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Message-ID: <alpine.DEB.2.01.1404150017080.11665@pmeerw.net>
Date: Tue, 15 Apr 2014 00:19:06 +0200 (CEST)
From: Peter Meerwald <pmeerw@...erw.net>
To: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
cc: jic23@...nel.org, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [Patch v5 2/6] IIO: core: Introduce read_raw_multi
> 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.
> ---
> 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);
last parameter of prototype should be *vals to match the naming of the
implementation
> /* 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..e22a984 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 += snprintf(&buf[len], PAGE_SIZE - len, "%d ",
> + vals[i]);
> + len += snprintf(&buf[len], PAGE_SIZE - len, "\n");
> + 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
> + * 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
>
>
--
Peter Meerwald
+43-664-2444418 (mobile)
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