net: Distributed Switch Architecture protocol support

Distributed Switch Architecture is a protocol for managing hardware
switch chips.  It consists of a set of MII management registers and
commands to configure the switch, and an ethernet header format to
signal which of the ports of the switch a packet was received from
or is intended to be sent to.

The switches that this driver supports are typically embedded in
access points and routers, and a typical setup with a DSA switch
looks something like this:

	+-----------+       +-----------+
	|           | RGMII |           |
	|           +-------+           +------ 1000baseT MDI ("WAN")
	|           |       |  6-port   +------ 1000baseT MDI ("LAN1")
	|    CPU    |       |  ethernet +------ 1000baseT MDI ("LAN2")
	|           |MIImgmt|  switch   +------ 1000baseT MDI ("LAN3")
	|           +-------+  w/5 PHYs +------ 1000baseT MDI ("LAN4")
	|           |       |           |
	+-----------+       +-----------+

The switch driver presents each port on the switch as a separate
network interface to Linux, polls the switch to maintain software
link state of those ports, forwards MII management interface
accesses to those network interfaces (e.g. as done by ethtool) to
the switch, and exposes the switch's hardware statistics counters
via the appropriate Linux kernel interfaces.

This initial patch supports the MII management interface register
layout of the Marvell 88E6123, 88E6161 and 88E6165 switch chips, and
supports the "Ethertype DSA" packet tagging format.

(There is no officially registered ethertype for the Ethertype DSA
packet format, so we just grab a random one.  The ethertype to use
is programmed into the switch, and the switch driver uses the value
of ETH_P_EDSA for this, so this define can be changed at any time in
the future if the one we chose is allocated to another protocol or
if Ethertype DSA gets its own officially registered ethertype, and
everything will continue to work.)

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Tested-by: Nicolas Pitre <nico@marvell.com>
Tested-by: Byron Bradley <byron.bbradley@gmail.com>
Tested-by: Tim Ellis <tim.ellis@mac.com>
Tested-by: Peter van Valderen <linux@ddcrew.com>
Tested-by: Dirk Teurlings <dirk@upexia.nl>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/if_ether.h

@@ -77,6 +77,7 @@
 #define ETH_P_PAE	0x888E		/* Port Access Entity (IEEE 802.1X) */
 #define ETH_P_AOE	0x88A2		/* ATA over Ethernet		*/
 #define ETH_P_TIPC	0x88CA		/* TIPC 			*/
+#define ETH_P_EDSA	0xDADA		/* Ethertype DSA [ NOT AN OFFICIALLY REGISTERED ID ] */
 
 /*
  *	Non DIX types. Won't clash for 1500 types.

include/linux/netdevice.h

@@ -607,6 +607,9 @@ struct net_device
 
 	/* Protocol specific pointers */
 
+#ifdef CONFIG_NET_DSA
+	void			*dsa_ptr;	/* dsa specific data */
+#endif
 	void 			*atalk_ptr;	/* AppleTalk link 	*/
 	void			*ip_ptr;	/* IPv4 specific data	*/  
 	void                    *dn_ptr;        /* DECnet specific data */

include/net/dsa.h

@@ -0,0 +1,34 @@
+/*
+ * include/net/dsa.h - Driver for Distributed Switch Architecture switch chips
+ * Copyright (c) 2008 Marvell Semiconductor
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __LINUX_NET_DSA_H
+#define __LINUX_NET_DSA_H
+
+#define DSA_MAX_PORTS	12
+
+struct dsa_platform_data {
+	/*
+	 * Reference to a Linux network interface that connects
+	 * to the switch chip.
+	 */
+	struct device	*netdev;
+
+	/*
+	 * How to access the switch configuration registers, and
+	 * the names of the switch ports (use "cpu" to designate
+	 * the switch port that the cpu is connected to).
+	 */
+	struct device	*mii_bus;
+	int		sw_addr;
+	char		*port_names[DSA_MAX_PORTS];
+};
+
+
+#endif

net/Kconfig

@@ -180,6 +180,7 @@ source "net/tipc/Kconfig"
 source "net/atm/Kconfig"
 source "net/802/Kconfig"
 source "net/bridge/Kconfig"
+source "net/dsa/Kconfig"
 source "net/8021q/Kconfig"
 source "net/decnet/Kconfig"
 source "net/llc/Kconfig"

net/Makefile

@@ -26,6 +26,7 @@ obj-$(CONFIG_PACKET)		+= packet/
 obj-$(CONFIG_NET_KEY)		+= key/
 obj-$(CONFIG_NET_SCHED)		+= sched/
 obj-$(CONFIG_BRIDGE)		+= bridge/
+obj-$(CONFIG_NET_DSA)		+= dsa/
 obj-$(CONFIG_IPX)		+= ipx/
 obj-$(CONFIG_ATALK)		+= appletalk/
 obj-$(CONFIG_WAN_ROUTER)	+= wanrouter/

net/dsa/Kconfig

@@ -0,0 +1,31 @@
+menuconfig NET_DSA
+	bool "Distributed Switch Architecture support"
+	default n
+	depends on EXPERIMENTAL
+	---help---
+	  This allows you to use hardware switch chips that use
+	  the Distributed Switch Architecture.
+
+
+if NET_DSA
+
+# tagging formats
+config NET_DSA_TAG_EDSA
+	bool
+	default n
+
+
+# switch drivers
+config NET_DSA_MV88E6XXX
+	bool
+	default n
+
+config NET_DSA_MV88E6123_61_65
+	bool "Marvell 88E6123/6161/6165 ethernet switch chip support"
+	select NET_DSA_MV88E6XXX
+	select NET_DSA_TAG_EDSA
+	---help---
+	  This enables support for the Marvell 88E6123/6161/6165
+	  ethernet switch chips.
+
+endif

net/dsa/Makefile

@@ -0,0 +1,9 @@
+# tagging formats
+obj-$(CONFIG_NET_DSA_TAG_EDSA) += tag_edsa.o
+
+# switch drivers
+obj-$(CONFIG_NET_DSA_MV88E6XXX) += mv88e6xxx.o
+obj-$(CONFIG_NET_DSA_MV88E6123_61_65) += mv88e6123_61_65.o
+
+# the core
+obj-$(CONFIG_NET_DSA) += dsa.o slave.o