpress_config_func *__vexpress_config_func_get(struct device *dev,
+                struct device_node *node);
+#define vexpress_config_func_get_by_dev(dev) \
+                __vexpress_config_func_get(dev, NULL)
+#define vexpress_config_func_get_by_node(node) \
+                __vexpress_config_func_get(NULL, node)
+void vexpress_config_func_put(struct vexpress_config_func *func);
+
+/* Both may sleep! */
+int vexpress_config_read(struct vexpress_config_func *func, int offset,
+                u32 *data);
+int vexpress_config_write(struct vexpress_config_func *func, int offset,
+                u32 data);
+
+#endif