at32ap700x spi: enable pullups on MISO
This is a minor tweak to the at32ap700x pin configuration for the SPI
input pin (MISO), enabling the on-chip weak pullup (typical 190K) to
(a) ensure a fixed data value for missing or input-only slaves;
(b) prevent power waste associated with inputs floating near VDDIO/2.
Atmel's boards have no external pullup or pulldown on these pins, so
it's unlikely other boards would address these issues with external
pulldowns. Were there trouble, board-specific code could turn off
the relevant pullup(s).
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
diff --git a/arch/avr32/mach-at32ap/at32ap700x.c b/arch/avr32/mach-at32ap/at32ap700x.c
index a9ae7bb..a2e7b96 100644
--- a/arch/avr32/mach-at32ap/at32ap700x.c
+++ b/arch/avr32/mach-at32ap/at32ap700x.c
@@ -1181,7 +1181,8 @@
switch (id) {
case 0:
pdev = &atmel_spi0_device;
- select_peripheral(PA(0), PERIPH_A, 0); /* MISO */
+ /* pullup MISO so a level is always defined */
+ select_peripheral(PA(0), PERIPH_A, AT32_GPIOF_PULLUP);
select_peripheral(PA(1), PERIPH_A, 0); /* MOSI */
select_peripheral(PA(2), PERIPH_A, 0); /* SCK */
at32_spi_setup_slaves(0, b, n, spi0_pins);
@@ -1189,7 +1190,8 @@
case 1:
pdev = &atmel_spi1_device;
- select_peripheral(PB(0), PERIPH_B, 0); /* MISO */
+ /* pullup MISO so a level is always defined */
+ select_peripheral(PB(0), PERIPH_B, AT32_GPIOF_PULLUP);
select_peripheral(PB(1), PERIPH_B, 0); /* MOSI */
select_peripheral(PB(5), PERIPH_B, 0); /* SCK */
at32_spi_setup_slaves(1, b, n, spi1_pins);