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https://github.com/RIOT-OS/RIOT.git
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9e5f7b6797
There is no way to properly handle incorrect SPI parameters at run time, so just having an assertion blow up is the better choice here. As most instances of `spi_acquire()` don't check the return value anyway, this will improve debugging experience quite a bit. Some implementation of spi_acquire() don't even check parameters anyway.
430 lines
15 KiB
C
430 lines
15 KiB
C
/*
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* Copyright (C) 2014-2016 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @defgroup drivers_periph_spi SPI
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* @ingroup drivers_periph
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* @brief Low-level SPI peripheral driver
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*
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* This interface defines an abstraction for using a CPU's hardware SPI units.
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* The interface only supports SPI master mode.
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*
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* As SPI buses can have multiple devices connected to them they are to be
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* considered as shared resources. To reflect this, the SPI interface is based
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* on a transaction model. This requires that the bus needs to be acquired
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* before usage and released afterwards, using the `spi_acquire()` and the
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* `spi_release()` functions.
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*
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* This interface supports both software and hardware chip select lines. This is
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* reflected by the cpi_cs_t type, which overloads the gpio_t type with platform
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* specific values for defining platform dependent hardware chip select lines.
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*
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* Some devices have however very uncommon requirements on the usage and the
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* timings of their chip select line. For those cases this interface allows to
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* manage the chip select line manually from the user code (e.g. by calling
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* gpio_set/clear explicitly) while deactivating the SPI driver internal chip
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* select handling by passing @ref GPIO_UNDEF as CS parameter.
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*
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* In the time, when the SPI bus is not used, the SPI unit should be in
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* low-power mode to save energy.
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*
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* The SPI unit's initialization is split into 3 parts:
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* 1. `spi_init()` should be called once for each SPI unit defined by a board
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* during system initialization.
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* 2. `spi_init_cs()` should be called during device driver initialization, as
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* each chip select pin/line is used uniquely by a specific device, i.e. chip
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* select lines are no shared resource.
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* 3. `spi_acquire()` needs to be called for each new transaction. This function
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* configures the bus with specific parameters (clock, mode) for the duration
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* of that transaction.
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*
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* # (Low-) Power Implications
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*
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* As SPI buses are shared peripherals and the interfaces implements a
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* transaction based paradigm, we leverage this for the SPI peripherals power
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* management. After calling spi_init(), the SPI peripheral **should** be
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* completely powered off (e.g. through peripheral clock gating). It **should**
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* subsequently only be powered on and enabled in between spi_acquire() and
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* spi_release() blocks.
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*
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* In case the SPI driver implementation puts the active thread to sleep during
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* data transfer (e.g. when using DMA), the implementation might need to block
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* certain power states during that time.
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*
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* @{
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* @file
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* @brief Low-level SPI peripheral driver interface definition
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*
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* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
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*/
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#ifndef PERIPH_SPI_H
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#define PERIPH_SPI_H
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#include <errno.h>
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#include <limits.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include "periph_cpu.h"
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#include "periph_conf.h"
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#include "periph/gpio.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Default SPI device access macro
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*/
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#ifndef SPI_DEV
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#define SPI_DEV(x) (x)
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#endif
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/**
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* @brief Define global value for undefined SPI device
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*/
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#ifndef SPI_UNDEF
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#define SPI_UNDEF (UINT_MAX)
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#endif
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/**
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* @brief Define value for unused CS line
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*/
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#ifndef SPI_CS_UNDEF
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#define SPI_CS_UNDEF (GPIO_UNDEF)
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#endif
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/**
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* @brief Default SPI hardware chip select access macro
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*
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* Per default, we map all hardware chip select lines to be not defined. If an
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* implementation makes use of HW chip select lines, this value needs to be
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* overridden by the corresponding CPU.
