Re: [Patch v3 2/6] IIO: core: Introduce read_raw_multi

Jonathan Cameron
2014-04-14T07:53:51Z

On April 14, 2014 2:51:22 AM GMT+01:00, Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> wrote:
>
>On 04/12/2014 09:52 AM, Jonathan Cameron wrote:
>> On 09/04/14 01:56, Srinivas Pandruvada wrote:
>>> This callback is introduced to overcome some limitations of existing
>>> read_raw callback. The functionality of both existing read_raw and
>>> read_raw_multi is similar, both are used to request values from the
>>> device. The current read_raw callback allows only two return values.
>>> The new read_raw_multi allows returning multiple values. Instead of
>>> passing just address of val and val2, it passes length and pointer
>>> to values. Depending on the type and length of passed buffer, iio
>>> client drivers can return multiple values.
>>>
>>> Signed-off-by: Srinivas Pandruvada
><srinivas.pandruvada@linux.intel.com>
>> Hi Srinivas.
>>
>> This has come together pretty much how I thought it would. Very nice.
>> Only comment inline is that I'd prefer we took care now with
>possiblity
>> of really long sets of values so that we don't get bitten by it
>sometime
>> in the future.
>>
>I was thinking of using snprintf, but buf had no length passed. If we
>assume PAGE_SIZE as max length
>then I can do what you suggested below,
IIRC sysfs buffers are always PAGE_SIZE long. Easy enough to check I guess.
>
>Thanks,
>Srinivas
>> If you want to drop the reference to 0 having special meaning in the
>> comment as well, thats fine by me.
>>
>> Jonathan
>>> ---
>>> drivers/iio/iio_core.h | 2 +-
>>> drivers/iio/industrialio-core.c | 65
>>> ++++++++++++++++++++++++++--------------
>>> drivers/iio/industrialio-event.c | 6 ++--
>>> drivers/iio/inkern.c | 16 ++++++++--
>>> include/linux/iio/iio.h | 17 +++++++++++
>>> include/linux/iio/types.h | 1 +
>>> 6 files changed, 80 insertions(+), 27 deletions(-)
>>>
>>> diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
>>> index f6db6af..30327ad 100644
>>> --- a/drivers/iio/iio_core.h
>>> +++ b/drivers/iio/iio_core.h
>>> @@ -35,7 +35,7 @@ int __iio_add_chan_devattr(const char *postfix,
>>> struct list_head *attr_list);
>>> void iio_free_chan_devattr_list(struct list_head *attr_list);
>>>
>>> -ssize_t iio_format_value(char *buf, unsigned int type, int val, int
>
>>> val2);
>>> +ssize_t iio_format_value(char *buf, unsigned int type, int size,
>int
>>> *val);
>>>
>>> /* Event interface flags */
>>> #define IIO_BUSY_BIT_POS 1
>>> diff --git a/drivers/iio/industrialio-core.c
>>> b/drivers/iio/industrialio-core.c
>>> index ede16aec..3bd565c 100644
>>> --- a/drivers/iio/industrialio-core.c
>>> +++ b/drivers/iio/industrialio-core.c
>>> @@ -373,41 +373,53 @@ EXPORT_SYMBOL_GPL(iio_enum_write);
>>> * @buf: The buffer to which the formated value gets written
>>> * @type: One of the IIO_VAL_... constants. This decides how the
>>> val and val2
>>> * parameters are formatted.
>>> - * @val: First part of the value, exact meaning depends on the type
>
>>> parameter.
>>> - * @val2: Second part of the value, exact meaning depends on the
>>> type parameter.
>>> + * @vals: pointer to the values, exact meaning depends on the type
>>> parameter.
