include/spi.h

   1 /*
   2  * Common SPI Interface: Controller-specific definitions
   3  *
   4  * (C) Copyright 2001
   5  * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
   6  *
   7  * SPDX-License-Identifier:     GPL-2.0+
   8  */
   9
  10 #ifndef _SPI_H_
  11 #define _SPI_H_
  12
  13 /* SPI mode flags */
  14 #define SPI_CPHA        0x01                    /* clock phase */
  15 #define SPI_CPOL        0x02                    /* clock polarity */
  16 #define SPI_MODE_0      (0|0)                   /* (original MicroWire) */
  17 #define SPI_MODE_1      (0|SPI_CPHA)
  18 #define SPI_MODE_2      (SPI_CPOL|0)
  19 #define SPI_MODE_3      (SPI_CPOL|SPI_CPHA)
  20 #define SPI_CS_HIGH     0x04                    /* CS active high */
  21 #define SPI_LSB_FIRST   0x08                    /* per-word bits-on-wire */
  22 #define SPI_3WIRE       0x10                    /* SI/SO signals shared */
  23 #define SPI_LOOP        0x20                    /* loopback mode */
  24 #define SPI_SLAVE       0x40                    /* slave mode */
  25 #define SPI_PREAMBLE    0x80                    /* Skip preamble bytes */
  26
  27 /* SPI transfer flags */
  28 #define SPI_XFER_BEGIN          0x01    /* Assert CS before transfer */
  29 #define SPI_XFER_END            0x02    /* Deassert CS after transfer */
  30 #define SPI_XFER_MMAP           0x08    /* Memory Mapped start */
  31 #define SPI_XFER_MMAP_END       0x10    /* Memory Mapped End */
  32 #define SPI_XFER_ONCE           (SPI_XFER_BEGIN | SPI_XFER_END)
  33 #define SPI_XFER_U_PAGE         (1 << 5)
  34
  35 /* SPI TX operation modes */
  36 #define SPI_OPM_TX_QPP          1 << 0
  37
  38 /* SPI RX operation modes */
  39 #define SPI_OPM_RX_AS           1 << 0
  40 #define SPI_OPM_RX_DOUT         1 << 1
  41 #define SPI_OPM_RX_DIO          1 << 2
  42 #define SPI_OPM_RX_QOF          1 << 3
  43 #define SPI_OPM_RX_QIOF         1 << 4
  44 #define SPI_OPM_RX_EXTN         SPI_OPM_RX_AS | SPI_OPM_RX_DOUT | \
  45                                 SPI_OPM_RX_DIO | SPI_OPM_RX_QOF | \
  46                                 SPI_OPM_RX_QIOF
  47
  48 /* SPI bus connection options */
  49 #define SPI_CONN_DUAL_SHARED    1 << 0
  50 #define SPI_CONN_DUAL_SEPARATED 1 << 1
  51
  52 /* Header byte that marks the start of the message */
  53 #define SPI_PREAMBLE_END_BYTE   0xec
  54
  55 #define SPI_DEFAULT_WORDLEN 8
  56
  57 /**
  58  * struct spi_slave - Representation of a SPI slave
  59  *
  60  * Drivers are expected to extend this with controller-specific data.
  61  *
  62  * @bus:                ID of the bus that the slave is attached to.
  63  * @cs:                 ID of the chip select connected to the slave.
  64  * @op_mode_rx:         SPI RX operation mode.
  65  * @op_mode_tx:         SPI TX operation mode.
  66  * @wordlen:            Size of SPI word in number of bits
  67  * @max_write_size:     If non-zero, the maximum number of bytes which can
  68  *                      be written at once, excluding command bytes.
  69  * @memory_map:         Address of read-only SPI flash access.
  70  * @option:             Varies SPI bus options - separate, shared bus.
  71  * @flags:              Indication of SPI flags.
  72  */
  73 struct spi_slave {
  74         unsigned int bus;
  75         unsigned int cs;
  76         u8 op_mode_rx;
  77         u8 op_mode_tx;
  78         unsigned int wordlen;
  79         unsigned int max_write_size;
  80         void *memory_map;
  81         u8 option;
  82         u8 flags;
  83 };
  84
  85 /**
  86  * Initialization, must be called once on start up.
