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path: root/gpxe/src/drivers/bitbash/i2c_bit.c
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Diffstat (limited to 'gpxe/src/drivers/bitbash/i2c_bit.c')
-rw-r--r--gpxe/src/drivers/bitbash/i2c_bit.c147
1 files changed, 108 insertions, 39 deletions
diff --git a/gpxe/src/drivers/bitbash/i2c_bit.c b/gpxe/src/drivers/bitbash/i2c_bit.c
index a3af610b..b85057af 100644
--- a/gpxe/src/drivers/bitbash/i2c_bit.c
+++ b/gpxe/src/drivers/bitbash/i2c_bit.c
@@ -19,6 +19,7 @@
#include <stddef.h>
#include <stdint.h>
#include <errno.h>
+#include <string.h>
#include <assert.h>
#include <unistd.h>
#include <gpxe/bitbash.h>
@@ -49,6 +50,7 @@ static void i2c_delay ( void ) {
* @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();
}
@@ -60,6 +62,7 @@ static void setscl ( struct bit_basher *basher, int state ) {
* @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();
}
@@ -71,7 +74,10 @@ static void setsda ( struct bit_basher *basher, int state ) {
* @ret state State of SDA
*/
static int getsda ( struct bit_basher *basher ) {
- return read_bit ( basher, I2C_BIT_SDA );
+ int state;
+ state = read_bit ( basher, I2C_BIT_SDA );
+ DBG2 ( "%c", ( state ? '+' : '-' ) );
+ return state;
}
/**
@@ -137,15 +143,20 @@ static void i2c_stop ( struct bit_basher *basher ) {
*/
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 */
- return ( i2c_recv_bit ( basher ) == 0 ? 0 : -EIO );
+ ack = ( i2c_recv_bit ( basher ) == 0 );
+ DBG2 ( "%s", ( ack ? "[acked]" : "[not acked]" ) );
+
+ return ( ack ? 0 : -EIO );
}
/**
@@ -157,19 +168,20 @@ static int i2c_send_byte ( struct bit_basher *basher, uint8_t 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 value = 0;
+ uint8_t byte = 0;
int i;
/* Receive byte */
for ( i = 8 ; i ; i-- ) {
- value <<= 1;
- value |= ( i2c_recv_bit ( basher ) & 0x1 );
+ byte <<= 1;
+ byte |= ( i2c_recv_bit ( basher ) & 0x1 );
}
/* Send NACK */
i2c_send_bit ( basher, 1 );
- return value;
+ DBG2 ( "[rcvd %02x]", byte );
+ return byte;
}
/**
@@ -177,30 +189,29 @@ static uint8_t i2c_recv_byte ( struct bit_basher *basher ) {
*
* @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 direction ) {
+ unsigned int offset, unsigned int direction ) {
unsigned int address;
+ int shift;
+ unsigned int byte;
int rc;
i2c_start ( basher );
- /* First byte of the address */
- address = i2cdev->address;
- if ( i2cdev->tenbit ) {
- address |= I2C_TENBIT_ADDRESS;
- address >>= 8;
- }
- if ( ( rc = i2c_send_byte ( basher,
- ( ( address << 1 ) | direction ) ) ) != 0 )
- return rc;
+ /* Calculate address to appear on bus */
+ address = ( ( ( i2cdev->dev_addr |
+ ( offset >> ( 8 * i2cdev->word_addr_len ) ) ) << 1 )
+ | direction );
- /* Second byte of the address (10-bit addresses only) */
- if ( i2cdev->tenbit ) {
- if ( ( rc = i2c_send_byte ( basher,
- ( i2cdev->address & 0xff ) ) ) !=0)
+ /* 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;
}
@@ -208,6 +219,46 @@ static int i2c_select ( struct bit_basher *basher, struct i2c_device *i2cdev,
}
/**
+ * 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
@@ -228,12 +279,14 @@ static int i2c_bit_read ( struct i2c_interface *i2c,
struct bit_basher *basher = &i2cbit->basher;
int rc = 0;
- DBG ( "Reading from I2C device %x: ", i2cdev->address );
+ DBGC ( basher, "I2CBIT %p reading from device %x: ",
+ basher, i2cdev->dev_addr );
- while ( 1 ) {
+ for ( ; ; data++, offset++ ) {
/* Select device for writing */
- if ( ( rc = i2c_select ( basher, i2cdev, I2C_WRITE ) ) != 0 )
+ if ( ( rc = i2c_select ( basher, i2cdev, offset,
+ I2C_WRITE ) ) != 0 )
break;
/* Abort at end of data */
@@ -241,19 +294,20 @@ static int i2c_bit_read ( struct i2c_interface *i2c,
break;
/* Select offset */
- if ( ( rc = i2c_send_byte ( basher, offset++ ) ) != 0 )
+ if ( ( rc = i2c_send_byte ( basher, offset ) ) != 0 )
break;
/* Select device for reading */
- if ( ( rc = i2c_select ( basher, i2cdev, I2C_READ ) ) != 0 )
+ if ( ( rc = i2c_select ( basher, i2cdev, offset,
+ I2C_READ ) ) != 0 )
break;
/* Read byte */
- *data++ = i2c_recv_byte ( basher );
- DBG ( "%02x ", *(data - 1) );
+ *data = i2c_recv_byte ( basher );
+ DBGC ( basher, "%02x ", *data );
}
- DBG ( "%s\n", ( rc ? "failed" : "" ) );
+ DBGC ( basher, "%s\n", ( rc ? "failed" : "" ) );
i2c_stop ( basher );
return rc;
}
@@ -279,12 +333,14 @@ static int i2c_bit_write ( struct i2c_interface *i2c,
struct bit_basher *basher = &i2cbit->basher;
int rc = 0;
- DBG ( "Writing to I2C device %x: ", i2cdev->address );
+ DBGC ( basher, "I2CBIT %p writing to device %x: ",
+ basher, i2cdev->dev_addr );
- while ( 1 ) {
+ for ( ; ; data++, offset++ ) {
/* Select device for writing */
- if ( ( rc = i2c_select ( basher, i2cdev, I2C_WRITE ) ) != 0 )
+ if ( ( rc = i2c_select ( basher, i2cdev, offset,
+ I2C_WRITE ) ) != 0 )
break;
/* Abort at end of data */
@@ -292,16 +348,16 @@ static int i2c_bit_write ( struct i2c_interface *i2c,
break;
/* Select offset */
- if ( ( rc = i2c_send_byte ( basher, offset++ ) ) != 0 )
+ if ( ( rc = i2c_send_byte ( basher, offset ) ) != 0 )
break;
/* Write data to device */
- DBG ( "%02x ", *data );
- if ( ( rc = i2c_send_byte ( basher, *data++ ) ) != 0 )
+ DBGC ( basher, "%02x ", *data );
+ if ( ( rc = i2c_send_byte ( basher, *data ) ) != 0 )
break;
}
- DBG ( "%s\n", ( rc ? "failed" : "" ) );
+ DBGC ( basher, "%s\n", ( rc ? "failed" : "" ) );
i2c_stop ( basher );
return rc;
}
@@ -310,13 +366,26 @@ static int i2c_bit_write ( struct i2c_interface *i2c,
* Initialise I2C bit-bashing interface
*
* @v i2cbit I2C bit-bashing interface
+ * @v bash_op Bit-basher operations
*/
-void init_i2c_bit_basher ( struct i2c_bit_basher *i2cbit ) {
+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;
- i2c_stop ( basher );
+
+ /* 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;
}
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