[mii] Add bit-bashing interface

Signed-off-by: Sylvie Barlow <sylvie.c.barlow@gmail.com>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/bitbash/mii_bit.c

@@ -0,0 +1,162 @@
+/*
+ * Copyright (C) 2018 Sylvie Barlow <sylvie.c.barlow@gmail.com>.
+ *
+ * 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 any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <stdint.h>
+#include <unistd.h>
+#include <ipxe/bitbash.h>
+#include <ipxe/mii_bit.h>
+
+/**
+ * Transfer bits over MII bit-bashing interface
+ *
+ * @v basher		Bit basher
+ * @v mask		Mask
+ * @v write		Data to write
+ * @ret read		Data read
+ */
+static uint32_t mii_bit_xfer ( struct bit_basher *basher,
+			       uint32_t mask, uint32_t write ) {
+	uint32_t read = 0;
+	int bit;
+
+	for ( ; mask ; mask >>= 1 ) {
+
+		/* Delay */
+		udelay ( 1 );
+
+		/* Write bit to basher */
+		write_bit ( basher, MII_BIT_MDIO, ( write & mask ) );
+
+		/* Read bit from basher */
+		bit = read_bit ( basher, MII_BIT_MDIO );
+		read <<= 1;
+		read |= ( bit & 1 );
+
+		/* Set clock high */
+		write_bit ( basher, MII_BIT_MDC, 1 );
+
+		/* Delay */
+		udelay ( 1 );
+
+		/* Set clock low */
+		write_bit ( basher, MII_BIT_MDC, 0 );
+	}
+	return read;
+}
+
+/**
+ * Read or write via MII bit-bashing interface
+ *
+ * @v basher		Bit basher
+ * @v phy		PHY address
+ * @v reg		Register address
+ * @v data		Data to write
+ * @v cmd		Command
+ * @ret data		Data read
+ */
+static unsigned int mii_bit_rw ( struct bit_basher *basher,
+				 unsigned int phy, unsigned int reg,
+				 unsigned int data, unsigned int cmd ) {
+
+	/* Initiate drive for write */
+	write_bit ( basher, MII_BIT_DRIVE, 1 );
+
+	/* Write start */
+	mii_bit_xfer ( basher, MII_BIT_START_MASK, MII_BIT_START );
+
+	/* Write command */
+	mii_bit_xfer ( basher, MII_BIT_CMD_MASK, cmd );
+
+	/* Write PHY address */
+	mii_bit_xfer ( basher, MII_BIT_PHY_MASK, phy );
+
+	/* Write register address */
+	mii_bit_xfer ( basher, MII_BIT_REG_MASK, reg );
+
+	/* Switch drive to read if applicable */
+	write_bit ( basher, MII_BIT_DRIVE, ( cmd & MII_BIT_CMD_RW ) );
+
+	/* Allow space for turnaround */
+	mii_bit_xfer ( basher, MII_BIT_SWITCH_MASK, MII_BIT_SWITCH );
+
+	/* Read or write data */
+	data = mii_bit_xfer (basher, MII_BIT_DATA_MASK, data );
+
+	/* Initiate drive for read */
+	write_bit ( basher, MII_BIT_DRIVE, 0 );
+
+	return data;
+}
+
+/**
+ * Read from MII register
+ *
+ * @v mdio		MII interface
+ * @v phy		PHY address
+ * @v reg		Register address
+ * @ret data		Data read, or negative error
+ */
+static int mii_bit_read ( struct mii_interface *mdio, unsigned int phy,
+			  unsigned int reg ) {
+	struct mii_bit_basher *miibit =
+		container_of ( mdio, struct mii_bit_basher, mdio );
+	struct bit_basher *basher = &miibit->basher;
+
+	return mii_bit_rw ( basher, phy, reg, 0, MII_BIT_CMD_READ );
+}
+
+/**
+ * Write to MII register
+ *
+ * @v mdio		MII interface
+ * @v phy		PHY address
+ * @v reg		Register address
+ * @v data		Data to write
+ * @ret rc		Return status code
+ */
+static int mii_bit_write ( struct mii_interface *mdio, unsigned int phy,
+			   unsigned int reg, unsigned int data ) {
+	struct mii_bit_basher *miibit =
+		container_of ( mdio, struct mii_bit_basher, mdio );
+	struct bit_basher *basher = &miibit->basher;
+
+	mii_bit_rw ( basher, phy, reg, data, MII_BIT_CMD_WRITE );
+	return 0;
+}
+
+/** MII bit basher operations */
+static struct mii_operations mii_bit_op = {
+	.read = mii_bit_read,
+	.write = mii_bit_write,
+};
+
+/**
+ * Initialise bit-bashing interface
+ *
+ * @v miibit		MII bit basher
+ */
+void init_mii_bit_basher ( struct mii_bit_basher *miibit ) {
+	mdio_init ( &miibit->mdio, &mii_bit_op );
+};

src/include/ipxe/mii_bit.h

@@ -0,0 +1,55 @@
+#ifndef _IPXE_MII_BIT_H
+#define _IPXE_MII_BIT_H
+
+/** @file
+ *
+ * MII bit-bashing interface
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <ipxe/mii.h>
+#include <ipxe/bitbash.h>
+
+#define MII_BIT_START		0xffffffff	/**< Start */
+#define MII_BIT_START_MASK	0x80000000	/**< Start mask */
+
+#define MII_BIT_CMD_MASK	0x00000008	/**< Command mask */
+#define MII_BIT_CMD_READ	0x00000006	/**< Command read */
+#define MII_BIT_CMD_WRITE	0x00000005	/**< Command write */
+#define MII_BIT_CMD_RW		0x00000001	/**< Command read or write */
+
+#define MII_BIT_PHY_MASK	0x00000010	/**< PHY mask */
+
+#define MII_BIT_REG_MASK	0x00000010	/**< Register mask */
+
+#define MII_BIT_SWITCH		0x00000002	/**< Switch */
+#define MII_BIT_SWITCH_MASK	0x00000002	/**< Switch mask */
+
+#define MII_BIT_DATA_MASK	0x00008000	/**< Data mask */
+
+/** A bit-bashing MII interface */
+struct mii_bit_basher {
+	/** MII interface */
+	struct mii_interface mdio;
+	/** Bit-bashing interface */
+	struct bit_basher basher;
+};
+
+/** Bit indices used for MII bit-bashing interface */
+enum {
+	/** MII clock */
+	MII_BIT_MDC = 0,
+	/** MII data */
+	MII_BIT_MDIO,
+	/** MII data direction */
+	MII_BIT_DRIVE,
+};
+
+/** Delay between MDC transitions */
+#define MII_BIT_UDELAY 1
+
+extern void init_mii_bit_basher ( struct mii_bit_basher *miibit );
+
+#endif /* _IPXE_MII_BIT_H */