zephyr/drivers/spi/spi_context.h

/*
 * Copyright (c) 2017 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @file
 * @brief Private API for SPI drivers
 */

#ifndef ZEPHYR_DRIVERS_SPI_SPI_CONTEXT_H_
#define ZEPHYR_DRIVERS_SPI_SPI_CONTEXT_H_

#include <zephyr/drivers/gpio.h>
#include <zephyr/drivers/spi.h>
#include <zephyr/kernel.h>
#include <zephyr/pm/device_runtime.h>

#ifdef __cplusplus
extern "C" {
#endif

enum spi_ctx_runtime_op_mode {
	SPI_CTX_RUNTIME_OP_MODE_MASTER = BIT(0),
	SPI_CTX_RUNTIME_OP_MODE_SLAVE  = BIT(1),
};

struct spi_context {
	const struct spi_config *config;
#ifdef CONFIG_MULTITHREADING
	const struct spi_config *owner;
#endif
	const struct gpio_dt_spec *cs_gpios;
	size_t num_cs_gpios;

#ifdef CONFIG_MULTITHREADING
	struct k_sem lock;
	struct k_sem sync;
#else
	/* An atomic flag that signals completed transfer
	 * when threads are not enabled.
	 */
	atomic_t ready;
#endif /* CONFIG_MULTITHREADING */
	int sync_status;

#ifdef CONFIG_SPI_ASYNC
	spi_callback_t callback;
	void *callback_data;
	bool asynchronous;
#endif /* CONFIG_SPI_ASYNC */
	const struct spi_buf *current_tx;
	size_t tx_count;
	const struct spi_buf *current_rx;
	size_t rx_count;

	const uint8_t *tx_buf;
	size_t tx_len;
	uint8_t *rx_buf;
	size_t rx_len;

#ifdef CONFIG_SPI_SLAVE
	int recv_frames;
#endif /* CONFIG_SPI_SLAVE */
};

#define SPI_CONTEXT_INIT_LOCK(_data, _ctx_name)				\
	._ctx_name.lock = Z_SEM_INITIALIZER(_data._ctx_name.lock, 0, 1)

#define SPI_CONTEXT_INIT_SYNC(_data, _ctx_name)				\
	._ctx_name.sync = Z_SEM_INITIALIZER(_data._ctx_name.sync, 0, 1)

#define SPI_CONTEXT_CS_GPIO_SPEC_ELEM(_node_id, _prop, _idx)		\
	GPIO_DT_SPEC_GET_BY_IDX(_node_id, _prop, _idx),

#define SPI_CONTEXT_CS_GPIOS_FOREACH_ELEM(_node_id)				\
	DT_FOREACH_PROP_ELEM(_node_id, cs_gpios,				\
				SPI_CONTEXT_CS_GPIO_SPEC_ELEM)

#define SPI_CONTEXT_CS_GPIOS_INITIALIZE(_node_id, _ctx_name)				\
	._ctx_name.cs_gpios = (const struct gpio_dt_spec []) {				\
		COND_CODE_1(DT_SPI_HAS_CS_GPIOS(_node_id),				\
			    (SPI_CONTEXT_CS_GPIOS_FOREACH_ELEM(_node_id)), ({0}))	\
	},										\
	._ctx_name.num_cs_gpios = DT_PROP_LEN_OR(_node_id, cs_gpios, 0),

/*
 * Checks if a spi config is the same as the one stored in the spi_context
 * The intention of this function is to be used to check if a driver can skip
 * some reconfiguration for a transfer in a fast code path.
 */
static inline bool spi_context_configured(struct spi_context *ctx,
					  const struct spi_config *config)
{
	return !!(ctx->config == config);
}

/* Returns true if the spi configuration stored for this context
 * specifies a slave mode configuration, returns false otherwise
 */
static inline bool spi_context_is_slave(struct spi_context *ctx)
{
	return (ctx->config->operation & SPI_OP_MODE_SLAVE);
}

