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c1c0dd2644
This mirrors the conventions used in other SPI drivers (kirkwood, davinci, atmel, et al) where the din/dout buffer can be NULL when the received/transmitted data isn't important. This reduces the need for allocating additional buffers when write-only/read-only functionality is needed. In the din == NULL case, the received data is simply not stored. In the dout == NULL case, zeroes are transmitted. Signed-off-by: Andrew Ruder <andrew.ruder@elecsyscorp.com> Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com> Reviewed-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
182 lines
3.9 KiB
C
182 lines
3.9 KiB
C
/*
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* (C) Copyright 2002
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* Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
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*
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* Influenced by code from:
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* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <common.h>
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#include <spi.h>
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#include <malloc.h>
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/*-----------------------------------------------------------------------
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* Definitions
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*/
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#ifdef DEBUG_SPI
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#define PRINTD(fmt,args...) printf (fmt ,##args)
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#else
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#define PRINTD(fmt,args...)
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#endif
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struct soft_spi_slave {
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struct spi_slave slave;
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unsigned int mode;
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};
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static inline struct soft_spi_slave *to_soft_spi(struct spi_slave *slave)
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{
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return container_of(slave, struct soft_spi_slave, slave);
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}
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/*=====================================================================*/
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/* Public Functions */
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/*=====================================================================*/
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/*-----------------------------------------------------------------------
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* Initialization
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*/
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void spi_init (void)
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{
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#ifdef SPI_INIT
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volatile immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
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SPI_INIT;
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#endif
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}
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struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
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unsigned int max_hz, unsigned int mode)
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{
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struct soft_spi_slave *ss;
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if (!spi_cs_is_valid(bus, cs))
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return NULL;
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ss = spi_alloc_slave(struct soft_spi_slave, bus, cs);
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if (!ss)
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return NULL;
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ss->mode = mode;
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/* TODO: Use max_hz to limit the SCK rate */
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return &ss->slave;
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}
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void spi_free_slave(struct spi_slave *slave)
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{
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struct soft_spi_slave *ss = to_soft_spi(slave);
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free(ss);
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}
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int spi_claim_bus(struct spi_slave *slave)
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{
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#ifdef CONFIG_SYS_IMMR
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volatile immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
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#endif
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struct soft_spi_slave *ss = to_soft_spi(slave);
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/*
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* Make sure the SPI clock is in idle state as defined for
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* this slave.
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*/
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if (ss->mode & SPI_CPOL)
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SPI_SCL(1);
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else
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SPI_SCL(0);
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return 0;
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}
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void spi_release_bus(struct spi_slave *slave)
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{
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/* Nothing to do */
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}
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/*-----------------------------------------------------------------------
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* SPI transfer
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*
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* This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
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* "bitlen" bits in the SPI MISO port. That's just the way SPI works.
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*
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* The source of the outgoing bits is the "dout" parameter and the
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* destination of the input bits is the "din" parameter. Note that "dout"
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* and "din" can point to the same memory location, in which case the
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* input data overwrites the output data (since both are buffered by
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* temporary variables, this is OK).
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*/
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int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
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const void *dout, void *din, unsigned long flags)
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{
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#ifdef CONFIG_SYS_IMMR
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volatile immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
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#endif
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struct soft_spi_slave *ss = to_soft_spi(slave);
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uchar tmpdin = 0;
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uchar tmpdout = 0;
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const u8 *txd = dout;
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u8 *rxd = din;
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int cpol = ss->mode & SPI_CPOL;
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int cpha = ss->mode & SPI_CPHA;
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unsigned int j;
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PRINTD("spi_xfer: slave %u:%u dout %08X din %08X bitlen %u\n",
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slave->bus, slave->cs, *(uint *)txd, *(uint *)rxd, bitlen);
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if (flags & SPI_XFER_BEGIN)
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spi_cs_activate(slave);
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for(j = 0; j < bitlen; j++) {
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/*
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* Check if it is time to work on a new byte.
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*/
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if ((j % 8) == 0) {
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if (txd)
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tmpdout = *txd++;
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else
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tmpdout = 0;
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if(j != 0) {
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if (rxd)
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*rxd++ = tmpdin;
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}
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tmpdin = 0;
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}
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if (!cpha)
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SPI_SCL(!cpol);
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SPI_SDA(tmpdout & 0x80);
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SPI_DELAY;
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if (cpha)
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SPI_SCL(!cpol);
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else
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SPI_SCL(cpol);
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tmpdin <<= 1;
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tmpdin |= SPI_READ;
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tmpdout <<= 1;
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SPI_DELAY;
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if (cpha)
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SPI_SCL(cpol);
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}
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/*
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* If the number of bits isn't a multiple of 8, shift the last
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* bits over to left-justify them. Then store the last byte
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* read in.
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*/
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if (rxd) {
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if ((bitlen % 8) != 0)
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tmpdin <<= 8 - (bitlen % 8);
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*rxd++ = tmpdin;
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}
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if (flags & SPI_XFER_END)
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spi_cs_deactivate(slave);
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return(0);
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}
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