>>> */
>>> -ssize_t iio_format_value(char *buf, unsigned int type, int val, int
>
>>> val2)
>>> +ssize_t iio_format_value(char *buf, unsigned int type, int size,
>int
>>> *vals)
>>> {
>>> unsigned long long tmp;
>>> bool scale_db = false;
>>>
>>> switch (type) {
>>> case IIO_VAL_INT:
>>> - return sprintf(buf, "%d\n", val);
>>> + return sprintf(buf, "%d\n", vals[0]);
>>> case IIO_VAL_INT_PLUS_MICRO_DB:
>>> scale_db = true;
>>> case IIO_VAL_INT_PLUS_MICRO:
>>> - if (val2 < 0)
>>> - return sprintf(buf, "-%ld.%06u%s\n", abs(val), -val2,
>>> + if (vals[1] < 0)
>>> + return sprintf(buf, "-%ld.%06u%s\n", abs(vals[0]),
>>> + -vals[1],
>>> scale_db ? " dB" : "");
>>> else
>>> - return sprintf(buf, "%d.%06u%s\n", val, val2,
>>> + return sprintf(buf, "%d.%06u%s\n", vals[0], vals[1],
>>> scale_db ? " dB" : "");
>>> case IIO_VAL_INT_PLUS_NANO:
>>> - if (val2 < 0)
>>> - return sprintf(buf, "-%ld.%09u\n", abs(val), -val2);
>>> + if (vals[1] < 0)
>>> + return sprintf(buf, "-%ld.%09u\n", abs(vals[0]),
>>> + -vals[1]);
>>> else
>>> - return sprintf(buf, "%d.%09u\n", val, val2);
>>> + return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
>>> case IIO_VAL_FRACTIONAL:
>>> - tmp = div_s64((s64)val * 1000000000LL, val2);
>>> - val2 = do_div(tmp, 1000000000LL);
>>> - val = tmp;
>>> - return sprintf(buf, "%d.%09u\n", val, val2);
>>> + tmp = div_s64((s64)vals[0] * 1000000000LL, vals[1]);
>>> + vals[1] = do_div(tmp, 1000000000LL);
>>> + vals[0] = tmp;
>>> + return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
>>> case IIO_VAL_FRACTIONAL_LOG2:
>>> - tmp = (s64)val * 1000000000LL >> val2;
>>> - val2 = do_div(tmp, 1000000000LL);
>>> - val = tmp;
>>> - return sprintf(buf, "%d.%09u\n", val, val2);
>>> + tmp = (s64)vals[0] * 1000000000LL >> vals[1];
>>> + vals[1] = do_div(tmp, 1000000000LL);
>>> + vals[0] = tmp;
>>> + return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
>>> + case IIO_VAL_INT_MULTIPLE:
>>> + {
>>> + int i;
>>> + int len = 0;
>>> +
>>> + for (i = 0; i < size; ++i)
>>> + len += sprintf(&buf[len], "%d ", vals[i]);
>>> + buf[len++] = '\n';
>>> + buf[len++] = '\0';
>> Whilst we know this is of a fixed maxium length, I think we
>> want to take more care to ensure that we don't overrun the maximum
>> sysfs length. I'd also prefer specific use of snprintf for the new
>> line as well to make sure that doesn't cause trouble. i.e.
>>
>> for (i = 0; i < size; ++i)
>> len += snprintf(&buf[len], PAGE_SIZE - len, "%d ", vals[i]);
>> len += snprintf(&buf[len], PAGE_SIZE - len, "/n");
>>
>> The reasoning being that we could easily mess something up and hit
>these
>> limits sometime in the future. Also not using the explicit character
>> settting, but doing it with snprintf is easier to read (slightly ;)
>>
>>
>>> + return len;
>>> + }
>>> default:
>>> return 0;
>>> }
>>> @@ -419,14 +431,23 @@ static ssize_t iio_read_channel_info(struct
>>> device *dev,
>>> {
>>> struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>> struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
>>> - int val, val2;
>>> - int ret = indio_dev->info->read_raw(indio_dev, this_attr->c,
>>> - &val, &val2, this_attr->address);
>>> + int vals[INDIO_MAX_RAW_ELEMENTS];
>>> + int ret;
>>> + int val_len = 2;
>>> +
>>> + if (indio_dev->info->read_raw_multi)
>>> + ret = indio_dev->info->read_raw_multi(indio_dev,
>this_attr->c,
>>> + INDIO_MAX_RAW_ELEMENTS,
>>> + vals, &val_len,
>>> + this_attr->address);
>>> + else
>>> + ret = indio_dev->info->read_raw(indio_dev, this_attr->c,
>>> + &vals[0], &vals[1], this_attr->address);
>>>
>>> if (ret < 0)
>>> return ret;
>>>
>>> - return iio_format_value(buf, ret, val, val2);
>>> + return iio_format_value(buf, ret, val_len, vals);
>>> }
>>>
>>> /**
>>> diff --git a/drivers/iio/industrialio-event.c
>>> b/drivers/iio/industrialio-event.c
>>> index ea6e06b..1b4f31b 100644
>>> --- a/drivers/iio/industrialio-event.c
>>> +++ b/drivers/iio/industrialio-event.c
>>> @@ -270,7 +270,7 @@ static ssize_t iio_ev_value_show(struct device
