mlxsw: Introduce support for I2C bus

Add I2C bus implementation for Mellanox Technologies Switch ASICs.
This includes command interface implementation using input / out mailboxes,
whose location is retrieved from the firmware during probe time.

Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/Kconfig

@@ -29,6 +29,16 @@ config MLXSW_PCI
 	  To compile this driver as a module, choose M here: the
 	  module will be called mlxsw_pci.
 
+config MLXSW_I2C
+	tristate "I2C bus implementation for Mellanox Technologies Switch ASICs"
+	depends on I2C && MLXSW_CORE
+	default m
+	---help---
+	  This is I2C bus implementation for Mellanox Technologies Switch ASICs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called mlxsw_i2c.
+
 config MLXSW_SWITCHIB
 	tristate "Mellanox Technologies SwitchIB and SwitchIB-2 support"
 	depends on MLXSW_CORE && NET_SWITCHDEV

drivers/net/ethernet/mellanox/mlxsw/Makefile

@@ -3,6 +3,8 @@ mlxsw_core-objs			:= core.o
 mlxsw_core-$(CONFIG_MLXSW_CORE_HWMON) += core_hwmon.o
 obj-$(CONFIG_MLXSW_PCI)		+= mlxsw_pci.o
 mlxsw_pci-objs			:= pci.o
+obj-$(CONFIG_MLXSW_I2C)		+= mlxsw_i2c.o
+mlxsw_i2c-objs			:= i2c.o
 obj-$(CONFIG_MLXSW_SWITCHIB)	+= mlxsw_switchib.o
 mlxsw_switchib-objs		:= switchib.o
 obj-$(CONFIG_MLXSW_SWITCHX2)	+= mlxsw_switchx2.o

drivers/net/ethernet/mellanox/mlxsw/i2c.h

@@ -0,0 +1,60 @@
+/*
+ * drivers/net/ethernet/mellanox/mlxsw/i2c.h
+ * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2016 Vadim Pasternak <vadimp@mellanox.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MLXSW_I2C_H
+#define _MLXSW_I2C_H
+
+#include <linux/i2c.h>
+
+#if IS_ENABLED(CONFIG_MLXSW_I2C)
+
+int mlxsw_i2c_driver_register(struct i2c_driver *i2c_driver);
+void mlxsw_i2c_driver_unregister(struct i2c_driver *i2c_driver);
+
+#else
+
+static inline int
+mlxsw_i2c_driver_register(struct i2c_driver *i2c_driver)
+{
+	return -ENODEV;
+}
+
+static inline void
+mlxsw_i2c_driver_unregister(struct i2c_driver *i2c_driver)
+{
+}
+
+#endif
+
+#endif