1 files changed, 31 insertions, 11 deletions

diff --git a/drivers/i2c/i2c-slave-eeprom.c b/drivers/i2c/i2c-slave-eeprom.c
index be65d3842878..92ff9991bae8 100644
--- a/drivers/i2c/i2c-slave-eeprom.c
+++ b/drivers/i2c/i2c-slave-eeprom.c
@@ -11,6 +11,13 @@
  * pointer, yet implementation is deferred until the need actually arises.
  */
 
+/*
+ * FIXME: What to do if only 8 bits of a 16 bit address are sent?
+ * The ST-M24C64 sends only 0xff then. Needs verification with other
+ * EEPROMs, though. We currently use the 8 bit as a valid address.
+ */
+
+#include <linux/bitfield.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/module.h>
@@ -21,12 +28,18 @@
 
 struct eeprom_data {
         struct bin_attribute bin;
-        bool first_write;
         spinlock_t buffer_lock;
-        u8 buffer_idx;
+        u16 buffer_idx;
+        u16 address_mask;
+        u8 num_address_bytes;
+        u8 idx_write_cnt;
         u8 buffer[];
 };
 
+#define I2C_SLAVE_BYTELEN GENMASK(15, 0)
+#define I2C_SLAVE_FLAG_ADDR16 BIT(16)
+#define I2C_SLAVE_DEVICE_MAGIC(_len, _flags) ((_flags) | (_len))
+
 static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
                                      enum i2c_slave_event event, u8 *val)
 {
@@ -34,12 +47,14 @@ static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
 
         switch (event) {
         case I2C_SLAVE_WRITE_RECEIVED:
-                if (eeprom->first_write) {
-                        eeprom->buffer_idx = *val;
-                        eeprom->first_write = false;
+                if (eeprom->idx_write_cnt < eeprom->num_address_bytes) {
+                        if (eeprom->idx_write_cnt == 0)
+                                eeprom->buffer_idx = 0;
+                        eeprom->buffer_idx = *val | (eeprom->buffer_idx << 8);
+                        eeprom->idx_write_cnt++;
                 } else {
                         spin_lock(&eeprom->buffer_lock);
-                        eeprom->buffer[eeprom->buffer_idx++] = *val;
+                        eeprom->buffer[eeprom->buffer_idx++ & eeprom->address_mask] = *val;
                         spin_unlock(&eeprom->buffer_lock);
                 }
                 break;
@@ -50,7 +65,7 @@ static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
                 /* fallthrough */
         case I2C_SLAVE_READ_REQUESTED:
                 spin_lock(&eeprom->buffer_lock);
-                *val = eeprom->buffer[eeprom->buffer_idx];
+                *val = eeprom->buffer[eeprom->buffer_idx & eeprom->address_mask];
                 spin_unlock(&eeprom->buffer_lock);
                 /*
                  * Do not increment buffer_idx here, because we don't know if
@@ -61,7 +76,7 @@ static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
 
         case I2C_SLAVE_STOP:
         case I2C_SLAVE_WRITE_REQUESTED:
-                eeprom->first_write = true;
+                eeprom->idx_write_cnt = 0;
                 break;
 
         default:
@@ -105,13 +120,16 @@ static int i2c_slave_eeprom_probe(struct i2c_client *client, const struct i2c_de
 {
         struct eeprom_data *eeprom;
         int ret;
-        unsigned size = id->driver_data;
+        unsigned int size = FIELD_GET(I2C_SLAVE_BYTELEN, id->driver_data);
+        unsigned int flag_addr16 = FIELD_GET(I2C_SLAVE_FLAG_ADDR16, id->driver_data);
 
         eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL);
         if (!eeprom)
                 return -ENOMEM;
 
-        eeprom->first_write = true;
+        eeprom->idx_write_cnt = 0;
+        eeprom->num_address_bytes = flag_addr16 ? 2 : 1;
+        eeprom->address_mask = size - 1;
         spin_lock_init(&eeprom->buffer_lock);
         i2c_set_clientdata(client, eeprom);
 
@@ -146,7 +164,9 @@ static int i2c_slave_eeprom_remove(struct i2c_client *client)
 }
 
 static const struct i2c_device_id i2c_slave_eeprom_id[] = {
-        { "slave-24c02", 2048 / 8 },
+        { "slave-24c02", I2C_SLAVE_DEVICE_MAGIC(2048 / 8,  0) },
+        { "slave-24c32", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16) },
+        { "slave-24c64", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16) },
         { }
 };
 MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id);