drivers/misc/eeprom/ee1004.c

Source file repositories/reference/linux-study-clean/drivers/misc/eeprom/ee1004.c

File Facts

System
Linux kernel
Corpus path
drivers/misc/eeprom/ee1004.c
Extension
.c
Size
8829 bytes
Lines
353
Domain
Driver Families
Bucket
drivers/misc
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

if (!ee1004_bus_data[i].adap) {
			ee1004_bus_data[i].adap = adap;
			return ee1004_bus_data + i;
		}

	return NULL;
}

static int ee1004_get_current_page(struct ee1004_bus_data *bd)
{
	int err;

	err = i2c_smbus_read_byte(bd->set_page[0]);
	if (err == -ENXIO) {
		/* Nack means page 1 is selected */
		return 1;
	}
	if (err < 0) {
		/* Anything else is a real error, bail out */
		return err;
	}

	/* Ack means page 0 is selected, returned value meaningless */
	return 0;
}

static int ee1004_set_current_page(struct i2c_client *client, int page)
{
	struct ee1004_bus_data *bd = i2c_get_clientdata(client);
	int ret;

	if (page == bd->current_page)
		return 0;

	/* Data is ignored */
	ret = i2c_smbus_write_byte(bd->set_page[page], 0x00);
	/*
	 * Don't give up just yet. Some memory modules will select the page
	 * but not ack the command. Check which page is selected now.
	 */
	if (ret == -ENXIO && ee1004_get_current_page(bd) == page)
		ret = 0;
	if (ret < 0) {
		dev_err(&client->dev, "Failed to select page %d (%d)\n", page, ret);
		return ret;
	}

	dev_dbg(&client->dev, "Selected page %d\n", page);
	bd->current_page = page;

	return 0;
}

static ssize_t ee1004_eeprom_read(struct i2c_client *client, char *buf,
				  unsigned int offset, size_t count)
{
	int status, page;

	page = offset >> EE1004_PAGE_SHIFT;
	offset &= (1 << EE1004_PAGE_SHIFT) - 1;

	status = ee1004_set_current_page(client, page);
	if (status)
		return status;

	/* Can't cross page boundaries */
	if (offset + count > EE1004_PAGE_SIZE)
		count = EE1004_PAGE_SIZE - offset;

	if (count > I2C_SMBUS_BLOCK_MAX)
		count = I2C_SMBUS_BLOCK_MAX;

	return i2c_smbus_read_i2c_block_data_or_emulated(client, offset, count, buf);
}

static int ee1004_read(void *priv, unsigned int off, void *val, size_t count)
{
	struct i2c_client *client = priv;
	char *buf = val;
	int ret;

	if (unlikely(!count))
		return count;

	if (off + count > EE1004_EEPROM_SIZE)
		return -EINVAL;

	/*
	 * Read data from chip, protecting against concurrent access to
	 * other EE1004 SPD EEPROMs on the same adapter.

Annotation

Implementation Notes