diff options
Diffstat (limited to 'src/cc1111/ao_spi.c')
| -rw-r--r-- | src/cc1111/ao_spi.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/src/cc1111/ao_spi.c b/src/cc1111/ao_spi.c new file mode 100644 index 00000000..fbe613c7 --- /dev/null +++ b/src/cc1111/ao_spi.c @@ -0,0 +1,157 @@ +/* + * Copyright © 2010 Keith Packard <keithp@keithp.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. + */ + +#include "ao.h" + +/* Shared mutex to protect SPI bus, must cover the entire + * operation, from CS low to CS high. This means that any SPI + * user must protect the SPI bus with this mutex + */ +__xdata uint8_t ao_spi_mutex; +__xdata uint8_t ao_spi_dma_in_done; +__xdata uint8_t ao_spi_dma_out_done; + +uint8_t ao_spi_dma_out_id; +uint8_t ao_spi_dma_in_id; + +static __xdata uint8_t ao_spi_const = 0xff; + +/* Send bytes over SPI. + * + * This sets up two DMA engines, one writing the data and another reading + * bytes coming back. We use the bytes coming back to tell when the transfer + * is complete, as the transmit register is double buffered and hence signals + * completion one byte before the transfer is actually complete + */ +void +ao_spi_send(void __xdata *block, uint16_t len) __reentrant +{ + ao_dma_set_transfer(ao_spi_dma_in_id, + &U0DBUFXADDR, + &ao_spi_const, + len, + DMA_CFG0_WORDSIZE_8 | + DMA_CFG0_TMODE_SINGLE | + DMA_CFG0_TRIGGER_URX0, + DMA_CFG1_SRCINC_0 | + DMA_CFG1_DESTINC_0 | + DMA_CFG1_PRIORITY_NORMAL); + + ao_dma_set_transfer(ao_spi_dma_out_id, + block, + &U0DBUFXADDR, + len, + DMA_CFG0_WORDSIZE_8 | + DMA_CFG0_TMODE_SINGLE | + DMA_CFG0_TRIGGER_UTX0, + DMA_CFG1_SRCINC_1 | + DMA_CFG1_DESTINC_0 | + DMA_CFG1_PRIORITY_NORMAL); + + ao_dma_start(ao_spi_dma_in_id); + ao_dma_start(ao_spi_dma_out_id); + ao_dma_trigger(ao_spi_dma_out_id); + __critical while (!ao_spi_dma_in_done) + ao_sleep(&ao_spi_dma_in_done); +} + +/* Receive bytes over SPI. + * + * This sets up tow DMA engines, one reading the data and another + * writing constant values to the SPI transmitter as that is what + * clocks the data coming in. + */ +void +ao_spi_recv(void __xdata *block, uint16_t len) __reentrant +{ + ao_dma_set_transfer(ao_spi_dma_in_id, + &U0DBUFXADDR, + block, + len, + DMA_CFG0_WORDSIZE_8 | + DMA_CFG0_TMODE_SINGLE | + DMA_CFG0_TRIGGER_URX0, + DMA_CFG1_SRCINC_0 | + DMA_CFG1_DESTINC_1 | + DMA_CFG1_PRIORITY_NORMAL); + + ao_dma_set_transfer(ao_spi_dma_out_id, + &ao_spi_const, + &U0DBUFXADDR, + len, + DMA_CFG0_WORDSIZE_8 | + DMA_CFG0_TMODE_SINGLE | + DMA_CFG0_TRIGGER_UTX0, + DMA_CFG1_SRCINC_0 | + DMA_CFG1_DESTINC_0 | + DMA_CFG1_PRIORITY_NORMAL); + + ao_dma_start(ao_spi_dma_in_id); + ao_dma_start(ao_spi_dma_out_id); + ao_dma_trigger(ao_spi_dma_out_id); + __critical while (!ao_spi_dma_in_done) + ao_sleep(&ao_spi_dma_in_done); +} + +/* + * Initialize USART0 for SPI using config alt 2 + * + * MO P1_5 + * MI P1_4 + * CLK P1_3 + * + * Chip select is the responsibility of the caller + */ + +void +ao_spi_init(void) +{ + /* Set up the USART pin assignment */ + PERCFG = (PERCFG & ~PERCFG_U0CFG_ALT_MASK) | PERCFG_U0CFG_ALT_2; + + /* Ensure that USART0 takes precidence over USART1 for pins that + * they share + */ + P2SEL = (P2SEL & ~P2SEL_PRI3P1_MASK) | P2SEL_PRI3P1_USART0; + + /* Make the SPI pins be controlled by the USART peripheral */ + P1SEL |= ((1 << 5) | (1 << 4) | (1 << 3)); + + /* Set up OUT DMA */ + ao_spi_dma_out_id = ao_dma_alloc(&ao_spi_dma_out_done); + + /* Set up IN DMA */ + ao_spi_dma_in_id = ao_dma_alloc(&ao_spi_dma_in_done); + + /* Set up the USART. + * + * SPI master mode + */ + U0CSR = (UxCSR_MODE_SPI | UxCSR_RE | UxCSR_MASTER); + + /* Set the baud rate and signal parameters + * + * The cc1111 is limited to a 24/8 MHz SPI clock. + * Every peripheral I've ever seen goes faster than that, + * so set the clock to 3MHz (BAUD_E 17, BAUD_M 0) + */ + U0BAUD = 0; + U0GCR = (UxGCR_CPOL_NEGATIVE | + UxGCR_CPHA_FIRST_EDGE | + UxGCR_ORDER_MSB | + (17 << UxGCR_BAUD_E_SHIFT)); +} |