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/*
* (C) Copyright 2001
* Gerald Van Baren, Custom IDEAS, vanbaren@cideas.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; 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.
*/
#ifndef _SPI_GENERIC_H_
#define _SPI_GENERIC_H_
#include <stdint.h>
#include <stddef.h>
/* Controller-specific definitions: */
struct spi_ctrlr;
/*-----------------------------------------------------------------------
* Representation of a SPI slave, i.e. what we're communicating with.
*
* bus: ID of the bus that the slave is attached to.
* cs: ID of the chip select connected to the slave.
* ctrlr: Pointer to SPI controller structure.
*/
struct spi_slave {
unsigned int bus;
unsigned int cs;
const struct spi_ctrlr *ctrlr;
};
/*-----------------------------------------------------------------------
* Representation of a SPI contoller.
*
* claim_bus: Claim SPI bus and prepare for communication.
* release_bus: Release SPI bus.
* xfer: SPI transfer
*/
struct spi_ctrlr {
int (*claim_bus)(const struct spi_slave *slave);
void (*release_bus)(const struct spi_slave *slave);
int (*xfer)(const struct spi_slave *slave, const void *dout,
size_t bytesout, void *din, size_t bytesin);
};
/*-----------------------------------------------------------------------
* 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.
* slave: Pointer to slave structure that needs to be initialized.
*
* Returns:
* 0 on success, -1 on error
*/
int spi_setup_slave(unsigned int bus, unsigned int cs, struct spi_slave *slave);
/*-----------------------------------------------------------------------
* 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(const 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(const struct spi_slave *slave);
/*-----------------------------------------------------------------------
* SPI transfer
*
* spi_xfer() interface:
* slave: The SPI slave which will be sending/receiving the data.
* dout: Pointer to a string of bytes to send out.
* bytesout: How many bytes to write.
* din: Pointer to a string of bytes that will be filled in.
* bytesin: How many bytes to read.
*
* Returns: 0 on success, not 0 on failure
*/
int spi_xfer(const struct spi_slave *slave, const void *dout, size_t bytesout,
void *din, size_t bytesin);
unsigned int spi_crop_chunk(unsigned int cmd_len, unsigned int buf_len);
/*-----------------------------------------------------------------------
* 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(const 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, 2, din, 2);
return ret < 0 ? ret : din[1];
}
#endif /* _SPI_GENERIC_H_ */
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