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| author | David Brownell <david-b@pacbell.net> | 2008-06-18 02:31:43 -0700 |
|---|---|---|
| committer | Haavard Skinnemoen <haavard.skinnemoen@atmel.com> | 2008-06-27 15:32:29 +0200 |
| commit | 9c2baf785e90419d6f9af6bd07aa0694020cba8d (patch) | |
| tree | 8cc1a3721b31d7b09fd260c6bd86e960b2d91ee5 /arch/avr32/mach-at32ap/at32ap700x.c | |
| parent | 7ef31e9c4e711bfb817a15b54e428e5c4a7c0032 (diff) | |
| download | linux-9c2baf785e90419d6f9af6bd07aa0694020cba8d.tar.gz linux-9c2baf785e90419d6f9af6bd07aa0694020cba8d.tar.bz2 linux-9c2baf785e90419d6f9af6bd07aa0694020cba8d.zip | |
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>
Diffstat (limited to 'arch/avr32/mach-at32ap/at32ap700x.c')
| -rw-r--r-- | arch/avr32/mach-at32ap/at32ap700x.c | 6 |
1 files 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); |