include/linux/spi/spidev.h

   1 /*
   2  * include/linux/spi/spidev.h
   3  *
   4  * Copyright (C) 2006 SWAPP
   5  *      Andrea Paterniani <a.paterniani@swapp-eng.it>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20   */
  21
  22 #ifndef SPIDEV_H
  23 #define SPIDEV_H
  24
  25
  26 /* User space versions of kernel symbols for SPI clocking modes,
  27  * matching <linux/spi/spi.h>
  28  */
  29
  30 #define SPI_CPHA                0x01
  31 #define SPI_CPOL                0x02
  32
  33 #define SPI_MODE_0              (0|0)
  34 #define SPI_MODE_1              (0|SPI_CPHA)
  35 #define SPI_MODE_2              (SPI_CPOL|0)
  36 #define SPI_MODE_3              (SPI_CPOL|SPI_CPHA)
  37
  38
  39 /*---------------------------------------------------------------------------*/
  40
  41 /* IOCTL commands */
  42
  43 #define SPI_IOC_MAGIC                   'k'
  44
  45 /**
  46  * struct spi_ioc_transfer - describes a single SPI transfer
  47  * @tx_buf: Holds pointer to userspace buffer with transmit data, or null.
  48  *      If no data is provided, zeroes are shifted out.
  49  * @rx_buf: Holds pointer to userspace buffer for receive data, or null.
  50  * @len: Length of tx and rx buffers, in bytes.
  51  * @speed_hz: Temporary override of the device's bitrate.
  52  * @bits_per_word: Temporary override of the device's wordsize.
  53  * @delay_usecs: If nonzero, how long to delay after the last bit transfer
  54  *      before optionally deselecting the device before the next transfer.
  55  * @cs_change: True to deselect device before starting the next transfer.
  56  *
  57  * This structure is mapped directly to the kernel spi_transfer structure;
  58  * the fields have the same meanings, except of course that the pointers
  59  * are in a different address space (and may be of different sizes in some
  60  * cases, such as 32-bit i386 userspace over a 64-bit x86_64 kernel).
  61  * Zero-initialize the structure, including currently unused fields, to
  62  * accomodate potential future updates.
  63  *
  64  * SPI_IOC_MESSAGE gives userspace the equivalent of kernel spi_sync().
  65  * Pass it an array of related transfers, they'll execute together.
  66  * Each transfer may be half duplex (either direction) or full duplex.
  67  *
  68  *      struct spi_ioc_transfer mesg[4];
  69  *      ...
  70  *      status = ioctl(fd, SPI_IOC_MESSAGE(4), mesg);
  71  *
  72  * So for example one transfer might send a nine bit command (right aligned
  73  * in a 16-bit word), the next could read a block of 8-bit data before
  74  * terminating that command by temporarily deselecting the chip; the next
  75  * could send a different nine bit command (re-selecting the chip), and the
  76  * last transfer might write some register values.
  77  */
  78 struct spi_ioc_transfer {
  79         __u64           tx_buf;
  80         __u64           rx_buf;
  81
  82         __u32           len;
  83         __u32           speed_hz;
  84
  85         __u16           delay_usecs;
  86         __u8            bits_per_word;
  87         __u8            cs_change;
  88         __u32           pad;
  89
  90         /* If the contents of 'struct spi_ioc_transfer' ever change
  91          * incompatibly, then the ioctl number (currently 0) must change;
  92          * ioctls with constant size fields get a bit more in the way of
  93          * error checking than ones (like this) where that field varies.
  94          *
  95          * NOTE: struct layout is the same in 64bit and 32bit userspace.
  96          */
  97 };
  98
  99 /* not all platforms use <asm-generic/ioctl.h> or _IOC_TYPECHECK() ... */
 100 #define SPI_MSGSIZE(N) \
 101         ((((N)*(sizeof (struct spi_ioc_transfer))) < (1 << _IOC_SIZEBITS)) \
 102                 ? ((N)*(sizeof (struct spi_ioc_transfer))) : 0)
 103 #define SPI_IOC_MESSAGE(N) _IOW(SPI_IOC_MAGIC, 0, char[SPI_MSGSIZE(N)])
 104
 105
 106 /* Read / Write of SPI mode (SPI_MODE_0..SPI_MODE_3) */
 107 #define SPI_IOC_RD_MODE                 _IOR(SPI_IOC_MAGIC, 1, __u8)
 108 #define SPI_IOC_WR_MODE                 _IOW(SPI_IOC_MAGIC, 1, __u8)
 109
 110 /* Read / Write SPI bit justification */
 111 #define SPI_IOC_RD_LSB_FIRST            _IOR(SPI_IOC_MAGIC, 2, __u8)
 112 #define SPI_IOC_WR_LSB_FIRST            _IOW(SPI_IOC_MAGIC, 2, __u8)
 113
 114 /* Read / Write SPI device word length (1..N) */
 115 #define SPI_IOC_RD_BITS_PER_WORD        _IOR(SPI_IOC_MAGIC, 3, __u8)
 116 #define SPI_IOC_WR_BITS_PER_WORD        _IOW(SPI_IOC_MAGIC, 3, __u8)
 117
 118 /* Read / Write SPI device default max speed hz */
 119 #define SPI_IOC_RD_MAX_SPEED_HZ         _IOR(SPI_IOC_MAGIC, 4, __u32)
 120 #define SPI_IOC_WR_MAX_SPEED_HZ         _IOW(SPI_IOC_MAGIC, 4, __u32)
 121
 122
 123
 124 #endif /* SPIDEV_H */