/*
 * The purpose of the context lock is to synchronize the usage of the driver/hardware.
 * The driver should call this function to claim or wait for ownership of the spi resource.
 * Usually the appropriate time to call this is at the start of the transceive API implementation.
 */
static inline void spi_context_lock(struct spi_context *ctx,
				    bool asynchronous,
				    spi_callback_t callback,
				    void *callback_data,
				    const struct spi_config *spi_cfg)
{
#ifdef CONFIG_MULTITHREADING
	bool already_locked = (spi_cfg->operation & SPI_LOCK_ON) &&
			      (k_sem_count_get(&ctx->lock) == 0) &&
			      (ctx->owner == spi_cfg);

	if (!already_locked) {
		k_sem_take(&ctx->lock, K_FOREVER);
		ctx->owner = spi_cfg;
	}
#endif /* CONFIG_MULTITHREADING */

#ifdef CONFIG_SPI_ASYNC
	ctx->asynchronous = asynchronous;
	ctx->callback = callback;
	ctx->callback_data = callback_data;
#endif /* CONFIG_SPI_ASYNC */
}

/*
 * This function must be called by a driver which has called spi_context_lock in order
 * to release the ownership of the spi resource.
 * Usually the appropriate time to call this would be at the end of a transfer that was
 * initiated by a transceive API call, except in the case that the SPI_LOCK_ON bit was set
 * in the configuration.
 */
static inline void spi_context_release(struct spi_context *ctx, int status)
{
#ifdef CONFIG_MULTITHREADING
#ifdef CONFIG_SPI_SLAVE
	if (status >= 0 && ((ctx->config == NULL) || (ctx->config->operation & SPI_LOCK_ON))) {
		return;
	}
#endif /* CONFIG_SPI_SLAVE */

#ifdef CONFIG_SPI_ASYNC
	if (!ctx->asynchronous || (status < 0)) {
		ctx->owner = NULL;
		k_sem_give(&ctx->lock);
	}
#else
	if ((ctx->config == NULL) || !(ctx->config->operation & SPI_LOCK_ON)) {
		ctx->owner = NULL;
		k_sem_give(&ctx->lock);
	}
#endif /* CONFIG_SPI_ASYNC */
#endif /* CONFIG_MULTITHREADING */
}

static inline size_t spi_context_total_tx_len(struct spi_context *ctx);
static inline size_t spi_context_total_rx_len(struct spi_context *ctx);

/* This function essentially is a way for a driver to seamlessly implement both the
 * synchronous transceive API and the asynchronous transceive_async API in the same way.
 *
 * The exact way this function is used may depend on driver implementation, but
 * essentially this will block waiting for a signal from spi_context_complete,
 * unless the transfer is asynchronous, in which case it does nothing in master mode.
 */
static inline int spi_context_wait_for_completion(struct spi_context *ctx)
{
	int status = 0;
	bool wait;

#ifdef CONFIG_SPI_ASYNC
	wait = !ctx->asynchronous;
#else
	wait = true;
#endif

	if (wait) {
		k_timeout_t timeout;
		uint32_t timeout_ms;

		/* Do not use any timeout in the slave mode, as in this case
		 * it is not known when the transfer will actually start and
		 * what the frequency will be.
		 */
		if (IS_ENABLED(CONFIG_SPI_SLAVE) && spi_context_is_slave(ctx)) {
			timeout = K_FOREVER;
			timeout_ms = UINT32_MAX;
		} else {
			uint32_t tx_len = spi_context_total_tx_len(ctx);
			uint32_t rx_len = spi_context_total_rx_len(ctx);

			timeout_ms = MAX(tx_len, rx_len) * 8 * 1000 /
				     ctx->config->frequency;
			timeout_ms += CONFIG_SPI_COMPLETION_TIMEOUT_TOLERANCE;