  87  *
  88  * TODO: I don't think we really need this.
  89  */
  90 void spi_init(void);
  91
  92 /**
  93  * spi_do_alloc_slave - Allocate a new SPI slave (internal)
  94  *
  95  * Allocate and zero all fields in the spi slave, and set the bus/chip
  96  * select. Use the helper macro spi_alloc_slave() to call this.
  97  *
  98  * @offset:     Offset of struct spi_slave within slave structure.
  99  * @size:       Size of slave structure.
 100  * @bus:        Bus ID of the slave chip.
 101  * @cs:         Chip select ID of the slave chip on the specified bus.
 102  */
 103 void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
 104                          unsigned int cs);
 105
 106 /**
 107  * spi_alloc_slave - Allocate a new SPI slave
 108  *
 109  * Allocate and zero all fields in the spi slave, and set the bus/chip
 110  * select.
 111  *
 112  * @_struct:    Name of structure to allocate (e.g. struct tegra_spi).
 113  *              This structure must contain a member 'struct spi_slave *slave'.
 114  * @bus:        Bus ID of the slave chip.
 115  * @cs:         Chip select ID of the slave chip on the specified bus.
 116  */
 117 #define spi_alloc_slave(_struct, bus, cs) \
 118         spi_do_alloc_slave(offsetof(_struct, slave), \
 119                             sizeof(_struct), bus, cs)
 120
 121 /**
 122  * spi_alloc_slave_base - Allocate a new SPI slave with no private data
 123  *
 124  * Allocate and zero all fields in the spi slave, and set the bus/chip
 125  * select.
 126  *
 127  * @bus:        Bus ID of the slave chip.
 128  * @cs:         Chip select ID of the slave chip on the specified bus.
 129  */
 130 #define spi_alloc_slave_base(bus, cs) \
 131         spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)
 132
 133 /**
 134  * Set up communications parameters for a SPI slave.
 135  *
 136  * This must be called once for each slave. Note that this function
 137  * usually doesn't touch any actual hardware, it only initializes the
 138  * contents of spi_slave so that the hardware can be easily
 139  * initialized later.
 140  *
 141  * @bus:        Bus ID of the slave chip.
 142  * @cs:         Chip select ID of the slave chip on the specified bus.
 143  * @max_hz:     Maximum SCK rate in Hz.
 144  * @mode:       Clock polarity, clock phase and other parameters.
 145  *
 146  * Returns: A spi_slave reference that can be used in subsequent SPI
 147  * calls, or NULL if one or more of the parameters are not supported.
 148  */
 149 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
 150                 unsigned int max_hz, unsigned int mode);
 151
 152 /**
 153  * Free any memory associated with a SPI slave.
 154  *
 155  * @slave:      The SPI slave
 156  */
 157 void spi_free_slave(struct spi_slave *slave);
 158
 159 /**
 160  * Claim the bus and prepare it for communication with a given slave.
 161  *
 162  * This must be called before doing any transfers with a SPI slave. It
 163  * will enable and initialize any SPI hardware as necessary, and make
 164  * sure that the SCK line is in the correct idle state. It is not
 165  * allowed to claim the same bus for several slaves without releasing
 166  * the bus in between.
 167  *
 168  * @slave:      The SPI slave
 169  *
 170  * Returns: 0 if the bus was claimed successfully, or a negative value
 171  * if it wasn't.
 172  */
 173 int spi_claim_bus(struct spi_slave *slave);
 174
 175 /**
 176  * Release the SPI bus
 177  *
 178  * This must be called once for every call to spi_claim_bus() after
 179  * all transfers have finished. It may disable any SPI hardware as
 180  * appropriate.
 181  *
 182  * @slave:      The SPI slave
 183  */
 184 void spi_release_bus(struct spi_slave *slave);
 185
 186 /**
 187  * Set the word length for SPI transactions
 188  *
 189  * Set the word length (number of bits per word) for SPI transactions.
 190  *
 191  * @slave:      The SPI slave
 192  * @wordlen:    The number of bits in a word
 193  *
 194  * Returns: 0 on success, -1 on failure.
