pinctrl: Add pinmux property support to pinctrl-generic

The pinmux property allows for smaller and more compact device trees,
especially when there are many pins which need to be assigned individually.
Instead of specifying an array of strings to be parsed as pins and a
function property, the pinmux property contains an array of integers
representing pinmux groups. A pinmux group consists of the pin identifier
and mux settings represented as a single integer or an array of integers.
Each individual pin controller driver specifies the exact format of a
pinmux group. As specified in the Linux documentation, a pinmux group may
be multiple integers long. However, no existing drivers use multi-integer
pinmux groups, so I have chosen to omit this feature. This makes the
implementation easier, since there is no need to allocate a buffer to do
endian conversions.

Support for the pinmux property is done differently than in Linux.  As far
as I can tell, inversion of control is used when implementing support for
the pins and groups properties to avoid allocating. This results in some
duplication of effort; every property in a config node is parsed once for
each pin in that node. This is not such an overhead with pins and groups
properties, since having multiple pins in one config node does not occur
especially often. However, the semantics of the pinmux property make such a
configuration much more appealing. A future patch could parse all config
properties at once and store them in an array. This would make it easier to
create drivers which do not function solely as callbacks from
pinctrl-generic.

This commit increases the size of the sandbox build by approximately 48
bytes.  However, it also decreases the size of the K210 device tree by 2
KiB from the previous version of this series.

The documentation has been updated from the last Linux commit before it was
split off into yaml files.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 13 insertions, 8 deletions

diff --git a/include/dm/pinctrl.h b/include/dm/pinctrl.h
index 692e5fc8cbf..d50af1ce381 100644
--- a/include/dm/pinctrl.h
+++ b/include/dm/pinctrl.h
@@ -34,29 +34,33 @@ struct pinconf_param {
  * depending on your necessity.
  *
  * @get_pins_count: return number of selectable named pins available
- *	in this driver.  (necessary to parse "pins" property in DTS)
+ *	in this driver. (necessary to parse "pins" property in DTS)
  * @get_pin_name: return the pin name of the pin selector,
  *	called by the core to figure out which pin it shall do
- *	operations to.  (necessary to parse "pins" property in DTS)
+ *	operations to. (necessary to parse "pins" property in DTS)
  * @get_groups_count: return number of selectable named groups available
- *	in this driver.  (necessary to parse "groups" property in DTS)
+ *	in this driver. (necessary to parse "groups" property in DTS)
  * @get_group_name: return the group name of the group selector,
  *	called by the core to figure out which pin group it shall do
- *	operations to.  (necessary to parse "groups" property in DTS)
+ *	operations to. (necessary to parse "groups" property in DTS)
  * @get_functions_count: return number of selectable named functions available
- *	in this driver.  (necessary for pin-muxing)
+ *	in this driver. (necessary for pin-muxing)
  * @get_function_name: return the function name of the muxing selector,
  *	called by the core to figure out which mux setting it shall map a
- *	certain device to.  (necessary for pin-muxing)
+ *	certain device to. (necessary for pin-muxing)
  * @pinmux_set: enable a certain muxing function with a certain pin.
  *	The @func_selector selects a certain function whereas @pin_selector
  *	selects a certain pin to be used. On simple controllers one of them
- *	may be ignored.  (necessary for pin-muxing against a single pin)
+ *	may be ignored. (necessary for pin-muxing against a single pin)
  * @pinmux_group_set: enable a certain muxing function with a certain pin
- *	group.  The @func_selector selects a certain function whereas
+ *	group. The @func_selector selects a certain function whereas
  *	@group_selector selects a certain set of pins to be used. On simple
  *	controllers one of them may be ignored.
  *	(necessary for pin-muxing against a pin group)
+ * @pinmux_property_set: enable a pinmux group. @pinmux_group should specify the
+ *      pin identifier and mux settings. The exact format of a pinmux group is
+ *      left up to the driver. The pin selector for the mux-ed pin should be
+ *      returned on success. (necessary to parse the "pinmux" property in DTS)
  * @pinconf_num_params: number of driver-specific parameters to be parsed
  *	from device trees  (necessary for pin-configuration)
  * @pinconf_params: list of driver_specific parameters to be parsed from
@@ -90,6 +94,7 @@ struct pinctrl_ops {
 			  unsigned func_selector);
 	int (*pinmux_group_set)(struct udevice *dev, unsigned group_selector,
 				unsigned func_selector);
+	int (*pinmux_property_set)(struct udevice *dev, u32 pinmux_group);
 	unsigned int pinconf_num_params;
 	const struct pinconf_param *pinconf_params;
 	int (*pinconf_set)(struct udevice *dev, unsigned pin_selector,