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: 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>

diff --git a/drivers/misc/eeprom/ee1004.c b/drivers/misc/eeprom/ee1004.c
index a1acd77130f26de8217efbcdb45b16abd58aaabf..fd12ce06a4d5efaf9c8e0b944ec19a13c04aec25 100644 (file)
--- a/drivers/misc/eeprom/ee1004.c
+++ b/drivers/misc/eeprom/ee1004.c
@@ -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);
 }