dm: i2c: Add a sandbox I2C driver

This driver includes some test features such as only supporting certain
bus speeds. It passes its I2C traffic through to an emulator.

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

drivers/i2c/Makefile

@@ -27,7 +27,7 @@ obj-$(CONFIG_SYS_I2C_OMAP34XX) += omap24xx_i2c.o
 obj-$(CONFIG_SYS_I2C_PPC4XX) += ppc4xx_i2c.o
 obj-$(CONFIG_SYS_I2C_RCAR) += rcar_i2c.o
 obj-$(CONFIG_SYS_I2C_S3C24X0) += s3c24x0_i2c.o
-obj-$(CONFIG_SYS_I2C_SANDBOX) += i2c-emul-uclass.o
+obj-$(CONFIG_SYS_I2C_SANDBOX) += sandbox_i2c.o i2c-emul-uclass.o
 obj-$(CONFIG_SYS_I2C_SH) += sh_i2c.o
 obj-$(CONFIG_SYS_I2C_SOFT) += soft_i2c.o
 obj-$(CONFIG_SYS_I2C_TEGRA) += tegra_i2c.o

drivers/i2c/sandbox_i2c.c

@@ -0,0 +1,111 @@
+/*
+ * Simulate an I2C port
+ *
+ * Copyright (c) 2014 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <fdtdec.h>
+#include <i2c.h>
+#include <asm/test.h>
+#include <dm/lists.h>
+#include <dm/device-internal.h>
+#include <dm/root.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct dm_sandbox_i2c_emul_priv {
+	struct udevice *emul;
+};
+
+static int get_emul(struct udevice *dev, struct udevice **devp,
+		    struct dm_i2c_ops **opsp)
+{
+	struct dm_i2c_chip *priv;
+	int ret;
+
+	*devp = NULL;
+	*opsp = NULL;
+	priv = dev_get_parentdata(dev);
+	if (!priv->emul) {
+		ret = dm_scan_fdt_node(dev, gd->fdt_blob, dev->of_offset,
+				       false);
+		if (ret)
+			return ret;
+
+		ret = device_get_child(dev, 0, &priv->emul);
+		if (ret)
+			return ret;
+	}
+	*devp = priv->emul;
+	*opsp = i2c_get_ops(priv->emul);
+
+	return 0;
+}
+
+static int sandbox_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
+			    int nmsgs)
+{
+	struct dm_i2c_bus *i2c = bus->uclass_priv;
+	struct dm_i2c_ops *ops;
+	struct udevice *emul, *dev;
+	bool is_read;
+	int ret;
+
+	/* Special test code to return success but with no emulation */
+	if (msg->addr == SANDBOX_I2C_TEST_ADDR)
+		return 0;
+
+	ret = i2c_get_chip(bus, msg->addr, &dev);
+	if (ret)
+		return ret;
+
+	ret = get_emul(dev, &emul, &ops);
+	if (ret)
+		return ret;
+
+	/*
+	 * For testing, don't allow writing above 100KHz for writes and
+	 * 400KHz for reads
+	 */
+	is_read = nmsgs > 1;
+	if (i2c->speed_hz > (is_read ? 400000 : 100000))
+		return -EINVAL;
+	return ops->xfer(emul, msg, nmsgs);
+}
+
+static const struct dm_i2c_ops sandbox_i2c_ops = {
+	.xfer		= sandbox_i2c_xfer,
+};
+
+static int sandbox_i2c_child_pre_probe(struct udevice *dev)
+{
+	struct dm_i2c_chip *i2c_chip = dev_get_parentdata(dev);
+
+	/* Ignore our test address */
+	if (i2c_chip->chip_addr == SANDBOX_I2C_TEST_ADDR)
+		return 0;
+	if (dev->of_offset == -1)
+		return 0;
+
+	return i2c_chip_ofdata_to_platdata(gd->fdt_blob, dev->of_offset,
+					   i2c_chip);
+}
+
+static const struct udevice_id sandbox_i2c_ids[] = {
+	{ .compatible = "sandbox,i2c" },
+	{ }
+};
+
+U_BOOT_DRIVER(i2c_sandbox) = {
+	.name	= "i2c_sandbox",
+	.id	= UCLASS_I2C,
+	.of_match = sandbox_i2c_ids,
+	.per_child_auto_alloc_size = sizeof(struct dm_i2c_chip),
+	.child_pre_probe = sandbox_i2c_child_pre_probe,
+	.ops	= &sandbox_i2c_ops,
+};