 195  */
 196 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen);
 197
 198 /**
 199  * SPI transfer
 200  *
 201  * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
 202  * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
 203  *
 204  * The source of the outgoing bits is the "dout" parameter and the
 205  * destination of the input bits is the "din" parameter.  Note that "dout"
 206  * and "din" can point to the same memory location, in which case the
 207  * input data overwrites the output data (since both are buffered by
 208  * temporary variables, this is OK).
 209  *
 210  * spi_xfer() interface:
 211  * @slave:      The SPI slave which will be sending/receiving the data.
 212  * @bitlen:     How many bits to write and read.
 213  * @dout:       Pointer to a string of bits to send out.  The bits are
 214  *              held in a byte array and are sent MSB first.
 215  * @din:        Pointer to a string of bits that will be filled in.
 216  * @flags:      A bitwise combination of SPI_XFER_* flags.
 217  *
 218  * Returns: 0 on success, not 0 on failure
 219  */
 220 int  spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
 221                 void *din, unsigned long flags);
 222
 223 /**
 224  * Determine if a SPI chipselect is valid.
 225  * This function is provided by the board if the low-level SPI driver
 226  * needs it to determine if a given chipselect is actually valid.
 227  *
 228  * Returns: 1 if bus:cs identifies a valid chip on this board, 0
 229  * otherwise.
 230  */
 231 int  spi_cs_is_valid(unsigned int bus, unsigned int cs);
 232
 233 /**
 234  * Activate a SPI chipselect.
 235  * This function is provided by the board code when using a driver
 236  * that can't control its chipselects automatically (e.g.
 237  * common/soft_spi.c). When called, it should activate the chip select
 238  * to the device identified by "slave".
 239  */
 240 void spi_cs_activate(struct spi_slave *slave);
 241
 242 /**
 243  * Deactivate a SPI chipselect.
 244  * This function is provided by the board code when using a driver
 245  * that can't control its chipselects automatically (e.g.
 246  * common/soft_spi.c). When called, it should deactivate the chip
 247  * select to the device identified by "slave".
 248  */
 249 void spi_cs_deactivate(struct spi_slave *slave);
 250
 251 /**
 252  * Set transfer speed.
 253  * This sets a new speed to be applied for next spi_xfer().
 254  * @slave:      The SPI slave
 255  * @hz:         The transfer speed
 256  */
 257 void spi_set_speed(struct spi_slave *slave, uint hz);
 258
 259 /**
 260  * Write 8 bits, then read 8 bits.
 261  * @slave:      The SPI slave we're communicating with
 262  * @byte:       Byte to be written
 263  *
 264  * Returns: The value that was read, or a negative value on error.
 265  *
 266  * TODO: This function probably shouldn't be inlined.
 267  */
 268 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
 269 {
 270         unsigned char dout[2];
 271         unsigned char din[2];
 272         int ret;
 273
 274         dout[0] = byte;
 275         dout[1] = 0;
 276
 277         ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
 278         return ret < 0 ? ret : din[1];
 279 }
 280
 281 /**
 282  * Set up a SPI slave for a particular device tree node
 283  *
 284  * This calls spi_setup_slave() with the correct bus number. Call
 285  * spi_free_slave() to free it later.
 286  *
 287  * @param blob:         Device tree blob
 288  * @param slave_node:   Slave node to use
 289  * @param spi_node:     SPI peripheral node to use
 290  * @return pointer to new spi_slave structure
 291  */
 292 struct spi_slave *spi_setup_slave_fdt(const void *blob, int slave_node,
 293                                       int spi_node);
 294
 295 /**
 296  * spi_base_setup_slave_fdt() - helper function to set up a SPI slace
 297  *
 298  * This decodes SPI properties from the slave node to determine the
 299  * chip select and SPI parameters.
 300  *
 301  * @blob:       Device tree blob
 302  * @busnum:     Bus number to use
 303  * @node:       Device tree node for the SPI bus
 304  */
 305 struct spi_slave *spi_base_setup_slave_fdt(const void *blob, int busnum,
 306                                            int node);
 307
 308 #endif  /* _SPI_H_ */