x86: i2c: Add a stub driver for Intel I2C/SMbus

This is used on most Intel platforms. We don't have a driver for it yet, but
add a stub to handle the init. For now this targets ivybridge so we may want
to add a device tree binding and generalise it when other platforms are
supported.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

drivers/i2c/Kconfig

@@ -58,6 +58,15 @@ config DM_I2C_GPIO
 	  bindings are supported.
 	  Binding info: doc/device-tree-bindings/i2c/i2c-gpio.txt
 
+config SYS_I2C_INTEL
+	bool "Intel I2C/SMBUS driver"
+	depends on DM_I2C
+	help
+	  Add support for the Intel SMBUS driver. So far this driver is just
+	  a stub which perhaps some basic init. There is no implementation of
+	  the I2C API meaning that any I2C operations will immediately fail
+	  for now.
+
 config SYS_I2C_ROCKCHIP
 	bool "Rockchip I2C driver"
 	depends on DM_I2C

drivers/i2c/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_SYS_I2C_DW) += designware_i2c.o
 obj-$(CONFIG_SYS_I2C_FSL) += fsl_i2c.o
 obj-$(CONFIG_SYS_I2C_FTI2C010) += fti2c010.o
 obj-$(CONFIG_SYS_I2C_IHS) += ihs_i2c.o
+obj-$(CONFIG_SYS_I2C_INTEL) += intel_i2c.o
 obj-$(CONFIG_SYS_I2C_KONA) += kona_i2c.o
 obj-$(CONFIG_SYS_I2C_LPC32XX) += lpc32xx_i2c.o
 obj-$(CONFIG_SYS_I2C_MVTWSI) += mvtwsi.o

drivers/i2c/intel_i2c.c

+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <i2c.h>
+#include <asm/io.h>
+
+int intel_i2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs)
+{
+	return -ENOSYS;
+}
+
+int intel_i2c_probe_chip(struct udevice *bus, uint chip_addr, uint chip_flags)
+{
+	return -ENOSYS;
+}
+
+int intel_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
+{
+	return 0;
+}
+
+static int intel_i2c_probe(struct udevice *dev)
+{
+	return 0;
+}
+
+static const struct dm_i2c_ops intel_i2c_ops = {
+	.xfer		= intel_i2c_xfer,
+	.probe_chip	= intel_i2c_probe_chip,
+	.set_bus_speed	= intel_i2c_set_bus_speed,
+};
+
+static const struct udevice_id intel_i2c_ids[] = {
+	{ .compatible = "intel,ich-i2c" },
+	{ }
+};
+
+U_BOOT_DRIVER(intel_i2c) = {
+	.name	= "i2c_intel",
+	.id	= UCLASS_I2C,
+	.of_match = intel_i2c_ids,
+	.per_child_auto_alloc_size = sizeof(struct dm_i2c_chip),
+	.ops	= &intel_i2c_ops,
+	.probe	= intel_i2c_probe,
+};