Merge branch 'ib-array-bitmaps' into devel

2 files changed, 48 insertions, 13 deletions

diff --git a/Documentation/driver-api/gpio/board.rst b/Documentation/driver-api/gpio/board.rst
index 2c112553df84..c66821e033c2 100644
--- a/Documentation/driver-api/gpio/board.rst
+++ b/Documentation/driver-api/gpio/board.rst
@@ -193,3 +193,18 @@ And the table can be added to the board code as follows::
 
 The line will be hogged as soon as the gpiochip is created or - in case the
 chip was created earlier - when the hog table is registered.
+
+Arrays of pins
+--------------
+In addition to requesting pins belonging to a function one by one, a device may
+also request an array of pins assigned to the function.  The way those pins are
+mapped to the device determines if the array qualifies for fast bitmap
+processing.  If yes, a bitmap is passed over get/set array functions directly
+between a caller and a respective .get/set_multiple() callback of a GPIO chip.
+
+In order to qualify for fast bitmap processing, the pin mapping must meet the
+following requirements:
+- it must belong to the same chip as other 'fast' pins of the function,
+- its index within the function must match its hardware number within the chip.
+
+Open drain and open source pins are excluded from fast bitmap output processing.
diff --git a/Documentation/driver-api/gpio/consumer.rst b/Documentation/driver-api/gpio/consumer.rst
index aa03f389d41d..cf992e5ab976 100644
--- a/Documentation/driver-api/gpio/consumer.rst
+++ b/Documentation/driver-api/gpio/consumer.rst
@@ -109,9 +109,11 @@ For a function using multiple GPIOs all of those can be obtained with one call::
 					   enum gpiod_flags flags)
 
 This function returns a struct gpio_descs which contains an array of
-descriptors::
+descriptors.  It also contains a pointer to a gpiolib private structure which,
+if passed back to get/set array functions, may speed up I/O proocessing::
 
 	struct gpio_descs {
+		struct gpio_array *info;
 		unsigned int ndescs;
 		struct gpio_desc *desc[];
 	}
@@ -323,29 +325,37 @@ The following functions get or set the values of an array of GPIOs::
 
 	int gpiod_get_array_value(unsigned int array_size,
 				  struct gpio_desc **desc_array,
-				  int *value_array);
+				  struct gpio_array *array_info,
+				  unsigned long *value_bitmap);
 	int gpiod_get_raw_array_value(unsigned int array_size,
 				      struct gpio_desc **desc_array,
-				      int *value_array);
+				      struct gpio_array *array_info,
+				      unsigned long *value_bitmap);
 	int gpiod_get_array_value_cansleep(unsigned int array_size,
 					   struct gpio_desc **desc_array,
-					   int *value_array);
+					   struct gpio_array *array_info,
+					   unsigned long *value_bitmap);
 	int gpiod_get_raw_array_value_cansleep(unsigned int array_size,
 					   struct gpio_desc **desc_array,
-					   int *value_array);
+					   struct gpio_array *array_info,
+					   unsigned long *value_bitmap);
 
 	void gpiod_set_array_value(unsigned int array_size,
 				   struct gpio_desc **desc_array,
-				   int *value_array)
+				   struct gpio_array *array_info,
+				   unsigned long *value_bitmap)
 	void gpiod_set_raw_array_value(unsigned int array_size,
 				       struct gpio_desc **desc_array,
-				       int *value_array)
+				       struct gpio_array *array_info,
+				       unsigned long *value_bitmap)
 	void gpiod_set_array_value_cansleep(unsigned int array_size,
 					    struct gpio_desc **desc_array,
-					    int *value_array)
+					    struct gpio_array *array_info,
+					    unsigned long *value_bitmap)
 	void gpiod_set_raw_array_value_cansleep(unsigned int array_size,
 						struct gpio_desc **desc_array,
-						int *value_array)
+						struct gpio_array *array_info,
+						unsigned long *value_bitmap)
 
 The array can be an arbitrary set of GPIOs. The functions will try to access
 GPIOs belonging to the same bank or chip simultaneously if supported by the
@@ -356,8 +366,9 @@ accessed sequentially.
 The functions take three arguments:
 	* array_size	- the number of array elements
 	* desc_array	- an array of GPIO descriptors
-	* value_array	- an array to store the GPIOs' values (get) or
-			  an array of values to assign to the GPIOs (set)
+	* array_info	- optional information obtained from gpiod_array_get()
+	* value_bitmap	- a bitmap to store the GPIOs' values (get) or
+			  a bitmap of values to assign to the GPIOs (set)
 
 The descriptor array can be obtained using the gpiod_get_array() function
 or one of its variants. If the group of descriptors returned by that function
@@ -366,16 +377,25 @@ the struct gpio_descs returned by gpiod_get_array()::
 
 	struct gpio_descs *my_gpio_descs = gpiod_get_array(...);
 	gpiod_set_array_value(my_gpio_descs->ndescs, my_gpio_descs->desc,
-			      my_gpio_values);
+			      my_gpio_descs->info, my_gpio_value_bitmap);
 
 It is also possible to access a completely arbitrary array of descriptors. The
 descriptors may be obtained using any combination of gpiod_get() and
 gpiod_get_array(). Afterwards the array of descriptors has to be setup
-manually before it can be passed to one of the above functions.
+manually before it can be passed to one of the above functions.  In that case,
+array_info should be set to NULL.
 
 Note that for optimal performance GPIOs belonging to the same chip should be
 contiguous within the array of descriptors.
 
+Still better performance may be achieved if array indexes of the descriptors
+match hardware pin numbers of a single chip.  If an array passed to a get/set
+array function matches the one obtained from gpiod_get_array() and array_info
+associated with the array is also passed, the function may take a fast bitmap
+processing path, passing the value_bitmap argument directly to the respective
+.get/set_multiple() callback of the chip.  That allows for utilization of GPIO
+banks as data I/O ports without much loss of performance.
+
 The return value of gpiod_get_array_value() and its variants is 0 on success
 or negative on error. Note the difference to gpiod_get_value(), which returns
 0 or 1 on success to convey the GPIO value. With the array functions, the GPIO