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author | Mike Frysinger <vapier@gentoo.org> | 2013-12-03 16:43:26 -0700 |
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committer | Simon Glass <sjg@chromium.org> | 2013-12-09 12:22:18 -0700 |
commit | 6122813fa2cb9eef4a211bd47292322096db9fa8 (patch) | |
tree | e795422d0412c6093736dd1c31b72155e254a5b6 /arch/sandbox/include/asm/spi.h | |
parent | afb6134f30db2f97bae81ff56c7c9e4eee07b396 (diff) | |
download | u-boot-imx-6122813fa2cb9eef4a211bd47292322096db9fa8.zip u-boot-imx-6122813fa2cb9eef4a211bd47292322096db9fa8.tar.gz u-boot-imx-6122813fa2cb9eef4a211bd47292322096db9fa8.tar.bz2 |
sandbox: spi: Add SPI emulation bus
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>
Diffstat (limited to 'arch/sandbox/include/asm/spi.h')
-rw-r--r-- | arch/sandbox/include/asm/spi.h | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/arch/sandbox/include/asm/spi.h b/arch/sandbox/include/asm/spi.h new file mode 100644 index 0000000..49b4a0f --- /dev/null +++ b/arch/sandbox/include/asm/spi.h @@ -0,0 +1,58 @@ +/* + * 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 |