1 files changed, 393 insertions, 0 deletions
diff --git a/debian/grub-extras/disabled/gpxe/src/drivers/bitbash/i2c_bit.c b/debian/grub-extras/disabled/gpxe/src/drivers/bitbash/i2c_bit.c
new file mode 100644
index 0000000..1319727
--- /dev/null
+++ b/debian/grub-extras/disabled/gpxe/src/drivers/bitbash/i2c_bit.c
@@ -0,0 +1,393 @@
+/*
+ * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stddef.h>
+#include <stdint.h>
+#include <errno.h>
+#include <string.h>
+#include <assert.h>
+#include <unistd.h>
+#include <gpxe/bitbash.h>
+#include <gpxe/i2c.h>
+
+/** @file
+ *
+ * I2C bit-bashing interface
+ *
+ * This implements a simple I2C master via a bit-bashing interface
+ * that provides two lines: SCL (clock) and SDA (data).
+ */
+
+/**
+ * Delay between output state changes
+ *
+ * Max rated i2c speed (for the basic i2c protocol) is 100kbps,
+ * i.e. 200k clock transitions per second.
+ */
+static void i2c_delay ( void ) {
+	udelay ( I2C_UDELAY );
+}
+
+/**
+ * Set state of I2C SCL line
+ *
+ * @v basher		Bit-bashing interface
+ * @v state		New state of SCL
+ */
+static void setscl ( struct bit_basher *basher, int state ) {
+	DBG2 ( "%c", ( state ? '/' : '\\' ) );
+	write_bit ( basher, I2C_BIT_SCL, state );
+	i2c_delay();
+}
+
+/**
+ * Set state of I2C SDA line
+ *
+ * @v basher		Bit-bashing interface
+ * @v state		New state of SDA
+ */
+static void setsda ( struct bit_basher *basher, int state ) {
+	DBG2 ( "%c", ( state ? '1' : '0' ) );
+	write_bit ( basher, I2C_BIT_SDA, state );
+	i2c_delay();
+}
+
+/**
+ * Get state of I2C SDA line
+ *
+ * @v basher		Bit-bashing interface
+ * @ret state		State of SDA
+ */
+static int getsda ( struct bit_basher *basher ) {
+	int state;
+	state = read_bit ( basher, I2C_BIT_SDA );
+	DBG2 ( "%c", ( state ? '+' : '-' ) );
+	return state;
+}
+
+/**
+ * Send an I2C start condition
+ *
+ * @v basher		Bit-bashing interface
+ */
+static void i2c_start ( struct bit_basher *basher ) {
+	setscl ( basher, 1 );
+	setsda ( basher, 0 );
+	setscl ( basher, 0 );
+	setsda ( basher, 1 );
+}
+
+/**
+ * Send an I2C data bit
+ *
+ * @v basher		Bit-bashing interface
+ * @v bit		Bit to send
+ */
+static void i2c_send_bit ( struct bit_basher *basher, int bit ) {
+	setsda ( basher, bit );
+	setscl ( basher, 1 );
+	setscl ( basher, 0 );
+	setsda ( basher, 1 );
+}
+
+/**
+ * Receive an I2C data bit
+ *
+ * @v basher		Bit-bashing interface
+ * @ret bit		Received bit
+ */
+static int i2c_recv_bit ( struct bit_basher *basher ) {
+	int bit;
+
+	setscl ( basher, 1 );
+	bit = getsda ( basher );
+	setscl ( basher, 0 );
+	return bit;
+}
+
+/**
+ * Send an I2C stop condition
+ *
+ * @v basher		Bit-bashing interface
+ */
+static void i2c_stop ( struct bit_basher *basher ) {
+	setsda ( basher, 0 );
+	setscl ( basher, 1 );
+	setsda ( basher, 1 );
+}
+
+/**
+ * Send byte via I2C bus and check for acknowledgement
+ *
+ * @v basher		Bit-bashing interface
+ * @v byte		Byte to send
+ * @ret rc		Return status code
+ *
+ * Sends a byte via the I2C bus and checks for an acknowledgement from
+ * the slave device.