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*/
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#ifndef SPI_HWCS
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#define SPI_HWCS(x) (SPI_CS_UNDEF)
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#endif
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/**
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* @brief Default type for SPI devices
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*/
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#ifndef HAVE_SPI_T
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typedef unsigned int spi_t;
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#endif
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/**
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* @brief Chip select pin type overlaps with gpio_t so it can be casted to
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* this
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*/
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#ifndef HAVE_SPI_CS_T
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typedef gpio_t spi_cs_t;
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#endif
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/**
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* @brief Status codes used by the SPI driver interface
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*
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* @deprecated Use negative errno codes instead. The enum is still provided
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* for backwards compatibility
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*/
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enum {
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SPI_OK = 0, /**< everything went as planned */
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SPI_NODEV = -ENXIO, /**< invalid SPI bus specified */
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SPI_NOCS = -EINVAL, /**< invalid chip select line specified */
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SPI_NOMODE = -EINVAL, /**< selected mode is not supported */
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SPI_NOCLK = -EINVAL /**< selected clock value is not supported */
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};
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/**
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* @brief Available SPI modes, defining the configuration of clock polarity
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* and clock phase
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*
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* RIOT is using the mode numbers as commonly defined by most vendors
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* (https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus#Mode_numbers):
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*
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* - MODE_0: CPOL=0, CPHA=0 - The first data bit is sampled by the receiver on
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* the first SCK rising SCK edge (this mode is used most often).
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* - MODE_1: CPOL=0, CPHA=1 - The first data bit is sampled by the receiver on
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* the second rising SCK edge.
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* - MODE_2: CPOL=1, CPHA=0 - The first data bit is sampled by the receiver on
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* the first falling SCK edge.
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* - MODE_3: CPOL=1, CPHA=1 - The first data bit is sampled by the receiver on
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* the second falling SCK edge.
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*/
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#ifndef HAVE_SPI_MODE_T
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typedef enum {
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SPI_MODE_0 = 0, /**< CPOL=0, CPHA=0 */
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SPI_MODE_1, /**< CPOL=0, CPHA=1 */
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SPI_MODE_2, /**< CPOL=1, CPHA=0 */
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SPI_MODE_3 /**< CPOL=1, CPHA=1 */
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} spi_mode_t;
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#endif
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/**
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* @brief Available SPI clock speeds
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*
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* The actual speed of the bus can vary to some extend, as the combination of
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* CPU clock and available prescaler values on certain platforms may not make
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* the exact values possible.
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*/
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#ifndef HAVE_SPI_CLK_T
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typedef enum {
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SPI_CLK_100KHZ = 0, /**< drive the SPI bus with 100KHz */
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SPI_CLK_400KHZ, /**< drive the SPI bus with 400KHz */
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SPI_CLK_1MHZ, /**< drive the SPI bus with 1MHz */
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SPI_CLK_5MHZ, /**< drive the SPI bus with 5MHz */
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SPI_CLK_10MHZ /**< drive the SPI bus with 10MHz */
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} spi_clk_t;
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#endif
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/**
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* @brief Basic initialization of the given SPI bus
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*
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* This function does the basic initialization including pin configuration for
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* MISO, MOSI, and CLK pins. After initialization, the given device should be
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* in power down state.
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*
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* This function is intended to be called by the board initialization code
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* during system startup to prepare the (shared) SPI device for further usage.
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* It uses the board specific initialization parameters as defined in the
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* board's `periph_conf.h`.
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*
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* Errors (e.g. invalid @p bus parameter) are not signaled through a return
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* value, but should be signaled using the assert() function internally.
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*
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* @note This function MUST not be called more than once per bus!
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*
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* @param[in] bus SPI device to initialize
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*/
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void spi_init(spi_t bus);
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/**
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* @brief Initialize the used SPI bus pins, i.e. MISO, MOSI, and CLK
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*
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* After calling spi_init, the pins must be initialized (i.e. spi_init is
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* calling this function internally). In normal cases, this function will not be
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* used. But there are some devices (e.g. CC110x), that use SPI bus lines also
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* for other purposes and need the option to dynamically re-configure one or
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* more of the used pins. So they can take control over certain pins and return
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* control back to the SPI driver using this function.
