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129 lines
4.5 KiB
129 lines
4.5 KiB
/*
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* include/linux/spi/spidev.h
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*
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* Copyright (C) 2006 SWAPP
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* Andrea Paterniani <a.paterniani@swapp-eng.it>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef SPIDEV_H
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#define SPIDEV_H
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#include <linux/types.h>
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/* User space versions of kernel symbols for SPI clocking modes,
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* matching <linux/spi/spi.h>
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*/
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#define SPI_CPHA 0x01
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#define SPI_CPOL 0x02
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#define SPI_MODE_0 (0|0)
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#define SPI_MODE_1 (0|SPI_CPHA)
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#define SPI_MODE_2 (SPI_CPOL|0)
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#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
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#define SPI_CS_HIGH 0x04
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#define SPI_LSB_FIRST 0x08
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#define SPI_3WIRE 0x10
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#define SPI_LOOP 0x20
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/*---------------------------------------------------------------------------*/
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/* IOCTL commands */
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#define SPI_IOC_MAGIC 'k'
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/**
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* struct spi_ioc_transfer - describes a single SPI transfer
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* @tx_buf: Holds pointer to userspace buffer with transmit data, or null.
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* If no data is provided, zeroes are shifted out.
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* @rx_buf: Holds pointer to userspace buffer for receive data, or null.
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* @len: Length of tx and rx buffers, in bytes.
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* @speed_hz: Temporary override of the device's bitrate.
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* @bits_per_word: Temporary override of the device's wordsize.
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* @delay_usecs: If nonzero, how long to delay after the last bit transfer
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* before optionally deselecting the device before the next transfer.
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* @cs_change: True to deselect device before starting the next transfer.
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*
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* This structure is mapped directly to the kernel spi_transfer structure;
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* the fields have the same meanings, except of course that the pointers
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* are in a different address space (and may be of different sizes in some
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* cases, such as 32-bit i386 userspace over a 64-bit x86_64 kernel).
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* Zero-initialize the structure, including currently unused fields, to
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* accomodate potential future updates.
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*
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* SPI_IOC_MESSAGE gives userspace the equivalent of kernel spi_sync().
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* Pass it an array of related transfers, they'll execute together.
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* Each transfer may be half duplex (either direction) or full duplex.
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*
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* struct spi_ioc_transfer mesg[4];
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* ...
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* status = ioctl(fd, SPI_IOC_MESSAGE(4), mesg);
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*
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* So for example one transfer might send a nine bit command (right aligned
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* in a 16-bit word), the next could read a block of 8-bit data before
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* terminating that command by temporarily deselecting the chip; the next
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* could send a different nine bit command (re-selecting the chip), and the
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* last transfer might write some register values.
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*/
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struct spi_ioc_transfer {
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__u64 tx_buf;
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__u64 rx_buf;
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__u32 len;
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__u32 speed_hz;
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__u16 delay_usecs;
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__u8 bits_per_word;
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__u8 cs_change;
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__u32 pad;
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/* If the contents of 'struct spi_ioc_transfer' ever change
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* incompatibly, then the ioctl number (currently 0) must change;
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* ioctls with constant size fields get a bit more in the way of
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* error checking than ones (like this) where that field varies.
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*
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* NOTE: struct layout is the same in 64bit and 32bit userspace.
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*/
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};
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/* not all platforms use <asm-generic/ioctl.h> or _IOC_TYPECHECK() ... */
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#define SPI_MSGSIZE(N) \
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((((N)*(sizeof (struct spi_ioc_transfer))) < (1 << _IOC_SIZEBITS)) \
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? ((N)*(sizeof (struct spi_ioc_transfer))) : 0)
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#define SPI_IOC_MESSAGE(N) _IOW(SPI_IOC_MAGIC, 0, char[SPI_MSGSIZE(N)])
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/* Read / Write of SPI mode (SPI_MODE_0..SPI_MODE_3) */
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#define SPI_IOC_RD_MODE _IOR(SPI_IOC_MAGIC, 1, __u8)
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#define SPI_IOC_WR_MODE _IOW(SPI_IOC_MAGIC, 1, __u8)
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/* Read / Write SPI bit justification */
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#define SPI_IOC_RD_LSB_FIRST _IOR(SPI_IOC_MAGIC, 2, __u8)
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#define SPI_IOC_WR_LSB_FIRST _IOW(SPI_IOC_MAGIC, 2, __u8)
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/* Read / Write SPI device word length (1..N) */
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#define SPI_IOC_RD_BITS_PER_WORD _IOR(SPI_IOC_MAGIC, 3, __u8)
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#define SPI_IOC_WR_BITS_PER_WORD _IOW(SPI_IOC_MAGIC, 3, __u8)
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/* Read / Write SPI device default max speed hz */
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#define SPI_IOC_RD_MAX_SPEED_HZ _IOR(SPI_IOC_MAGIC, 4, __u32)
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#define SPI_IOC_WR_MAX_SPEED_HZ _IOW(SPI_IOC_MAGIC, 4, __u32)
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#endif /* SPIDEV_H */
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