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path: root/drivers/i2c/i2c-slave-eeprom.c
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Diffstat (limited to 'drivers/i2c/i2c-slave-eeprom.c')
-rw-r--r--drivers/i2c/i2c-slave-eeprom.c42
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);