drivers/rtc/rtc-x1205.c

Source file repositories/reference/linux-study-clean/drivers/rtc/rtc-x1205.c

File Facts

System
Linux kernel
Corpus path
drivers/rtc/rtc-x1205.c
Extension
.c
Size
16260 bytes
Lines
694
Domain
Driver Families
Bucket
drivers/rtc
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 x1205_limit {
	unsigned char reg, mask, min, max;
};

static int x1205_validate_client(struct i2c_client *client)
{
	int i, xfer;

	/* Probe array. We will read the register at the specified
	 * address and check if the given bits are zero.
	 */
	static const unsigned char probe_zero_pattern[] = {
		/* register, mask */
		X1205_REG_SR,	0x18,
		X1205_REG_DTR,	0xF8,
		X1205_REG_ATR,	0xC0,
		X1205_REG_INT,	0x18,
		X1205_REG_0,	0xFF,
	};

	static const struct x1205_limit probe_limits_pattern[] = {
		/* register, mask, min, max */
		{ X1205_REG_Y2K,	0xFF,	19,	20	},
		{ X1205_REG_DW,		0xFF,	0,	6	},
		{ X1205_REG_YR,		0xFF,	0,	99	},
		{ X1205_REG_MO,		0xFF,	0,	12	},
		{ X1205_REG_DT,		0xFF,	0,	31	},
		{ X1205_REG_HR,		0x7F,	0,	23	},
		{ X1205_REG_MN,		0xFF,	0,	59	},
		{ X1205_REG_SC,		0xFF,	0,	59	},
		{ X1205_REG_Y2K1,	0xFF,	19,	20	},
		{ X1205_REG_Y2K0,	0xFF,	19,	20	},
	};

	/* check that registers have bits a 0 where expected */
	for (i = 0; i < ARRAY_SIZE(probe_zero_pattern); i += 2) {
		unsigned char buf;

		unsigned char addr[2] = { 0, probe_zero_pattern[i] };

		struct i2c_msg msgs[2] = {
			{
				.addr = client->addr,
				.len = 2,
				.buf = addr
			},
			{
				.addr = client->addr,
				.flags = I2C_M_RD,
				.len = 1,
				.buf = &buf
			},
		};

		xfer = i2c_transfer(client->adapter, msgs, 2);
		if (xfer != 2) {
			dev_err(&client->dev,
				"%s: could not read register %x\n",
				__func__, probe_zero_pattern[i]);

			return -EIO;
		}

		if ((buf & probe_zero_pattern[i+1]) != 0) {
			dev_err(&client->dev,
				"%s: register=%02x, zero pattern=%d, value=%x\n",
				__func__, probe_zero_pattern[i], i, buf);

			return -ENODEV;
		}
	}

	/* check limits (only registers with bcd values) */
	for (i = 0; i < ARRAY_SIZE(probe_limits_pattern); i++) {
		unsigned char reg, value;

		unsigned char addr[2] = { 0, probe_limits_pattern[i].reg };

		struct i2c_msg msgs[2] = {
			{
				.addr = client->addr,
				.len = 2,
				.buf = addr
			},
			{
				.addr = client->addr,
				.flags = I2C_M_RD,
				.len = 1,
				.buf = &reg
			},

Annotation

Implementation Notes