POSIX: Add proper I2C driver (via /dev/i2c)

1 files changed, 60 insertions, 0 deletions

diff --git a/src/arch/posix/driver/i2c.cc b/src/arch/posix/driver/i2c.cc
new file mode 100644
index 0000000..b408320
--- /dev/null
+++ b/src/arch/posix/driver/i2c.cc
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2021 Daniel Friesel
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+#include "driver/i2c.h"
+#include "arch.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <linux/i2c-dev.h>
+#include <i2c/smbus.h>
+
+
+signed char I2C::setup()
+{
+	return 0;
+}
+
+signed char I2C::xmit(unsigned char address,
+		unsigned char tx_len, unsigned char *tx_buf,
+		unsigned char rx_len, unsigned char *rx_buf)
+{
+	struct i2c_msg messages[2];
+	struct i2c_rdwr_ioctl_data transaction;
+	transaction.nmsgs = 0;
+	transaction.msgs = messages;
+
+	if (tx_len) {
+		messages[transaction.nmsgs].addr = address;
+		messages[transaction.nmsgs].flags = 0;
+		messages[transaction.nmsgs].len = tx_len;
+		messages[transaction.nmsgs].buf = tx_buf;
+		transaction.nmsgs++;
+	}
+	if (rx_len) {
+		messages[transaction.nmsgs].addr = address;
+		messages[transaction.nmsgs].flags = I2C_M_RD;
+		messages[transaction.nmsgs].len = rx_len;
+		messages[transaction.nmsgs].buf = rx_buf;
+		transaction.nmsgs++;
+	}
+
+	int fh = open(i2cbus, O_RDWR);
+
+	if (fh < 0) {
+		return -1;
+	}
+
+	if (ioctl(fh, I2C_RDWR, &transaction) == -1) {
+		return -1;
+	}
+
+	close(fh);
+	return 0;
+}
+
+I2C i2c("/dev/i2c-1");