drivers/w1/masters/sgi_w1.c

Source file repositories/reference/linux-study-clean/drivers/w1/masters/sgi_w1.c

File Facts

System
Linux kernel
Corpus path
drivers/w1/masters/sgi_w1.c
Extension
.c
Size
2754 bytes
Lines
127
Domain
Driver Families
Bucket
drivers/w1
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 sgi_w1_device {
	u32 __iomem *mcr;
	struct w1_bus_master bus_master;
	char dev_id[64];
};

static u8 sgi_w1_wait(u32 __iomem *mcr)
{
	u32 mcr_val;

	do {
		mcr_val = readl(mcr);
	} while (!(mcr_val & MCR_DONE));

	return (mcr_val & MCR_RD_DATA) ? 1 : 0;
}

/*
 * this is the low level routine to
 * reset the device on the One Wire interface
 * on the hardware
 */
static u8 sgi_w1_reset_bus(void *data)
{
	struct sgi_w1_device *dev = data;
	u8 ret;

	writel(MCR_PACK(520, 65), dev->mcr);
	ret = sgi_w1_wait(dev->mcr);
	udelay(500); /* recovery time */
	return ret;
}

/*
 * this is the low level routine to read/write a bit on the One Wire
 * interface on the hardware. It does write 0 if parameter bit is set
 * to 0, otherwise a write 1/read.
 */
static u8 sgi_w1_touch_bit(void *data, u8 bit)
{
	struct sgi_w1_device *dev = data;
	u8 ret;

	if (bit)
		writel(MCR_PACK(6, 13), dev->mcr);
	else
		writel(MCR_PACK(80, 30), dev->mcr);

	ret = sgi_w1_wait(dev->mcr);
	if (bit)
		udelay(100); /* recovery */
	return ret;
}

static int sgi_w1_probe(struct platform_device *pdev)
{
	struct sgi_w1_device *sdev;
	struct sgi_w1_platform_data *pdata;

	sdev = devm_kzalloc(&pdev->dev, sizeof(struct sgi_w1_device),
			    GFP_KERNEL);
	if (!sdev)
		return -ENOMEM;

	sdev->mcr = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(sdev->mcr))
		return PTR_ERR(sdev->mcr);

	sdev->bus_master.data = sdev;
	sdev->bus_master.reset_bus = sgi_w1_reset_bus;
	sdev->bus_master.touch_bit = sgi_w1_touch_bit;

	pdata = dev_get_platdata(&pdev->dev);
	if (pdata) {
		strscpy(sdev->dev_id, pdata->dev_id, sizeof(sdev->dev_id));
		sdev->bus_master.dev_id = sdev->dev_id;
	}

	platform_set_drvdata(pdev, sdev);

	return w1_add_master_device(&sdev->bus_master);
}

/*
 * disassociate the w1 device from the driver
 */
static void sgi_w1_remove(struct platform_device *pdev)
{
	struct sgi_w1_device *sdev = platform_get_drvdata(pdev);

Annotation

Implementation Notes