The at24 driver is now capable of reading the serial number from at24cs
EEPROM chips. Export the serial number through sysfs.

Signed-off-by: Bartosz Golaszewski <bgolaszew...@baylibre.com>
---
 drivers/misc/eeprom/at24.c | 44 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 442aac7..dfc7b55 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -64,6 +64,7 @@ struct at24_data {
         */
        struct mutex lock;
        struct bin_attribute bin;
+       struct bin_attribute *bin_serial;
 
        u8 *writebuf;
        unsigned write_max;
@@ -102,6 +103,7 @@ MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes 
(default 25)");
 
 #define AT24_BITMASK(x) (BIT(x) - 1)
 
+#define AT24CS_SERIAL_SIZE 16
 #define AT24CS_SERIAL_ADDR(addr) (addr + 0x08)
 
 /* create non-zero magic value for given eeprom parameters */
@@ -156,10 +158,8 @@ static struct i2c_client *at24_translate_offset(struct 
at24_data *at24,
        return at24->client[i];
 }
 
-static int __attribute__((unused)) at24cs_eeprom_serial_read(
-                                               struct at24_data *at24,
-                                               char *buf, unsigned offset,
-                                               size_t count)
+static int at24cs_eeprom_serial_read(struct at24_data *at24, char *buf,
+                                    unsigned offset, size_t count)
 {
        unsigned long timeout, read_time;
        struct i2c_client *client;
@@ -227,6 +227,16 @@ static int __attribute__((unused)) 
at24cs_eeprom_serial_read(
        return -ETIMEDOUT;
 }
 
+static ssize_t at24cs_bin_serial_read(struct file *filp, struct kobject *kobj,
+                                     struct bin_attribute *attr,
+                                     char *buf, loff_t off, size_t count)
+{
+       struct at24_data *at24;
+
+       at24 = dev_get_drvdata(container_of(kobj, struct device, kobj));
+       return at24cs_eeprom_serial_read(at24, buf, off, count);
+}
+
 static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
                unsigned offset, size_t count)
 {
@@ -643,6 +653,30 @@ static int at24_probe(struct i2c_client *client, const 
struct i2c_device_id *id)
        at24->bin.read = at24_bin_read;
        at24->bin.size = chip.byte_len;
 
+       if (at24->chip.flags & AT24_FLAG_SERIAL) {
+               /*
+                * For EEPROMs containing the serial number export an
+                * additional file allowing allowing convenvient access
+                * to it from user-space.
+                */
+               at24->bin_serial = devm_kzalloc(&client->dev,
+                                               sizeof(struct bin_attribute),
+                                               GFP_KERNEL);
+               if (!at24->bin_serial)
+                       return -ENOMEM;
+
+               sysfs_bin_attr_init(at24->bin_serial);
+               at24->bin_serial->attr.name = "serial";
+               at24->bin_serial->attr.mode = S_IRUSR;
+               at24->bin_serial->read = at24cs_bin_serial_read;
+               at24->bin_serial->size = AT24CS_SERIAL_SIZE;
+
+               err = sysfs_create_bin_file(&client->dev.kobj,
+                                           at24->bin_serial);
+               if (err)
+                       goto err_clients;
+       }
+
        at24->macc.read = at24_macc_read;
 
        writable = !(chip.flags & AT24_FLAG_READONLY);
@@ -742,6 +776,8 @@ static int at24_remove(struct i2c_client *client)
 
        at24 = i2c_get_clientdata(client);
        sysfs_remove_bin_file(&client->dev.kobj, &at24->bin);
+       if (at24->bin_serial)
+               sysfs_remove_bin_file(&client->dev.kobj, at24->bin_serial);
 
        for (i = 1; i < at24->num_addresses; i++)
                i2c_unregister_device(at24->client[i]);
-- 
2.1.4

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