i2c-eeprom_slave: Add support for more eeprom models

Add a 32 and a 64 kbit memory. These needs 16 bit address
so added support for that as well.
Signed-off-by: Björn Ardö <bjorn.ardo@axis.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/i2c-slave-eeprom.c

@@ -11,6 +11,7 @@
  * pointer, yet implementation is deferred until the need actually arises.
  */
 
+#include <linux/bitfield.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/module.h>
@@ -21,12 +22,18 @@
 
 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 +41,14 @@ 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 +59,7 @@ 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 +70,7 @@ 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 +114,16 @@ 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 +158,9 @@ 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);