axi: Add AXI sandbox driver and simple emulator

Add test infrastructure and tests for the AXI uclass.
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>

arch/sandbox/include/asm/axi.h

+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * (C) Copyright 2018
+ * Mario Six, Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+#ifndef __asm_axi_h
+#define __asm_axi_h
+
+#define axi_emul_get_ops(dev)	((struct axi_emul_ops *)(dev)->driver->ops)
+
+/**
+ * axi_sandbox_get_emul() - Retrieve a pointer to a AXI emulation device
+ * @bus:     The AXI bus from which to retrieve a emulation device
+ * @address: The address of a transfer that should be handled by a emulation
+ *	     device
+ * @length:  The data width of a transfer that should be handled by a emulation
+ *	     device
+ * @emulp:   Pointer to a buffer receiving the emulation device that handles
+ *	     the transfer specified by the address and length parameters
+ *
+ * To test the AXI uclass, we implement a simple AXI emulation device, which is
+ * a virtual device on a AXI bus that exposes a simple storage interface: When
+ * reading and writing from the device, the addresses are translated to offsets
+ * within the device's storage. For write accesses the data is written to the
+ * specified storage offset, and for read accesses the data is read from the
+ * specified storage offset.
+ *
+ * A DTS entry might look like this:
+ *
+ * axi: axi@0 {
+ *	compatible = "sandbox,axi";
+ *	#address-cells = <0x1>;
+ *	#size-cells = <0x1>;
+ *	store@0 {
+ *		compatible = "sandbox,sandbox_store";
+ *		reg = <0x0 0x400>;
+ *	};
+ * };
+ *
+ * This function may then be used to retrieve the pointer to the sandbox_store
+ * emulation device given the AXI bus device, and the data (address, data
+ * width) of a AXI transfer which should be handled by a emulation device.
+ *
+ * Return: 0 of OK, -ENODEV if no device capable of handling the specified
+ *	   transfer exists or the device could not be retrieved
+ */
+int axi_sandbox_get_emul(struct udevice *bus, ulong address, uint length,
+			 struct udevice **emulp);
+/**
+ * axi_get_store() - Get address of internal storage of a emulated AXI device
+ * @dev:	Emulated AXI device to get the pointer of the internal storage
+ *		for.
+ * @storep:	Pointer to the internal storage of the emulated AXI device.
+ *
+ * To preset or read back the contents internal storage of the emulated AXI
+ * device, this function returns the pointer to the storage. Changes to the
+ * contents of the storage are reflected when using the AXI read/write API
+ * methods, and vice versa, so by using this method expected read data can be
+ * set up in advance, and written data can be checked in unit tests.
+ *
+ * Return: 0 if OK, -ve on error.
+ */
+int axi_get_store(struct udevice *dev, u8 **storep);
+
+#endif /* __asm_axi_h */

drivers/axi/Kconfig

@@ -22,4 +22,11 @@ config IHS_AXI
 	  Interface (IHS AXI) bus on a gdsys IHS FPGA used to communicate with
 	  IP cores in the FPGA (e.g. video transmitter cores).
 
+config AXI_SANDBOX
+	bool "Enable AXI sandbox driver"
+	depends on DM
+	help
+	  Support AXI (Advanced eXtensible Interface) emulation for the sandbox
+	  environment.
+
 endif

drivers/axi/Makefile

@@ -7,3 +7,6 @@
 
 obj-$(CONFIG_AXI) += axi-uclass.o
 obj-$(CONFIG_IHS_AXI) += ihs_axi.o
+obj-$(CONFIG_SANDBOX) += axi-emul-uclass.o
+obj-$(CONFIG_SANDBOX) += sandbox_store.o
+obj-$(CONFIG_AXI_SANDBOX) += axi_sandbox.o

