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at32ap700x spi: enable pullups on MISO

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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>
This commit is contained in:
David Brownell 2008-06-18 02:31:43 -07:00 committed by Haavard Skinnemoen
parent 7ef31e9c4e
commit 9c2baf785e
1 changed files with 4 additions and 2 deletions
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6
arch/avr32/mach-at32ap/at32ap700x.c
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@ -1181,7 +1181,8 @@ at32_add_device_spi(unsigned int id, struct spi_board_info *b, unsigned int n)
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 @@ at32_add_device_spi(unsigned int id, struct spi_board_info *b, unsigned int n)
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);