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npcx: gpio: Configure pin attributes before setting as output

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When a pin power-on default is input, it is necessary to configure output
level, pull up, etc. before setting the pin to output. Otherwise, the
pin may be set to an undesired logic level for a short time.

BUG=chrome-os-partner:51722
TEST=Power-up kevin, verify that CR50_RESET_L (default input, configured
as high + open drain output by default) does not go low for a short
period at boot.
BRANCH=None

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Change-Id: Ieaa08e14e6ea15a908f3ff4ee9188e14b17583cf
Reviewed-on: https://chromium-review.googlesource.com/335344
Commit-Ready: Shawn N <shawnn@chromium.org>
Tested-by: Shawn N <shawnn@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Mulin Chao <mlchao@nuvoton.com>
This commit is contained in:
Shawn Nematbakhsh
2016-03-28 05:50:18 -07:00
committed by chrome-bot
parent fa2b676d6c
commit 4c294d144b
1 changed files with 10 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
chip/npcx/gpio.c
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@@ -583,20 +583,19 @@ void gpio_set_level(enum gpio_signal signal, int value)
void gpio_set_flags_by_mask(uint32_t port, uint32_t mask, uint32_t flags)
{
/*
* Select open drain first, so that we don't glitch the signal
* when changing the line to an output. 0:push-pull 1:open-drain
* Configure pin as input, if requested. Output is configured only
* after setting all other attributes, so as not to create a
* temporary incorrect logic state 0:input 1:output
*/
if (!(flags & GPIO_OUTPUT))
NPCX_PDIR(port) &= ~mask;
/* Select open drain 0:push-pull 1:open-drain */
if (flags & GPIO_OPEN_DRAIN)
NPCX_PTYPE(port) |= mask;
else
NPCX_PTYPE(port) &= ~mask;
/* Select direction of GPIO 0:input 1:output */
if (flags & GPIO_OUTPUT)
NPCX_PDIR(port) |= mask;
else
NPCX_PDIR(port) &= ~mask;
/* Select pull-up/down of GPIO 0:pull-up 1:pull-down */
if (flags & GPIO_PULL_UP) {
NPCX_PPUD(port) &= ~mask;
@@ -631,6 +630,9 @@ void gpio_set_flags_by_mask(uint32_t port, uint32_t mask, uint32_t flags)
else if (flags & GPIO_LOW)
NPCX_PDOUT(port) &= ~mask;
/* Configure pin as output, if requested 0:input 1:output */
if (flags & GPIO_OUTPUT)
NPCX_PDIR(port) |= mask;
}
int gpio_enable_interrupt(enum gpio_signal signal)