On Tue, 23 Feb 2021 18:44:04 +0200
<[email protected]> wrote:

> From: Alexandru Tachici <[email protected]>
> 
> Currently AD7124-8 driver cannot use more than 8 IIO channels
> because it was assigning the channel configurations bijectively
> to channels specified in the device-tree. This is not possible
> to do when using more than 8 channels as AD7124-8 has only 8
> configuration registers.
> 
> To allow the user to use all channels at once the driver
> will keep in memory configurations for all channels but
> will program only 8 of them at a time on the device.
> If multiple channels have the same configuration, only
> one configuration register will be used. If there
> are more configurations than available registers only
> the last 8 used configurations will be allowed to exist
> on the device in a LRU fashion.
> 
> Signed-off-by: Alexandru Tachici <[email protected]>

Hi Alexandru,

I like the solution you've gone with here. Its fairly intuitive
solution to a fiddly problem :)

All comments inline are fairly minor tweaks.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/ad7124.c | 461 ++++++++++++++++++++++++++-------------
>  1 file changed, 308 insertions(+), 153 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
> index 766c73333604..d5d0596eb6ed 100644
> --- a/drivers/iio/adc/ad7124.c
> +++ b/drivers/iio/adc/ad7124.c
> @@ -11,6 +11,7 @@
>  #include <linux/err.h>
>  #include <linux/interrupt.h>
>  #include <linux/kernel.h>
> +#include <linux/kfifo.h>
>  #include <linux/module.h>
>  #include <linux/of_device.h>
>  #include <linux/regulator/consumer.h>
> @@ -86,6 +87,10 @@
>  #define AD7124_SINC3_FILTER 2
>  #define AD7124_SINC4_FILTER 0
>  
> +#define AD7124_CONF_ADDR_OFFSET      20
> +#define AD7124_MAX_CONFIGS   8
> +#define AD7124_MAX_CHANNELS  16
> +
>  enum ad7124_ids {
>       ID_AD7124_4,
>       ID_AD7124_8,
> @@ -136,25 +141,36 @@ struct ad7124_chip_info {
>  };
>  
>  struct ad7124_channel_config {
> +     bool live;
> +     unsigned int cfg_slot;
>       enum ad7124_ref_sel refsel;
>       bool bipolar;
>       bool buf_positive;
>       bool buf_negative;
> -     unsigned int ain;
>       unsigned int vref_mv;
>       unsigned int pga_bits;
>       unsigned int odr;
> +     unsigned int odr_sel_bits;
>       unsigned int filter_type;
>  };
>  
> +struct ad7124_channel {
> +     unsigned int nr;
> +     struct ad7124_channel_config cfg;
> +     unsigned int ain;
> +     unsigned int slot;
> +};
> +
>  struct ad7124_state {
>       const struct ad7124_chip_info *chip_info;
>       struct ad_sigma_delta sd;
> -     struct ad7124_channel_config *channel_config;
> +     struct ad7124_channel *channels;
>       struct regulator *vref[4];
>       struct clk *mclk;
>       unsigned int adc_control;
>       unsigned int num_channels;
> +     struct mutex cfgs_lock; /* lock for configs access */
> +     DECLARE_KFIFO(live_cfgs_fifo, struct ad7124_channel_config *, 
> AD7124_MAX_CONFIGS);
>  };
>  
>  static const struct iio_chan_spec ad7124_channel_template = {
> @@ -238,33 +254,9 @@ static int ad7124_set_mode(struct ad_sigma_delta *sd,
>       return ad_sd_write_reg(&st->sd, AD7124_ADC_CONTROL, 2, st->adc_control);
>  }
>  
> -static int ad7124_set_channel(struct ad_sigma_delta *sd, unsigned int 
> channel)
> -{
> -     struct ad7124_state *st = container_of(sd, struct ad7124_state, sd);
> -     unsigned int val;
> -
> -     val = st->channel_config[channel].ain | AD7124_CHANNEL_EN(1) |
> -           AD7124_CHANNEL_SETUP(channel);
> -
> -     return ad_sd_write_reg(&st->sd, AD7124_CHANNEL(channel), 2, val);
> -}
> -
> -static const struct ad_sigma_delta_info ad7124_sigma_delta_info = {
> -     .set_channel = ad7124_set_channel,
> -     .set_mode = ad7124_set_mode,
> -     .has_registers = true,
> -     .addr_shift = 0,
> -     .read_mask = BIT(6),
> -     .data_reg = AD7124_DATA,
> -     .irq_flags = IRQF_TRIGGER_FALLING,
> -};
> -
> -static int ad7124_set_channel_odr(struct ad7124_state *st,
> -                               unsigned int channel,
> -                               unsigned int odr)
> +static void ad7124_set_channel_odr(struct ad7124_state *st, unsigned int 
> channel, unsigned int odr)
>  {
>       unsigned int fclk, odr_sel_bits;
> -     int ret;
>  
>       fclk = clk_get_rate(st->mclk);
>       /*
> @@ -280,36 +272,10 @@ static int ad7124_set_channel_odr(struct ad7124_state 
> *st,
>       else if (odr_sel_bits > 2047)
>               odr_sel_bits = 2047;
>  
> -     ret = ad7124_spi_write_mask(st, AD7124_FILTER(channel),
