pinctrl: Add core support for Aspeed SoCs

The Aspeed SoCs typically provide more than 200 pins for GPIO and other
functions. The signal enabled on a pin is determined on a priority
basis, where a given pin can provide a number of different signal types.

In addition to the priority levels, the Aspeed pin controllers describe
the signal active on a pin by compound logical expressions involving
multiple operators, registers and bits. Some difficulty arises as a
pin's function bit masks for each priority level are frequently not the
same (i.e. we cannot just flip a bit to change from a high to low
priority signal), or even in the same register(s). Some configuration
bits affect multiple pins, while in other cases the signals for a bus
must each be enabled individually.

Together, these features give rise to some complexity in the
implementation. A more complete description of the complexities is
provided in the associated header file.

The patch doesn't implement pinctrl/pinmux/pinconf for any particular
Aspeed SoC, rather it adds the framework for defining pinmux
configurations.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/pinctrl/aspeed/Makefile b/drivers/pinctrl/aspeed/Makefile
new file mode 100644
index 000000000000..a0fc61d31ccf
--- /dev/null
+++ b/drivers/pinctrl/aspeed/Makefile
@@ -0,0 +1,4 @@
+# Aspeed pinctrl support
+
+ccflags-y += -Woverride-init
+obj-$(CONFIG_PINCTRL_ASPEED)	+= pinctrl-aspeed.o