axi: Add ihs_axi driver

Add a driver for the gdsys IHS AXI bus used on IHS FPGAs.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>

Documentation/devicetree/bindings/axi/gdsys,ihs_axi.txt

@@ -0,0 +1,22 @@
+gdsys AXI busses of IHS FPGA devices
+
+Certain gdsys IHS FPGAs offer a interface to their built-in AXI bus with which
+the connected devices (usually IP cores) can be controlled via software.
+
+Required properties:
+- compatible: must be "gdsys,ihs_axi"
+- reg: describes the address and length of the AXI bus's register map (within
+  the FPGA's register space)
+
+Example:
+
+fpga0_axi_video0 {
+	#address-cells = <1>;
+	#size-cells = <1>;
+	compatible = "gdsys,ihs_axi";
+	reg = <0x170 0x10>;
+
+	axi_dev_1 {
+        ...
+	};
+};

drivers/axi/Kconfig

@@ -11,3 +11,15 @@ menuconfig AXI
 	  for now).
 
 	  Other similar bus architectures may be compatible as well.
+
+if AXI
+
+config IHS_AXI
+	bool "Enable IHS AXI driver"
+	depends on DM
+	help
+	  Support for gdsys Integrated Hardware Systems Advanced eXtensible
+	  Interface (IHS AXI) bus on a gdsys IHS FPGA used to communicate with
+	  IP cores in the FPGA (e.g. video transmitter cores).
+
+endif