drivers/axi/axi-emul-uclass.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2018
+ * Mario Six, Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+#include <common.h>
+#include <axi.h>
+#include <dm.h>
+#include <dm/device-internal.h>
+#include <asm/axi.h>
+
+int axi_sandbox_get_emul(struct udevice *bus, ulong address,
+			 enum axi_size_t size, struct udevice **emulp)
+{
+	struct udevice *dev;
+	u32 reg[2];
+	uint offset;
+
+	switch (size) {
+	case AXI_SIZE_8:
+		offset = 1;
+		break;
+	case AXI_SIZE_16:
+		offset = 2;
+		break;
+	case AXI_SIZE_32:
+		offset = 4;
+		break;
+	default:
+		debug("%s: Unknown AXI transfer size '%d'", bus->name, size);
+		offset = 0;
+	}
+
+	/*
+	 * Note: device_find_* don't activate the devices; they're activated
+	 *	 as-needed below.
+	 */
+	for (device_find_first_child(bus, &dev);
+	     dev;
+	     device_find_next_child(&dev)) {
+		int ret;
+
+		ret = dev_read_u32_array(dev, "reg", reg, ARRAY_SIZE(reg));
+		if (ret) {
+			debug("%s: Could not read 'reg' property of %s\n",
+			      bus->name, dev->name);
+			continue;
+		}
+
+		/*
+		 * Does the transfer's address fall into this device's address
+		 * space?
+		 */
+		if (address >= reg[0] && address <= reg[0] + reg[1] - offset) {
+			/* If yes, activate it... */
+			if (device_probe(dev)) {
+				debug("%s: Could not activate %s\n",
+				      bus->name, dev->name);
+				return -ENODEV;
+			}
+
+			/* ...and return it */
+			*emulp = dev;
+			return 0;
+		}
+	}
+
+	return -ENODEV;
+}
+
+int axi_get_store(struct udevice *dev, u8 **storep)
+{
+	struct axi_emul_ops *ops = axi_emul_get_ops(dev);
+
+	if (!ops->get_store)
+		return -ENOSYS;
+
+	return ops->get_store(dev, storep);
+}
+
+UCLASS_DRIVER(axi_emul) = {
+	.id		= UCLASS_AXI_EMUL,
+	.name		= "axi_emul",
+};

drivers/axi/axi_sandbox.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2018
+ * Mario Six, Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+#include <common.h>
+#include <axi.h>
+#include <dm.h>
+#include <asm/axi.h>
+
+/*
+ * This driver implements a AXI bus for the sandbox architecture for testing
+ * purposes.
+ *
+ * The bus forwards every access to it to a special AXI emulation device (which
+ * it gets via the axi_emul_get_ops function) that implements a simple
+ * read/write storage.
+ *
+ * The emulator device must still be contained in the device tree in the usual
+ * way, since configuration data for the storage is read from the DT.
+ */
+
+static int axi_sandbox_read(struct udevice *bus, ulong address, void *data,
+			    enum axi_size_t size)
+{
+	struct axi_emul_ops *ops;
+	struct udevice *emul;
+	int ret;
+
+	/* Get emulator device */
+	ret = axi_sandbox_get_emul(bus, address, size, &emul);
+	if (ret)
+		return ret == -ENODEV ? 0 : ret;
+	/* Forward all reads to the AXI emulator */
+	ops = axi_emul_get_ops(emul);
+	if (!ops || !ops->read)
+		return -ENOSYS;
+
+	return ops->read(emul, address, data, size);
+}
+
+static int axi_sandbox_write(struct udevice *bus, ulong address, void *data,
+			     enum axi_size_t size)
+{
+	struct axi_emul_ops *ops;
+	struct udevice *emul;
+	int ret;
+
+	/* Get emulator device */
+	ret = axi_sandbox_get_emul(bus, address, size, &emul);
+	if (ret)
+		return ret == -ENODEV ? 0 : ret;
+	/* Forward all writes to the AXI emulator */
+	ops = axi_emul_get_ops(emul);
+	if (!ops || !ops->write)
+		return -ENOSYS;
+
+	return ops->write(emul, address, data, size);
+}
+
+static const struct udevice_id axi_sandbox_ids[] = {
+	{ .compatible = "sandbox,axi" },
+	{ /* sentinel */ }
+};
+
+static const struct axi_ops axi_sandbox_ops = {
+	.read = axi_sandbox_read,
+	.write = axi_sandbox_write,
+};
+
+U_BOOT_DRIVER(axi_sandbox_bus) = {
+	.name           = "axi_sandbox_bus",
+	.id             = UCLASS_AXI,
+	.of_match       = axi_sandbox_ids,
+	.ops		= &axi_sandbox_ops,
+};

