include/spi.h

   1 /*
   2  * (C) Copyright 2001
   3  * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 #ifndef _SPI_H_
  25 #define _SPI_H_
  26
  27 /* Controller-specific definitions: */
  28
  29 /* SPI mode flags */
  30 #define SPI_CPHA        0x01                    /* clock phase */
  31 #define SPI_CPOL        0x02                    /* clock polarity */
  32 #define SPI_MODE_0      (0|0)                   /* (original MicroWire) */
  33 #define SPI_MODE_1      (0|SPI_CPHA)
  34 #define SPI_MODE_2      (SPI_CPOL|0)
  35 #define SPI_MODE_3      (SPI_CPOL|SPI_CPHA)
  36 #define SPI_CS_HIGH     0x04                    /* CS active high */
  37 #define SPI_LSB_FIRST   0x08                    /* per-word bits-on-wire */
  38 #define SPI_3WIRE       0x10                    /* SI/SO signals shared */
  39 #define SPI_LOOP        0x20                    /* loopback mode */
  40 #define SPI_SLAVE       0x40                    /* slave mode */
  41 #define SPI_PREAMBLE    0x80                    /* Skip preamble bytes */
  42
  43 /* SPI transfer flags */
  44 #define SPI_XFER_BEGIN  0x01                    /* Assert CS before transfer */
  45 #define SPI_XFER_END    0x02                    /* Deassert CS after transfer */
  46
  47 /* Header byte that marks the start of the message */
  48 #define SPI_PREAMBLE_END_BYTE   0xec
  49
  50 /*-----------------------------------------------------------------------
  51  * Representation of a SPI slave, i.e. what we're communicating with.
  52  *
  53  * Drivers are expected to extend this with controller-specific data.
  54  *
  55  *   bus:       ID of the bus that the slave is attached to.
  56  *   cs:        ID of the chip select connected to the slave.
  57  *   max_write_size:    If non-zero, the maximum number of bytes which can
  58  *              be written at once, excluding command bytes.
  59  */
  60 struct spi_slave {
  61         unsigned int    bus;
  62         unsigned int    cs;
  63         unsigned int max_write_size;
  64 };
  65
  66 /*-----------------------------------------------------------------------
  67  * Initialization, must be called once on start up.
  68  *
  69  * TODO: I don't think we really need this.
  70  */
  71 void spi_init(void);
  72
  73 /**
  74  * spi_do_alloc_slave - Allocate a new SPI slave (internal)
  75  *
  76  * Allocate and zero all fields in the spi slave, and set the bus/chip
  77  * select. Use the helper macro spi_alloc_slave() to call this.
  78  *
  79  * @offset: Offset of struct spi_slave within slave structure
  80  * @size: Size of slave structure
  81  * @bus: Bus ID of the slave chip.
  82  * @cs: Chip select ID of the slave chip on the specified bus.
  83  */
  84 void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
  85                          unsigned int cs);
  86
  87 /**
  88  * spi_alloc_slave - Allocate a new SPI slave
  89  *
  90  * Allocate and zero all fields in the spi slave, and set the bus/chip
  91  * select.
  92  *
  93  * @_struct: Name of structure to allocate (e.g. struct tegra_spi). This
  94  *      structure must contain a member 'struct spi_slave *slave'.
  95  * @bus: Bus ID of the slave chip.
  96  * @cs: Chip select ID of the slave chip on the specified bus.
  97  */
  98 #define spi_alloc_slave(_struct, bus, cs) \
  99         spi_do_alloc_slave(offsetof(_struct, slave), \
 100                             sizeof(_struct), bus, cs)
 101
 102 /**
 103  * spi_alloc_slave_base - Allocate a new SPI slave with no private data
 104  *
 105  * Allocate and zero all fields in the spi slave, and set the bus/chip
 106  * select.
 107  *
 108  * @bus: Bus ID of the slave chip.
 109  * @cs: Chip select ID of the slave chip on the specified bus.
 110  */
 111 #define spi_alloc_slave_base(bus, cs) \
 112         spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)
 113
 114 /*-----------------------------------------------------------------------
 115  * Set up communications parameters for a SPI slave.
 116  *
 117  * This must be called once for each slave. Note that this function
 118  * usually doesn't touch any actual hardware, it only initializes the
 119  * contents of spi_slave so that the hardware can be easily
 120  * initialized later.
 121  *
 122  *   bus:     Bus ID of the slave chip.
 123  *   cs:      Chip select ID of the slave chip on the specified bus.
 124  *   max_hz:  Maximum SCK rate in Hz.
 125  *   mode:    Clock polarity, clock phase and other parameters.
 126  *
 127  * Returns: A spi_slave reference that can be used in subsequent SPI
 128  * calls, or NULL if one or more of the parameters are not supported.
 129  */
 130 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
 131                 unsigned int max_hz, unsigned int mode);
 132
 133 /*-----------------------------------------------------------------------
 134  * Free any memory associated with a SPI slave.