drivers/axi/Makefile

@@ -6,3 +6,4 @@
 #
 
 obj-$(CONFIG_AXI) += axi-uclass.o
+obj-$(CONFIG_IHS_AXI) += ihs_axi.o

drivers/axi/ihs_axi.c

@@ -0,0 +1,293 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2016
+ * Dirk Eibach,  Guntermann & Drunck GmbH, dirk.eibach@gdsys.cc
+ *
+ * (C) Copyright 2017, 2018
+ * Mario Six,  Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+#include <common.h>
+#include <axi.h>
+#include <dm.h>
+#include <regmap.h>
+
+/**
+ * struct ihs_axi_regs - Structure for the register map of a IHS AXI device
+ * @interrupt_status:         Status register to indicate certain events (e.g.
+ *			      error during transfer, transfer complete, etc.)
+ * @interrupt_enable_control: Register to both control which statuses will be
+ *			      indicated in the interrupt_status register, and
+ *			      to change bus settings
+ * @address_lsb:              Least significant 16-bit word of the address of a
+ *			      device to transfer data from/to
+ * @address_msb:              Most significant 16-bit word of the address of a
+ *			      device to transfer data from/to
+ * @write_data_lsb:           Least significant 16-bit word of the data to be
+ *			      written to a device
+ * @write_data_msb:           Most significant 16-bit word of the data to be
+ *			      written to a device
+ * @read_data_lsb:            Least significant 16-bit word of the data read
+ *			      from a device
+ * @read_data_msb:            Most significant 16-bit word of the data read
+ *			      from a device
+ */
+struct ihs_axi_regs {
+	u16 interrupt_status;
+	u16 interrupt_enable_control;
+	u16 address_lsb;
+	u16 address_msb;
+	u16 write_data_lsb;
+	u16 write_data_msb;
+	u16 read_data_lsb;
+	u16 read_data_msb;
+};
+
+/**
+ * ihs_axi_set() - Convenience macro to set values in register map
+ * @map:    The register map to write to
+ * @member: The member of the ihs_axi_regs structure to write
+ * @val:    The value to write to the register map
+ */
+#define ihs_axi_set(map, member, val) \
+	regmap_set(map, struct ihs_axi_regs, member, val)
+
+/**
+ * ihs_axi_get() - Convenience macro to read values from register map
+ * @map:    The register map to read from
+ * @member: The member of the ihs_axi_regs structure to read
+ * @valp:   Pointer to a buffer to receive the value read
+ */
+#define ihs_axi_get(map, member, valp) \
+	regmap_get(map, struct ihs_axi_regs, member, valp)
+
+/**
+ * struct ihs_axi_priv - Private data structure of IHS AXI devices
+ * @map: Register map for the IHS AXI device
+ */
+struct ihs_axi_priv {
+	struct regmap *map;
+};
+
+/**
+ * enum status_reg - Description of bits in the interrupt_status register
+ * @STATUS_READ_COMPLETE_EVENT:  A read transfer was completed
+ * @STATUS_WRITE_COMPLETE_EVENT: A write transfer was completed
+ * @STATUS_TIMEOUT_EVENT:        A timeout has occurred during the transfer
+ * @STATUS_ERROR_EVENT:          A error has occurred during the transfer
+ * @STATUS_AXI_INT:              A AXI interrupt has occurred
+ * @STATUS_READ_DATA_AVAILABLE:  Data is available to be read
+ * @STATUS_BUSY:                 The bus is busy
+ * @STATUS_INIT_DONE:            The bus has finished initializing
+ */
+enum status_reg {
+	STATUS_READ_COMPLETE_EVENT = BIT(15),
+	STATUS_WRITE_COMPLETE_EVENT = BIT(14),
+	STATUS_TIMEOUT_EVENT = BIT(13),
+	STATUS_ERROR_EVENT = BIT(12),
+	STATUS_AXI_INT = BIT(11),
+	STATUS_READ_DATA_AVAILABLE = BIT(7),
+	STATUS_BUSY = BIT(6),
+	STATUS_INIT_DONE = BIT(5),
+};
+
+/**
+ * enum control_reg - Description of bit fields in the interrupt_enable_control
+ *		      register
+ * @CONTROL_READ_COMPLETE_EVENT_ENABLE:  STATUS_READ_COMPLETE_EVENT will be
+ *					 raised in the interrupt_status register
+ * @CONTROL_WRITE_COMPLETE_EVENT_ENABLE: STATUS_WRITE_COMPLETE_EVENT will be
+ *					 raised in the interrupt_status register
+ * @CONTROL_TIMEOUT_EVENT_ENABLE:        STATUS_TIMEOUT_EVENT will be raised in
+ *					 the interrupt_status register
+ * @CONTROL_ERROR_EVENT_ENABLE:          STATUS_ERROR_EVENT will be raised in
+ *					 the interrupt_status register
+ * @CONTROL_AXI_INT_ENABLE:              STATUS_AXI_INT will be raised in the
+ *					 interrupt_status register
+ * @CONTROL_CMD_NOP:                     Configure bus to send a NOP command
+ *					 for the next transfer
+ * @CONTROL_CMD_WRITE:                   Configure bus to do a write transfer
+ * @CONTROL_CMD_WRITE_POST_INC:          Auto-increment address after write
+ *					 transfer
+ * @CONTROL_CMD_READ:                    Configure bus to do a read transfer
