wip

common/i2c.cc

@@ -0,0 +1,92 @@
+#include "common/i2c.h"
+
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+#include <cassert>
+#include <cstdio>
+#include <stdexcept>
+
+#include "common/swaglog.h"
+#include "common/util.h"
+
+#define UNUSED(x) (void)(x)
+
+#ifdef QCOM2
+// TODO: decide if we want to install libi2c-dev everywhere
+extern "C" {
+  #include <linux/i2c-dev.h>
+  #include <i2c/smbus.h>
+}
+
+I2CBus::I2CBus(uint8_t bus_id) {
+  char bus_name[20];
+  snprintf(bus_name, 20, "/dev/i2c-%d", bus_id);
+
+  i2c_fd = HANDLE_EINTR(open(bus_name, O_RDWR));
+  if (i2c_fd < 0) {
+    throw std::runtime_error("Failed to open I2C bus");
+  }
+}
+
+I2CBus::~I2CBus() {
+  if (i2c_fd >= 0) {
+    close(i2c_fd);
+  }
+}
+
+int I2CBus::read_register(uint8_t device_address, uint register_address, uint8_t *buffer, uint8_t len) {
+  std::lock_guard lk(m);
+
+  int ret = 0;
+
+  ret = HANDLE_EINTR(ioctl(i2c_fd, I2C_SLAVE, device_address));
+  if (ret < 0) { goto fail; }
+
+  ret = i2c_smbus_read_i2c_block_data(i2c_fd, register_address, len, buffer);
+  if ((ret < 0) || (ret != len)) { goto fail; }
+
+fail:
+  return ret;
+}
+
+int I2CBus::set_register(uint8_t device_address, uint register_address, uint8_t data) {
+  std::lock_guard lk(m);
+
+  int ret = 0;
+
+  ret = HANDLE_EINTR(ioctl(i2c_fd, I2C_SLAVE, device_address));
+  if (ret < 0) { goto fail; }
+
+  ret = i2c_smbus_write_byte_data(i2c_fd, register_address, data);
+  if (ret < 0) { goto fail; }
+
+fail:
+  return ret;
+}
+
+#else
+
+I2CBus::I2CBus(uint8_t bus_id) {
+  UNUSED(bus_id);
+  i2c_fd = -1;
+}
+
+I2CBus::~I2CBus() {}
+
+int I2CBus::read_register(uint8_t device_address, uint register_address, uint8_t *buffer, uint8_t len) {
+  UNUSED(device_address);
+  UNUSED(register_address);
+  UNUSED(buffer);
+  UNUSED(len);
+  return -1;
+}
+
+int I2CBus::set_register(uint8_t device_address, uint register_address, uint8_t data) {
+  UNUSED(device_address);
+  UNUSED(register_address);
+  UNUSED(data);
+  return -1;
+}
+#endif