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| author | Christian Mauderer <christian.mauderer@embedded-brains.de> | 2018-08-06 10:29:14 +0200 |
|---|---|---|
| committer | Christian Mauderer <christian.mauderer@embedded-brains.de> | 2018-08-09 08:37:38 +0200 |
| commit | 8e6cfccf8c8f4313117a86a36b69532b1bf81545 (patch) | |
| tree | 6e27e017cfd1604f91d2066ce8923c8890c57d4e | |
| parent | sys/event.h: Update version FreeBSD tag (diff) | |
| download | rtems-8e6cfccf8c8f4313117a86a36b69532b1bf81545.tar.bz2 | |
bsp/atsam: Fix handling of slow SPI speeds.
This patch fixes an overflow in the frequency calculation of the SPI
driver for slow SPI speeds.
| -rw-r--r-- | bsps/arm/atsam/spi/atsam_spi_bus.c | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/bsps/arm/atsam/spi/atsam_spi_bus.c b/bsps/arm/atsam/spi/atsam_spi_bus.c index 35f44f525d..b40fa56f7a 100644 --- a/bsps/arm/atsam/spi/atsam_spi_bus.c +++ b/bsps/arm/atsam/spi/atsam_spi_bus.c @@ -85,6 +85,23 @@ static uint8_t atsam_calculate_dlybcs(uint16_t delay_in_us) (BOARD_MCK / delay_in_us) : 0xFF; } +static uint32_t atsam_calculate_scbr(uint32_t speed_hz) +{ + uint32_t scbr; + + scbr = BOARD_MCK / speed_hz; + if (scbr > 0x0FF) { + /* Best estimation we can offer with the hardware. */ + scbr = 0x0FF; + } + if (scbr == 0) { + /* SCBR = 0 isn't allowed. */ + scbr = 1; + } + + return scbr; +} + static void atsam_set_phase_and_polarity(uint32_t mode, uint32_t *csr) { uint32_t mode_mask = mode & SPI_MODE_3; @@ -109,11 +126,13 @@ static void atsam_set_phase_and_polarity(uint32_t mode, uint32_t *csr) static void atsam_configure_spi(atsam_spi_bus *bus) { uint8_t delay_cs; + uint32_t scbr; uint32_t csr = 0; uint32_t mode = 0; uint32_t cs = bus->base.cs; delay_cs = atsam_calculate_dlybcs(bus->base.delay_usecs); + scbr = atsam_calculate_scbr(bus->base.speed_hz); mode |= SPI_MR_DLYBCS(delay_cs); mode |= SPI_MR_MSTR; @@ -137,7 +156,7 @@ static void atsam_configure_spi(atsam_spi_bus *bus) csr = SPI_DLYBCT(1000, BOARD_MCK) | SPI_DLYBS(1000, BOARD_MCK) | - SPI_SCBR(bus->base.speed_hz, BOARD_MCK) | + SPI_CSR_SCBR(scbr) | SPI_CSR_BITS(bus->base.bits_per_word - 8); atsam_set_phase_and_polarity(bus->base.mode, &csr); |