			timeout = K_MSEC(timeout_ms);
		}
#ifdef CONFIG_MULTITHREADING
		if (k_sem_take(&ctx->sync, timeout)) {
			LOG_ERR("Timeout waiting for transfer complete");
			return -ETIMEDOUT;
		}
#else
		if (timeout_ms == UINT32_MAX) {
			/* In slave mode, we wait indefinitely, so we can go idle. */
			unsigned int key = irq_lock();

			while (!atomic_get(&ctx->ready)) {
				k_cpu_atomic_idle(key);
				key = irq_lock();
			}

			ctx->ready = 0;
			irq_unlock(key);
		} else {
			const uint32_t tms = k_uptime_get_32();

			while (!atomic_get(&ctx->ready) && (k_uptime_get_32() - tms < timeout_ms)) {
				k_busy_wait(1);
			}

			if (!ctx->ready) {
				LOG_ERR("Timeout waiting for transfer complete");
				return -ETIMEDOUT;
			}

			ctx->ready = 0;
		}
#endif /* CONFIG_MULTITHREADING */
		status = ctx->sync_status;
	}

#ifdef CONFIG_SPI_SLAVE
	if (spi_context_is_slave(ctx) && !status) {
		return ctx->recv_frames;
	}
#endif /* CONFIG_SPI_SLAVE */

	return status;
}

/* For synchronous transfers, this will signal to a thread waiting
 * on spi_context_wait for completion.
 *
 * For asynchronous tranfers, this will call the async callback function
 * with the user data.
 */
static inline void spi_context_complete(struct spi_context *ctx,
					const struct device *dev,
					int status)
{
#ifdef CONFIG_SPI_ASYNC
	if (!ctx->asynchronous) {
		ctx->sync_status = status;
		k_sem_give(&ctx->sync);
	} else {
		if (ctx->callback) {
#ifdef CONFIG_SPI_SLAVE
			if (spi_context_is_slave(ctx) && !status) {
				/* Let's update the status so it tells
				 * about number of received frames.
				 */
				status = ctx->recv_frames;
			}
#endif /* CONFIG_SPI_SLAVE */
			ctx->callback(dev, status, ctx->callback_data);
		}

		if (!(ctx->config->operation & SPI_LOCK_ON)) {
			ctx->owner = NULL;
			k_sem_give(&ctx->lock);
		}

	}
#else
	ctx->sync_status = status;
#ifdef CONFIG_MULTITHREADING
	k_sem_give(&ctx->sync);
#else
	atomic_set(&ctx->ready, 1);
#endif /* CONFIG_MULTITHREADING */
#endif /* CONFIG_SPI_ASYNC */
}

/*
 * This function initializes all the chip select GPIOs associated with a spi controller.
 * The context first must be initialized using the SPI_CONTEXT_CS_GPIOS_INITIALIZE macro.
 * This function should be called during the device init sequence so that
 * all the CS lines are configured properly before the first transfer begins.
 * Note: If a controller has native CS control in SPI hardware, they should also be initialized
 * during device init by the driver with hardware-specific code.
 */
static inline int spi_context_cs_configure_all(struct spi_context *ctx)
{
	int ret;
	const struct gpio_dt_spec *cs_gpio;

	for (cs_gpio = ctx->cs_gpios; cs_gpio < &ctx->cs_gpios[ctx->num_cs_gpios]; cs_gpio++) {
		if (!device_is_ready(cs_gpio->port)) {
			LOG_ERR("CS GPIO port %s pin %d is not ready",
				cs_gpio->port->name, cs_gpio->pin);
			return -ENODEV;
		}

		ret = gpio_pin_configure_dt(cs_gpio, GPIO_OUTPUT_INACTIVE);
		if (ret < 0) {
			return ret;
		}
	}

	return 0;
}

/* Helper function to power manage the GPIO CS pins, not meant to be used directly by drivers */
static inline int _spi_context_cs_pm_all(struct spi_context *ctx, bool get)
{
	const struct gpio_dt_spec *cs_gpio;
	int ret;

	for (cs_gpio = ctx->cs_gpios; cs_gpio < &ctx->cs_gpios[ctx->num_cs_gpios]; cs_gpio++) {
		if (get) {
			ret = pm_device_runtime_get(cs_gpio->port);
		} else {
			ret = pm_device_runtime_put(cs_gpio->port);
		}

		if (ret < 0) {
			return ret;
		}
	}

	return 0;
}

/* This function should be called by drivers to pm get all the chip select lines in
 * master mode in the case of any CS being a GPIO. This should be called from the
 * drivers pm action hook on pm resume.
 */
static inline int spi_context_cs_get_all(struct spi_context *ctx)
{
	return _spi_context_cs_pm_all(ctx, true);
}