+ */
+static int i2c_send_byte ( struct bit_basher *basher, uint8_t byte ) {
+	int i;
+	int ack;
+
+	/* Send byte */
+	DBG2 ( "[send %02x]", byte );
+	for ( i = 8 ; i ; i-- ) {
+		i2c_send_bit ( basher, byte & 0x80 );
+		byte <<= 1;
+	}
+
+	/* Check for acknowledgement from slave */
+	ack = ( i2c_recv_bit ( basher ) == 0 );
+	DBG2 ( "%s", ( ack ? "[acked]" : "[not acked]" ) );
+
+	return ( ack ? 0 : -EIO );
+}
+
+/**
+ * Receive byte via I2C bus
+ *
+ * @v basher		Bit-bashing interface
+ * @ret byte		Received byte
+ *
+ * Receives a byte via the I2C bus and sends NACK to the slave device.
+ */
+static uint8_t i2c_recv_byte ( struct bit_basher *basher ) {
+	uint8_t byte = 0;
+	int i;
+
+	/* Receive byte */
+	for ( i = 8 ; i ; i-- ) {
+		byte <<= 1;
+		byte |= ( i2c_recv_bit ( basher ) & 0x1 );
+	}
+
+	/* Send NACK */
+	i2c_send_bit ( basher, 1 );
+
+	DBG2 ( "[rcvd %02x]", byte );
+	return byte;
+}
+
+/**
+ * Select I2C device for reading or writing
+ *
+ * @v basher		Bit-bashing interface
+ * @v i2cdev		I2C device
+ * @v offset		Starting offset within the device
+ * @v direction		I2C_READ or I2C_WRITE
+ * @ret rc		Return status code
+ */
+static int i2c_select ( struct bit_basher *basher, struct i2c_device *i2cdev,
+			unsigned int offset, unsigned int direction ) {
+	unsigned int address;
+	int shift;
+	unsigned int byte;
+	int rc;
+
+	i2c_start ( basher );
+
+	/* Calculate address to appear on bus */
+	address = ( ( ( i2cdev->dev_addr |
+			( offset >> ( 8 * i2cdev->word_addr_len ) ) ) << 1 )
+		    | direction );
+
+	/* Send address a byte at a time */
+	for ( shift = ( 8 * ( i2cdev->dev_addr_len - 1 ) ) ;
+	      shift >= 0 ; shift -= 8 ) {
+		byte = ( ( address >> shift ) & 0xff );
+		if ( ( rc = i2c_send_byte ( basher, byte ) ) != 0 )
+			return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Reset I2C bus
+ *
+ * @v basher		Bit-bashing interface
+ * @ret rc		Return status code
+ *
+ * i2c devices often don't have a reset line, so even a reboot or
+ * system power cycle is sometimes not enough to bring them back to a
+ * known state.
+ */
+static int i2c_reset ( struct bit_basher *basher ) {
+	unsigned int i;
+	int sda;
+
+	/* Clock through several cycles, waiting for an opportunity to
+	 * pull SDA low while SCL is high (which creates a start
+	 * condition).
+	 */
+	setscl ( basher, 0 );
+	setsda ( basher, 1 );
+	for ( i = 0 ; i < I2C_RESET_MAX_CYCLES ; i++ ) {
+		setscl ( basher, 1 );
+		sda = getsda ( basher );
+		if ( sda ) {
+			/* Now that the device will see a start, issue it */
+			i2c_start ( basher );
+			/* Stop the bus to leave it in a known good state */
+			i2c_stop ( basher );
+			DBGC ( basher, "I2CBIT %p reset after %d attempts\n",
+			       basher, ( i + 1 ) );
+			return 0;
+		}
+		setscl ( basher, 0 );
+	}
+
+	DBGC ( basher, "I2CBIT %p could not reset after %d attempts\n",
+	       basher, i );
+	return -ETIMEDOUT;
+}
+
+/**
+ * Read data from I2C device via bit-bashing interface
+ *
+ * @v i2c		I2C interface
+ * @v i2cdev		I2C device
+ * @v offset		Starting offset within the device
+ * @v data		Data buffer
+ * @v len		Length of data buffer
+ * @ret rc		Return status code
+ *
+ * Note that attempting to read zero bytes of data is a valid way to
+ * check for I2C device presence.
