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/*
* Simulate a SPI port and clients (see README.sandbox for details)
*
* Copyright (c) 2011-2013 The Chromium OS Authors.
* See file CREDITS for list of people who contributed to this
* project.
*
* Licensed under the GPL-2 or later.
*/
#ifndef __ASM_SPI_H__
#define __ASM_SPI_H__
#include <linux/types.h>
/*
* The interface between the SPI bus and the SPI client. The bus will
* instantiate a client, and that then call into it via these entry
* points. These should be enough for the client to emulate the SPI
* device just like the real hardware.
*/
struct sandbox_spi_emu_ops {
/* The bus wants to instantiate a new client, so setup everything */
int (*setup)(void **priv, const char *spec);
/* The bus is done with us, so break things down */
void (*free)(void *priv);
/* The CS has been "activated" -- we won't worry about low/high */
void (*cs_activate)(void *priv);
/* The CS has been "deactivated" -- we won't worry about low/high */
void (*cs_deactivate)(void *priv);
/* The client is rx-ing bytes from the bus, so it should tx some */
int (*xfer)(void *priv, const u8 *rx, u8 *tx, uint bytes);
};
/*
* There are times when the data lines are allowed to tristate. What
* is actually sensed on the line depends on the hardware. It could
* always be 0xFF/0x00 (if there are pull ups/downs), or things could
* float and so we'd get garbage back. This func encapsulates that
* scenario so we can worry about the details here.
*/
static inline void sandbox_spi_tristate(u8 *buf, uint len)
{
/* XXX: make this into a user config option ? */
memset(buf, 0xff, len);
}
/*
* Extract the bus/cs from the spi spec and return the start of the spi
* client spec. If the bus/cs are invalid for the current config, then
* it returns NULL.
*
* Example: arg="0:1:foo" will set bus to 0, cs to 1, and return "foo"
*/
const char *sandbox_spi_parse_spec(const char *arg, unsigned long *bus,
unsigned long *cs);
#endif
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