eeprom: at24: check if the chip is functional in probe() (00f0ea70) · Commits · 戴 / test

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>

drivers/misc/eeprom/at24.c

+13 −2

Original line number	Diff line number	Diff line
		@@ -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);

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