From e84665c9cb4db963393fafad6fefe5efdd7e4a09 Mon Sep 17 00:00:00 2001 From: Lennert Buytenhek Date: Fri, 20 Mar 2009 09:52:09 +0000 Subject: dsa: add switch chip cascading support The initial version of the DSA driver only supported a single switch chip per network interface, while DSA-capable switch chips can be interconnected to form a tree of switch chips. This patch adds support for multiple switch chips on a network interface. An example topology for a 16-port device with an embedded CPU is as follows: +-----+ +--------+ +--------+ | |eth0 10| switch |9 10| switch | | CPU +----------+ +-------+ | | | | chip 0 | | chip 1 | +-----+ +---++---+ +---++---+ || || || || ||1000baseT ||1000baseT ||ports 1-8 ||ports 9-16 This requires a couple of interdependent changes in the DSA layer: - The dsa platform driver data needs to be extended: there is still only one netdevice per DSA driver instance (eth0 in the example above), but each of the switch chips in the tree needs its own mii_bus device pointer, MII management bus address, and port name array. (include/net/dsa.h) The existing in-tree dsa users need some small changes to deal with this. (arch/arm) - The DSA and Ethertype DSA tagging modules need to be extended to use the DSA device ID field on receive and demultiplex the packet accordingly, and fill in the DSA device ID field on transmit according to which switch chip the packet is heading to. (net/dsa/tag_{dsa,edsa}.c) - The concept of "CPU port", which is the switch chip port that the CPU is connected to (port 10 on switch chip 0 in the example), needs to be extended with the concept of "upstream port", which is the port on the switch chip that will bring us one hop closer to the CPU (port 10 for both switch chips in the example above). - The dsa platform data needs to specify which ports on which switch chips are links to other switch chips, so that we can enable DSA tagging mode on them. (For inter-switch links, we always use non-EtherType DSA tagging, since it has lower overhead. The CPU link uses dsa or edsa tagging depending on what the 'root' switch chip supports.) This is done by specifying "dsa" for the given port in the port array. - The dsa platform data needs to be extended with information on via which port to reach any given switch chip from any given switch chip. This info is specified via the per-switch chip data struct ->rtable[] array, which gives the nexthop ports for each of the other switches in the tree. For the example topology above, the dsa platform data would look something like this: static struct dsa_chip_data sw[2] = { { .mii_bus = &foo, .sw_addr = 1, .port_names[0] = "p1", .port_names[1] = "p2", .port_names[2] = "p3", .port_names[3] = "p4", .port_names[4] = "p5", .port_names[5] = "p6", .port_names[6] = "p7", .port_names[7] = "p8", .port_names[9] = "dsa", .port_names[10] = "cpu", .rtable = (s8 []){ -1, 9, }, }, { .mii_bus = &foo, .sw_addr = 2, .port_names[0] = "p9", .port_names[1] = "p10", .port_names[2] = "p11", .port_names[3] = "p12", .port_names[4] = "p13", .port_names[5] = "p14", .port_names[6] = "p15", .port_names[7] = "p16", .port_names[10] = "dsa", .rtable = (s8 []){ 10, -1, }, }, }, static struct dsa_platform_data pd = { .netdev = &foo, .nr_switches = 2, .sw = sw, }; Signed-off-by: Lennert Buytenhek Tested-by: Gary Thomas Signed-off-by: David S. Miller --- include/net/dsa.h | 42 +++++++++++++++++++++++++++++++++--------- 1 file changed, 33 insertions(+), 9 deletions(-) (limited to 'include/net') diff --git a/include/net/dsa.h b/include/net/dsa.h index 52e97bfca5a1..839f768f9e35 100644 --- a/include/net/dsa.h +++ b/include/net/dsa.h @@ -1,6 +1,6 @@ /* * include/net/dsa.h - Driver for Distributed Switch Architecture switch chips - * Copyright (c) 2008 Marvell Semiconductor + * Copyright (c) 2008-2009 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 @@ -11,23 +11,47 @@ #ifndef __LINUX_NET_DSA_H #define __LINUX_NET_DSA_H -#define DSA_MAX_PORTS 12 +#define DSA_MAX_SWITCHES 4 +#define DSA_MAX_PORTS 12 + +struct dsa_chip_data { + /* + * How to access the switch configuration registers. + */ + struct device *mii_bus; + int sw_addr; + + /* + * The names of the switch's ports. Use "cpu" to + * designate the switch port that the cpu is connected to, + * "dsa" to indicate that this port is a DSA link to + * another switch, NULL to indicate the port is unused, + * or any other string to indicate this is a physical port. + */ + char *port_names[DSA_MAX_PORTS]; + + /* + * An array (with nr_chips elements) of which element [a] + * indicates which port on this switch should be used to + * send packets to that are destined for switch a. Can be + * NULL if there is only one switch chip. + */ + s8 *rtable; +}; struct dsa_platform_data { /* * Reference to a Linux network interface that connects - * to the switch chip. + * to the root switch chip of the tree. */ 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). + * Info structs describing each of the switch chips + * connected via this network interface. */ - struct device *mii_bus; - int sw_addr; - char *port_names[DSA_MAX_PORTS]; + int nr_chips; + struct dsa_chip_data *chip; }; extern bool dsa_uses_dsa_tags(void *dsa_ptr); -- cgit v1.2.2