/* This function should be called by drivers to pm put all the chip select lines in
 * master mode in the case of any CS being a GPIO. This should be called from the
 * drivers pm action hook on pm suspend.
 */
static inline int spi_context_cs_put_all(struct spi_context *ctx)
{
	return _spi_context_cs_pm_all(ctx, false);
}

/* Helper function to control the GPIO CS, not meant to be used directly by drivers */
static inline void _spi_context_cs_control(struct spi_context *ctx,
					   bool on, bool force_off)
{
	if (ctx->config && spi_cs_is_gpio(ctx->config)) {
		if (on) {
			gpio_pin_set_dt(&ctx->config->cs.gpio, 1);
			k_busy_wait(ctx->config->cs.delay);
		} else {
			if (!force_off &&
			    ctx->config->operation & SPI_HOLD_ON_CS) {
				return;
			}

			k_busy_wait(ctx->config->cs.delay);
			gpio_pin_set_dt(&ctx->config->cs.gpio, 0);
		}
	}
}

/* This function should be called by drivers to control the chip select line in master mode
 * in the case of the CS being a GPIO. The de facto usage of the zephyr SPI API expects that the
 * chip select be asserted throughout the entire transfer specified by a transceive call,
 * ie all buffers in a spi_buf_set should be finished before deasserting CS. And usually
 * the deassertion is at the end of the transfer, except in the case that the
 * SPI_HOLD_ON_CS bit was set in the configuration.
 */
static inline void spi_context_cs_control(struct spi_context *ctx, bool on)
{
	_spi_context_cs_control(ctx, on, false);
}

/* Forcefully releases the spi context and removes the owner, allowing taking the lock
 * with spi_context_lock without the previous owner releasing the lock.
 * This is usually used to aid in implementation of the spi_release driver API.
 */
static inline void spi_context_unlock_unconditionally(struct spi_context *ctx)
{
	/* Forcing CS to go to inactive status */
	_spi_context_cs_control(ctx, false, true);

#ifdef CONFIG_MULTITHREADING
	if (!k_sem_count_get(&ctx->lock)) {
		ctx->owner = NULL;
		k_sem_give(&ctx->lock);
	}
#endif /* CONFIG_MULTITHREADING */
}

/*
 * Helper function for incrementing buffer pointer.
 * Generally not needed to be used directly by drivers.
 * Use spi_context_update_(tx/rx) instead.
 */
static inline void *spi_context_get_next_buf(const struct spi_buf **current,
					     size_t *count,
					     size_t *buf_len,
					     uint8_t dfs)
{
	/* This loop skips zero-length buffers in the set, if any. */
	while (*count) {
		if (((*current)->len / dfs) != 0) {
			*buf_len = (*current)->len / dfs;
			return (*current)->buf;
		}
		++(*current);
		--(*count);
	}

	*buf_len = 0;
	return NULL;
}

/*
 * The spi context private api works with the driver by providing code to
 * keep track of how much of the transfer has been completed. The driver
 * calls functions to report when some tx or rx has finished, and the driver
 * then can use the spi context to keep track of how much is left to do.
 */

