Changes between Initial Version and Version 1 of NewDriverClass

Timestamp:

Oct 8, 2009, 6:48:14 AM (15 years ago)

Author:

Nicolas Pouillon

Comment:

--

NewDriverClass

@@ +1 @@
+Adding a new driver class takes a few steps:
+
+ * Add the class in the class enumeration
+ * Add a header describing the class
+  * its request functions
+  * a structure containing pointer to request functions
+  * utility function prototypes (blocking request wrappers, …) [1]
+ * Add reference to the class in the driver structure
+ * Add a directory for the class
+ * Add a C-file with utility functions [1]
+
+[1]: This is only needed if the class has such utility functions.
+
+
+In the examples, we'll call the new class `foobar`.
+
+= Adding the class in the device type enumeration =
+
+Edit [source:trunk/mutekh/hexo/include/hexo/device.h hexo/include/hexo/device.h], you'll see a `enum device_class_e`. Add the new device type at the end.
+
+{{{
+    device_class_lcd,
+    device_class_gpio,
+    device_class_i2c,
++   device_class_foobar,
+  };
+}}}
+
+= Adding a header describing the class =
+
+Create a file in `driver/include/device/foobar.h`. It may contain
+
+ * Callback definitions,
+ * Request function prototypes,
+ * Global utility functions.
+
+See [source:trunk/mutekh/driver/include/device/char.h] for sample file.
+
+The `struct dev_class_foobar_s` is a structure holding all the class-specific request functions.
+You may ensure this structure holds less pointers than the `DRV_MAX_FUNC_COUNT`
+constant defined in [source:trunk/mutekh/driver/include/device/driver.h].
+
+Don't forget to protect the new header against circular inclusions with the lines:
+{{{
+#ifndef __DEVICE_FOOBAR_H__
+#define __DEVICE_FOOBAR_H__
+
+#endif
+}}}
+We'll use that macro later.
+
+= Adding a reference to the class in the driver structure =
+
+Edit [source:trunk/mutekh/driver/include/device/driver.h] and add an entry in the `f` union of the `struct driver_s`.
+
+You must protect it with the macros defined in the header of the class, in case the class is not included in legacy code.
+
+Dont `#include` your driver class in `driver.h`.
+
+{{{
+#ifdef __DEVICE_FOOBAR_H__
+    struct dev_class_foobar_s foobar;
+#endif
+}}}
+
+= Create a directory for the class =
+
+ * create a `driver/device/foobar` directory,
+ * add a Makefile inside it,
+ * add `foobar` in the list of subdirectories in `driver/device/Makefile`.
+
+= Create the global helper functions file for your class =
+
+ * create a `driver/device/foobar/device_foobar.c`,
+ * add it in `driver/device/foobar/Makefile`.