drivers/i2c/busses/i2c-pasemi-platform.c

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

File Facts

System
Linux kernel
Corpus path
drivers/i2c/busses/i2c-pasemi-platform.c
Extension
.c
Size
2876 bytes
Lines
114
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 pasemi_platform_i2c_data {
	struct pasemi_smbus smbus;
	struct clk *clk_ref;
};

static int
pasemi_platform_i2c_calc_clk_div(struct pasemi_platform_i2c_data *data,
				 u32 frequency)
{
	unsigned long clk_rate = clk_get_rate(data->clk_ref);

	if (!clk_rate)
		return -EINVAL;

	data->smbus.clk_div = DIV_ROUND_UP(clk_rate, 16 * frequency);
	if (data->smbus.clk_div < 4)
		return dev_err_probe(data->smbus.dev, -EINVAL,
				     "Bus frequency %d is too fast.\n",
				     frequency);
	if (data->smbus.clk_div > 0xff)
		return dev_err_probe(data->smbus.dev, -EINVAL,
				     "Bus frequency %d is too slow.\n",
				     frequency);

	return 0;
}

static int pasemi_platform_i2c_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct pasemi_platform_i2c_data *data;
	struct pasemi_smbus *smbus;
	u32 frequency;
	int error;
	int irq_num;

	data = devm_kzalloc(dev, sizeof(struct pasemi_platform_i2c_data),
			    GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	smbus = &data->smbus;
	smbus->dev = dev;

	smbus->ioaddr = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(smbus->ioaddr))
		return PTR_ERR(smbus->ioaddr);

	if (of_property_read_u32(dev->of_node, "clock-frequency", &frequency))
		frequency = I2C_MAX_STANDARD_MODE_FREQ;

	data->clk_ref = devm_clk_get_enabled(dev, NULL);
	if (IS_ERR(data->clk_ref))
		return PTR_ERR(data->clk_ref);

	error = pasemi_platform_i2c_calc_clk_div(data, frequency);
	if (error)
		return error;

	smbus->adapter.dev.of_node = pdev->dev.of_node;
	error = pasemi_i2c_common_probe(smbus);
	if (error)
		return error;

	irq_num = platform_get_irq(pdev, 0);
	error = devm_request_irq(smbus->dev, irq_num, pasemi_irq_handler, 0, "pasemi_apple_i2c", (void *)smbus);

	if (!error)
		smbus->use_irq = 1;
	platform_set_drvdata(pdev, data);

	return 0;
}

static void pasemi_platform_i2c_remove(struct platform_device *pdev) { }

static const struct of_device_id pasemi_platform_i2c_of_match[] = {
	{ .compatible = "apple,t8103-i2c" },
	{ .compatible = "apple,i2c" },
	{},
};
MODULE_DEVICE_TABLE(of, pasemi_platform_i2c_of_match);

static struct platform_driver pasemi_platform_i2c_driver = {
	.driver	= {
		.name			= "i2c-apple",
		.of_match_table		= pasemi_platform_i2c_of_match,
	},
	.probe	= pasemi_platform_i2c_probe,
	.remove = pasemi_platform_i2c_remove,

Annotation

Implementation Notes