diff options
Diffstat (limited to 'src/vlib/i2c.c')
| -rw-r--r-- | src/vlib/i2c.c | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/src/vlib/i2c.c b/src/vlib/i2c.c new file mode 100644 index 00000000000..97f5bb21cc7 --- /dev/null +++ b/src/vlib/i2c.c @@ -0,0 +1,231 @@ +/* + * Copyright (c) 2016 Cisco and/or its affiliates. + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at: + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include <vlib/vlib.h> +#include <vlib/i2c.h> + +static inline void +i2c_delay (i2c_bus_t * b, f64 timeout) +{ + vlib_main_t *vm = vlib_get_main (); + vlib_time_wait (vm, timeout); +} + +static void +i2c_wait_for_scl (i2c_bus_t * b) +{ + f64 t = 0; + + while (t < b->hold_time) + { + int sda, scl; + i2c_delay (b, b->rise_fall_time); + b->get_bits (b, &scl, &sda); + + if (scl) + return; + + t += b->rise_fall_time; + } + b->timeout = 1; +} + +static void +i2c_start (i2c_bus_t * b) +{ + b->timeout = 0; + + b->put_bits (b, 1, 1); + i2c_wait_for_scl (b); + + if (vlib_i2c_bus_timed_out (b)) + return; + + b->put_bits (b, 1, 0); + i2c_delay (b, b->hold_time); + b->put_bits (b, 0, 0); + i2c_delay (b, b->hold_time); +} + +static void +i2c_stop (i2c_bus_t * b) +{ + b->put_bits (b, 0, 0); + i2c_delay (b, b->rise_fall_time); + + b->put_bits (b, 1, 0); + i2c_delay (b, b->hold_time); + + b->put_bits (b, 1, 1); + i2c_delay (b, b->hold_time); +} + +static void +i2c_write_bit (i2c_bus_t * b, int sda) +{ + b->put_bits (b, 0, sda); + i2c_delay (b, b->rise_fall_time); + + b->put_bits (b, 1, sda); + i2c_wait_for_scl (b); + i2c_delay (b, b->hold_time); + + b->put_bits (b, 0, sda); + i2c_delay (b, b->rise_fall_time); +} + +static void +i2c_read_bit (i2c_bus_t * b, int *sda) +{ + int scl; + + b->put_bits (b, 1, 1); + i2c_wait_for_scl (b); + i2c_delay (b, b->hold_time); + + b->get_bits (b, &scl, sda); + + b->put_bits (b, 0, 1); + i2c_delay (b, b->rise_fall_time); +} + +static void +i2c_write_byte (i2c_bus_t * b, u8 data) +{ + int i, sda; + + for (i = 7; i >= 0; i--) + { + i2c_write_bit (b, (data >> i) & 1); + if (b->timeout) + return; + } + + b->put_bits (b, 0, 1); + i2c_delay (b, b->rise_fall_time); + + i2c_read_bit (b, &sda); + + if (sda) + b->timeout = 1; +} + + +static void +i2c_read_byte (i2c_bus_t * b, u8 * data, int ack) +{ + int i, sda; + + *data = 0; + + b->put_bits (b, 0, 1); + i2c_delay (b, b->rise_fall_time); + + for (i = 7; i >= 0; i--) + { + i2c_read_bit (b, &sda); + if (b->timeout) + return; + + *data |= (sda != 0) << i; + } + + i2c_write_bit (b, ack == 0); +} + + +void +vlib_i2c_init (i2c_bus_t * b) +{ + f64 tick; + if (!b->clock) + b->clock = 400000; + + tick = 1.0 / b->clock; + + /* Spend 40% of time in low and high states */ + if (!b->hold_time) + b->hold_time = 0.4 * tick; + + /* Spend 10% of time waiting for rise and fall */ + if (!b->rise_fall_time) + b->rise_fall_time = 0.1 * tick; +} + +void +vlib_i2c_xfer (i2c_bus_t * bus, i2c_msg_t * msgs) +{ + i2c_msg_t *msg; + int i; + + vec_foreach (msg, msgs) + { + i2c_start (bus); + i2c_write_byte (bus, + (msg->addr << 1) + (msg->flags == I2C_MSG_FLAG_READ)); + + if (msg->flags & I2C_MSG_FLAG_READ) + for (i = 0; i < msg->len; i++) + { + i2c_read_byte (bus, &msg->buffer[i], /* ack */ i + 1 != msg->len); + if (bus->timeout) + goto done; + } + + else + for (i = 0; i < msg->len; i++) + { + i2c_write_byte (bus, msg->buffer[i]); + if (bus->timeout) + goto done; + } + } + +done: + i2c_stop (bus); +} + +void +vlib_i2c_read_eeprom (i2c_bus_t * bus, u8 i2c_addr, u16 start_addr, + u16 length, u8 * data) +{ + i2c_msg_t *msg = 0; + u8 start_address[1]; + + vec_validate (msg, 1); + + start_address[0] = start_addr; + msg[0].addr = i2c_addr; + msg[0].flags = I2C_MSG_FLAG_WRITE; + msg[0].buffer = (u8 *) & start_address; + msg[0].len = 1; + + msg[1].addr = i2c_addr; + msg[1].flags = I2C_MSG_FLAG_READ; + msg[1].buffer = data; + msg[1].len = length; + + vlib_i2c_xfer (bus, msg); + + vec_free (msg); +} + +/* + * fd.io coding-style-patch-verification: ON + * + * Local Variables: + * eval: (c-set-style "gnu") + * End: + */ |