diff options
Diffstat (limited to 'src/include/spi-generic.h')
| -rw-r--r-- | src/include/spi-generic.h | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/src/include/spi-generic.h b/src/include/spi-generic.h new file mode 100644 index 0000000000..d394531712 --- /dev/null +++ b/src/include/spi-generic.h @@ -0,0 +1,204 @@ +/* + * (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_ */ |