drivers/axi/sandbox_store.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2018
+ * Mario Six, Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+#include <common.h>
+#include <axi.h>
+#include <dm.h>
+
+/**
+ * struct sandbox_store_priv - Private data structure of a AXI store device
+ * @store: The buffer holding the device's internal memory, which is read from
+ *	   and written to using the driver's methods
+ */
+struct sandbox_store_priv {
+	u8 *store;
+};
+
+/**
+ * copy_axi_data() - Copy data from source to destination with a given AXI
+ *		     transfer width
+ * @src:  Pointer to the data source from where data will be read
+ * @dst:  Pointer to the data destination where data will be written to
+ * @size: Size of the data to be copied given by a axi_size_t enum value
+ *
+ * Return: 0 if OK, -ve on error
+ */
+static int copy_axi_data(void *src, void *dst, enum axi_size_t size)
+{
+	switch (size) {
+	case AXI_SIZE_8:
+		*((u8 *)dst) = *((u8 *)src);
+		return 0;
+	case AXI_SIZE_16:
+		*((u16 *)dst) = be16_to_cpu(*((u16 *)src));
+		return 0;
+	case AXI_SIZE_32:
+		*((u32 *)dst) = be32_to_cpu(*((u32 *)src));
+		return 0;
+	default:
+		debug("%s: Unknown AXI transfer size '%d'\n", __func__, size);
+		return -EINVAL;
+	}
+}
+
+static int sandbox_store_read(struct udevice *dev, ulong address, void *data,
+			      enum axi_size_t size)
+{
+	struct sandbox_store_priv *priv = dev_get_priv(dev);
+
+	return copy_axi_data(priv->store + address, data, size);
+}
+
+static int sandbox_store_write(struct udevice *dev, ulong address, void *data,
+			       enum axi_size_t size)
+{
+	struct sandbox_store_priv *priv = dev_get_priv(dev);
+
+	return copy_axi_data(data, priv->store + address, size);
+}
+
+static int sandbox_store_get_store(struct udevice *dev, u8 **store)
+{
+	struct sandbox_store_priv *priv = dev_get_priv(dev);
+
+	*store = priv->store;
+
+	return 0;
+}
+
+static const struct udevice_id sandbox_store_ids[] = {
+	{ .compatible = "sandbox,sandbox_store" },
+	{ /* sentinel */ }
+};
+
+static const struct axi_emul_ops sandbox_store_ops = {
+	.read = sandbox_store_read,
+	.write = sandbox_store_write,
+	.get_store = sandbox_store_get_store,
+};
+
+static int sandbox_store_probe(struct udevice *dev)
+{
+	struct sandbox_store_priv *priv = dev_get_priv(dev);
+	u32 reg[2];
+	int ret;
+
+	ret = dev_read_u32_array(dev, "reg", reg, ARRAY_SIZE(reg));
+	if (ret) {
+		debug("%s: Could not read 'reg' property\n", dev->name);
+		return -EINVAL;
+	}
+
+	/*
+	 * Allocate the device's internal storage that will be read
+	 * from/written to
+	 */
+	priv->store = calloc(reg[1], 1);
+	if (!priv->store)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int sandbox_store_remove(struct udevice *dev)
+{
+	struct sandbox_store_priv *priv = dev_get_priv(dev);
+
+	free(priv->store);
+
+	return 0;
+}
+
+U_BOOT_DRIVER(sandbox_axi_store) = {
+	.name           = "sandbox_axi_store",
+	.id             = UCLASS_AXI_EMUL,
+	.of_match       = sandbox_store_ids,
+	.ops		= &sandbox_store_ops,
+	.priv_auto_alloc_size = sizeof(struct sandbox_store_priv),
+	.probe          = sandbox_store_probe,
+	.remove		= sandbox_store_remove,
+};

include/axi.h

 /* SPDX-License-Identifier: GPL-2.0+ */
 /*
- * (C) Copyright 2017
- * Mario Six,  Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ * (C) Copyright 2017, 2018
+ * Mario Six, Guntermann & Drunck GmbH, mario.six@gdsys.cc
  */
 
 #ifndef _AXI_H_
 #define _AXI_H_
 
+/**
+ * enum axi_size_t - Determine size of AXI transfer
+ * @AXI_SIZE_8:  AXI sransfer is 8-bit wide
+ * @AXI_SIZE_16: AXI sransfer is 16-bit wide
+ * @AXI_SIZE_32: AXI sransfer is 32-bit wide
+ */
 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.
+	 *
+	 * 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.
+	 *
+	 * Return 0 if OK, -ve on error.
 	 */
 	int (*write)(struct udevice *dev, ulong address, void *data,
 		     enum axi_size_t size);
@@ -52,27 +51,68 @@ struct axi_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.
+ *
+ * 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.
+ *
+ * Return: 0 if OK, -ve on error.
  */
 int axi_write(struct udevice *dev, ulong address, void *data,
 	      enum axi_size_t size);
+
+struct axi_emul_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);
+
+	/**
+	 * get_store() - Get address of internal storage of a emulated AXI
+	 *		 device
+	 * @dev:	Emulated AXI device to get the pointer of the internal
+	 *		storage for.
+	 * @storep:	Pointer to the internal storage of the emulated AXI
+	 *		device.
+	 *
+	 * Return: 0 if OK, -ve on error.
+	 */
+	int (*get_store)(struct udevice *dev, u8 **storep);
+};
+
 #endif

include/dm/uclass-id.h

@@ -23,6 +23,7 @@ enum uclass_id {
 	UCLASS_I2C_EMUL,	/* sandbox I2C device emulator */
 	UCLASS_PCI_EMUL,	/* sandbox PCI device emulator */
 	UCLASS_USB_EMUL,	/* sandbox USB bus device emulator */
+	UCLASS_AXI_EMUL,	/* sandbox AXI bus device emulator */
 	UCLASS_SIMPLE_BUS,	/* bus with child devices */
 
 	/* U-Boot uclasses start here - in alphabetical order */