summaryrefslogtreecommitdiffstats
path: root/Documentation/pinctrl.txt
diff options
context:
space:
mode:
authorSonic Zhang <sonic.zhang@analog.com>2015-04-09 11:13:07 +0800
committerLinus Walleij <linus.walleij@linaro.org>2015-05-06 14:45:19 +0200
commitfa76a3db7093a527333c380df82a0f158d9b8299 (patch)
treeadd57323d26140a8e2358da9b93066d096c9c38d /Documentation/pinctrl.txt
parentc30024a6449070d6fde51a8bddf4c97f884db2cc (diff)
downloadlinux-fa76a3db7093a527333c380df82a0f158d9b8299.tar.bz2
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>
Diffstat (limited to 'Documentation/pinctrl.txt')
-rw-r--r--Documentation/pinctrl.txt11
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/pinctrl.txt b/Documentation/pinctrl.txt
index a9b47163bb5d..d6b2bed94c43 100644
--- a/Documentation/pinctrl.txt
+++ b/Documentation/pinctrl.txt
@@ -73,6 +73,7 @@ static struct pinctrl_desc foo_desc = {
.pins = foo_pins,
.npins = ARRAY_SIZE(foo_pins),
.owner = THIS_MODULE,
+ .strict = true,
};
int __init foo_probe(void)
@@ -830,6 +831,11 @@ separate memory range only intended for GPIO driving, and the register
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 @@ possible that the GPIO, pin config and pin multiplex registers are placed into
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: