Re: [RFC PATCH 1/2] i2c: add i2c_get_device_id() to get the standard i2c device id

[Peter Rosin]

Hi Wolfram,

Did you have an opinion on this patch?

In case you like it, do you which to take it (don't forget to add a
Tested-by-tag from Adrian in that case), or should I take it and you
then get it in a pull request?

Cheers,
Peter

On 2018-01-22 12:36, Peter Rosin wrote:
> Can be used during probe to double check that the probed device is
> what is expected.
> 
> Loosely based on code from Adrian Fiergolski <adrian.fiergolski@xxxxxxx>.
> 
> Signed-off-by: Peter Rosin <peda@xxxxxxxxxx>
> ---
>  drivers/i2c/i2c-core-base.c | 33 +++++++++++++++++++++++++++++++++
>  include/linux/i2c.h         | 30 ++++++++++++++++++++++++++++++
>  2 files changed, 63 insertions(+)
> 
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 5a00bf443d06..f496b917529d 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -58,6 +58,8 @@
>  #define I2C_ADDR_7BITS_MAX	0x77
>  #define I2C_ADDR_7BITS_COUNT	(I2C_ADDR_7BITS_MAX + 1)
>  
> +#define I2C_ADDR_DEVICE_ID	0x7c
> +
>  /*
>   * core_lock protects i2c_adapter_idr, and guarantees that device detection,
>   * deletion of detected devices, and attach_adapter calls are serialized
> @@ -1968,6 +1970,37 @@ int i2c_transfer_buffer_flags(const struct i2c_client *client, char *buf,
>  }
>  EXPORT_SYMBOL(i2c_transfer_buffer_flags);
>  
> +/**
> + * i2c_get_device_id - get manufacturer, part id and die revision of a device
> + * @client: The device to query
> + * @id: The queried information
> + *
> + * Returns negative errno on error, zero on success.
> + */
> +int i2c_get_device_id(const struct i2c_client *client,
> +		      struct i2c_device_identity *id)
> +{
> +	struct i2c_adapter *adap = client->adapter;
> +	union i2c_smbus_data raw_id;
> +	int ret;
> +
> +	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
> +		return -EOPNOTSUPP;
> +
> +	raw_id.block[0] = 3;
> +	ret = i2c_smbus_xfer(adap, I2C_ADDR_DEVICE_ID, client->flags,
> +			     I2C_SMBUS_READ, client->addr << 1,
> +			     I2C_SMBUS_I2C_BLOCK_DATA, &raw_id);
> +	if (ret)
> +		return ret;
> +
> +	id->manufacturer_id = (raw_id.block[1] << 4) | (raw_id.block[2] >> 4);
> +	id->part_id = ((raw_id.block[2] & 0xf) << 5) | (raw_id.block[3] >> 3);
> +	id->die_revision = raw_id.block[3] & 0x7;
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(i2c_get_device_id);
> +
>  /* ----------------------------------------------------
>   * the i2c address scanning function
>   * Will not work for 10-bit addresses!
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index 419a38e7c315..44ad14e016b5 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -47,6 +47,7 @@ struct i2c_algorithm;
>  struct i2c_adapter;
>  struct i2c_client;
>  struct i2c_driver;
> +struct i2c_device_identity;
>  union i2c_smbus_data;
>  struct i2c_board_info;
>  enum i2c_slave_event;
> @@ -186,8 +187,37 @@ extern s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client,
>  extern s32
>  i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client *client,
>  					  u8 command, u8 length, u8 *values);
> +int i2c_get_device_id(const struct i2c_client *client,
> +		      struct i2c_device_identity *id);
>  #endif /* I2C */
>  
> +/**
> + * struct i2c_device_identity - i2c client device identification
> + * @manufacturer_id: 0 - 4095, database maintained by NXP
> + * @part_id: 0 - 511, according to manufacturer
> + * @die_revision: 0 - 7, according to manufacturer
> + */
> +struct i2c_device_identity {
> +	u16 manufacturer_id;
> +#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS                0
> +#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS_1              1
> +#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS_2              2
> +#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS_3              3
> +#define I2C_DEVICE_ID_RAMTRON_INTERNATIONAL             4
> +#define I2C_DEVICE_ID_ANALOG_DEVICES                    5
> +#define I2C_DEVICE_ID_STMICROELECTRONICS                6
> +#define I2C_DEVICE_ID_ON_SEMICONDUCTOR                  7
> +#define I2C_DEVICE_ID_SPRINTEK_CORPORATION              8
> +#define I2C_DEVICE_ID_ESPROS_PHOTONICS_AG               9
> +#define I2C_DEVICE_ID_FUJITSU_SEMICONDUCTOR            10
> +#define I2C_DEVICE_ID_FLIR                             11
> +#define I2C_DEVICE_ID_O2MICRO                          12
> +#define I2C_DEVICE_ID_ATMEL                            13
> +#define I2C_DEVICE_ID_NONE                         0xffff
> +	u16 part_id;
> +	u8 die_revision;
> +};
> +
>  enum i2c_alert_protocol {
>  	I2C_PROTOCOL_SMBUS_ALERT,
>  	I2C_PROTOCOL_SMBUS_HOST_NOTIFY,
>