dm: i2c: Add an I2C EEPROM simulator

To enable testing of I2C, add a simple I2C EEPROM simulator for sandbox.
It supports reading and writing from a small data store.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

arch/sandbox/include/asm/test.h

@@ -0,0 +1,26 @@
+/*
+ * Test-related constants for sandbox
+ *
+ * Copyright (c) 2014 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __ASM_TEST_H
+#define __ASM_TEST_H
+
+/* The sandbox driver always permits an I2C device with this address */
+#define SANDBOX_I2C_TEST_ADDR	0x59
+
+enum sandbox_i2c_eeprom_test_mode {
+	SIE_TEST_MODE_NONE,
+	/* Permits read/write of only one byte per I2C transaction */
+	SIE_TEST_MODE_SINGLE_BYTE,
+};
+
+void sandbox_i2c_eeprom_set_test_mode(struct udevice *dev,
+				      enum sandbox_i2c_eeprom_test_mode mode);
+
+void sandbox_i2c_eeprom_set_offset_len(struct udevice *dev, int offset_len);
+
+#endif

drivers/misc/Makefile

@@ -20,6 +20,9 @@ obj-$(CONFIG_MXC_OCOTP) += mxc_ocotp.o
 obj-$(CONFIG_MXS_OCOTP) += mxs_ocotp.o
 obj-$(CONFIG_NS87308) += ns87308.o
 obj-$(CONFIG_PDSP188x) += pdsp188x.o
+ifdef CONFIG_DM_I2C
+obj-$(CONFIG_SANDBOX) += i2c_eeprom_emul.o
+endif
 obj-$(CONFIG_STATUS_LED) += status_led.o
 obj-$(CONFIG_TWL4030_LED) += twl4030_led.o
 obj-$(CONFIG_FSL_IFC) += fsl_ifc.o

