drivers: Add AXI uclass

Add a uclass for AXI (Advanced eXtensible Interface) busses, and a
driver for the gdsys IHS AXI bus on IHS FPGAs.
Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/Kconfig

@@ -8,6 +8,8 @@ source "drivers/adc/Kconfig"
 
 source "drivers/ata/Kconfig"
 
+source "drivers/axi/Kconfig"
+
 source "drivers/block/Kconfig"
 
 source "drivers/bootcount/Kconfig"

drivers/Makefile

@@ -103,6 +103,7 @@ obj-y += smem/
 obj-y += soc/
 obj-$(CONFIG_REMOTEPROC) += remoteproc/
 obj-y += thermal/
+obj-y += axi/
 
 obj-$(CONFIG_MACH_PIC32) += ddr/microchip/
 endif

drivers/axi/Kconfig

+menuconfig AXI
+	bool "AXI bus drivers"
+	help
+	  Support AXI (Advanced eXtensible Interface) busses, a on-chip
+	  interconnect specification for managing functional blocks in SoC
+	  designs, which is also often used in designs involving FPGAs (e.g.
+	  communication with IP cores in Xilinx FPGAs).
+
+	  These types of busses expose a virtual address space that can be
+	  accessed using different address widths (8, 16, and 32 are supported
+	  for now).
+
+	  Other similar bus architectures may be compatible as well.

drivers/axi/Makefile

+#
+# (C) Copyright 2017
+# Mario Six,  Guntermann & Drunck GmbH, mario.six@gdsys.cc
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+obj-$(CONFIG_AXI) += axi-uclass.o

drivers/axi/axi-uclass.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2017
+ * Mario Six,  Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <axi.h>
+
+int axi_read(struct udevice *dev, ulong address, void *data,
+	     enum axi_size_t size)
+{
+	struct axi_ops *ops = axi_get_ops(dev);
+
+	if (!ops->read)
+		return -ENOSYS;
+
+	return ops->read(dev, address, data, size);
+}
+
+int axi_write(struct udevice *dev, ulong address, void *data,
+	      enum axi_size_t size)
+{
+	struct axi_ops *ops = axi_get_ops(dev);
+
+	if (!ops->write)
+		return -ENOSYS;
+
+	return ops->write(dev, address, data, size);
+}
+
+UCLASS_DRIVER(axi) = {
+	.id		= UCLASS_AXI,
+	.name		= "axi",
+	.post_bind	= dm_scan_fdt_dev,
+	.flags		= DM_UC_FLAG_SEQ_ALIAS,
+};
+

include/axi.h

+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * (C) Copyright 2017
+ * Mario Six,  Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+#ifndef _AXI_H_
+#define _AXI_H_
+
+enum axi_size_t {
+	AXI_SIZE_8,
+	AXI_SIZE_16,
+	AXI_SIZE_32,
+};
+
+/**
+ * struct axi_ops - driver operations for AXI uclass
+ *
+ * Drivers should support these operations unless otherwise noted. These
+ * operations are intended to be used by uclass code, not directly from
+ * other code.
+ */
+struct axi_ops {
+	/**
+	 * read() - Read a single value from a specified address on a AXI bus
+	 *
+	 * @dev:	AXI bus to read from.
+	 * @address:	The address to read from.
+	 * @data:	Pointer to a variable that takes the data value read
+	 *		from the address on the AXI bus.
+	 * @size:	The size of the data to be read.
+	 * @return 0 if OK, -ve on error.
+	 */
+	int (*read)(struct udevice *dev, ulong address, void *data,
+		    enum axi_size_t size);
+
+	/**
+	 * write() - Write a single value to a specified address on a AXI bus
+	 *
+	 * @dev:	AXI bus to write to.
+	 * @address:	The address to write to.
+	 * @data:	Pointer to the data value to be written to the address
+	 *		on the AXI bus.
+	 * @size:	The size of the data to write.
+	 * @return 0 if OK, -ve on error.
+	 */
+	int (*write)(struct udevice *dev, ulong address, void *data,
+		     enum axi_size_t size);
+};
+
+#define axi_get_ops(dev)	((struct axi_ops *)(dev)->driver->ops)
+
+/**
+ * axi_read() - Read a single value from a specified address on a AXI bus
+ *
+ * @dev:	AXI bus to read from.
+ * @address:	The address to read from.
+ * @data:	Pointer to a variable that takes the data value read from the
+ *              address on the AXI bus.
+ * @size:	The size of the data to write.
+ * @return 0 if OK, -ve on error.
+ */
+int axi_read(struct udevice *dev, ulong address, void *data,
+	     enum axi_size_t size);
+
+/**
+ * axi_write() - Write a single value to a specified address on a AXI bus
+ *
+ * @dev:	AXI bus to write to.
+ * @address:	The address to write to.
+ * @data:	Pointer to the data value to be written to the address on the
+ *		AXI bus.
+ * @size:	The size of the data to write.
+ * @return 0 if OK, -ve on error.
+ */
+int axi_write(struct udevice *dev, ulong address, void *data,
+	      enum axi_size_t size);
+#endif

include/dm/uclass-id.h

@@ -43,6 +43,7 @@ enum uclass_id {
 	UCLASS_I2C_GENERIC,	/* Generic I2C device */
 	UCLASS_I2C_MUX,		/* I2C multiplexer */
 	UCLASS_IDE,		/* IDE device */
+	UCLASS_AXI,		/* AXI bus */
 	UCLASS_IRQ,		/* Interrupt controller */
 	UCLASS_KEYBOARD,	/* Keyboard input device */
 	UCLASS_LED,		/* Light-emitting diode (LED) */