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eeprom: ee1004: Add support for multiple i2c busses

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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: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/f1a216a8-e77c-49f2-8838-561349b30ab8@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Heiner Kallweit 2023-11-16 15:31:59 +01:00 committed by Greg Kroah-Hartman
parent ad66d50305
commit 431c03095d
1 changed files with 63 additions and 31 deletions
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94
drivers/misc/eeprom/ee1004.c
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@ -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);
}