+ * @CONTROL_CMD_READ_POST_INC:           Auto-increment address after read
+ *					 transfer
+ */
+enum control_reg {
+	CONTROL_READ_COMPLETE_EVENT_ENABLE = BIT(15),
+	CONTROL_WRITE_COMPLETE_EVENT_ENABLE = BIT(14),
+	CONTROL_TIMEOUT_EVENT_ENABLE = BIT(13),
+	CONTROL_ERROR_EVENT_ENABLE = BIT(12),
+	CONTROL_AXI_INT_ENABLE = BIT(11),
+
+	CONTROL_CMD_NOP = 0x0,
+	CONTROL_CMD_WRITE = 0x8,
+	CONTROL_CMD_WRITE_POST_INC = 0x9,
+	CONTROL_CMD_READ = 0xa,
+	CONTROL_CMD_READ_POST_INC = 0xb,
+};
+
+/**
+ * enum axi_cmd - Determine if transfer is read or write transfer
+ * @AXI_CMD_READ:  The transfer should be a read transfer
+ * @AXI_CMD_WRITE: The transfer should be a write transfer
+ */
+enum axi_cmd {
+	AXI_CMD_READ,
+	AXI_CMD_WRITE,
+};
+
+/**
+ * ihs_axi_transfer() - Run transfer on the AXI bus
+ * @bus:           The AXI bus device on which to run the transfer on
+ * @address:       The address to use in the transfer (i.e. which address to
+ *		   read/write from/to)
+ * @cmd:           Should the transfer be a read or write transfer?
+ *
+ * Return: 0 if OK, -ve on error
+ */
+static int ihs_axi_transfer(struct udevice *bus, ulong address,
+			    enum axi_cmd cmd)
+{
+	struct ihs_axi_priv *priv = dev_get_priv(bus);
+	/* Try waiting for events up to 10 times */
+	const uint WAIT_TRIES = 10;
+	u16 wait_mask = STATUS_TIMEOUT_EVENT |
+			STATUS_ERROR_EVENT;
+	u16 complete_flag;
+	u16 status;
+	uint k;
+
+	if (cmd == AXI_CMD_READ) {
+		complete_flag = STATUS_READ_COMPLETE_EVENT;
+		cmd = CONTROL_CMD_READ;
+	} else {
+		complete_flag = STATUS_WRITE_COMPLETE_EVENT;
+		cmd = CONTROL_CMD_WRITE;
+	}
+
+	wait_mask |= complete_flag;
+
+	/* Lower 16 bit */
+	ihs_axi_set(priv->map, address_lsb, address & 0xffff);
+	/* Upper 16 bit */
+	ihs_axi_set(priv->map, address_msb, (address >> 16) & 0xffff);
+
+	ihs_axi_set(priv->map, interrupt_status, wait_mask);
+	ihs_axi_set(priv->map, interrupt_enable_control, cmd);
+
+	for (k = WAIT_TRIES; k > 0; --k) {
+		ihs_axi_get(priv->map, interrupt_status, &status);
+		if (status & wait_mask)
+			break;
+		udelay(1);
+	}
+
+	/*
+	 * k == 0 -> Tries ran out with no event we were waiting for actually
+	 * occurring.
+	 */
+	if (!k)
+		ihs_axi_get(priv->map, interrupt_status, &status);
+
+	if (status & complete_flag)
+		return 0;
+
+	if (status & STATUS_ERROR_EVENT) {
+		debug("%s: Error occurred during transfer\n", bus->name);
+		return -EIO;
+	}
+
+	debug("%s: Transfer timed out\n", bus->name);
+	return -ETIMEDOUT;
+}
+
+/*
+ * API
+ */
+
+static int ihs_axi_read(struct udevice *dev, ulong address, void *data,
+			enum axi_size_t size)
+{
+	struct ihs_axi_priv *priv = dev_get_priv(dev);
+	int ret;
+	u16 data_lsb, data_msb;
+	u32 *p = data;
+
+	if (size != AXI_SIZE_32) {
+		debug("%s: transfer size '%d' not supported\n",
+		      dev->name, size);
+		return -ENOSYS;
+	}
+
+	ret = ihs_axi_transfer(dev, address, AXI_CMD_READ);
+	if (ret < 0) {
+		debug("%s: Error during AXI transfer (err = %d)\n",
+		      dev->name, ret);
+		return ret;
+	}
+
+	ihs_axi_get(priv->map, read_data_lsb, &data_lsb);
+	ihs_axi_get(priv->map, read_data_msb, &data_msb);
+
+	/* Assemble data from two 16-bit words */
+	*p = (data_msb << 16) | data_lsb;
+
+	return 0;
+}
+
+static int ihs_axi_write(struct udevice *dev, ulong address, void *data,
+			 enum axi_size_t size)
+{
+	struct ihs_axi_priv *priv = dev_get_priv(dev);
+	int ret;
+	u32 *p = data;
+
+	if (size != AXI_SIZE_32) {
+		debug("%s: transfer size '%d' not supported\n",
+		      dev->name, size);
+		return -ENOSYS;
+	}
+
+	/* Lower 16 bit */
+	ihs_axi_set(priv->map, write_data_lsb, *p & 0xffff);
+	/* Upper 16 bit */
+	ihs_axi_set(priv->map, write_data_msb, (*p >> 16) & 0xffff);
+
+	ret = ihs_axi_transfer(dev, address, AXI_CMD_WRITE);
+	if (ret < 0) {
+		debug("%s: Error during AXI transfer (err = %d)\n",
+		      dev->name, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct udevice_id ihs_axi_ids[] = {
+	{ .compatible = "gdsys,ihs_axi" },
+	{ /* sentinel */ }
+};
+
+static const struct axi_ops ihs_axi_ops = {
+	.read = ihs_axi_read,
+	.write = ihs_axi_write,
+};
+
+static int ihs_axi_probe(struct udevice *dev)
+{
+	struct ihs_axi_priv *priv = dev_get_priv(dev);
+
+	regmap_init_mem(dev_ofnode(dev), &priv->map);
+
+	return 0;
+}
+
+U_BOOT_DRIVER(ihs_axi_bus) = {
+	.name           = "ihs_axi_bus",
+	.id             = UCLASS_AXI,
+	.of_match       = ihs_axi_ids,
+	.ops		= &ihs_axi_ops,
+	.priv_auto_alloc_size = sizeof(struct ihs_axi_priv),
+	.probe          = ihs_axi_probe,
+};