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 <buytenh@marvell.com>
Tested-by: Gary Thomas <gary@mlbassoc.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 50 insertions, 28 deletions

diff --git a/net/dsa/mv88e6131.c b/net/dsa/mv88e6131.c
index 002995721ecf..bb2b41bc854e 100644
--- a/net/dsa/mv88e6131.c
+++ b/net/dsa/mv88e6131.c
@@ -102,17 +102,17 @@ static int mv88e6131_setup_global(struct dsa_switch *ds)
         REG_WRITE(REG_GLOBAL, 0x19, 0x8100);
 
         /*
-         * Disable ARP mirroring, and configure the cpu port as the
-         * port to which ingress and egress monitor frames are to be
-         * sent.
+         * Disable ARP mirroring, and configure the upstream port as
+         * the port to which ingress and egress monitor frames are to
+         * be sent.
          */
-        REG_WRITE(REG_GLOBAL, 0x1a, (ds->cpu_port * 0x1100) | 0x00f0);
+        REG_WRITE(REG_GLOBAL, 0x1a, (dsa_upstream_port(ds) * 0x1100) | 0x00f0);
 
         /*
          * Disable cascade port functionality, and set the switch's
-         * DSA device number to zero.
+         * DSA device number.
          */
-        REG_WRITE(REG_GLOBAL, 0x1c, 0xe000);
+        REG_WRITE(REG_GLOBAL, 0x1c, 0xe000 | (ds->index & 0x1f));
 
         /*
          * Send all frames with destination addresses matching
@@ -129,10 +129,17 @@ static int mv88e6131_setup_global(struct dsa_switch *ds)
         REG_WRITE(REG_GLOBAL2, 0x05, 0x00ff);
 
         /*
-         * Map all DSA device IDs to the CPU port.
+         * Program the DSA routing table.
          */
-        for (i = 0; i < 32; i++)
-                REG_WRITE(REG_GLOBAL2, 0x06, 0x8000 | (i << 8) | ds->cpu_port);
+        for (i = 0; i < 32; i++) {
+                int nexthop;
+
+                nexthop = 0x1f;
+                if (i != ds->index && i < ds->dst->pd->nr_chips)
+                        nexthop = ds->pd->rtable[i] & 0x1f;
+
+                REG_WRITE(REG_GLOBAL2, 0x06, 0x8000 | (i << 8) | nexthop);
+        }
 
         /*
          * Clear all trunk masks.
@@ -158,13 +165,15 @@ static int mv88e6131_setup_global(struct dsa_switch *ds)
 static int mv88e6131_setup_port(struct dsa_switch *ds, int p)
 {
         int addr = REG_PORT(p);
+        u16 val;
 
         /*
          * MAC Forcing register: don't force link, speed, duplex
          * or flow control state to any particular values on physical
-         * ports, but force the CPU port to 1000 Mb/s full duplex.
+         * ports, but force the CPU port and all DSA ports to 1000 Mb/s
+         * full duplex.
          */
-        if (p == ds->cpu_port)
+        if (dsa_is_cpu_port(ds, p) || ds->dsa_port_mask & (1 << p))
                 REG_WRITE(addr, 0x01, 0x003e);
         else
                 REG_WRITE(addr, 0x01, 0x0003);
@@ -175,29 +184,40 @@ static int mv88e6131_setup_port(struct dsa_switch *ds, int p)
          * enable IGMP/MLD snoop, disable DoubleTag, disable VLAN
          * tunneling, determine priority by looking at 802.1p and
          * IP priority fields (IP prio has precedence), and set STP
-         * state to Forwarding.  Finally, if this is the CPU port,
-         * additionally enable DSA tagging and forwarding of unknown
-         * unicast addresses.
+         * state to Forwarding.
+         *
+         * If this is the upstream port for this switch, enable
+         * forwarding of unknown unicasts, and enable DSA tagging
+         * mode.
+         *
+         * If this is the link to another switch, use DSA tagging
+         * mode, but do not enable forwarding of unknown unicasts.
          */
-        REG_WRITE(addr, 0x04, (p == ds->cpu_port) ? 0x0537 : 0x0433);
+        val = 0x0433;
+        if (p == dsa_upstream_port(ds))
+                val |= 0x0104;
+        if (ds->dsa_port_mask & (1 << p))
+                val |= 0x0100;
+        REG_WRITE(addr, 0x04, val);
 
         /*
          * Port Control 1: disable trunking.  Also, if this is the
          * CPU port, enable learn messages to be sent to this port.
          */
-        REG_WRITE(addr, 0x05, (p == ds->cpu_port) ? 0x8000 : 0x0000);
+        REG_WRITE(addr, 0x05, dsa_is_cpu_port(ds, p) ? 0x8000 : 0x0000);
 
         /*
          * Port based VLAN map: give each port its own address
          * database, allow the CPU port to talk to each of the 'real'
          * ports, and allow each of the 'real' ports to only talk to
-         * the CPU port.
+         * the upstream port.
          */
-        REG_WRITE(addr, 0x06,
-                        ((p & 0xf) << 12) |
-                         ((p == ds->cpu_port) ?
-                                ds->valid_port_mask :
-                                (1 << ds->cpu_port)));
+        val = (p & 0xf) << 12;
+        if (dsa_is_cpu_port(ds, p))
+                val |= ds->phys_port_mask;
+        else
+                val |= 1 << dsa_upstream_port(ds);
+        REG_WRITE(addr, 0x06, val);
 
         /*
          * Default VLAN ID and priority: don't set a default VLAN
@@ -213,13 +233,15 @@ static int mv88e6131_setup_port(struct dsa_switch *ds, int p)
          * untagged frames on this port, do a destination address
          * lookup on received packets as usual, don't send a copy
          * of all transmitted/received frames on this port to the
-         * CPU, and configure the CPU port number.  Also, if this
-         * is the CPU port, enable forwarding of unknown multicast
-         * addresses.
+         * CPU, and configure the upstream port number.
+         *
+         * If this is the upstream port for this switch, enable
+         * forwarding of unknown multicast addresses.
          */
-        REG_WRITE(addr, 0x08,
-                        ((p == ds->cpu_port) ? 0x00c0 : 0x0080) |
-                         ds->cpu_port);
+        val = 0x0080 | dsa_upstream_port(ds);
+        if (p == dsa_upstream_port(ds))
+                val |= 0x0040;
+        REG_WRITE(addr, 0x08, val);
 
         /*
          * Rate Control: disable ingress rate limiting.