From 8d92813827c5979c9298cbdd98b0503c427fd42a Mon Sep 17 00:00:00 2001
From: Daniel Friesel <derf@finalrewind.org>
Date: Sun, 21 Nov 2021 22:33:33 +0100
Subject: POSIX: Add proper I2C driver (via /dev/i2c)

---
 src/arch/posix/Kconfig       |  4 +++
 src/arch/posix/Makefile.inc  |  5 ++++
 src/arch/posix/driver/i2c.cc | 60 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 69 insertions(+)
 create mode 100644 src/arch/posix/driver/i2c.cc

(limited to 'src/arch/posix')

diff --git a/src/arch/posix/Kconfig b/src/arch/posix/Kconfig
index ad5e85e..42ed413 100644
--- a/src/arch/posix/Kconfig
+++ b/src/arch/posix/Kconfig
@@ -8,6 +8,10 @@ config arch_posix_driver_counter
 bool "Cycle counter"
 select meta_driver_counter
 
+config arch_posix_driver_i2c
+bool "I2C via /dev/i2c"
+select meta_driver_i2c
+
 config arch_posix_driver_uptime
 bool "Uptime counter"
 select meta_driver_uptime
diff --git a/src/arch/posix/Makefile.inc b/src/arch/posix/Makefile.inc
index 2f938a8..539e5f4 100644
--- a/src/arch/posix/Makefile.inc
+++ b/src/arch/posix/Makefile.inc
@@ -5,6 +5,7 @@
 # SPDX-License-Identifier: BSD-2-Clause
 
 COMMON_FLAGS += -DMULTIPASS_ARCH_posix
+COMMON_FLAGS += -DMULTIPASS_ARCH_HAS_I2C
 
 CC = gcc
 CXX = g++
@@ -27,6 +28,10 @@ ifeq (${timer_s}, 1)
 	CONFIG_arch_posix_driver_uptime = y
 endif
 
+ifdef CONFIG_arch_posix_driver_i2c
+	CXX_TARGETS += src/arch/posix/driver/i2c.cc
+endif
+
 ifdef CONFIG_arch_posix_driver_counter
 	CXX_TARGETS += src/arch/posix/driver/counter.cc
 endif
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");
-- 
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