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cpu/kinetis_common/i2c.c: add _i2c_reset function, minor fixes #6

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merged 1 commit into from
Jul 7, 2015
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cpu/kinetis_common/i2c.c: add _i2c_reset function, minor fixes #6

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74 changes: 44 additions & 30 deletions cpu/kinetis_common/i2c.c
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Original file line number Diff line number Diff line change
Expand Up @@ -162,6 +162,23 @@ int i2c_init_slave(i2c_t dev, uint8_t address)
return -1;
}

/*
* Check for bus master arbitration lost.
* Arbitration is lost in the following circumstances:
* 1. SDA is sampled as low when the master drives high during an
* address or data transmit cycle.
* 2. SDA is sampled as low when the master drives high during the
* acknowledge bit of a data receive cycle.
* 3. A START cycle is attempted when the bus is busy.
* 4. A repeated START cycle is requested in slave mode.
* 5. A STOP condition is detected when the master did not request
* it.
*/
static inline int _i2c_arbitration_lost(I2C_Type *dev)
{
return (int)(dev->S & I2C_S_ARBL_MASK);
}

static inline int _i2c_start(I2C_Type *dev, uint8_t address, uint8_t rw_flag)
{
/* bus free ? */
Expand All @@ -176,21 +193,7 @@ static inline int _i2c_start(I2C_Type *dev, uint8_t address, uint8_t rw_flag)

/* wait for bus-busy to be set */
while (!(dev->S & I2C_S_BUSY_MASK)) {
if (dev->S & I2C_S_ARBL_MASK) {
/* Bus master arbitration lost */
/*
* Arbitration is lost in the following circumstances:
* 1. SDA is sampled as low when the master drives high during an
* address or data transmit cycle.
* 2. SDA is sampled as low when the master drives high during the
* acknowledge bit of a data receive cycle.
* 3. A START cycle is attempted when the bus is busy.
* 4. A repeated START cycle is requested in slave mode.
* 5. A STOP condition is detected when the master did not request
* it.
*/
/* Clear ARBL flag */
dev->S = I2C_S_ARBL_MASK;
if (_i2c_arbitration_lost(dev)) {
return -1;
}
}
Expand All @@ -200,9 +203,7 @@ static inline int _i2c_start(I2C_Type *dev, uint8_t address, uint8_t rw_flag)

dev->S = I2C_S_IICIF_MASK;

if ((dev->S & I2C_S_ARBL_MASK) != 0) {
/* Bus master arbitration lost */
dev->S = I2C_S_ARBL_MASK;
if (_i2c_arbitration_lost(dev)) {
return -1;
}

Expand All @@ -225,9 +226,7 @@ static inline int _i2c_restart(I2C_Type *dev, uint8_t address, uint8_t rw_flag)

dev->S = I2C_S_IICIF_MASK;

if ((dev->S & I2C_S_ARBL_MASK) != 0) {
/* Bus master arbitration lost */
dev->S = I2C_S_ARBL_MASK;
if (_i2c_arbitration_lost(dev)) {
return -1;
}

Expand Down Expand Up @@ -259,9 +258,7 @@ static inline int _i2c_receive(I2C_Type *dev, uint8_t *data, int length)

dev->S = I2C_S_IICIF_MASK;

if ((dev->S & I2C_S_ARBL_MASK) != 0) {
/* Bus master arbitration lost */
dev->S = I2C_S_ARBL_MASK;
if (_i2c_arbitration_lost(dev)) {
return -1;
}

Expand Down Expand Up @@ -310,6 +307,14 @@ static inline void _i2c_stop(I2C_Type *dev)
while (dev->S & I2C_S_BUSY_MASK);
}

static inline void _i2c_reset(I2C_Type *dev)
{
/* put bus in idle state */
dev->C1 = I2C_C1_IICEN_MASK;
/* reset status flags */
dev->S = I2C_S_ARBL_MASK | I2C_S_IICIF_MASK;
}


int i2c_read_byte(i2c_t dev, uint8_t address, char *data)
{
Expand All @@ -334,11 +339,16 @@ int i2c_read_bytes(i2c_t dev, uint8_t address, char *data, int length)
}

if (_i2c_start(i2c, address, I2C_FLAG_READ)) {
_i2c_stop(i2c);
_i2c_reset(i2c);
return -1;
}

n = _i2c_receive(i2c, (uint8_t *)data, length);
if (n < 0) {
_i2c_reset(i2c);
return -1;
}

_i2c_stop(i2c);

return n;
Expand Down Expand Up @@ -367,7 +377,7 @@ int i2c_write_bytes(i2c_t dev, uint8_t address, char *data, int length)
}

if (_i2c_start(i2c, address, I2C_FLAG_WRITE)) {
_i2c_stop(i2c);
_i2c_reset(i2c);
return -1;
}

Expand Down Expand Up @@ -401,7 +411,7 @@ int i2c_read_regs(i2c_t dev, uint8_t address, uint8_t reg, char *data, int lengt
}

if (_i2c_start(i2c, address, I2C_FLAG_WRITE)) {
_i2c_stop(i2c);
_i2c_reset(i2c);
return -1;
}

Expand All @@ -414,17 +424,21 @@ int i2c_read_regs(i2c_t dev, uint8_t address, uint8_t reg, char *data, int lengt
}

if (_i2c_restart(i2c, address, I2C_FLAG_READ)) {
_i2c_stop(i2c);
_i2c_reset(i2c);
return -1;
}

n = _i2c_receive(i2c, (uint8_t *)data, length);
if (n < 0) {
_i2c_reset(i2c);
return -1;
}

_i2c_stop(i2c);

return n;
}


int i2c_write_reg(i2c_t dev, uint8_t address, uint8_t reg, char data)
{
return i2c_write_regs(dev, address, reg, &data, 1);
Expand All @@ -448,7 +462,7 @@ int i2c_write_regs(i2c_t dev, uint8_t address, uint8_t reg, char *data, int leng
}

if (_i2c_start(i2c, address, I2C_FLAG_WRITE)) {
_i2c_stop(i2c);
_i2c_reset(i2c);
return -1;
}

Expand Down