>*dev,
>>> {
>>> struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>> struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
>>> - int val, val2;
>>> + int val, val2, val_arr[2];
>>> int ret;
>>>
>>> ret = indio_dev->info->read_event_value(indio_dev,
>>> @@ -279,7 +279,9 @@ static ssize_t iio_ev_value_show(struct device
>*dev,
>>> &val, &val2);
>>> if (ret < 0)
>>> return ret;
>>> - return iio_format_value(buf, ret, val, val2);
>>> + val_arr[0] = val;
>>> + val_arr[1] = val2;
>>> + return iio_format_value(buf, ret, 2, val_arr);
>>> }
>>>
>>> static ssize_t iio_ev_value_store(struct device *dev,
>>> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
>>> index 0cf5f8e..75e5386 100644
>>> --- a/drivers/iio/inkern.c
>>> +++ b/drivers/iio/inkern.c
>>> @@ -417,12 +417,24 @@ static int iio_channel_read(struct iio_channel
>
>>> *chan, int *val, int *val2,
>>> enum iio_chan_info_enum info)
>>> {
>>> int unused;
>>> + int vals[INDIO_MAX_RAW_ELEMENTS];
>>> + int ret;
>>> + int val_len = 2;
>>>
>>> if (val2 == NULL)
>>> val2 = &unused;
>>>
>>> - return chan->indio_dev->info->read_raw(chan->indio_dev,
>>> chan->channel,
>>> - val, val2, info);
>>> + if (chan->indio_dev->info->read_raw_multi) {
>>> + ret =
>chan->indio_dev->info->read_raw_multi(chan->indio_dev,
>>> + chan->channel, INDIO_MAX_RAW_ELEMENTS,
>>> + vals, &val_len, info);
>>> + *val = vals[0];
>>> + *val2 = vals[1];
>>> + } else
>>> + ret = chan->indio_dev->info->read_raw(chan->indio_dev,
>>> + chan->channel, val, val2, info);
>>> +
>>> + return ret;
>>> }
>>>
>>> int iio_read_channel_raw(struct iio_channel *chan, int *val)
>>> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
>>> index 5f2d00e..5629c92 100644
>>> --- a/include/linux/iio/iio.h
>>> +++ b/include/linux/iio/iio.h
>>> @@ -288,6 +288,8 @@ static inline s64 iio_get_time_ns(void)
>>> #define INDIO_ALL_BUFFER_MODES \
>>> (INDIO_BUFFER_TRIGGERED | INDIO_BUFFER_HARDWARE)
>>>
>>> +#define INDIO_MAX_RAW_ELEMENTS 4
>>> +
>>> struct iio_trigger; /* forward declaration */
>>> struct iio_dev;
>>>
>>> @@ -302,6 +304,14 @@ struct iio_dev;
>>> * the channel in question. Return value will specify
>the
>>> * type of value returned by the device. val and val2
>will
>>> * contain the elements making up the returned value.
>>> + * @read_raw_multi: function to return values from the device.
>>> + * mask specifies which value. Note 0 means a reading of
>> This note 0 bit wants to go now it is much more explicit in the way
>> the code
>> works, but leave it here for now and we can tidy up both this and the
>
>> read_raw
>> callback at the same time.
>>> + * the channel in question. Return value will specify
>the
>>> + * type of value returned by the device. vals pointer
>>> + * contain the elements making up the returned value.
>>> + * max_len specifies maximum number of elements
>>> + * vals pointer can contain. val_len is used to return
>>> + * length of valid elements in vals.
>>> * @write_raw: function to write a value to the device.
>>> * Parameters are the same as for read_raw.
>>> * @write_raw_get_fmt: callback function to query the expected
>>> @@ -328,6 +338,13 @@ struct iio_info {
>>> int *val2,
>>> long mask);
>>>
>>> + int (*read_raw_multi)(struct iio_dev *indio_dev,
>>> + struct iio_chan_spec const *chan,
>>> + int max_len,
>>> + int *vals,
>>> + int *val_len,
>>> + long mask);
>>> +
>>> int (*write_raw)(struct iio_dev *indio_dev,
>>> struct iio_chan_spec const *chan,
>>> int val,
>>> diff --git a/include/linux/iio/types.h b/include/linux/iio/types.h
>>> index 084d882..a13c224 100644
>>> --- a/include/linux/iio/types.h
>>> +++ b/include/linux/iio/types.h
>>> @@ -79,6 +79,7 @@ enum iio_event_direction {
>>> #define IIO_VAL_INT_PLUS_MICRO 2
>>> #define IIO_VAL_INT_PLUS_NANO 3
>>> #define IIO_VAL_INT_PLUS_MICRO_DB 4
>>> +#define IIO_VAL_INT_MULTIPLE 5
>>> #define IIO_VAL_FRACTIONAL 10
>>> #define IIO_VAL_FRACTIONAL_LOG2 11
>>>
>>>
>>
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