1 files changed, 87 insertions, 0 deletions
diff --git a/c/src/libchip/i2c/i2c-ds1621.c b/c/src/libchip/i2c/i2c-ds1621.c
new file mode 100644
index 0000000000..fc76e83750
--- /dev/null
+++ b/c/src/libchip/i2c/i2c-ds1621.c
@@ -0,0 +1,87 @@
+/* $Id$ */
+
+/* Trivial i2c driver for the maxim DS1621 temperature sensor;
+ * just implements reading constant conversions with 8-bit
+ * resolution.
+ * Demonstrates the implementation of a i2c high-level driver.
+ */
+
+/* Author: Till Straumann, 2005 */
+#include <rtems.h>
+#include <rtems/libi2c.h>
+
+#include <libchip/i2c-ds1621.h>
+
+#include <rtems/libio.h>
+
+
+static rtems_status_code
+ds1621_init (rtems_device_major_number major, rtems_device_minor_number minor,
+             void *arg)
+{
+  int sc;
+  char csr[2] = { DS1621_CMD_CSR_ACCESS, 0 }, cmd;
+
+  /* First start command acquires a lock for the bus */
+
+  /* Initialize; switch continuous conversion on */
+  sc = rtems_libi2c_start_write_bytes (minor, csr, 1);
+  if (sc < 0)
+    return -sc;
+
+  sc = rtems_libi2c_start_read_bytes (minor, csr + 1, 1);
+  if (sc < 0)
+    return -sc;
+
+  csr[1] &= ~DS1621_CSR_1SHOT;
+
+  sc = rtems_libi2c_start_write_bytes (minor, csr, 2);
+  if (sc < 0)
+    return -sc;
+
+  /* Start conversion */
+  cmd = DS1621_CMD_START_CONV;
+
+  sc = rtems_libi2c_start_write_bytes (minor, &cmd, 1);
+  if (sc < 0)
+    return -sc;
+
+  /* sending 'stop' relinquishes the bus mutex -- don't hold it
+   * across system calls!
+   */
+  return rtems_libi2c_send_stop (minor);
+}
+
+static rtems_status_code
+ds1621_read (rtems_device_major_number major, rtems_device_minor_number minor,
+             void *arg)
+{
+  int sc;
+  rtems_libio_rw_args_t *rwargs = arg;
+  char cmd = DS1621_CMD_READ_TEMP;
+
+  sc = rtems_libi2c_start_write_bytes (minor, &cmd, 1);
+  if (sc < 0)
+    return -sc;
+  if (sc < 1)
+    return RTEMS_IO_ERROR;
+  sc = rtems_libi2c_start_read_bytes (minor, rwargs->buffer, 1);
+  if (sc < 0) {
+    rwargs->bytes_moved = 0;
+    return -sc;
+  }
+  rwargs->bytes_moved = 1;
+  return rtems_libi2c_send_stop (minor);
+}
+
+static rtems_driver_address_table myops = {
+  initialization_entry: ds1621_init,
+  read_entry:           ds1621_read,
+};
+
+static rtems_libi2c_drv_t my_drv_tbl = {
+  ops:                  &myops,
+  size:                 sizeof (my_drv_tbl),
+};
+
+rtems_libi2c_drv_t *i2c_ds1621_driver_descriptor = &my_drv_tbl;