drivers/spi/spi-at91-usart.c

Source file repositories/reference/linux-study-clean/drivers/spi/spi-at91-usart.c

File Facts

System
Linux kernel
Corpus path
drivers/spi/spi-at91-usart.c
Extension
.c
Size
15841 bytes
Lines
637
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 at91_usart_spi {
	struct platform_device  *mpdev;
	struct spi_transfer	*current_transfer;
	void __iomem		*regs;
	struct device		*dev;
	struct clk		*clk;

	struct completion	xfer_completion;

	/*used in interrupt to protect data reading*/
	spinlock_t		lock;

	phys_addr_t		phybase;

	int			irq;
	unsigned int		current_tx_remaining_bytes;
	unsigned int		current_rx_remaining_bytes;

	u32			spi_clk;
	u32			status;

	bool			xfer_failed;
	bool			use_dma;
};

static void dma_callback(void *data)
{
	struct spi_controller   *ctlr = data;
	struct at91_usart_spi   *aus = spi_controller_get_devdata(ctlr);

	at91_usart_spi_writel(aus, IER, US_IR_RXRDY);
	aus->current_rx_remaining_bytes = 0;
	complete(&aus->xfer_completion);
}

static bool at91_usart_spi_can_dma(struct spi_controller *ctrl,
				   struct spi_device *spi,
				   struct spi_transfer *xfer)
{
	struct at91_usart_spi *aus = spi_controller_get_devdata(ctrl);

	return aus->use_dma && xfer->len >= US_DMA_MIN_BYTES;
}

static int at91_usart_spi_configure_dma(struct spi_controller *ctlr,
					struct at91_usart_spi *aus)
{
	struct dma_slave_config slave_config;
	struct device *dev = &aus->mpdev->dev;
	phys_addr_t phybase = aus->phybase;
	dma_cap_mask_t mask;
	int err = 0;

	dma_cap_zero(mask);
	dma_cap_set(DMA_SLAVE, mask);

	ctlr->dma_tx = dma_request_chan(dev, "tx");
	if (IS_ERR(ctlr->dma_tx)) {
		err = PTR_ERR(ctlr->dma_tx);
		goto at91_usart_spi_error_clear;
	}

	ctlr->dma_rx = dma_request_chan(dev, "rx");
	if (IS_ERR(ctlr->dma_rx)) {
		err = PTR_ERR(ctlr->dma_rx);
		goto at91_usart_spi_error;
	}

	slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
	slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
	slave_config.dst_addr = (dma_addr_t)phybase + US_THR;
	slave_config.src_addr = (dma_addr_t)phybase + US_RHR;
	slave_config.src_maxburst = 1;
	slave_config.dst_maxburst = 1;
	slave_config.device_fc = false;

	slave_config.direction = DMA_DEV_TO_MEM;
	if (dmaengine_slave_config(ctlr->dma_rx, &slave_config)) {
		dev_err(&ctlr->dev,
			"failed to configure rx dma channel\n");
		err = -EINVAL;
		goto at91_usart_spi_error;
	}

	slave_config.direction = DMA_MEM_TO_DEV;
	if (dmaengine_slave_config(ctlr->dma_tx, &slave_config)) {
		dev_err(&ctlr->dev,
			"failed to configure tx dma channel\n");
		err = -EINVAL;
		goto at91_usart_spi_error;

Annotation

Implementation Notes