/*
 * This function must be called at the start of a transfer by the driver
 * to initialize the spi context fields for tracking the progress.
 */
static inline
void spi_context_buffers_setup(struct spi_context *ctx,
			       const struct spi_buf_set *tx_bufs,
			       const struct spi_buf_set *rx_bufs,
			       uint8_t dfs)
{
	LOG_DBG("tx_bufs %p - rx_bufs %p - %u", tx_bufs, rx_bufs, dfs);

	ctx->current_tx = tx_bufs ? tx_bufs->buffers : NULL;
	ctx->tx_count = ctx->current_tx ? tx_bufs->count : 0;
	ctx->tx_buf = (const uint8_t *)
		spi_context_get_next_buf(&ctx->current_tx, &ctx->tx_count,
					 &ctx->tx_len, dfs);

	ctx->current_rx = rx_bufs ? rx_bufs->buffers : NULL;
	ctx->rx_count = ctx->current_rx ? rx_bufs->count : 0;
	ctx->rx_buf = (uint8_t *)
		spi_context_get_next_buf(&ctx->current_rx, &ctx->rx_count,
					 &ctx->rx_len, dfs);

	ctx->sync_status = 0;

#ifdef CONFIG_SPI_SLAVE
	ctx->recv_frames = 0;
#endif /* CONFIG_SPI_SLAVE */

	LOG_DBG("current_tx %p (%zu), current_rx %p (%zu),"
		" tx buf/len %p/%zu, rx buf/len %p/%zu",
		ctx->current_tx, ctx->tx_count,
		ctx->current_rx, ctx->rx_count,
		(void *)ctx->tx_buf, ctx->tx_len,
		(void *)ctx->rx_buf, ctx->rx_len);
}

/*
 * Should be called to update the tracking of TX being completed.
 *
 * Parameter "dfs" is the number of bytes needed to store a data frame.
 * Parameter "len" is the number of data frames of TX that were sent.
 */
static ALWAYS_INLINE
void spi_context_update_tx(struct spi_context *ctx, uint8_t dfs, uint32_t len)
{
	if (!ctx->tx_len) {
		return;
	}

	if (len > ctx->tx_len) {
		LOG_ERR("Update exceeds current buffer");
		return;
	}

	ctx->tx_len -= len;
	if (!ctx->tx_len) {
		/* Current buffer is done. Get the next one to be processed. */
		++ctx->current_tx;
		--ctx->tx_count;
		ctx->tx_buf = (const uint8_t *)
			spi_context_get_next_buf(&ctx->current_tx,
						 &ctx->tx_count,
						 &ctx->tx_len, dfs);
	} else if (ctx->tx_buf) {
		ctx->tx_buf += dfs * len;
	}

	LOG_DBG("tx buf/len %p/%zu", (void *)ctx->tx_buf, ctx->tx_len);
}

/* Returns true if there is still TX buffers left in the spi_buf_set
 * even if they are "null" (nop) buffers.
 */
static ALWAYS_INLINE
bool spi_context_tx_on(struct spi_context *ctx)
{
	return !!(ctx->tx_len);
}

/* Similar to spi_context_tx_on, but only returns true if the current buffer is
 * not a null/NOP placeholder.
 */
static ALWAYS_INLINE
bool spi_context_tx_buf_on(struct spi_context *ctx)
{
	return !!(ctx->tx_buf && ctx->tx_len);
}

/*
 * Should be called to update the tracking of RX being completed.
 *
 * @param dfs is the number of bytes needed to store a data frame.
 * @param len is the number of data frames of RX that were received.
 */
static ALWAYS_INLINE
void spi_context_update_rx(struct spi_context *ctx, uint8_t dfs, uint32_t len)
{
#ifdef CONFIG_SPI_SLAVE
	if (spi_context_is_slave(ctx)) {
		ctx->recv_frames += len;
	}

#endif /* CONFIG_SPI_SLAVE */

	if (!ctx->rx_len) {
		return;
	}

	if (len > ctx->rx_len) {
		LOG_ERR("Update exceeds current buffer");
		return;
	}

	ctx->rx_len -= len;
	if (!ctx->rx_len) {
		/* Current buffer is done. Get the next one to be processed. */
		++ctx->current_rx;
		--ctx->rx_count;
		ctx->rx_buf = (uint8_t *)
			spi_context_get_next_buf(&ctx->current_rx,
						 &ctx->rx_count,
						 &ctx->rx_len, dfs);
	} else if (ctx->rx_buf) {
		ctx->rx_buf += dfs * len;
	}

