drivers/spi/spi-mux.c

Source file repositories/reference/linux-study-clean/drivers/spi/spi-mux.c

File Facts

System
Linux kernel
Corpus path
drivers/spi/spi-mux.c
Extension
.c
Size
5328 bytes
Lines
193
Domain
Driver Families
Bucket
drivers/spi
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct spi_mux_priv {
	struct spi_device	*spi;
	unsigned int		current_cs;

	void			(*child_msg_complete)(void *context);
	void			*child_msg_context;
	struct spi_device	*child_msg_dev;
	struct mux_control	*mux;
};

/* should not get called when the parent controller is doing a transfer */
static int spi_mux_select(struct spi_device *spi)
{
	struct spi_mux_priv *priv = spi_controller_get_devdata(spi->controller);
	int ret;

	ret = mux_control_select(priv->mux, spi_get_chipselect(spi, 0));
	if (ret)
		return ret;

	if (priv->current_cs == spi_get_chipselect(spi, 0))
		return 0;

	dev_dbg(&priv->spi->dev, "setting up the mux for cs %d\n",
		spi_get_chipselect(spi, 0));

	/* copy the child device's settings except for the cs */
	priv->spi->max_speed_hz = spi->max_speed_hz;
	priv->spi->mode = spi->mode;
	priv->spi->bits_per_word = spi->bits_per_word;

	priv->current_cs = spi_get_chipselect(spi, 0);

	return spi_setup(priv->spi);
}

static int spi_mux_setup(struct spi_device *spi)
{
	struct spi_mux_priv *priv = spi_controller_get_devdata(spi->controller);

	/*
	 * can be called multiple times, won't do a valid setup now but we will
	 * change the settings when we do a transfer (necessary because we
	 * can't predict from which device it will be anyway)
	 */
	return spi_setup(priv->spi);
}

static void spi_mux_complete_cb(void *context)
{
	struct spi_mux_priv *priv = (struct spi_mux_priv *)context;
	struct spi_controller *ctlr = spi_get_drvdata(priv->spi);
	struct spi_message *m = ctlr->cur_msg;

	m->complete = priv->child_msg_complete;
	m->context = priv->child_msg_context;
	m->spi = priv->child_msg_dev;
	spi_finalize_current_message(ctlr);
	mux_control_deselect(priv->mux);
}

static int spi_mux_transfer_one_message(struct spi_controller *ctlr,
						struct spi_message *m)
{
	struct spi_mux_priv *priv = spi_controller_get_devdata(ctlr);
	struct spi_device *spi = m->spi;
	int ret;

	ret = spi_mux_select(spi);
	if (ret)
		return ret;

	/*
	 * Replace the complete callback, context and spi_device with our own
	 * pointers. Save originals
	 */
	priv->child_msg_complete = m->complete;
	priv->child_msg_context = m->context;
	priv->child_msg_dev = m->spi;

	m->complete = spi_mux_complete_cb;
	m->context = priv;
	m->spi = priv->spi;

	/* do the transfer */
	return spi_async(priv->spi, m);
}

static int spi_mux_probe(struct spi_device *spi)
{

Annotation

Implementation Notes