drivers/spi/spi_nrfx_spi.c

/*
 * Copyright (c) 2017 - 2018, Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <spi.h>
#include <nrfx_spi.h>

#define SYS_LOG_DOMAIN "spi_nrfx_spi"
#define SYS_LOG_LEVEL CONFIG_SYS_LOG_SPI_LEVEL
#include <logging/sys_log.h>

#include "spi_context.h"

struct spi_nrfx_data {
	struct spi_context ctx;
	size_t chunk_len;
	bool   busy;
};

struct spi_nrfx_config {
	nrfx_spi_t spi;
};

static inline struct spi_nrfx_data *get_dev_data(struct device *dev)
{
	return dev->driver_data;
}

static inline const struct spi_nrfx_config *get_dev_config(struct device *dev)
{
	return dev->config->config_info;
}

static inline nrf_spi_frequency_t get_nrf_spi_frequency(u32_t frequency)
{
	/* Get the highest supported frequency not exceeding the requested one.
	 */
	if (frequency < 250000) {
		return NRF_SPI_FREQ_125K;
	} else if (frequency < 500000) {
		return NRF_SPI_FREQ_250K;
	} else if (frequency < 1000000) {
		return NRF_SPI_FREQ_500K;
	} else if (frequency < 2000000) {
		return NRF_SPI_FREQ_1M;
	} else if (frequency < 4000000) {
		return NRF_SPI_FREQ_2M;
	} else if (frequency < 8000000) {
		return NRF_SPI_FREQ_4M;
	} else {
		return NRF_SPI_FREQ_8M;
	}
}

static inline nrf_spi_mode_t get_nrf_spi_mode(u16_t operation)
{
	if (SPI_MODE_GET(operation) & SPI_MODE_CPOL) {
		if (SPI_MODE_GET(operation) & SPI_MODE_CPHA) {
			return NRF_SPI_MODE_3;
		} else {
			return NRF_SPI_MODE_2;
		}
	} else {
		if (SPI_MODE_GET(operation) & SPI_MODE_CPHA) {
			return NRF_SPI_MODE_1;
		} else {
			return NRF_SPI_MODE_0;
		}
	}
}

static inline nrf_spi_bit_order_t get_nrf_spi_bit_order(u16_t operation)
{
	if (operation & SPI_TRANSFER_LSB) {
		return NRF_SPI_BIT_ORDER_LSB_FIRST;
	} else {
		return NRF_SPI_BIT_ORDER_MSB_FIRST;
	}
}

static int configure(struct device *dev,
		     const struct spi_config *spi_cfg)
{
	struct spi_context *ctx = &get_dev_data(dev)->ctx;
	const nrfx_spi_t *spi = &get_dev_config(dev)->spi;

	if (spi_context_configured(ctx, spi_cfg)) {
		/* Already configured. No need to do it again. */
		return 0;
	}

	if (SPI_OP_MODE_GET(spi_cfg->operation) != SPI_OP_MODE_MASTER) {
		SYS_LOG_ERR("Slave mode is not supported on %s",
			    dev->config->name);
		return -EINVAL;
	}

	if (spi_cfg->operation & SPI_MODE_LOOP) {
		SYS_LOG_ERR("Loopback mode is not supported");
		return -EINVAL;
	}

	if ((spi_cfg->operation & SPI_LINES_MASK) != SPI_LINES_SINGLE) {
		SYS_LOG_ERR("Only single line mode is supported");
		return -EINVAL;
	}

	if (SPI_WORD_SIZE_GET(spi_cfg->operation) != 8) {
		SYS_LOG_ERR("Word sizes other than 8 bits"
			    " are not supported");
		return -EINVAL;
	}

	if (spi_cfg->frequency < 125000) {
		SYS_LOG_ERR("Frequencies lower than 125 kHz are not supported");
		return -EINVAL;
	}

	ctx->config = spi_cfg;
	spi_context_cs_configure(ctx);

	nrf_spi_configure(spi->p_reg,
			  get_nrf_spi_mode(spi_cfg->operation),
			  get_nrf_spi_bit_order(spi_cfg->operation));
	nrf_spi_frequency_set(spi->p_reg,
			      get_nrf_spi_frequency(spi_cfg->frequency));

	return 0;
}

static void transfer_next_chunk(struct device *dev)
{
	struct spi_nrfx_data *dev_data = get_dev_data(dev);
	struct spi_context *ctx = &dev_data->ctx;
	int error = 0;

	size_t chunk_len = spi_context_longest_current_buf(ctx);

	if (chunk_len > 0) {
		nrfx_spi_xfer_desc_t xfer;
		nrfx_err_t result;

		dev_data->chunk_len = chunk_len;

		xfer.p_tx_buffer = ctx->tx_buf;
		xfer.tx_length   = spi_context_tx_buf_on(ctx) ? chunk_len : 0;
		xfer.p_rx_buffer = ctx->rx_buf;
		xfer.rx_length   = spi_context_rx_buf_on(ctx) ? chunk_len : 0;
		result = nrfx_spi_xfer(&get_dev_config(dev)->spi, &xfer, 0);
		if (result == NRFX_SUCCESS) {
			return;
		}

		error = -EIO;
	}

	spi_context_cs_control(ctx, false);

