Commit 431c0309 authored by Heiner Kallweit's avatar Heiner Kallweit Committed by Greg Kroah-Hartman
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eeprom: ee1004: Add support for multiple i2c busses 



There are systems with more than 8 memory slots where the i2c bus for
SPD is multiplexed. i2c_register_spd() isn't used yet on such systems,
but it's planned. So we need to extend ee1004 accordingly.
With this extension a maximum of 8 i2c busses is supported.

I don't have such a system for testing, therefore I just verified
that the driver still works on a system with a single i2c bus.

For the sake of simplicity the extension uses the existing global
mutex to protect access on all busses. This could be improved,
but we support 8 busses only, and SPD data is small and rarely
accessed, so it shouldn't be a problem.

Signed-off-by: default avatarHeiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/f1a216a8-e77c-49f2-8838-561349b30ab8@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ad66d503

drivers/misc/eeprom/ee1004.c

+63 −31
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
 * over performance.

 */



#define EE1004_MAX_BUSSES		8

#define EE1004_ADDR_SET_PAGE		0x36

#define EE1004_NUM_PAGES		2

#define EE1004_PAGE_SIZE		256
@@ -42,9 +43,13 @@ 
 * from page selection to end of read.

 */

static DEFINE_MUTEX(ee1004_bus_lock);

static struct i2c_client *ee1004_set_page[EE1004_NUM_PAGES];

static unsigned int ee1004_dev_count;

static int ee1004_current_page;



static struct ee1004_bus_data {

	struct i2c_adapter *adap;

	struct i2c_client *set_page[EE1004_NUM_PAGES];

	unsigned int dev_count;

	int current_page;

} ee1004_bus_data[EE1004_MAX_BUSSES];



static const struct i2c_device_id ee1004_ids[] = {

	{ "ee1004", 0 },
@@ -54,11 +59,29 @@ MODULE_DEVICE_TABLE(i2c, ee1004_ids); 


/*-------------------------------------------------------------------------*/



static int ee1004_get_current_page(void)

static struct ee1004_bus_data *ee1004_get_bus_data(struct i2c_adapter *adap)

{

	int i;



	for (i = 0; i < EE1004_MAX_BUSSES; i++)

		if (ee1004_bus_data[i].adap == adap)

			return ee1004_bus_data + i;



	/* If not existent yet, create new entry */

	for (i = 0; i < EE1004_MAX_BUSSES; i++)

		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(ee1004_set_page[0]);

	err = i2c_smbus_read_byte(bd->set_page[0]);

	if (err == -ENXIO) {

		/* Nack means page 1 is selected */

		return 1;
@@ -72,28 +95,29 @@ static int ee1004_get_current_page(void) 
	return 0;

}



static int ee1004_set_current_page(struct device *dev, int page)

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 == ee1004_current_page)

	if (page == bd->current_page)

		return 0;



	/* Data is ignored */

	ret = i2c_smbus_write_byte(ee1004_set_page[page], 0x00);

	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() == page)

	if (ret == -ENXIO && ee1004_get_current_page(bd) == page)

		ret = 0;

	if (ret < 0) {

		dev_err(dev, "Failed to select page %d (%d)\n", page, ret);

		dev_err(&client->dev, "Failed to select page %d (%d)\n", page, ret);

		return ret;

	}



	dev_dbg(dev, "Selected page %d\n", page);

	ee1004_current_page = page;

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

	bd->current_page = page;



	return 0;

}
@@ -106,7 +130,7 @@ static ssize_t ee1004_eeprom_read(struct i2c_client *client, char *buf, 
	page = offset >> EE1004_PAGE_SHIFT;

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



	status = ee1004_set_current_page(&client->dev, page);

	status = ee1004_set_current_page(client, page);

	if (status)

		return status;
@@ -158,17 +182,18 @@ static struct bin_attribute *ee1004_attrs[] = { 


BIN_ATTRIBUTE_GROUPS(ee1004);



static void ee1004_cleanup(int idx)

static void ee1004_cleanup(int idx, struct ee1004_bus_data *bd)

{

	if (--ee1004_dev_count == 0)

		while (--idx >= 0) {

			i2c_unregister_device(ee1004_set_page[idx]);

			ee1004_set_page[idx] = NULL;

	if (--bd->dev_count == 0) {

		while (--idx >= 0)

			i2c_unregister_device(bd->set_page[idx]);

		memset(bd, 0, sizeof(struct ee1004_bus_data));

	}

}



static int ee1004_probe(struct i2c_client *client)

{

	struct ee1004_bus_data *bd;

	int err, cnr = 0;



	/* Make sure we can operate on this adapter */
@@ -178,9 +203,19 @@ static int ee1004_probe(struct i2c_client *client) 
				     I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_READ_BYTE_DATA))

		return -EPFNOSUPPORT;



	/* Use 2 dummy devices for page select command */

	mutex_lock(&ee1004_bus_lock);

	if (++ee1004_dev_count == 1) {



	bd = ee1004_get_bus_data(client->adapter);

	if (!bd) {

		mutex_unlock(&ee1004_bus_lock);

		return dev_err_probe(&client->dev, -ENOSPC,

				     "Only %d busses supported", EE1004_MAX_BUSSES);

	}



	i2c_set_clientdata(client, bd);



	if (++bd->dev_count == 1) {

		/* Use 2 dummy devices for page select command */

		for (cnr = 0; cnr < EE1004_NUM_PAGES; cnr++) {

			struct i2c_client *cl;
@@ -189,20 +224,15 @@ static int ee1004_probe(struct i2c_client *client) 
				err = PTR_ERR(cl);

				goto err_clients;

			}

			ee1004_set_page[cnr] = cl;

			bd->set_page[cnr] = cl;

		}



		/* Remember current page to avoid unneeded page select */

		err = ee1004_get_current_page();

		err = ee1004_get_current_page(bd);

		if (err < 0)

			goto err_clients;

		dev_dbg(&client->dev, "Currently selected page: %d\n", err);

		ee1004_current_page = err;

	} else if (client->adapter != ee1004_set_page[0]->adapter) {

		dev_err(&client->dev,

			"Driver only supports devices on a single I2C bus\n");

		err = -EOPNOTSUPP;

		goto err_clients;

		bd->current_page = err;

	}

	mutex_unlock(&ee1004_bus_lock);
@@ -213,7 +243,7 @@ static int ee1004_probe(struct i2c_client *client) 
	return 0;



 err_clients:

	ee1004_cleanup(cnr);

	ee1004_cleanup(cnr, bd);

	mutex_unlock(&ee1004_bus_lock);



	return err;
@@ -221,9 +251,11 @@ static int ee1004_probe(struct i2c_client *client) 


static void ee1004_remove(struct i2c_client *client)

{

	struct ee1004_bus_data *bd = i2c_get_clientdata(client);



	/* Remove page select clients if this is the last device */

	mutex_lock(&ee1004_bus_lock);

	ee1004_cleanup(EE1004_NUM_PAGES);

	ee1004_cleanup(EE1004_NUM_PAGES, bd);

	mutex_unlock(&ee1004_bus_lock);

}