drivers/i2c/busses/i2c-simtec.c

Source file repositories/reference/linux-study-clean/drivers/i2c/busses/i2c-simtec.c

File Facts

System
Linux kernel
Corpus path
drivers/i2c/busses/i2c-simtec.c
Extension
.c
Size
3180 bytes
Lines
156
Domain
Driver Families
Bucket
drivers/i2c
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 simtec_i2c_data {
	struct resource		*ioarea;
	void __iomem		*reg;
	struct i2c_adapter	 adap;
	struct i2c_algo_bit_data bit;
};

#define CMD_SET_SDA	(1<<2)
#define CMD_SET_SCL	(1<<3)

#define STATE_SDA	(1<<0)
#define STATE_SCL	(1<<1)

/* i2c bit-bus functions */

static void simtec_i2c_setsda(void *pw, int state)
{
	struct simtec_i2c_data *pd = pw;
	writeb(CMD_SET_SDA | (state ? STATE_SDA : 0), pd->reg);
}

static void simtec_i2c_setscl(void *pw, int state)
{
	struct simtec_i2c_data *pd = pw;
	writeb(CMD_SET_SCL | (state ? STATE_SCL : 0), pd->reg);
}

static int simtec_i2c_getsda(void *pw)
{
	struct simtec_i2c_data *pd = pw;
	return readb(pd->reg) & STATE_SDA ? 1 : 0;
}

static int simtec_i2c_getscl(void *pw)
{
	struct simtec_i2c_data *pd = pw;
	return readb(pd->reg) & STATE_SCL ? 1 : 0;
}

/* device registration */

static int simtec_i2c_probe(struct platform_device *dev)
{
	struct simtec_i2c_data *pd;
	struct resource *res;
	int size;
	int ret;

	pd = kzalloc_obj(struct simtec_i2c_data);
	if (pd == NULL)
		return -ENOMEM;

	platform_set_drvdata(dev, pd);

	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
	if (res == NULL) {
		dev_err(&dev->dev, "cannot find IO resource\n");
		ret = -ENOENT;
		goto err;
	}

	size = resource_size(res);

	pd->ioarea = request_mem_region(res->start, size, dev->name);
	if (pd->ioarea == NULL) {
		dev_err(&dev->dev, "cannot request IO\n");
		ret = -ENXIO;
		goto err;
	}

	pd->reg = ioremap(res->start, size);
	if (pd->reg == NULL) {
		dev_err(&dev->dev, "cannot map IO\n");
		ret = -ENXIO;
		goto err_res;
	}

	/* setup the private data */

	pd->adap.owner = THIS_MODULE;
	pd->adap.algo_data = &pd->bit;
	pd->adap.dev.parent = &dev->dev;

	strscpy(pd->adap.name, "Simtec I2C", sizeof(pd->adap.name));

	pd->bit.data = pd;
	pd->bit.setsda = simtec_i2c_setsda;
	pd->bit.setscl = simtec_i2c_setscl;
	pd->bit.getsda = simtec_i2c_getsda;
	pd->bit.getscl = simtec_i2c_getscl;

Annotation

Implementation Notes