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*
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* This function must be called after @ref spi_deinit_pins to return the pins to
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* SPI operation.
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*
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* The pins used are configured in the board's periph_conf.h.
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*
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* @param[in] bus SPI device the pins are configure for
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*/
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void spi_init_pins(spi_t bus);
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/**
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* @brief Initialize the given chip select pin
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*
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* The chip select can be any generic GPIO pin (e.g. GPIO_PIN(x,y)), or it can
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* be a hardware chip select line. The existence and number of hardware chip
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* select lines depends on the underlying platform and the actual pins used for
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* hardware chip select lines are defined in the board's `periph_conf.h`.
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*
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* Define the used chip select line using the @ref SPI_HWCS(x) macro for
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* hardware chip select line `x` or the GPIO_PIN(x,y) macro for using any
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* GPIO pin for manual chip select.
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*
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* @param[in] bus SPI device that is used with the given CS line
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* @param[in] cs chip select pin to initialize
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*
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* @retval 0 success
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* @retval -ENXIO invalid device
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* @retval -EINVAL invalid CS pin/line
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*/
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int spi_init_cs(spi_t bus, spi_cs_t cs);
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#if defined(MODULE_PERIPH_SPI_RECONFIGURE) || DOXYGEN
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/**
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* @brief Change the pins of the given SPI bus back to plain GPIO functionality
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*
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* The pin mux of the MISO, MOSI and CLK pins of the bus will be changed back to
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* default (GPIO) mode and the SPI bus is powered off.
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* This allows to use the SPI pins for another function and return to SPI
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* functionality again by calling spi_init_pins()
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*
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* If you want the pin to be in a defined state, call gpio_init() on it.
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*
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* The bus MUST not be acquired before initializing it, as this is handled
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* internally by the spi_deinit_pins() function!
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*
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* Calls to spi_acquire() will block until spi_init_pins() is called again.
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*
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* @note Until this is implemented on all platforms, this requires the
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* periph_spi_reconfigure feature to be used.
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*
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* @param[in] dev the device to de-initialize
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*/
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void spi_deinit_pins(spi_t dev);
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#if DOXYGEN
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/**
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* @brief Get the MISO pin of the given SPI bus.
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*
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* @param[in] dev The device to query
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*
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* @note Until this is implemented on all platforms, this requires the
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* periph_spi_reconfigure feature to be used.
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*
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* @return The GPIO used for the SPI MISO line.
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*/
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gpio_t spi_pin_miso(spi_t dev);
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/**
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* @brief Get the MOSI pin of the given SPI bus.
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*
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* @param[in] dev The device to query
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*
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* @note Until this is implemented on all platforms, this requires the
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* periph_spi_reconfigure feature to be used.
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*
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* @return The GPIO used for the SPI MOSI line.
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*/
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gpio_t spi_pin_mosi(spi_t dev);
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/**
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* @brief Get the CLK pin of the given SPI bus.
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*
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* @param[in] dev The device to query
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*
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* @note Until this is implemented on all platforms, this requires the
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* periph_spi_reconfigure feature to be used.
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*
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* @return The GPIO used for the SPI CLK line.
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*/
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gpio_t spi_pin_clk(spi_t dev);
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#endif /* DOXYGEN */
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#endif /* MODULE_PERIPH_SPI_RECONFIGURE */
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#if defined(MODULE_PERIPH_SPI_GPIO_MODE) || DOXYGEN
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/**
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* @brief SPI gpio mode
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*/
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typedef struct {
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gpio_mode_t mosi; /**< GPIO mode used for MOSI pin */
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gpio_mode_t miso; /**< GPIO mode used for MISO pin */
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gpio_mode_t sclk; /**< GPIO mode used for SCLK pin */
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} spi_gpio_mode_t;
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/**
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* @brief Initialize MOSI/MISO/SCLK pins with adapted GPIO modes
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*
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* @param[in] bus SPI device that is used with the given CS line
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* @param[in] mode a struct containing the 3 modes to use on each pin
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*
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* @retval 0 success
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* @retval <0 error
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*/
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int spi_init_with_gpio_mode(spi_t bus, spi_gpio_mode_t mode);
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#endif
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/**
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* @brief Start a new SPI transaction
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*
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* Starting a new SPI transaction will get exclusive access to the SPI bus
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* and configure it according to the given values. If another SPI transaction
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* is active when this function is called, this function will block until the
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* other transaction is complete (spi_relase was called).
