pinctrl: allow exlusive GPIO/mux pin allocation
Disallow simultaneous use of the the GPIO and peripheral mux
functions by setting a flag "strict" in struct pinctrl_desc.
The blackfin pinmux and gpio controller doesn't allow user to
set up a pin for both GPIO and peripheral function. So, add flag
strict in struct pinctrl_desc to check both gpio_owner and
mux_owner before approving the pin request.
v2-changes:
- if strict flag is set, check gpio_owner and mux_onwer in if and
else clause
v3-changes:
- add kerneldoc for this struct
- augment Documentation/pinctrl.txt
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/Documentation/pinctrl.txt b/Documentation/pinctrl.txt
index a9b4716..d6b2bed 100644
--- a/Documentation/pinctrl.txt
+++ b/Documentation/pinctrl.txt
@@ -73,6 +73,7 @@
.pins = foo_pins,
.npins = ARRAY_SIZE(foo_pins),
.owner = THIS_MODULE,
+ .strict = true,
};
int __init foo_probe(void)
@@ -830,6 +831,11 @@
range dealing with pin config and pin multiplexing get placed into a
different memory range and a separate section of the data sheet.
+A flag "strict" in struct pinctrl_desc is available to check and deny
+simultaneous access to the same pin from GPIO and pin multiplexing
+consumers on hardware of this type. The pinctrl driver should set this flag
+accordingly.
+
(B)
pin config
@@ -850,6 +856,11 @@
the same memory range and the same section of the data sheet, although that
need not be the case.
+In some pin controllers, although the physical pins are designed in the same
+way as (B), the GPIO function still can't be enabled at the same time as the
+peripheral functions. So again the "strict" flag should be set, denying
+simultaneous activation by GPIO and other muxed in devices.
+
From a kernel point of view, however, these are different aspects of the
hardware and shall be put into different subsystems: