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Diffstat (limited to 'include/linux/spi/spidev.h')
| -rw-r--r-- | include/linux/spi/spidev.h | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/include/linux/spi/spidev.h b/include/linux/spi/spidev.h new file mode 100644 index 00000000000..7d700be5749 --- /dev/null +++ b/include/linux/spi/spidev.h @@ -0,0 +1,124 @@ +/* + * include/linux/spi/spidev.h + * + * Copyright (C) 2006 SWAPP + * Andrea Paterniani <a.paterniani@swapp-eng.it> + * + * 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., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#ifndef SPIDEV_H +#define SPIDEV_H + + +/* User space versions of kernel symbols for SPI clocking modes, + * matching <linux/spi/spi.h> + */ + +#define SPI_CPHA 0x01 +#define SPI_CPOL 0x02 + +#define SPI_MODE_0 (0|0) +#define SPI_MODE_1 (0|SPI_CPHA) +#define SPI_MODE_2 (SPI_CPOL|0) +#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA) + + +/*---------------------------------------------------------------------------*/ + +/* IOCTL commands */ + +#define SPI_IOC_MAGIC 'k' + +/** + * struct spi_ioc_transfer - describes a single SPI transfer + * @tx_buf: Holds pointer to userspace buffer with transmit data, or null. + * If no data is provided, zeroes are shifted out. + * @rx_buf: Holds pointer to userspace buffer for receive data, or null. + * @len: Length of tx and rx buffers, in bytes. + * @speed_hz: Temporary override of the device's bitrate. + * @bits_per_word: Temporary override of the device's wordsize. + * @delay_usecs: If nonzero, how long to delay after the last bit transfer + * before optionally deselecting the device before the next transfer. + * @cs_change: True to deselect device before starting the next transfer. + * + * This structure is mapped directly to the kernel spi_transfer structure; + * the fields have the same meanings, except of course that the pointers + * are in a different address space (and may be of different sizes in some + * cases, such as 32-bit i386 userspace over a 64-bit x86_64 kernel). + * Zero-initialize the structure, including currently unused fields, to + * accomodate potential future updates. + * + * SPI_IOC_MESSAGE gives userspace the equivalent of kernel spi_sync(). + * Pass it an array of related transfers, they'll execute together. + * Each transfer may be half duplex (either direction) or full duplex. + * + * struct spi_ioc_transfer mesg[4]; + * ... + * status = ioctl(fd, SPI_IOC_MESSAGE(4), mesg); + * + * So for example one transfer might send a nine bit command (right aligned + * in a 16-bit word), the next could read a block of 8-bit data before + * terminating that command by temporarily deselecting the chip; the next + * could send a different nine bit command (re-selecting the chip), and the + * last transfer might write some register values. + */ +struct spi_ioc_transfer { + __u64 tx_buf; + __u64 rx_buf; + + __u32 len; + __u32 speed_hz; + + __u16 delay_usecs; + __u8 bits_per_word; + __u8 cs_change; + __u32 pad; + + /* If the contents of 'struct spi_ioc_transfer' ever change + * incompatibly, then the ioctl number (currently 0) must change; + * ioctls with constant size fields get a bit more in the way of + * error checking than ones (like this) where that field varies. + * + * NOTE: struct layout is the same in 64bit and 32bit userspace. + */ +}; + +/* not all platforms use <asm-generic/ioctl.h> or _IOC_TYPECHECK() ... */ +#define SPI_MSGSIZE(N) \ + ((((N)*(sizeof (struct spi_ioc_transfer))) < (1 << _IOC_SIZEBITS)) \ + ? ((N)*(sizeof (struct spi_ioc_transfer))) : 0) +#define SPI_IOC_MESSAGE(N) _IOW(SPI_IOC_MAGIC, 0, char[SPI_MSGSIZE(N)]) + + +/* Read / Write of SPI mode (SPI_MODE_0..SPI_MODE_3) */ +#define SPI_IOC_RD_MODE _IOR(SPI_IOC_MAGIC, 1, __u8) +#define SPI_IOC_WR_MODE _IOW(SPI_IOC_MAGIC, 1, __u8) + +/* Read / Write SPI bit justification */ +#define SPI_IOC_RD_LSB_FIRST _IOR(SPI_IOC_MAGIC, 2, __u8) +#define SPI_IOC_WR_LSB_FIRST _IOW(SPI_IOC_MAGIC, 2, __u8) + +/* Read / Write SPI device word length (1..N) */ +#define SPI_IOC_RD_BITS_PER_WORD _IOR(SPI_IOC_MAGIC, 3, __u8) +#define SPI_IOC_WR_BITS_PER_WORD _IOW(SPI_IOC_MAGIC, 3, __u8) + +/* Read / Write SPI device default max speed hz */ +#define SPI_IOC_RD_MAX_SPEED_HZ _IOR(SPI_IOC_MAGIC, 4, __u32) +#define SPI_IOC_WR_MAX_SPEED_HZ _IOW(SPI_IOC_MAGIC, 4, __u32) + + + +#endif /* SPIDEV_H */ |