152df810ff
Whenever spi_xfer is called and whenver it's implemented, the natural unit for the amount of data being transfered is bytes. The API expected things to be expressed in bits, however, which led to a lot of multiplying and dividing by eight, and checkes to make sure things were multiples of eight. All of that can now be removed. BUG=None TEST=Built and booted on link, falco, peach_pit and nyan and looked for SPI errors in the firmware log. Built for rambi. BRANCH=None Change-Id: I02365bdb6960a35def7be7a0cd1aa0a2cc09392f Signed-off-by: Gabe Black <gabeblack@google.com> Reviewed-on: https://chromium-review.googlesource.com/192049 Reviewed-by: Gabe Black <gabeblack@chromium.org> Tested-by: Gabe Black <gabeblack@chromium.org> Commit-Queue: Gabe Black <gabeblack@chromium.org>
139 lines
4.4 KiB
C
139 lines
4.4 KiB
C
/*
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* (C) Copyright 2001
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* Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (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., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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#ifndef _SPI_GENERIC_H_
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#define _SPI_GENERIC_H_
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#include <stdint.h>
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/* Controller-specific definitions: */
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/* SPI opcodes */
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#define SPI_OPCODE_WREN 0x06
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#define SPI_OPCODE_FAST_READ 0x0b
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#define SPI_READ_FLAG 0x01
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#define SPI_WRITE_FLAG 0x02
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/*-----------------------------------------------------------------------
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* Representation of a SPI slave, i.e. what we're communicating with.
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*
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* Drivers are expected to extend this with controller-specific data.
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*
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* bus: ID of the bus that the slave is attached to.
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* cs: ID of the chip select connected to the slave.
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* rw: Read or Write flag
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*/
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struct spi_slave {
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unsigned int bus;
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unsigned int cs;
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unsigned int rw;
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};
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/*-----------------------------------------------------------------------
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* Initialization, must be called once on start up.
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*
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*/
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void spi_init(void);
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/*-----------------------------------------------------------------------
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* Set up communications parameters for a SPI slave.
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*
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* This must be called once for each slave. Note that this function
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* usually doesn't touch any actual hardware, it only initializes the
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* contents of spi_slave so that the hardware can be easily
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* initialized later.
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*
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* bus: Bus ID of the slave chip.
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* cs: Chip select ID of the slave chip on the specified bus.
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*
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* Returns: A spi_slave reference that can be used in subsequent SPI
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* calls, or NULL if one or more of the parameters are not supported.
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*/
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struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs);
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/*-----------------------------------------------------------------------
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* Claim the bus and prepare it for communication with a given slave.
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*
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* This must be called before doing any transfers with a SPI slave. It
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* will enable and initialize any SPI hardware as necessary, and make
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* sure that the SCK line is in the correct idle state. It is not
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* allowed to claim the same bus for several slaves without releasing
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* the bus in between.
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*
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* slave: The SPI slave
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*
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* Returns: 0 if the bus was claimed successfully, or a negative value
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* if it wasn't.
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*/
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int spi_claim_bus(struct spi_slave *slave);
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/*-----------------------------------------------------------------------
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* Release the SPI bus
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*
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* This must be called once for every call to spi_claim_bus() after
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* all transfers have finished. It may disable any SPI hardware as
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* appropriate.
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*
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* slave: The SPI slave
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*/
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void spi_release_bus(struct spi_slave *slave);
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/*-----------------------------------------------------------------------
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* SPI transfer
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*
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* spi_xfer() interface:
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* slave: The SPI slave which will be sending/receiving the data.
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* dout: Pointer to a string of bytes to send out.
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* bytesout: How many bytes to write.
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* din: Pointer to a string of bytes that will be filled in.
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* bytesin: How many bytes to read.
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*
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* Returns: 0 on success, not 0 on failure
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*/
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int spi_xfer(struct spi_slave *slave, const void *dout, unsigned int bytesout,
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void *din, unsigned int bytesin);
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/*-----------------------------------------------------------------------
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* Write 8 bits, then read 8 bits.
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* slave: The SPI slave we're communicating with
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* byte: Byte to be written
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*
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* Returns: The value that was read, or a negative value on error.
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*
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* TODO: This function probably shouldn't be inlined.
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*/
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static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
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{
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unsigned char dout[2];
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unsigned char din[2];
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int ret;
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dout[0] = byte;
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dout[1] = 0;
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ret = spi_xfer(slave, dout, 2, din, 2);
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return ret < 0 ? ret : din[1];
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}
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#endif /* _SPI_GENERIC_H_ */
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