/* * (C) Copyright 2001 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com. * * 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 */ #ifndef _SPI_H_ #define _SPI_H_ #include <stdint.h> /* Controller-specific definitions: */ /* SPI mode flags */ #define SPI_CPHA 0x01 /* clock phase */ #define SPI_CPOL 0x02 /* clock polarity */ #define SPI_MODE_0 (0|0) /* (original MicroWire) */ #define SPI_MODE_1 (0|SPI_CPHA) #define SPI_MODE_2 (SPI_CPOL|0) #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA) #define SPI_CS_HIGH 0x04 /* CS active high */ #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */ #define SPI_3WIRE 0x10 /* SI/SO signals shared */ #define SPI_LOOP 0x20 /* loopback mode */ /* SPI transfer flags */ #define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */ #define SPI_XFER_END 0x02 /* Deassert CS after transfer */ /* SPI opcodes */ #define SPI_OPCODE_WREN 0x06 #define SPI_OPCODE_FAST_READ 0x0b #define SPI_READ_FLAG 0x01 #define SPI_WRITE_FLAG 0x02 /*----------------------------------------------------------------------- * Representation of a SPI slave, i.e. what we're communicating with. * * Drivers are expected to extend this with controller-specific data. * * bus: ID of the bus that the slave is attached to. * cs: ID of the chip select connected to the slave. * rw: Read or Write flag */ struct spi_slave { unsigned int bus; unsigned int cs; unsigned int rw; }; /*----------------------------------------------------------------------- * Initialization, must be called once on start up. * */ void spi_init(void); /*----------------------------------------------------------------------- * Set up communications parameters for a SPI slave. * * This must be called once for each slave. Note that this function * usually doesn't touch any actual hardware, it only initializes the * contents of spi_slave so that the hardware can be easily * initialized later. * * bus: Bus ID of the slave chip. * cs: Chip select ID of the slave chip on the specified bus. * max_hz: Maximum SCK rate in Hz. * mode: Clock polarity, clock phase and other parameters. * * Returns: A spi_slave reference that can be used in subsequent SPI * calls, or NULL if one or more of the parameters are not supported. */ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, unsigned int max_hz, unsigned int mode); /*----------------------------------------------------------------------- * Claim the bus and prepare it for communication with a given slave. * * This must be called before doing any transfers with a SPI slave. It * will enable and initialize any SPI hardware as necessary, and make * sure that the SCK line is in the correct idle state. It is not * allowed to claim the same bus for several slaves without releasing * the bus in between. * * slave: The SPI slave * * Returns: 0 if the bus was claimed successfully, or a negative value * if it wasn't. */ int spi_claim_bus(struct spi_slave *slave); /*----------------------------------------------------------------------- * Release the SPI bus * * This must be called once for every call to spi_claim_bus() after * all transfers have finished. It may disable any SPI hardware as * appropriate. * * slave: The SPI slave */ void spi_release_bus(struct spi_slave *slave); /*----------------------------------------------------------------------- * 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). * * spi_xfer() interface: * slave: The SPI slave which will be sending/receiving the data. * dout: Pointer to a string of bits to send out. The bits are * held in a byte array and are sent MSB first. * bitsout: How many bits to write. * din: Pointer to a string of bits that will be filled in. * bitsin: How many bits to read. * * Returns: 0 on success, not 0 on failure */ int spi_xfer(struct spi_slave *slave, const void *dout, unsigned int bitsout, void *din, unsigned int bitsin); /*----------------------------------------------------------------------- * Determine if a SPI chipselect is valid. * This function is provided by the board if the low-level SPI driver * needs it to determine if a given chipselect is actually valid. * * Returns: 1 if bus:cs identifies a valid chip on this board, 0 * otherwise. */ int spi_cs_is_valid(unsigned int bus, unsigned int cs); /*----------------------------------------------------------------------- * Activate a SPI chipselect. * This function is provided by the board code when using a driver * that can't control its chipselects automatically (e.g. * common/soft_spi.c). When called, it should activate the chip select * to the device identified by "slave". */ void spi_cs_activate(struct spi_slave *slave); /*----------------------------------------------------------------------- * Deactivate a SPI chipselect. * This function is provided by the board code when using a driver * that can't control its chipselects automatically (e.g. * common/soft_spi.c). When called, it should deactivate the chip * select to the device identified by "slave". */ void spi_cs_deactivate(struct spi_slave *slave); /*----------------------------------------------------------------------- * Set transfer speed. * This sets a new speed to be applied for next spi_xfer(). * slave: The SPI slave * hz: The transfer speed */ void spi_set_speed(struct spi_slave *slave, uint32_t hz); /*----------------------------------------------------------------------- * Write 8 bits, then read 8 bits. * slave: The SPI slave we're communicating with * byte: Byte to be written * * Returns: The value that was read, or a negative value on error. * * TODO: This function probably shouldn't be inlined. */ static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte) { unsigned char dout[2]; unsigned char din[2]; int ret; dout[0] = byte; dout[1] = 0; ret = spi_xfer(slave, dout, 16, din, 16); return ret < 0 ? ret : din[1]; } #endif /* _SPI_H_ */