drivers/misc/i2c_eeprom_emul.c

@@ -0,0 +1,168 @@
+/*
+ * Simulate an I2C eeprom
+ *
+ * Copyright (c) 2014 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <fdtdec.h>
+#include <i2c.h>
+#include <malloc.h>
+#include <asm/test.h>
+
+#ifdef DEBUG
+#define debug_buffer print_buffer
+#else
+#define debug_buffer(x, ...)
+#endif
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct sandbox_i2c_flash_plat_data {
+	enum sandbox_i2c_eeprom_test_mode test_mode;
+	const char *filename;
+	int offset_len;		/* Length of an offset in bytes */
+	int size;		/* Size of data buffer */
+};
+
+struct sandbox_i2c_flash {
+	uint8_t *data;
+};
+
+void sandbox_i2c_eeprom_set_test_mode(struct udevice *dev,
+				      enum sandbox_i2c_eeprom_test_mode mode)
+{
+	struct sandbox_i2c_flash_plat_data *plat = dev_get_platdata(dev);
+
+	plat->test_mode = mode;
+}
+
+void sandbox_i2c_eeprom_set_offset_len(struct udevice *dev, int offset_len)
+{
+	struct sandbox_i2c_flash_plat_data *plat = dev_get_platdata(dev);
+
+	plat->offset_len = offset_len;
+}
+
+static int sandbox_i2c_eeprom_xfer(struct udevice *emul, struct i2c_msg *msg,
+				  int nmsgs)
+{
+	struct sandbox_i2c_flash *priv = dev_get_priv(emul);
+	uint offset = 0;
+
+	debug("\n%s\n", __func__);
+	debug_buffer(0, priv->data, 1, 16, 0);
+	for (; nmsgs > 0; nmsgs--, msg++) {
+		struct sandbox_i2c_flash_plat_data *plat =
+				dev_get_platdata(emul);
+		int len;
+		u8 *ptr;
+
+		if (!plat->size)
+			return -ENODEV;
+		if (msg->addr + msg->len > plat->size) {
+			debug("%s: Address %x, len %x is outside range 0..%x\n",
+			      __func__, msg->addr, msg->len, plat->size);
+			return -EINVAL;
+		}
+		len = msg->len;
+		debug("   %s: msg->len=%d",
+		      msg->flags & I2C_M_RD ? "read" : "write",
+		      msg->len);
+		if (msg->flags & I2C_M_RD) {
+			if (plat->test_mode == SIE_TEST_MODE_SINGLE_BYTE)
+				len = 1;
+			debug(", offset %x, len %x: ", offset, len);
+			memcpy(msg->buf, priv->data + offset, len);
+			memset(msg->buf + len, '\xff', msg->len - len);
+			debug_buffer(0, msg->buf, 1, msg->len, 0);
+		} else if (len >= plat->offset_len) {
+			int i;
+
+			ptr = msg->buf;
+			for (i = 0; i < plat->offset_len; i++, len--)
+				offset = (offset << 8) | *ptr++;
+			debug(", set offset %x: ", offset);
+			debug_buffer(0, msg->buf, 1, msg->len, 0);
+			if (plat->test_mode == SIE_TEST_MODE_SINGLE_BYTE)
+				len = min(len, 1);
+
+			/* For testing, map offsets into our limited buffer */
+			for (i = 24; i > 0; i -= 8) {
+				if (offset > (1 << i)) {
+					offset = (offset >> i) |
+						(offset & ((1 << i) - 1));
+					offset += i;
+				}
+			}
+			memcpy(priv->data + offset, ptr, len);
+		}
+	}
+	debug_buffer(0, priv->data, 1, 16, 0);
+
+	return 0;
+}
+
+struct dm_i2c_ops sandbox_i2c_emul_ops = {
+	.xfer = sandbox_i2c_eeprom_xfer,
+};
+
+static int sandbox_i2c_eeprom_ofdata_to_platdata(struct udevice *dev)
+{
+	struct sandbox_i2c_flash_plat_data *plat = dev_get_platdata(dev);
+
+	plat->size = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
+				    "sandbox,size", 32);
+	plat->filename = fdt_getprop(gd->fdt_blob, dev->of_offset,
+				     "sandbox,filename", NULL);
+	if (!plat->filename) {
+		debug("%s: No filename for device '%s'\n", __func__,
+		      dev->name);
+		return -EINVAL;
+	}
+	plat->test_mode = SIE_TEST_MODE_NONE;
+	plat->offset_len = 1;
+
+	return 0;
+}
+
+static int sandbox_i2c_eeprom_probe(struct udevice *dev)
+{
+	struct sandbox_i2c_flash_plat_data *plat = dev_get_platdata(dev);
+	struct sandbox_i2c_flash *priv = dev_get_priv(dev);
+
+	priv->data = calloc(1, plat->size);
+	if (!priv->data)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int sandbox_i2c_eeprom_remove(struct udevice *dev)
+{
+	struct sandbox_i2c_flash *priv = dev_get_priv(dev);
+
+	free(priv->data);
+
+	return 0;
+}
+
+static const struct udevice_id sandbox_i2c_ids[] = {
+	{ .compatible = "sandbox,i2c-eeprom" },
+	{ }
+};
+
+U_BOOT_DRIVER(sandbox_i2c_emul) = {
+	.name		= "sandbox_i2c_eeprom_emul",
+	.id		= UCLASS_I2C_EMUL,
+	.of_match	= sandbox_i2c_ids,
+	.ofdata_to_platdata = sandbox_i2c_eeprom_ofdata_to_platdata,
+	.probe		= sandbox_i2c_eeprom_probe,
+	.remove		= sandbox_i2c_eeprom_remove,
+	.priv_auto_alloc_size = sizeof(struct sandbox_i2c_flash),
+	.platdata_auto_alloc_size = sizeof(struct sandbox_i2c_flash_plat_data),
+	.ops		= &sandbox_i2c_emul_ops,
+};