1 files changed, 113 insertions, 0 deletions
diff --git a/i2c_helper_linux.c b/i2c_helper_linux.c
new file mode 100644
index 000000000..0703518a7
--- /dev/null
+++ b/i2c_helper_linux.c
@@ -0,0 +1,113 @@
+/*
+ * This file is part of the flashrom project.
+ *
+ * Copyright (C) 2020 The Chromium OS Authors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/fcntl.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+#include <stdlib.h>
+#include <linux/i2c.h>
+#include <linux/i2c-dev.h>
+
+#include "flash.h"
+#include "i2c_helper.h"
+
+#define I2C_DEV_PREFIX	"/dev/i2c-"
+#define I2C_MAX_BUS	255
+
+int i2c_close(int fd)
+{
+	return fd == -1 ? 0 : close(fd);
+}
+
+int i2c_open(int bus, uint16_t addr, int force)
+{
+	int ret = -1;
+	int fd = -1;
+
+	/* Maximum i2c bus number is 255(3 char), +1 for null terminated string. */
+	int path_len = strlen(I2C_DEV_PREFIX) + 4;
+	int request = force ? I2C_SLAVE_FORCE : I2C_SLAVE;
+
+	if (bus < 0 || bus > I2C_MAX_BUS) {
+		msg_perr("Invalid I2C bus %d.\n", bus);
+		return ret;
+	}
+
+	char *dev = calloc(1, path_len);
+	if (!dev) {
+		msg_perr("Unable to allocate space for device name of len %d: %s.\n",
+			path_len, strerror(errno));
+		goto linux_i2c_open_err;
+	}
+
+	ret = snprintf(dev, path_len, "%s%d", I2C_DEV_PREFIX, bus);
+	if (ret < 0) {
+		msg_perr("Unable to join bus number to device name: %s.\n", strerror(errno));
+		goto linux_i2c_open_err;
+	}
+
+	fd = open(dev, O_RDWR);
+	if (fd < 0) {
+		msg_perr("Unable to open I2C device %s: %s.\n", dev, strerror(errno));
+		ret = fd;
+		goto linux_i2c_open_err;
+	}
+
+	ret = ioctl(fd, request, addr);
+	if (ret < 0) {
+		msg_perr("Unable to set I2C slave address to 0x%02x: %s.\n", addr, strerror(errno));
+		i2c_close(fd);
+		goto linux_i2c_open_err;
+	}
+
+linux_i2c_open_err:
+	if (dev)
+		free(dev);
+
+	return ret ? ret : fd;
+}
+
+int i2c_read(int fd, uint16_t addr, i2c_buffer_t *buf)
+{
+	if (buf->len == 0)
+		return 0;
+
+	int ret = ioctl(fd, I2C_SLAVE, addr);
+	if (ret < 0) {
+		msg_perr("Unable to set I2C slave address to 0x%02x: %s.\n", addr, strerror(errno));
+		return ret;
+	}
+
+	return read(fd, buf->buf, buf->len);
+}
+
+int i2c_write(int fd, uint16_t addr, const i2c_buffer_t *buf)
+{
+	if (buf->len == 0)
+		return 0;
+
+	int ret = ioctl(fd, I2C_SLAVE, addr);
+	if (ret < 0) {
+		msg_perr("Unable to set I2C slave address to 0x%02x: %s.\n", addr, strerror(errno));
+		return ret;
+	}
+
+	return write(fd, buf->buf, buf->len);
+}