On 09/03/15 16:45, Wolfram Sang wrote: > On Mon, Mar 09, 2015 at 03:41:30PM +0000, Jonathan Cameron wrote: >> On 09/03/15 15:35, Jonathan Cameron wrote: >>> On 25/02/15 15:55, Vianney le Clément de Saint-Marcq wrote: >>>> Add device attributes for getting/setting emissivity, IIR, and FIR >>>> coefficients, and getting the gain (which should not be modified in >>>> order to keep factory calibration). >>>> >>>> The attributes provide raw values whose meaning is described in the >>>> datasheet [1]. >>>> >>>> Writing to EEPROM requires an explicit erase by writing zero. In >>>> addition, it takes 20ms for the erase/write to complete. During this >>>> time no EEPROM register should be accessed. Therefore, two msleep()s >>>> are added to the write function and a mutex protects against concurrent >>>> access. >>>> >>>> Since it is not expected to be updated frequently, the configuration >>>> register is read before modifying it rather than caching it. >>>> >>>> [1] http://melexis.com/Assets/IR-sensor-thermometer-MLX90614-Datasheet-5152.aspx >>>> >>>> Signed-off-by: Vianney le Clément de Saint-Marcq <vianney.leclement@xxxxxxxxxxxxx> >>>> Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@xxxxxxx> >>> Wolfram, bit of odd i2c usage inline I'd like you to take quick look at. > > What do you mean? The direct calls to i2c_smbus_xfer? Was there any > reason given to use it directly? Apparently the returned PEC is present but wrong. However it requires a correct PEC to be transmitted to it. Genious > >> Sorry, this would work better if I cleared Wolfram's old email addresses out of >> my address book at somepoint! > > How about: right now? ;) Did so earlier - was hiding in several different places. > >> >>>> --- >>>> drivers/iio/temperature/mlx90614.c | 164 ++++++++++++++++++++++++++++++++++++- >>>> 1 file changed, 163 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/iio/temperature/mlx90614.c b/drivers/iio/temperature/mlx90614.c >>>> index 0b36746..ab98fb6 100644 >>>> --- a/drivers/iio/temperature/mlx90614.c >>>> +++ b/drivers/iio/temperature/mlx90614.c >>>> @@ -12,14 +12,16 @@ >>>> * >>>> * (7-bit I2C slave address 0x5a, 100KHz bus speed only!) >>>> * >>>> - * TODO: sleep mode, configuration EEPROM >>>> + * TODO: sleep mode >>>> */ >>>> >>>> #include <linux/err.h> >>>> #include <linux/i2c.h> >>>> #include <linux/module.h> >>>> +#include <linux/delay.h> >>>> >>>> #include <linux/iio/iio.h> >>>> +#include <linux/iio/sysfs.h> >>>> >>>> #define MLX90614_OP_RAM 0x00 >>>> #define MLX90614_OP_EEPROM 0x20 >>>> @@ -53,8 +55,47 @@ >>>> >>>> struct mlx90614_data { >>>> struct i2c_client *client; >>>> + struct mutex lock; /* for EEPROM access only */ >>>> }; >>>> >>>> +/* >>>> + * Erase an address and write word. >>>> + * The mutex must be locked before calling. >>>> + */ >>>> +static s32 mlx90614_write_word(const struct i2c_client *client, u8 command, >>>> + u16 value) >>>> +{ >>>> + /* >>>> + * Note: The mlx90614 requires a PEC on writing but does not send us a >>>> + * valid PEC on reading. Hence, we cannot set I2C_CLIENT_PEC in >>>> + * i2c_client.flags. As a workaround, we use i2c_smbus_xfer here. >>>> + */ >>> That's particularly hideous and someone should shout at whoever implemented that! >>> Ah well, such is life. I want a go ahead on doing this from Wolfram however. >>> It's the sort of thing that might well get randomly broken in the future. >>> Alternative is to add another flag that indicates to the i2c core that the PEC >>> that comes back will be wrong. >>> >>>> + union i2c_smbus_data data; >>>> + s32 ret; >>>> + >>>> + dev_dbg(&client->dev, "Writing 0x%x to address 0x%x", value, command); >>>> + >>>> + data.word = 0x0000; /* erase command */ >>>> + ret = i2c_smbus_xfer(client->adapter, client->addr, >>>> + client->flags | I2C_CLIENT_PEC, >>>> + I2C_SMBUS_WRITE, command, >>>> + I2C_SMBUS_WORD_DATA, &data); >>>> + if (ret < 0) >>>> + return ret; >>>> + >>>> + msleep(MLX90614_TIMING_EEPROM); >>>> + >>>> + data.word = value; /* actual write */ >>>> + ret = i2c_smbus_xfer(client->adapter, client->addr, >>>> + client->flags | I2C_CLIENT_PEC, >>>> + I2C_SMBUS_WRITE, command, >>>> + I2C_SMBUS_WORD_DATA, &data); >>>> + >>>> + msleep(MLX90614_TIMING_EEPROM); >>>> + >>>> + return ret; >>>> +} -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
