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[v2] i2c-eeprom_slave: Add read only mode

Message ID 1567695899-23385-1-git-send-email-bjorn.ardo@axis.com
State Changes Requested
Headers show
Series [v2] i2c-eeprom_slave: Add read only mode | expand

Commit Message

Bjorn Ardo Sept. 5, 2019, 3:04 p.m. UTC 
Add read-only versions of all EEPROMs. These versions are read-only
on the i2c side, but can be written from the sysfs side.

Signed-off-by: Björn Ardö <bjorn.ardo@axis.com>
---
 drivers/i2c/i2c-slave-eeprom.c | 8 ++++++++
 1 file changed, 8 insertions(+)
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Patch

diff --git a/drivers/i2c/i2c-slave-eeprom.c b/drivers/i2c/i2c-slave-eeprom.c
index 92ff999..b3d271b 100644
--- a/drivers/i2c/i2c-slave-eeprom.c
+++ b/drivers/i2c/i2c-slave-eeprom.c
@@ -33,11 +33,13 @@  struct eeprom_data {
 	u16 address_mask;
 	u8 num_address_bytes;
 	u8 idx_write_cnt;
+	bool read_only;
 	u8 buffer[];
 };
 
 #define I2C_SLAVE_BYTELEN GENMASK(15, 0)
 #define I2C_SLAVE_FLAG_ADDR16 BIT(16)
+#define I2C_SLAVE_FLAG_RO BIT(17)
 #define I2C_SLAVE_DEVICE_MAGIC(_len, _flags) ((_flags) | (_len))
 
 static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
@@ -53,6 +55,8 @@  static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
 			eeprom->buffer_idx = *val | (eeprom->buffer_idx << 8);
 			eeprom->idx_write_cnt++;
 		} else {
+			if (eeprom->read_only)
+				return 0;
 			spin_lock(&eeprom->buffer_lock);
 			eeprom->buffer[eeprom->buffer_idx++ & eeprom->address_mask] = *val;
 			spin_unlock(&eeprom->buffer_lock);
@@ -130,6 +134,7 @@  static int i2c_slave_eeprom_probe(struct i2c_client *client, const struct i2c_de
 	eeprom->idx_write_cnt = 0;
 	eeprom->num_address_bytes = flag_addr16 ? 2 : 1;
 	eeprom->address_mask = size - 1;
+	eeprom->read_only = FIELD_GET(I2C_SLAVE_FLAG_RO, id->driver_data);
 	spin_lock_init(&eeprom->buffer_lock);
 	i2c_set_clientdata(client, eeprom);
 
@@ -165,8 +170,11 @@  static int i2c_slave_eeprom_remove(struct i2c_client *client)
 
 static const struct i2c_device_id i2c_slave_eeprom_id[] = {
 	{ "slave-24c02", I2C_SLAVE_DEVICE_MAGIC(2048 / 8,  0) },
+	{ "slave-24c02ro", I2C_SLAVE_DEVICE_MAGIC(2048 / 8,  I2C_SLAVE_FLAG_RO) },
 	{ "slave-24c32", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16) },
+	{ "slave-24c32ro", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
 	{ "slave-24c64", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16) },
+	{ "slave-24c64ro", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id);