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The spidev driver doesn't currently expose all SPI communications modes to userspace. This passes them all through to the driver. Two of them are potentially troublesome, in the sense that they could cause hardware conflicts on shared busses. It might be appropriate to add some privilege checks for for those modes. Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
128 lines
4.5 KiB
C
128 lines
4.5 KiB
C
/*
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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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/* 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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