diff options
Diffstat (limited to 'drivers/spi/soft_spi.c')
| -rw-r--r-- | drivers/spi/soft_spi.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/drivers/spi/soft_spi.c b/drivers/spi/soft_spi.c new file mode 100644 index 0000000..25b589a --- /dev/null +++ b/drivers/spi/soft_spi.c @@ -0,0 +1,193 @@ +/* + * (C) Copyright 2002 + * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com. + * + * Influenced by code from: + * Wolfgang Denk, DENX Software Engineering, wd@denx.de. + * + * See file CREDITS for list of people who contributed to this + * project. + * + * 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; either version 2 of + * the License, or (at your option) any later version. + * + * 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 <common.h> +#include <spi.h> + +#include <malloc.h> + +/*----------------------------------------------------------------------- + * Definitions + */ + +#ifdef DEBUG_SPI +#define PRINTD(fmt,args...) printf (fmt ,##args) +#else +#define PRINTD(fmt,args...) +#endif + +struct soft_spi_slave { + struct spi_slave slave; + unsigned int mode; +}; + +static inline struct soft_spi_slave *to_soft_spi(struct spi_slave *slave) +{ + return container_of(slave, struct soft_spi_slave, slave); +} + +/*=====================================================================*/ +/* Public Functions */ +/*=====================================================================*/ + +/*----------------------------------------------------------------------- + * Initialization + */ +void spi_init (void) +{ +#ifdef SPI_INIT + volatile immap_t *immr = (immap_t *)CFG_IMMR; + + SPI_INIT; +#endif +} + +struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, + unsigned int max_hz, unsigned int mode) +{ + struct soft_spi_slave *ss; + + if (!spi_cs_is_valid(bus, cs)) + return NULL; + + ss = malloc(sizeof(struct soft_spi_slave)); + if (!ss) + return NULL; + + ss->slave.bus = bus; + ss->slave.cs = cs; + ss->mode = mode; + + /* TODO: Use max_hz to limit the SCK rate */ + + return &ss->slave; +} + +void spi_free_slave(struct spi_slave *slave) +{ + struct soft_spi_slave *ss = to_soft_spi(slave); + + free(ss); +} + +int spi_claim_bus(struct spi_slave *slave) +{ +#ifdef CFG_IMMR + volatile immap_t *immr = (immap_t *)CFG_IMMR; +#endif + struct soft_spi_slave *ss = to_soft_spi(slave); + + /* + * Make sure the SPI clock is in idle state as defined for + * this slave. + */ + if (ss->mode & SPI_CPOL) + SPI_SCL(1); + else + SPI_SCL(0); + + return 0; +} + +void spi_release_bus(struct spi_slave *slave) +{ + /* Nothing to do */ +} + +/*----------------------------------------------------------------------- + * SPI transfer + * + * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks + * "bitlen" bits in the SPI MISO port. That's just the way SPI works. + * + * The source of the outgoing bits is the "dout" parameter and the + * destination of the input bits is the "din" parameter. Note that "dout" + * and "din" can point to the same memory location, in which case the + * input data overwrites the output data (since both are buffered by + * temporary variables, this is OK). + */ +int spi_xfer(struct spi_slave *slave, unsigned int bitlen, + const void *dout, void *din, unsigned long flags) +{ +#ifdef CFG_IMMR + volatile immap_t *immr = (immap_t *)CFG_IMMR; +#endif + struct soft_spi_slave *ss = to_soft_spi(slave); + uchar tmpdin = 0; + uchar tmpdout = 0; + const u8 *txd = dout; + u8 *rxd = din; + int cpol = ss->mode & SPI_CPOL; + int cpha = ss->mode & SPI_CPHA; + unsigned int j; + + PRINTD("spi_xfer: slave %u:%u dout %08X din %08X bitlen %u\n", + slave->bus, slave->cs, *(uint *)txd, *(uint *)rxd, bitlen); + + if (flags & SPI_XFER_BEGIN) + spi_cs_activate(slave); + + for(j = 0; j < bitlen; j++) { + /* + * Check if it is time to work on a new byte. + */ + if((j % 8) == 0) { + tmpdout = *txd++; + if(j != 0) { + *rxd++ = tmpdin; + } + tmpdin = 0; + } + + if (!cpha) + SPI_SCL(!cpol); + SPI_SDA(tmpdout & 0x80); + SPI_DELAY; + if (cpha) + SPI_SCL(!cpol); + else + SPI_SCL(cpol); + tmpdin <<= 1; + tmpdin |= SPI_READ; + tmpdout <<= 1; + SPI_DELAY; + if (cpha) + SPI_SCL(cpol); + } + /* + * If the number of bits isn't a multiple of 8, shift the last + * bits over to left-justify them. Then store the last byte + * read in. + */ + if((bitlen % 8) != 0) + tmpdin <<= 8 - (bitlen % 8); + *rxd++ = tmpdin; + + if (flags & SPI_XFER_END) + spi_cs_deactivate(slave); + + return(0); +} |