From 9c2baf785e90419d6f9af6bd07aa0694020cba8d Mon Sep 17 00:00:00 2001 From: David Brownell Date: Wed, 18 Jun 2008 02:31:43 -0700 Subject: [PATCH] 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 Signed-off-by: Haavard Skinnemoen --- arch/avr32/mach-at32ap/at32ap700x.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/avr32/mach-at32ap/at32ap700x.c b/arch/avr32/mach-at32ap/at32ap700x.c index a9ae7bb108b2..a2e7b96b5e8c 100644 --- a/arch/avr32/mach-at32ap/at32ap700x.c +++ b/arch/avr32/mach-at32ap/at32ap700x.c @@ -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);