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-rw-r--r--src/vlib/i2c.c231
1 files changed, 231 insertions, 0 deletions
diff --git a/src/vlib/i2c.c b/src/vlib/i2c.c
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+++ b/src/vlib/i2c.c
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+/*
+ * 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:
+ */