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- #include <sys/param.h>
- #include <dev/i2c/i2cvar.h>
- #include <dev/i2c/i2c_bitbang.h>
- #define BB_SET(x) ops->ibo_set_bits(v, (x))
- #define BB_DIR(x) ops->ibo_set_dir(v, (x))
- #define BB_READ ops->ibo_read_bits(v)
- #define SDA ops->ibo_bits[I2C_BIT_SDA]
- #define SCL ops->ibo_bits[I2C_BIT_SCL]
- #define OUTPUT ops->ibo_bits[I2C_BIT_OUTPUT]
- #define INPUT ops->ibo_bits[I2C_BIT_INPUT]
- #define SCL_BAIL_COUNT 1000
- int i2c_wait_for_scl(void *, i2c_bitbang_ops_t);
- int
- i2c_wait_for_scl(void *v, i2c_bitbang_ops_t ops)
- {
- int bail = 0;
- while(((BB_READ & SCL) == 0) && bail < SCL_BAIL_COUNT) {
- delay(1);
- bail++;
- }
- if (bail == SCL_BAIL_COUNT) {
- i2c_bitbang_send_stop(v, 0, ops);
- return (EIO);
- }
- return (0);
- }
- int
- i2c_bitbang_send_start(void *v, int flags, i2c_bitbang_ops_t ops)
- {
- BB_DIR(OUTPUT);
- BB_SET(SDA | SCL);
- delay(5);
- BB_SET( SCL);
- if (i2c_wait_for_scl(v, ops) != 0)
- return (EIO);
- delay(4);
- BB_SET( 0);
- delay(5);
- return (0);
- }
- int
- i2c_bitbang_send_stop(void *v, int flags, i2c_bitbang_ops_t ops)
- {
- BB_DIR(OUTPUT);
- BB_SET( SCL);
- delay(4);
- BB_SET(SDA | SCL);
- return (0);
- }
- int
- i2c_bitbang_initiate_xfer(void *v, i2c_addr_t addr, int flags,
- i2c_bitbang_ops_t ops)
- {
- int i2caddr;
-
- if ((addr & 0x78) == 0x78)
- return (EINVAL);
- i2caddr = (addr << 1) | ((flags & I2C_F_READ) ? 1 : 0);
- (void) i2c_bitbang_send_start(v, flags, ops);
- return (i2c_bitbang_write_byte(v, i2caddr, flags & ~I2C_F_STOP, ops));
- }
- int
- i2c_bitbang_read_byte(void *v, uint8_t *valp, int flags,
- i2c_bitbang_ops_t ops)
- {
- int i;
- uint8_t val = 0;
- uint32_t bit;
- BB_DIR(INPUT);
- BB_SET(SDA );
- for (i = 0; i < 8; i++) {
- val <<= 1;
- BB_SET(SDA | SCL);
- if (i2c_wait_for_scl(v, ops) != 0)
- return (EIO);
- delay(4);
- if (BB_READ & SDA)
- val |= 1;
- BB_SET(SDA );
- delay(5);
- }
- bit = (flags & I2C_F_LAST) ? SDA : 0;
- BB_DIR(OUTPUT);
- BB_SET(bit );
- delay(1);
- BB_SET(bit | SCL);
- if (i2c_wait_for_scl(v, ops) != 0)
- return (EIO);
- delay(4);
- BB_SET(bit );
- delay(5);
- BB_DIR(INPUT);
- BB_SET(SDA );
- delay(5);
- if ((flags & (I2C_F_STOP | I2C_F_LAST)) == (I2C_F_STOP | I2C_F_LAST))
- (void) i2c_bitbang_send_stop(v, flags, ops);
- *valp = val;
- return (0);
- }
- int
- i2c_bitbang_write_byte(void *v, uint8_t val, int flags,
- i2c_bitbang_ops_t ops)
- {
- uint32_t bit;
- uint8_t mask;
- int error;
- BB_DIR(OUTPUT);
- for (mask = 0x80; mask != 0; mask >>= 1) {
- bit = (val & mask) ? SDA : 0;
- BB_SET(bit );
- delay(1);
- BB_SET(bit | SCL);
- if (i2c_wait_for_scl(v, ops) != 0)
- return (EIO);
- delay(4);
- BB_SET(bit );
- delay(5);
- }
- BB_DIR(INPUT);
- BB_SET(SDA );
- delay(5);
- BB_SET(SDA | SCL);
- if (i2c_wait_for_scl(v, ops) != 0)
- return (EIO);
- delay(4);
- error = (BB_READ & SDA) ? EIO : 0;
- BB_SET(SDA );
- delay(5);
- if (flags & I2C_F_STOP)
- (void) i2c_bitbang_send_stop(v, flags, ops);
- return (error);
- }
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