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authorBartosz Golaszewski2016-08-12 13:32:57 +0200
committerWolfram Sang2016-08-22 08:19:58 +0200
commit00f0ea70d2b82b7d7afeb1bdedc9169eb8ea6675 (patch)
tree9ff72c2731c936fd922b006edbf421282b8a2c8e /drivers/misc
parent56025e7bc2079cda92643b43bf26991d3d09717d (diff)
eeprom: at24: check if the chip is functional in probe()
The at24 driver doesn't check if the chip is functional in its probe function. This leads to instantiating devices that are not physically present. For example the cape EEPROMs for BeagleBone Black are defined in the device tree at four addresses on i2c2, but normally only one of them is present. If the userspace doesn't know the location in advance, it will need to check if reading the nvmem attributes fails to determine which EEPROM is actually there. Try to read a single byte in probe() and bail-out with -ENODEV if the read fails. Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/misc')
-rw-r--r--drivers/misc/eeprom/at24.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 3cdf8e1ca0ad..051b14766ef9 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -593,6 +593,7 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
struct at24_data *at24;
int err;
unsigned i, num_addresses;
+ u8 test_byte;
if (client->dev.platform_data) {
chip = *(struct at24_platform_data *)client->dev.platform_data;
@@ -743,6 +744,18 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
}
}
+ i2c_set_clientdata(client, at24);
+
+ /*
+ * Perform a one-byte test read to verify that the
+ * chip is functional.
+ */
+ err = at24_read(at24, 0, &test_byte, 1);
+ if (err) {
+ err = -ENODEV;
+ goto err_clients;
+ }
+
at24->nvmem_config.name = dev_name(&client->dev);
at24->nvmem_config.dev = &client->dev;
at24->nvmem_config.read_only = !writable;
@@ -764,8 +777,6 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
goto err_clients;
}
- i2c_set_clientdata(client, at24);
-
dev_info(&client->dev, "%u byte %s EEPROM, %s, %u bytes/write\n",
chip.byte_len, client->name,
writable ? "writable" : "read-only", at24->write_max);