	LOG_DBG("rx buf/len %p/%zu", (void *)ctx->rx_buf, ctx->rx_len);
}

/* Returns true if there is still RX buffers left in the spi_buf_set
 * even if they are "null" (nop) buffers.
 */
static ALWAYS_INLINE
bool spi_context_rx_on(struct spi_context *ctx)
{
	return !!(ctx->rx_len);
}

/* Similar to spi_context_rx_on, but only returns true if the current buffer is
 * not a null/NOP placeholder.
 */
static ALWAYS_INLINE
bool spi_context_rx_buf_on(struct spi_context *ctx)
{
	return !!(ctx->rx_buf && ctx->rx_len);
}

/*
 * Returns the maximum length of a transfer for which all currently active
 * directions have a continuous buffer, i.e. the maximum SPI transfer that
 * can be done with DMA that handles only non-scattered buffers.
 *
 * In other words, returns the length of the smaller of the current RX or current TX buffer.
 * Except if either RX or TX buf length is 0, returns the length of the other.
 * And if both are 0 then will return 0 and should indicate transfer completion.
 */
static inline size_t spi_context_max_continuous_chunk(struct spi_context *ctx)
{
	if (!ctx->tx_len) {
		return ctx->rx_len;
	} else if (!ctx->rx_len) {
		return ctx->tx_len;
	}

	return MIN(ctx->tx_len, ctx->rx_len);
}

/* Returns the length of the longer of the current RX or current TX buffer. */
static inline size_t spi_context_longest_current_buf(struct spi_context *ctx)
{
	return ctx->tx_len > ctx->rx_len ? ctx->tx_len : ctx->rx_len;
}

/* Helper function, not intended to be used by drivers directly */
static size_t spi_context_count_tx_buf_lens(struct spi_context *ctx, size_t start_index)
{
	size_t n;
	size_t total_len = 0;

	for (n = start_index; n < ctx->tx_count; ++n) {
		total_len += ctx->current_tx[n].len;
	}

	return total_len;
}

/* Helper function, not intended to be used by drivers directly */
static size_t spi_context_count_rx_buf_lens(struct spi_context *ctx, size_t start_index)
{
	size_t n;
	size_t total_len = 0;

	for (n = start_index; n < ctx->rx_count; ++n) {
		total_len += ctx->current_rx[n].len;
	}

	return total_len;
}


/* Returns the length of the sum of the remaining TX buffers in the buf set, including
 * the current buffer in the total.
 */
static inline size_t spi_context_total_tx_len(struct spi_context *ctx)
{
	return spi_context_count_tx_buf_lens(ctx, 0);
}

/* Returns the length of the sum of the remaining RX buffers in the buf set, including
 * the current buffer in the total.
 */
static inline size_t spi_context_total_rx_len(struct spi_context *ctx)
{
	return spi_context_count_rx_buf_lens(ctx, 0);
}

/* Similar to spi_context_total_tx_len, except does not count words that have been finished
 * in the current buffer, ie only including what is remaining in the current buffer in the sum.
 */
static inline size_t spi_context_tx_len_left(struct spi_context *ctx, uint8_t dfs)
{
	return (ctx->tx_len * dfs) + spi_context_count_tx_buf_lens(ctx, 1);
}

/* Similar to spi_context_total_rx_len, except does not count words that have been finished
 * in the current buffer, ie only including what is remaining in the current buffer in the sum.
 */
static inline size_t spi_context_rx_len_left(struct spi_context *ctx, uint8_t dfs)
{
	return (ctx->rx_len * dfs) + spi_context_count_rx_buf_lens(ctx, 1);
}

#ifdef __cplusplus
}
#endif

#endif /* ZEPHYR_DRIVERS_SPI_SPI_CONTEXT_H_ */