+ */
+static int i2c_bit_read ( struct i2c_interface *i2c,
+			  struct i2c_device *i2cdev, unsigned int offset,
+			  uint8_t *data, unsigned int len ) {
+	struct i2c_bit_basher *i2cbit
+		= container_of ( i2c, struct i2c_bit_basher, i2c );
+	struct bit_basher *basher = &i2cbit->basher;
+	int rc = 0;
+
+	DBGC ( basher, "I2CBIT %p reading from device %x: ",
+	       basher, i2cdev->dev_addr );
+
+	for ( ; ; data++, offset++ ) {
+
+		/* Select device for writing */
+		if ( ( rc = i2c_select ( basher, i2cdev, offset,
+					 I2C_WRITE ) ) != 0 )
+			break;
+
+		/* Abort at end of data */
+		if ( ! ( len-- ) )
+			break;
+
+		/* Select offset */
+		if ( ( rc = i2c_send_byte ( basher, offset ) ) != 0 )
+			break;
+		
+		/* Select device for reading */
+		if ( ( rc = i2c_select ( basher, i2cdev, offset,
+					 I2C_READ ) ) != 0 )
+			break;
+
+		/* Read byte */
+		*data = i2c_recv_byte ( basher );
+		DBGC ( basher, "%02x ", *data );
+	}
+	
+	DBGC ( basher, "%s\n", ( rc ? "failed" : "" ) );
+	i2c_stop ( basher );
+	return rc;
+}
+
+/**
+ * Write data to I2C device via bit-bashing interface
+ *
+ * @v i2c		I2C interface
+ * @v i2cdev		I2C device
+ * @v offset		Starting offset within the device
+ * @v data		Data buffer
+ * @v len		Length of data buffer
+ * @ret rc		Return status code
+ *
+ * Note that attempting to write zero bytes of data is a valid way to
+ * check for I2C device presence.
+ */
+static int i2c_bit_write ( struct i2c_interface *i2c,
+			   struct i2c_device *i2cdev, unsigned int offset,
+			   const uint8_t *data, unsigned int len ) {
+	struct i2c_bit_basher *i2cbit
+		= container_of ( i2c, struct i2c_bit_basher, i2c );
+	struct bit_basher *basher = &i2cbit->basher;
+	int rc = 0;
+
+	DBGC ( basher, "I2CBIT %p writing to device %x: ",
+	       basher, i2cdev->dev_addr );
+
+	for ( ; ; data++, offset++ ) {
+
+		/* Select device for writing */
+		if ( ( rc = i2c_select ( basher, i2cdev, offset,
+					 I2C_WRITE ) ) != 0 )
+			break;
+		
+		/* Abort at end of data */
+		if ( ! ( len-- ) )
+			break;
+
+		/* Select offset */
+		if ( ( rc = i2c_send_byte ( basher, offset ) ) != 0 )
+			break;
+		
+		/* Write data to device */
+		DBGC ( basher, "%02x ", *data );
+		if ( ( rc = i2c_send_byte ( basher, *data ) ) != 0 )
+			break;
+	}
+	
+	DBGC ( basher, "%s\n", ( rc ? "failed" : "" ) );
+	i2c_stop ( basher );
+	return rc;
+}
+
+/**
+ * Initialise I2C bit-bashing interface
+ *
+ * @v i2cbit		I2C bit-bashing interface
+ * @v bash_op		Bit-basher operations
+ */
+int init_i2c_bit_basher ( struct i2c_bit_basher *i2cbit,
+			  struct bit_basher_operations *bash_op ) {
+	struct bit_basher *basher = &i2cbit->basher;
+	int rc;
+
+	/* Initialise data structures */
+	basher->op = bash_op;
+	assert ( basher->op->read != NULL );
+	assert ( basher->op->write != NULL );
+	i2cbit->i2c.read = i2c_bit_read;
+	i2cbit->i2c.write = i2c_bit_write;
+
+	/* Reset I2C bus */
+	if ( ( rc = i2c_reset ( basher ) ) != 0 ) {
+		DBGC ( basher, "I2CBIT %p could not reset I2C bus: %s\n",
+		       basher, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}