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*
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* @param[in] bus SPI device to access
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* @param[in] cs chip select pin/line to use, set to SPI_CS_UNDEF if chip
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* select should not be handled by the SPI driver
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* @param[in] mode mode to use for the new transaction
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* @param[in] clk bus clock speed to use for the transaction
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*
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* @pre All parameters are valid and supported, otherwise an assertion blows
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* up (if assertions are enabled).
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*/
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void spi_acquire(spi_t bus, spi_cs_t cs, spi_mode_t mode, spi_clk_t clk);
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/**
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* @brief Finish an ongoing SPI transaction by releasing the given SPI bus
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*
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* After release, the given SPI bus should be fully powered down until acquired
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* again.
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*
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* @param[in] bus SPI device to release
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*/
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void spi_release(spi_t bus);
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/**
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* @brief Transfer one byte on the given SPI bus
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*
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* @param[in] bus SPI device to use
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* @param[in] cs chip select pin/line to use, set to SPI_CS_UNDEF if chip
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* select should not be handled by the SPI driver
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* @param[in] cont if true, keep device selected after transfer
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* @param[in] out byte to send out
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*
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* @return the received byte
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*/
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uint8_t spi_transfer_byte(spi_t bus, spi_cs_t cs, bool cont, uint8_t out);
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/**
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* @brief Transfer a number bytes using the given SPI bus
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*
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* @param[in] bus SPI device to use
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* @param[in] cs chip select pin/line to use, set to SPI_CS_UNDEF if chip
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* select should not be handled by the SPI driver
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* @param[in] cont if true, keep device selected after transfer
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* @param[in] out buffer to send data from, set NULL if only receiving
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* @param[out] in buffer to read into, set NULL if only sending
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* @param[in] len number of bytes to transfer
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*/
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void spi_transfer_bytes(spi_t bus, spi_cs_t cs, bool cont,
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const void *out, void *in, size_t len);
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/**
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* @brief Transfer one byte to/from a given register address
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*
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* This function is a shortcut function for easier handling of SPI devices that
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* implement a register based access scheme.
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*
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* @param[in] bus SPI device to use
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* @param[in] cs chip select pin/line to use, set to SPI_CS_UNDEF if chip
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* select should not be handled by the SPI driver
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* @param[in] reg register address to transfer data to/from
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* @param[in] out byte to send
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*
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* @return value that was read from the given register address
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*/
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uint8_t spi_transfer_reg(spi_t bus, spi_cs_t cs, uint8_t reg, uint8_t out);
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/**
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* @brief Transfer a number of bytes to/from a given register address
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*
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* This function is a shortcut function for easier handling of SPI devices that
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* implement a register based access scheme.
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*
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* @param[in] bus SPI device to use
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* @param[in] cs chip select pin/line to use, set to SPI_CS_UNDEF if chip
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* select should not be handled by the SPI driver
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* @param[in] reg register address to transfer data to/from
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* @param[in] out buffer to send data from, set NULL if only receiving
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* @param[out] in buffer to read into, set NULL if only sending
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* @param[in] len number of bytes to transfer
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*/
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void spi_transfer_regs(spi_t bus, spi_cs_t cs, uint8_t reg,
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const void *out, void *in, size_t len);
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#ifdef __cplusplus
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}
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#endif
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#endif /* PERIPH_SPI_H */
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/** @} */
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