1 files changed, 61 insertions, 20 deletions

diff --git a/drivers/input/touchscreen/ts_filter.h b/drivers/input/touchscreen/ts_filter.h
index 3746e45bccc..b5e8c7c3845 100644
--- a/drivers/input/touchscreen/ts_filter.h
+++ b/drivers/input/touchscreen/ts_filter.h
@@ -4,7 +4,7 @@
 /*
  * Touchscreen filter.
  *
- * (c) 2008 Andy Green <andy@openmoko.com>
+ * (c) 2008,2009 Andy Green <andy@openmoko.com>
  */
 
 #include <linux/platform_device.h>
@@ -17,11 +17,41 @@ struct ts_filter;
 /* Operations that a filter can perform. */
 
 struct ts_filter_api {
+	/* Create the filter - mandatory. */
 	struct ts_filter * (*create)(struct platform_device *pdev, void *config,
 				     int count_coords);
-	void (*destroy)(struct platform_device *pdev, struct ts_filter *filter);
+	/* Destroy the filter - mandatory. */
+	void (*destroy)(struct ts_filter *filter);
+	/* Clear the filter - optional. */
 	void (*clear)(struct ts_filter *filter);
+
+
+	/*
+	 * The next three API functions only make sense if all of them are
+	 * set for a filter. If a filter has the next three methods then
+	 * it can propagate coordinates in the chain.
+	 */
+
+	/*
+	 * Process the filter.
+	 * It returns non-zero if the filter reaches an error.
+	 */
 	int (*process)(struct ts_filter *filter, int *coords);
+	/*
+	 * Is the filter ready to return a point?
+	 * Please do not code side effects in this function.
+	 */
+	int (*haspoint)(struct ts_filter *filter);
+	/*
+	 * Get a point.
+	 * Do not call unless the filter actually has a point to deliver.
+	 */
+	void (*getpoint)(struct ts_filter *filter, int *coords);
+
+	/*
+	 * Scale the points - optional.
+	 * A filter could only scale coordinates.
+	 */
 	void (*scale)(struct ts_filter *filter, int *coords);
 };
 
@@ -31,32 +61,43 @@ struct ts_filter_api {
  * the actual filter.  Therefore you need one of these
  * at the start of your actual filter struct.
  */
-
 struct ts_filter {
-	struct ts_filter *next;		/* Next in chain. */
-	struct ts_filter_api *api;	/* Operations to use for this object. */
-	int count_coords;
-	int coords[MAX_TS_FILTER_COORDS];
+	struct ts_filter_api *api;	/* operations for this filter */
+	int count_coords;		/* how many coordinates to process */
+	int coords[MAX_TS_FILTER_COORDS];	/* count_coords coordinates */
 };
 
+#ifdef CONFIG_TOUCHSCREEN_FILTER
+
 /*
- * Helper to create a filter chain from an array of API pointers and
- * array of config ints. Leaves pointers to created filters in arr
- * array and fills in ->next pointers to create the chain.
+ * Helper to create a filter chain. It will allocate an array of
+ * null-terminated pointers to filters.
  */
-
-#ifdef CONFIG_TOUCHSCREEN_FILTER
-extern int ts_filter_create_chain(struct platform_device *pdev,
-				  struct ts_filter_api **api, void **config,
-				  struct ts_filter **arr, int count_coords);
+extern struct ts_filter **ts_filter_chain_create(
+	struct platform_device *pdev,
+	struct ts_filter_api **api, void **config, int count_coords);
 
 /* Helper to destroy a whole chain from the list of filter pointers. */
+extern void ts_filter_chain_destroy(struct ts_filter **arr);
+
+/* Helper to call the clear API function */
+extern void ts_filter_chain_clear(struct ts_filter **arr);
+
+/*
+ * Try to get one point. Returns 0 if no points are available.
+ * coords will be used as temporal space, thus you supply a point
+ * using coords but you shouldn't rely on its value on return unless
+ * it returns a nonzero value that is not -1.
+ * If one of the filters find an error then this function will
+ * return -1.
+ */
+int ts_filter_chain_feed(struct ts_filter **arr, int *coords);
 
-extern void ts_filter_destroy_chain(struct platform_device *pdev,
-				    struct ts_filter **arr);
-#else
-#define ts_filter_create_chain(pdev, api, config, arr, count_coords) (0)
-#define ts_filter_destroy_chain(pdev, arr) do { } while (0)
+#else /* !CONFIG_TOUCHSCREEN_FILTER */
+#define ts_filter_chain_create(pdev, api, config, arr, count_coords) (0)
+#define ts_filter_chain_destroy(pdev, arr) do { } while (0)
+#define ts_filter_chain_clear(arr) do { } while (0)
+#define ts_filter_chain_feed(arr, coords) (1)
 #endif
 
 #endif