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6122813fa2
This adds a SPI framework for people to hook up simulated SPI clients. Signed-off-by: Mike Frysinger <vapier@gentoo.org> Signed-off-by: Simon Glass <sjg@chromium.org>
58 lines
1.9 KiB
C
58 lines
1.9 KiB
C
/*
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* Simulate a SPI port and clients (see README.sandbox for details)
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*
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* Copyright (c) 2011-2013 The Chromium OS Authors.
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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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* Licensed under the GPL-2 or later.
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*/
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#ifndef __ASM_SPI_H__
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#define __ASM_SPI_H__
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#include <linux/types.h>
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/*
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* The interface between the SPI bus and the SPI client. The bus will
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* instantiate a client, and that then call into it via these entry
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* points. These should be enough for the client to emulate the SPI
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* device just like the real hardware.
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*/
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struct sandbox_spi_emu_ops {
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/* The bus wants to instantiate a new client, so setup everything */
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int (*setup)(void **priv, const char *spec);
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/* The bus is done with us, so break things down */
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void (*free)(void *priv);
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/* The CS has been "activated" -- we won't worry about low/high */
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void (*cs_activate)(void *priv);
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/* The CS has been "deactivated" -- we won't worry about low/high */
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void (*cs_deactivate)(void *priv);
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/* The client is rx-ing bytes from the bus, so it should tx some */
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int (*xfer)(void *priv, const u8 *rx, u8 *tx, uint bytes);
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};
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/*
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* There are times when the data lines are allowed to tristate. What
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* is actually sensed on the line depends on the hardware. It could
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* always be 0xFF/0x00 (if there are pull ups/downs), or things could
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* float and so we'd get garbage back. This func encapsulates that
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* scenario so we can worry about the details here.
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*/
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static inline void sandbox_spi_tristate(u8 *buf, uint len)
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{
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/* XXX: make this into a user config option ? */
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memset(buf, 0xff, len);
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}
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/*
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* Extract the bus/cs from the spi spec and return the start of the spi
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* client spec. If the bus/cs are invalid for the current config, then
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* it returns NULL.
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*
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* Example: arg="0:1:foo" will set bus to 0, cs to 1, and return "foo"
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*/
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const char *sandbox_spi_parse_spec(const char *arg, unsigned long *bus,
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unsigned long *cs);
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#endif
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