drivers/dma/lpc32xx-dmamux.c

Source file repositories/reference/linux-study-clean/drivers/dma/lpc32xx-dmamux.c

File Facts

System
Linux kernel
Corpus path
drivers/dma/lpc32xx-dmamux.c
Extension
.c
Size
4915 bytes
Lines
205
Domain
Driver Families
Bucket
drivers/dma
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 lpc32xx_dmamux {
	int signal;
	char *name_sel0;
	char *name_sel1;
	int muxval;
	int muxreg;
	int bit;
	bool busy;
};

struct lpc32xx_dmamux_data {
	struct dma_router dmarouter;
	struct regmap *reg;
	spinlock_t lock; /* protects busy status flag */
};

/* From LPC32x0 User manual "3.2.1 DMA request signals" */
static struct lpc32xx_dmamux lpc32xx_muxes[] = {
	{
		.signal = 3,
		.name_sel0 = "spi2-rx-tx",
		.name_sel1 = "ssp1-rx",
		.muxreg = LPC32XX_SSP_CLK_CTRL,
		.bit = 5,
	},
	{
		.signal = 10,
		.name_sel0 = "uart7-rx",
		.name_sel1 = "i2s1-dma1",
		.muxreg = LPC32XX_I2S_CLK_CTRL,
		.bit = 4,
	},
	{
		.signal = 11,
		.name_sel0 = "spi1-rx-tx",
		.name_sel1 = "ssp1-tx",
		.muxreg = LPC32XX_SSP_CLK_CTRL,
		.bit = 4,
	},
	{
		.signal = 14,
		.name_sel0 = "none",
		.name_sel1 = "ssp0-rx",
		.muxreg = LPC32XX_SSP_CLK_CTRL,
		.bit = 3,
	},
	{
		.signal = 15,
		.name_sel0 = "none",
		.name_sel1 = "ssp0-tx",
		.muxreg = LPC32XX_SSP_CLK_CTRL,
		.bit = 2,
	},
};

static void lpc32xx_dmamux_release(struct device *dev, void *route_data)
{
	struct lpc32xx_dmamux_data *dmamux = dev_get_drvdata(dev);
	struct lpc32xx_dmamux *mux = route_data;

	dev_dbg(dev, "releasing dma request signal %d routed to %s\n",
		mux->signal, mux->muxval ? mux->name_sel1 : mux->name_sel1);

	guard(spinlock)(&dmamux->lock);

	mux->busy = false;
}

static void *lpc32xx_dmamux_reserve(struct of_phandle_args *dma_spec,
				    struct of_dma *ofdma)
{
	struct platform_device *pdev = of_find_device_by_node(ofdma->of_node);
	struct device *dev = &pdev->dev;
	struct lpc32xx_dmamux_data *dmamux = platform_get_drvdata(pdev);
	unsigned long flags;
	struct lpc32xx_dmamux *mux = NULL;
	int ret = -EINVAL;
	int i;

	if (dma_spec->args_count != 3) {
		dev_err(&pdev->dev, "invalid number of dma mux args\n");
		goto err_put_pdev;
	}

	for (i = 0; i < ARRAY_SIZE(lpc32xx_muxes); i++) {
		if (lpc32xx_muxes[i].signal == dma_spec->args[0]) {
			mux = &lpc32xx_muxes[i];
			break;
		}
	}

Annotation

Implementation Notes