diff options
Diffstat (limited to 'include/spi.h')
| -rw-r--r-- | include/spi.h | 150 |
1 files changed, 127 insertions, 23 deletions
diff --git a/include/spi.h b/include/spi.h index 3a55a68..7744c2e 100644 --- a/include/spi.h +++ b/include/spi.h @@ -31,22 +31,87 @@ #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 /* chipselect active high? */ +#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 */ -/* - * The function call pointer type used to drive the chip select. - */ -typedef void (*spi_chipsel_type)(int cs); +/* SPI transfer flags */ +#define SPI_XFER_BEGIN 0x01 /* Assert CS before transfer */ +#define SPI_XFER_END 0x02 /* Deassert CS after transfer */ +/*----------------------------------------------------------------------- + * 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. + */ +struct spi_slave { + unsigned int bus; + unsigned int cs; +}; /*----------------------------------------------------------------------- * Initialization, must be called once on start up. + * + * TODO: I don't think we really need this. */ 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); + +/*----------------------------------------------------------------------- + * Free any memory associated with a SPI slave. + * + * slave: The SPI slave + */ +void spi_free_slave(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(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 @@ -60,28 +125,67 @@ void spi_init(void); * input data overwrites the output data (since both are buffered by * temporary variables, this is OK). * - * If the chipsel() function is not NULL, it is called with a parameter - * of '1' (chip select active) at the start of the transfer and again with - * a parameter of '0' at the end of the transfer. - * - * If the chipsel() function _is_ NULL, it the responsibility of the - * caller to make the appropriate chip select active before calling - * spi_xfer() and making it inactive after spi_xfer() returns. - * * spi_xfer() interface: - * chipsel: Routine to call to set/clear the chip select: - * if chipsel is NULL, it is not used. - * if(cs), make the chip select active (typically '0'). - * if(!cs), make the chip select inactive (typically '1'). - * dout: Pointer to a string of bits to send out. The bits are - * held in a byte array and are sent MSB first. - * din: Pointer to a string of bits that will be filled in. - * bitlen: How many bits to write and read. + * slave: The SPI slave which will be sending/receiving the data. + * bitlen: How many bits to write and read. + * dout: Pointer to a string of bits to send out. The bits are + * held in a byte array and are sent MSB first. + * din: Pointer to a string of bits that will be filled in. + * flags: A bitwise combination of SPI_XFER_* flags. * * Returns: 0 on success, not 0 on failure */ -int spi_xfer(spi_chipsel_type chipsel, int bitlen, uchar *dout, uchar *din); +int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, + void *din, unsigned long flags); + +/*----------------------------------------------------------------------- + * 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); + +/*----------------------------------------------------------------------- + * 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; -int spi_select(unsigned int bus, unsigned int dev, unsigned long mode); + ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); + return ret < 0 ? ret : din[1]; +} #endif /* _SPI_H_ */ |