 135  *
 136  *   slave:     The SPI slave
 137  */
 138 void spi_free_slave(struct spi_slave *slave);
 139
 140 /*-----------------------------------------------------------------------
 141  * Claim the bus and prepare it for communication with a given slave.
 142  *
 143  * This must be called before doing any transfers with a SPI slave. It
 144  * will enable and initialize any SPI hardware as necessary, and make
 145  * sure that the SCK line is in the correct idle state. It is not
 146  * allowed to claim the same bus for several slaves without releasing
 147  * the bus in between.
 148  *
 149  *   slave:     The SPI slave
 150  *
 151  * Returns: 0 if the bus was claimed successfully, or a negative value
 152  * if it wasn't.
 153  */
 154 int spi_claim_bus(struct spi_slave *slave);
 155
 156 /*-----------------------------------------------------------------------
 157  * Release the SPI bus
 158  *
 159  * This must be called once for every call to spi_claim_bus() after
 160  * all transfers have finished. It may disable any SPI hardware as
 161  * appropriate.
 162  *
 163  *   slave:     The SPI slave
 164  */
 165 void spi_release_bus(struct spi_slave *slave);
 166
 167 /*-----------------------------------------------------------------------
 168  * SPI transfer
 169  *
 170  * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
 171  * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
 172  *
 173  * The source of the outgoing bits is the "dout" parameter and the
 174  * destination of the input bits is the "din" parameter.  Note that "dout"
 175  * and "din" can point to the same memory location, in which case the
 176  * input data overwrites the output data (since both are buffered by
 177  * temporary variables, this is OK).
 178  *
 179  * spi_xfer() interface:
 180  *   slave:     The SPI slave which will be sending/receiving the data.
 181  *   bitlen:    How many bits to write and read.
 182  *   dout:      Pointer to a string of bits to send out.  The bits are
 183  *              held in a byte array and are sent MSB first.
 184  *   din:       Pointer to a string of bits that will be filled in.
 185  *   flags:     A bitwise combination of SPI_XFER_* flags.
 186  *
 187  *   Returns: 0 on success, not 0 on failure
 188  */
 189 int  spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
 190                 void *din, unsigned long flags);
 191
 192 /*-----------------------------------------------------------------------
 193  * Determine if a SPI chipselect is valid.
 194  * This function is provided by the board if the low-level SPI driver
 195  * needs it to determine if a given chipselect is actually valid.
 196  *
 197  * Returns: 1 if bus:cs identifies a valid chip on this board, 0
 198  * otherwise.
 199  */
 200 int  spi_cs_is_valid(unsigned int bus, unsigned int cs);
 201
 202 /*-----------------------------------------------------------------------
 203  * Activate a SPI chipselect.
 204  * This function is provided by the board code when using a driver
 205  * that can't control its chipselects automatically (e.g.
 206  * common/soft_spi.c). When called, it should activate the chip select
 207  * to the device identified by "slave".
 208  */
 209 void spi_cs_activate(struct spi_slave *slave);
 210
 211 /*-----------------------------------------------------------------------
 212  * Deactivate a SPI chipselect.
 213  * This function is provided by the board code when using a driver
 214  * that can't control its chipselects automatically (e.g.
 215  * common/soft_spi.c). When called, it should deactivate the chip
 216  * select to the device identified by "slave".
 217  */
 218 void spi_cs_deactivate(struct spi_slave *slave);
 219
 220 /*-----------------------------------------------------------------------
 221  * Set transfer speed.
 222  * This sets a new speed to be applied for next spi_xfer().
 223  *   slave:     The SPI slave
 224  *   hz:        The transfer speed
 225  */
 226 void spi_set_speed(struct spi_slave *slave, uint hz);
 227
 228 /*-----------------------------------------------------------------------
 229  * Write 8 bits, then read 8 bits.
 230  *   slave:     The SPI slave we're communicating with
 231  *   byte:      Byte to be written
 232  *
 233  * Returns: The value that was read, or a negative value on error.
 234  *
 235  * TODO: This function probably shouldn't be inlined.
 236  */
 237 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
 238 {
 239         unsigned char dout[2];
 240         unsigned char din[2];
 241         int ret;
 242
 243         dout[0] = byte;
 244         dout[1] = 0;
 245
 246         ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
 247         return ret < 0 ? ret : din[1];
 248 }
 249
 250 /**
 251  * Set up a SPI slave for a particular device tree node
 252  *
 253  * This calls spi_setup_slave() with the correct bus number. Call
 254  * spi_free_slave() to free it later.
 255  *
 256  * @param blob          Device tree blob
 257  * @param node          SPI peripheral node to use
 258  * @param cs            Chip select to use
 259  * @param max_hz        Maximum SCK rate in Hz (0 for default)
 260  * @param mode          Clock polarity, clock phase and other parameters
 261  * @return pointer to new spi_slave structure
 262  */
 263 struct spi_slave *spi_setup_slave_fdt(const void *blob, int node,
 264                 unsigned int cs, unsigned int max_hz, unsigned int mode);
 265
 266 #endif  /* _SPI_H_ */