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 #define SPI_CS_HIGH 0x04 39 #define SPI_LSB_FIRST 0x08 40 #define SPI_3WIRE 0x10 41 #define SPI_LOOP 0x20 42 43 /*---------------------------------------------------------------------------*/ 44 45 /* IOCTL commands */ 46 47 #define SPI_IOC_MAGIC 'k' 48 49 /** 50 * struct spi_ioc_transfer - describes a single SPI transfer 51 * @tx_buf: Holds pointer to userspace buffer with transmit data, or null. 52 * If no data is provided, zeroes are shifted out. 53 * @rx_buf: Holds pointer to userspace buffer for receive data, or null. 54 * @len: Length of tx and rx buffers, in bytes. 55 * @speed_hz: Temporary override of the device's bitrate. 56 * @bits_per_word: Temporary override of the device's wordsize. 57 * @delay_usecs: If nonzero, how long to delay after the last bit transfer 58 * before optionally deselecting the device before the next transfer. 59 * @cs_change: True to deselect device before starting the next transfer. 60 * 61 * This structure is mapped directly to the kernel spi_transfer structure; 62 * the fields have the same meanings, except of course that the pointers 63 * are in a different address space (and may be of different sizes in some 64 * cases, such as 32-bit i386 userspace over a 64-bit x86_64 kernel). 65 * Zero-initialize the structure, including currently unused fields, to 66 * accomodate potential future updates. 67 * 68 * SPI_IOC_MESSAGE gives userspace the equivalent of kernel spi_sync(). 69 * Pass it an array of related transfers, they'll execute together. 70 * Each transfer may be half duplex (either direction) or full duplex. 71 * 72 * struct spi_ioc_transfer mesg[4]; 73 * ... 74 * status = ioctl(fd, SPI_IOC_MESSAGE(4), mesg); 75 * 76 * So for example one transfer might send a nine bit command (right aligned 77 * in a 16-bit word), the next could read a block of 8-bit data before 78 * terminating that command by temporarily deselecting the chip; the next 79 * could send a different nine bit command (re-selecting the chip), and the 80 * last transfer might write some register values. 81 */ 82 struct spi_ioc_transfer { 83 __u64 tx_buf; 84 __u64 rx_buf; 85 86 __u32 len; 87 __u32 speed_hz; 88 89 __u16 delay_usecs; 90 __u8 bits_per_word; 91 __u8 cs_change; 92 __u32 pad; 93 94 /* If the contents of 'struct spi_ioc_transfer' ever change 95 * incompatibly, then the ioctl number (currently 0) must change; 96 * ioctls with constant size fields get a bit more in the way of 97 * error checking than ones (like this) where that field varies. 98 * 99 * NOTE: struct layout is the same in 64bit and 32bit userspace. 100 */ 101 }; 102 103 /* not all platforms use <asm-generic/ioctl.h> or _IOC_TYPECHECK() ... */ 104 #define SPI_MSGSIZE(N) \ 105 ((((N)*(sizeof (struct spi_ioc_transfer))) < (1 << _IOC_SIZEBITS)) \ 106 ? ((N)*(sizeof (struct spi_ioc_transfer))) : 0) 107 #define SPI_IOC_MESSAGE(N) _IOW(SPI_IOC_MAGIC, 0, char[SPI_MSGSIZE(N)]) 108 109 110 /* Read / Write of SPI mode (SPI_MODE_0..SPI_MODE_3) */ 111 #define SPI_IOC_RD_MODE _IOR(SPI_IOC_MAGIC, 1, __u8) 112 #define SPI_IOC_WR_MODE _IOW(SPI_IOC_MAGIC, 1, __u8) 113 114 /* Read / Write SPI bit justification */ 115 #define SPI_IOC_RD_LSB_FIRST _IOR(SPI_IOC_MAGIC, 2, __u8) 116 #define SPI_IOC_WR_LSB_FIRST _IOW(SPI_IOC_MAGIC, 2, __u8) 117 118 /* Read / Write SPI device word length (1..N) */ 119 #define SPI_IOC_RD_BITS_PER_WORD _IOR(SPI_IOC_MAGIC, 3, __u8) 120 #define SPI_IOC_WR_BITS_PER_WORD _IOW(SPI_IOC_MAGIC, 3, __u8) 121 122 /* Read / Write SPI device default max speed hz */ 123 #define SPI_IOC_RD_MAX_SPEED_HZ _IOR(SPI_IOC_MAGIC, 4, __u32) 124 #define SPI_IOC_WR_MAX_SPEED_HZ _IOW(SPI_IOC_MAGIC, 4, __u32) 125 126 127 128 #endif /* SPIDEV_H */ 129