blob: c42b7ab75711bfd43e60ef90ce525ef367d1eaac [file] [log] [blame]
/* Copyright 2012 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/* SPI interface for Chrome EC */
#ifndef __CROS_EC_SPI_H
#define __CROS_EC_SPI_H
/*
* SPI Clock polarity and phase mode (0 - 3)
* @code
* clk mode | POL PHA
* ---------+--------
* 0 | 0 0
* 1 | 0 1
* 2 | 1 0
* 3 | 1 1
* ---------+--------
* @endcode
*/
enum spi_clock_mode {
SPI_CLOCK_MODE0 = 0,
SPI_CLOCK_MODE1 = 1,
SPI_CLOCK_MODE2 = 2,
SPI_CLOCK_MODE3 = 3
};
struct spi_device_t {
/*
* SPI port the device is connected to.
* On some architecture, this is SPI master port index,
* on other the SPI port index directly.
*/
uint8_t port;
/*
* Clock divisor to talk to SPI device.
* If several devices share the same port, we select the lowest speed.
*/
uint8_t div;
/* gpio used for chip selection. */
enum gpio_signal gpio_cs;
};
extern const struct spi_device_t spi_devices[];
extern const unsigned int spi_devices_used;
/*
* The first port in spi_devices defines the port to access the SPI flash.
* The first gpio defines the CS GPIO to access the flash,
* if used.
*/
#define SPI_FLASH_DEVICE (&spi_devices[0])
/*
* Enable / disable the SPI port. When the port is disabled, all its I/O lines
* are high-Z so the EC won't interfere with other devices on the SPI bus.
*
* @param port port id to work on.
* @param enable 1 to enable the port, 0 to disable it.
*/
int spi_enable(int port, int enable);
#define SPI_READBACK_ALL (-1)
/* Issue a SPI transaction. Assumes SPI port has already been enabled.
*
* Transmits <txlen> bytes from <txdata>, throwing away the corresponding
* received data, then transmits <rxlen> dummy bytes, saving the received data
* in <rxdata>.
* If SPI_READBACK_ALL is set in <rxlen>, the received data during transmission
* is recorded in rxdata buffer and it assumes that the real <rxlen> is equal
* to <txlen>.
*
* @param spi_device the SPI device to use
* @param txdata buffer to transmit
* @param txlen number of bytes in txdata.
* @param rxdata receive buffer.
* @param rxlen number of bytes in rxdata or SPI_READBACK_ALL.
*/
int spi_transaction(const struct spi_device_t *spi_device,
const uint8_t *txdata, int txlen,
uint8_t *rxdata, int rxlen);
/* Similar to spi_transaction(), but hands over to DMA for reading response.
* Must call spi_transaction_flush() after this to make sure the response is
* received.
* Contrary the regular spi_transaction(), this function does NOT lock the
* SPI port, it's up to the caller to ensure proper mutual exclusion if needed.
*/
int spi_transaction_async(const struct spi_device_t *spi_device,
const uint8_t *txdata, int txlen,
uint8_t *rxdata, int rxlen);
/* Wait for async response received */
int spi_transaction_flush(const struct spi_device_t *spi_device);
/* Wait for async response received but do not de-assert chip select */
int spi_transaction_wait(const struct spi_device_t *spi_device);
#ifdef CONFIG_SPI
/**
* Called when the NSS level changes, signalling the start or end of a SPI
* transaction.
*
* @param signal GPIO signal that changed
*/
void spi_event(enum gpio_signal signal);
#else
static inline void spi_event(enum gpio_signal signal)
{
}
#endif
#endif /* __CROS_EC_SPI_H */