| /* |
| * (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_ |
| |
| /* Controller-specific definitions: */ |
| |
| /* CONFIG_HARD_SPI triggers SPI bus initialization in PowerPC */ |
| #ifdef CONFIG_MPC8XXX_SPI |
| # ifndef CONFIG_HARD_SPI |
| # define CONFIG_HARD_SPI |
| # endif |
| #endif |
| |
| /* 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 */ |
| |
| /*----------------------------------------------------------------------- |
| * 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 |
| * |
| * 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. |
| * 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(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; |
| |
| ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END); |
| return ret < 0 ? ret : din[1]; |
| } |
| |
| #endif /* _SPI_H_ */ |