	SYS_LOG_DBG("Transaction finished with status %d", error);

	spi_context_complete(ctx, error);
	dev_data->busy = false;
}

static int transceive(struct device *dev,
		      const struct spi_config *spi_cfg,
		      const struct spi_buf_set *tx_bufs,
		      const struct spi_buf_set *rx_bufs)
{
	struct spi_nrfx_data *dev_data = get_dev_data(dev);
	int error;

	error = configure(dev, spi_cfg);
	if (error == 0) {
		dev_data->busy = true;

		spi_context_buffers_setup(&dev_data->ctx, tx_bufs, rx_bufs, 1);
		spi_context_cs_control(&dev_data->ctx, true);

		transfer_next_chunk(dev);

		error = spi_context_wait_for_completion(&dev_data->ctx);
	}

	spi_context_release(&dev_data->ctx, error);

	return error;
}

static int spi_nrfx_transceive(struct device *dev,
			       const struct spi_config *spi_cfg,
			       const struct spi_buf_set *tx_bufs,
			       const struct spi_buf_set *rx_bufs)
{
	spi_context_lock(&get_dev_data(dev)->ctx, false, NULL);
	return transceive(dev, spi_cfg, tx_bufs, rx_bufs);
}

#ifdef CONFIG_SPI_ASYNC
static int spi_nrfx_transceive_async(struct device *dev,
				     const struct spi_config *spi_cfg,
				     const struct spi_buf_set *tx_bufs,
				     const struct spi_buf_set *rx_bufs,
				     struct k_poll_signal *async)
{
	spi_context_lock(&get_dev_data(dev)->ctx, true, async);
	return transceive(dev, spi_cfg, tx_bufs, rx_bufs);
}
#endif /* CONFIG_SPI_ASYNC */

static int spi_nrfx_release(struct device *dev,
			    const struct spi_config *spi_cfg)
{
	struct spi_nrfx_data *dev_data = get_dev_data(dev);

	if (!spi_context_configured(&dev_data->ctx, spi_cfg)) {
		return -EINVAL;
	}

	if (dev_data->busy) {
		return -EBUSY;
	}

	spi_context_unlock_unconditionally(&dev_data->ctx);

	return 0;
}

static const struct spi_driver_api spi_nrfx_driver_api = {
	.transceive = spi_nrfx_transceive,
#ifdef CONFIG_SPI_ASYNC
	.transceive_async = spi_nrfx_transceive_async,
#endif
	.release = spi_nrfx_release,
};


static void event_handler(const nrfx_spi_evt_t *p_event, void *p_context)
{
	struct device *dev = p_context;
	struct spi_nrfx_data *dev_data = get_dev_data(dev);

	if (p_event->type == NRFX_SPI_EVENT_DONE) {
		spi_context_update_tx(&dev_data->ctx, 1, dev_data->chunk_len);
		spi_context_update_rx(&dev_data->ctx, 1, dev_data->chunk_len);

		transfer_next_chunk(dev);
	}
}

static int init_spi(struct device *dev, const nrfx_spi_config_t *config)
{
	/* This sets only default values of frequency, mode and bit order.
	 * The proper ones are set in configure() when a transfer is started.
	 */
	nrfx_err_t result = nrfx_spi_init(&get_dev_config(dev)->spi,
					  config,
					  event_handler,
					  dev);
	if (result != NRFX_SUCCESS) {
		SYS_LOG_ERR("Failed to initialize device: %s",
			    dev->config->name);
		return -EBUSY;
	}

	spi_context_unlock_unconditionally(&get_dev_data(dev)->ctx);

	return 0;
}

#define SPI_NRFX_SPI_DEVICE(idx)					\
	static int spi_##idx##_init(struct device *dev)			\
	{								\
		IRQ_CONNECT(NRFX_IRQ_NUMBER_GET(NRF_SPI##idx),		\
			    CONFIG_SPI_##idx##_IRQ_PRI,			\
			    nrfx_isr, nrfx_spi_##idx##_irq_handler, 0);	\
		const nrfx_spi_config_t config = {			\
			.sck_pin   = CONFIG_SPI_##idx##_NRF_SCK_PIN,	\
			.mosi_pin  = CONFIG_SPI_##idx##_NRF_MOSI_PIN,	\
			.miso_pin  = CONFIG_SPI_##idx##_NRF_MISO_PIN,	\
			.ss_pin    = NRFX_SPI_PIN_NOT_USED,		\
			.orc       = CONFIG_SPI_##idx##_NRF_ORC,	\
			.frequency = NRF_SPI_FREQ_4M,			\
			.mode      = NRF_SPI_MODE_0,			\
			.bit_order = NRF_SPI_BIT_ORDER_MSB_FIRST,	\
		};							\
		return init_spi(dev, &config);				\
	}								\
	static struct spi_nrfx_data spi_##idx##_data = {		\
		SPI_CONTEXT_INIT_LOCK(spi_##idx##_data, ctx),		\
		SPI_CONTEXT_INIT_SYNC(spi_##idx##_data, ctx),		\
		.busy = false,						\
	};								\
	static const struct spi_nrfx_config spi_##idx##_config = {	\
		.spi = NRFX_SPI_INSTANCE(idx),				\
	};								\
	DEVICE_AND_API_INIT(spi_##idx, CONFIG_SPI_##idx##_NAME,		\
			    spi_##idx##_init,				\
			    &spi_##idx##_data,				\
			    &spi_##idx##_config,			\
			    POST_KERNEL, CONFIG_SPI_INIT_PRIORITY,	\
			    &spi_nrfx_driver_api)

#ifdef CONFIG_SPI_0_NRF_SPI
SPI_NRFX_SPI_DEVICE(0);
#endif

#ifdef CONFIG_SPI_1_NRF_SPI
SPI_NRFX_SPI_DEVICE(1);
#endif

#ifdef CONFIG_SPI_2_NRF_SPI
SPI_NRFX_SPI_DEVICE(2);
#endif