mpm: Add i2c APIs for simple transfers

1 files changed, 58 insertions, 0 deletions

diff --git a/mpm/lib/i2c/i2cdev.h b/mpm/lib/i2c/i2cdev.h
new file mode 100644
index 000000000..4c7f84972
--- /dev/null
+++ b/mpm/lib/i2c/i2cdev.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2018 Ettus Research, a National Instruments Company
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#ifndef _I2CDEV_H_FOUND_
+#define _I2CDEV_H_FOUND_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+#include <stddef.h>
+
+/*
+ * This API provides access to i2c devices. It uses the character device API
+ * from the Linux kernel and i2c-tools
+ *
+ * The kernel documentation can be found at
+ * https://www.kernel.org/doc/Documentation/i2c/dev-interface
+ */
+
+/*! Initialize a i2cdev interface
+ *
+ * \param fd Return value of the file descriptor
+ * \param device Path of i2cdev device, e.g. "/dev/i2c0"
+ * \param timeout_ms Timeout to wait for ACK in ms
+ *
+ * \returns 0 if all is good, or an error code otherwise
+ */
+int i2cdev_open(int *fd, const char *device, const unsigned int timeout_ms);
+
+/*! Do an i2c transaction over i2cdev
+ * If both tx and rx are to be done in one transaction, first tx data is
+ * transmitted, followed by a repeated start condition, then the rx data is
+ * read.
+ *
+ * \param fd File descriptor for the i2cdev bus segment
+ * \param addr i2c device address
+ * \param ten_bit_addr Nonzero if true (typically 0)
+ * \param tx Buffer of data to be written to device
+ * \param tx_len Total number of non-addr bytes to be written
+ * \param rx Buffer where read data can be stored
+ * \param rx_len Total number of bytes to be read
+ *
+ * Assumption: spidev was configured properly beforehand.
+ *
+ * \returns 0 if all is golden
+ */
+int i2cdev_transfer(int fd, uint16_t addr, int ten_bit_addr,
+                    uint8_t *tx, size_t tx_len,
+                    uint8_t *rx, size_t rx_len);
+#ifdef __cplusplus
+}
+#endif
+#endif /* _I2CDEV_H_FOUND_ */