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| author | Mulin Chao <mlchao@nuvoton.com> | 2017-05-02 16:11:05 +0800 |
|---|---|---|
| committer | chrome-bot <chrome-bot@chromium.org> | 2017-05-06 14:20:15 -0700 |
| commit | e7969f8245a3cde164caf1fa03cfe655c7e61d1e (patch) | |
| tree | e332d7a72b21ac02646f10affcfce3c775c60b3c /chip/npcx/keyboard_raw.c | |
| parent | 1bbcaa8df44c761b50a8f1649d2ab778b3ebaee7 (diff) | |
| download | chrome-ec-e7969f8245a3cde164caf1fa03cfe655c7e61d1e.tar.gz | |
npcx: keyboard: Add quasi-bidirectional buffers support on npcx7 ec.
This CL added the support for the quasi-bidirectional buffer which has
an open-drain output and a low-impedance pull-up resistance on KSO pins.
The low-impedance pull-up is active when ec changes the output data
buffers from 0 to 1, thereby reducing the low-to-high transition time.
Add CONFIG_KEYBOARD_KSO_HIGH_DRIVE to enable/disable this feature for
npcx7 series ec.
BRANCH=none
BUG=none
TEST=No build errors for all boards using npcx5 series.
Build poppy board and upload FW to platform. No issues found.
Change-Id: I138f0e433394816e1e5c58b5053580f202c1ac48
Signed-off-by: Mulin Chao <mlchao@nuvoton.com>
Reviewed-on: https://chromium-review.googlesource.com/497189
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Diffstat (limited to 'chip/npcx/keyboard_raw.c')
| -rw-r--r-- | chip/npcx/keyboard_raw.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/chip/npcx/keyboard_raw.c b/chip/npcx/keyboard_raw.c index 743520a96a..fa003c4336 100644 --- a/chip/npcx/keyboard_raw.c +++ b/chip/npcx/keyboard_raw.c @@ -25,6 +25,14 @@ void keyboard_raw_init(void) /* Ensure top-level interrupt is disabled */ keyboard_raw_enable_interrupt(0); + /* + * Select quasi-bidirectional buffers for KSO pins. It reduces the + * low-to-high transition time. This feature only supports in npcx7. + */ +#ifdef CONFIG_KEYBOARD_KSO_HIGH_DRIVE + SET_FIELD(NPCX_KBSCTL, NPCX_KBHDRV_FIELD, 0x01); +#endif + /* pull-up KBSIN 0-7 internally */ NPCX_KBSINPU = 0xFF; |