| /* |
| * (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_ */ |