NET: Support clause 45 MDIO commands at the MDIO bus level

IEEE 802.3ae clause 45 specifies a somewhat modified MDIO protocol
for use by 10GIGE phys. The main change is a 21 bit address split into
a 5 bit device ID and a 16 bit register offset. The definition is designed
so that normal and extended devices can run on the same MDIO bus.

Extend mdio-bitbang to do the new protocol. At the MDIO bus level the
protocol is requested by or'ing MII_ADDR_C45 into the register offset.

Make phy_read/phy_write/etc pass a full 32 bit register offset.

This does not attempt to make the phy layer support C45 style PHYs, just
to provide the MDIO bus support.

Tested against a Broadcom 10GE phy with ID 0x206034, and several
Broadcom 10/100/1000 Phys in normal mode.

Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 51 insertions, 9 deletions

diff --git a/drivers/net/phy/mdio-bitbang.c b/drivers/net/phy/mdio-bitbang.c
index 2576055b350b..0ff06617a4ab 100644
--- a/drivers/net/phy/mdio-bitbang.c
+++ b/drivers/net/phy/mdio-bitbang.c
@@ -23,8 +23,13 @@
 #include <linux/types.h>
 #include <linux/delay.h>
 
-#define MDIO_READ 1
-#define MDIO_WRITE 0
+#define MDIO_READ 2
+#define MDIO_WRITE 1
+
+#define MDIO_C45 (1<<15)
+#define MDIO_C45_ADDR (MDIO_C45 | 0)
+#define MDIO_C45_READ (MDIO_C45 | 3)
+#define MDIO_C45_WRITE (MDIO_C45 | 1)
 
 #define MDIO_SETUP_TIME 10
 #define MDIO_HOLD_TIME 10
@@ -90,7 +95,7 @@ static u16 mdiobb_get_num(struct mdiobb_ctrl *ctrl, int bits)
 /* Utility to send the preamble, address, and
  * register (common to read and write).
  */
-static void mdiobb_cmd(struct mdiobb_ctrl *ctrl, int read, u8 phy, u8 reg)
+static void mdiobb_cmd(struct mdiobb_ctrl *ctrl, int op, u8 phy, u8 reg)
 {
         const struct mdiobb_ops *ops = ctrl->ops;
         int i;
@@ -109,23 +114,56 @@ static void mdiobb_cmd(struct mdiobb_ctrl *ctrl, int read, u8 phy, u8 reg)
         for (i = 0; i < 32; i++)
                 mdiobb_send_bit(ctrl, 1);
 
-        /* send the start bit (01) and the read opcode (10) or write (10) */
+        /* send the start bit (01) and the read opcode (10) or write (10).
+           Clause 45 operation uses 00 for the start and 11, 10 for
+           read/write */
         mdiobb_send_bit(ctrl, 0);
-        mdiobb_send_bit(ctrl, 1);
-        mdiobb_send_bit(ctrl, read);
-        mdiobb_send_bit(ctrl, !read);
+        if (op & MDIO_C45)
+                mdiobb_send_bit(ctrl, 0);
+        else
+                mdiobb_send_bit(ctrl, 1);
+        mdiobb_send_bit(ctrl, (op >> 1) & 1);
+        mdiobb_send_bit(ctrl, (op >> 0) & 1);
 
         mdiobb_send_num(ctrl, phy, 5);
         mdiobb_send_num(ctrl, reg, 5);
 }
 
+/* In clause 45 mode all commands are prefixed by MDIO_ADDR to specify the
+   lower 16 bits of the 21 bit address. This transfer is done identically to a
+   MDIO_WRITE except for a different code. To enable clause 45 mode or
+   MII_ADDR_C45 into the address. Theoretically clause 45 and normal devices
+   can exist on the same bus. Normal devices should ignore the MDIO_ADDR
+   phase. */
+static int mdiobb_cmd_addr(struct mdiobb_ctrl *ctrl, int phy, u32 addr)
+{
+        unsigned int dev_addr = (addr >> 16) & 0x1F;
+        unsigned int reg = addr & 0xFFFF;
+        mdiobb_cmd(ctrl, MDIO_C45_ADDR, phy, dev_addr);
+
+        /* send the turnaround (10) */
+        mdiobb_send_bit(ctrl, 1);
+        mdiobb_send_bit(ctrl, 0);
+
+        mdiobb_send_num(ctrl, reg, 16);
+
+        ctrl->ops->set_mdio_dir(ctrl, 0);
+        mdiobb_get_bit(ctrl);
+
+        return dev_addr;
+}
 
 static int mdiobb_read(struct mii_bus *bus, int phy, int reg)
 {
         struct mdiobb_ctrl *ctrl = bus->priv;
         int ret, i;
 
-        mdiobb_cmd(ctrl, MDIO_READ, phy, reg);
+        if (reg & MII_ADDR_C45) {
+                reg = mdiobb_cmd_addr(ctrl, phy, reg);
+                mdiobb_cmd(ctrl, MDIO_C45_READ, phy, reg);
+        } else
+                mdiobb_cmd(ctrl, MDIO_READ, phy, reg);
+
         ctrl->ops->set_mdio_dir(ctrl, 0);
 
         /* check the turnaround bit: the PHY should be driving it to zero */
@@ -148,7 +186,11 @@ static int mdiobb_write(struct mii_bus *bus, int phy, int reg, u16 val)
 {
         struct mdiobb_ctrl *ctrl = bus->priv;
 
-        mdiobb_cmd(ctrl, MDIO_WRITE, phy, reg);
+        if (reg & MII_ADDR_C45) {
+                reg = mdiobb_cmd_addr(ctrl, phy, reg);
+                mdiobb_cmd(ctrl, MDIO_C45_WRITE, phy, reg);
+        } else
+                mdiobb_cmd(ctrl, MDIO_WRITE, phy, reg);
 
         /* send the turnaround (10) */
         mdiobb_send_bit(ctrl, 1);