> -                                 AD7124_FILTER_FS_MSK,
> -                                 AD7124_FILTER_FS(odr_sel_bits), 3);
> -     if (ret < 0)
> -             return ret;
> -     /* fADC = fCLK / (FS[10:0] x 32) */
> -     st->channel_config[channel].odr =
> -             DIV_ROUND_CLOSEST(fclk, odr_sel_bits * 32);
> -
> -     return 0;
> -}
> -
> -static int ad7124_set_channel_gain(struct ad7124_state *st,
> -                                unsigned int channel,
> -                                unsigned int gain)
> -{
> -     unsigned int res;
> -     int ret;
> -
> -     res = ad7124_find_closest_match(ad7124_gain,
> -                                     ARRAY_SIZE(ad7124_gain), gain);
> -     ret = ad7124_spi_write_mask(st, AD7124_CONFIG(channel),
> -                                 AD7124_CONFIG_PGA_MSK,
> -                                 AD7124_CONFIG_PGA(res), 2);
> -     if (ret < 0)
> -             return ret;
> -
> -     st->channel_config[channel].pga_bits = res;
>  
> -     return 0;
> +     /* fADC = fCLK / (FS[10:0] x 32) */
> +     st->channels[channel].cfg.odr = DIV_ROUND_CLOSEST(fclk, odr_sel_bits * 
> 32);
> +     st->channels[channel].cfg.odr_sel_bits = odr_sel_bits;
>  }
>  
>  static int ad7124_get_3db_filter_freq(struct ad7124_state *st,
> @@ -317,9 +283,9 @@ static int ad7124_get_3db_filter_freq(struct ad7124_state 
> *st,
>  {
>       unsigned int fadc;
>  
> -     fadc = st->channel_config[channel].odr;
> +     fadc = st->channels[channel].cfg.odr;
>  
> -     switch (st->channel_config[channel].filter_type) {
> +     switch (st->channels[channel].cfg.filter_type) {
>       case AD7124_SINC3_FILTER:
>               return DIV_ROUND_CLOSEST(fadc * 230, 1000);
>       case AD7124_SINC4_FILTER:
> @@ -329,9 +295,8 @@ static int ad7124_get_3db_filter_freq(struct ad7124_state 
> *st,
>       }
>  }
>  
> -static int ad7124_set_3db_filter_freq(struct ad7124_state *st,
> -                                   unsigned int channel,
> -                                   unsigned int freq)
> +static void ad7124_set_3db_filter_freq(struct ad7124_state *st, unsigned int 
> channel,
> +                                    unsigned int freq)
>  {
>       unsigned int sinc4_3db_odr;
>       unsigned int sinc3_3db_odr;
> @@ -349,21 +314,224 @@ static int ad7124_set_3db_filter_freq(struct 
> ad7124_state *st,
>               new_odr = sinc3_3db_odr;
>       }
>  
> -     if (st->channel_config[channel].filter_type != new_filter) {
> -             int ret;
> +     st->channels[channel].cfg.filter_type = new_filter;
> +     st->channels[channel].cfg.odr = new_odr;
> +}
>  
> -             st->channel_config[channel].filter_type = new_filter;
> -             ret = ad7124_spi_write_mask(st, AD7124_FILTER(channel),
> -                                         AD7124_FILTER_TYPE_MSK,
> -                                         AD7124_FILTER_TYPE_SEL(new_filter),
> -                                         3);
> -             if (ret < 0)
> -                     return ret;
> +static bool ad7124_configs_equal(struct ad7124_channel_config *cfg1,
> +                              struct ad7124_channel_config *cfg2)
> +{
> +     return ((cfg1->refsel == cfg2->refsel) &&
> +             (cfg1->bipolar == cfg2->bipolar) &&
> +             (cfg1->buf_positive == cfg2->buf_positive) &&
> +             (cfg1->buf_negative == cfg2->buf_negative) &&
> +             (cfg1->vref_mv == cfg2->vref_mv) &&
> +             (cfg1->pga_bits == cfg2->pga_bits) &&
> +             (cfg1->odr == cfg2->odr) &&
> +             (cfg1->odr_sel_bits == cfg2->odr_sel_bits) &&
> +             (cfg1->filter_type == cfg2->filter_type));
> +}
> +
> +static struct ad7124_channel_config *ad7124_find_similar_live_cfg(struct 
> ad7124_state *st,
> +                                                               struct 
> ad7124_channel_config *cfg)
> +{
> +     struct ad7124_channel_config *cfg_aux;
> +     int i;
> +
> +     for (i = 0; i < st->num_channels; i++) {
> +             cfg_aux = &st->channels[i].cfg;
> +
> +             if (cfg_aux->live && ad7124_configs_equal(cfg, cfg_aux))
> +                     return cfg_aux;
> +     }
> +
> +     return NULL;
> +}
> +
> +static int ad7124_find_free_config_slot(struct ad7124_state *st)
> +{
> +     int slots[AD7124_MAX_CONFIGS] = {0};
> +     struct ad7124_channel_config *cfg;
> +     int i = 0;
> +
> +     /* mark all currently used configuration slots */
> +     for (i = 0; i < st->num_channels; i++) {
> +             cfg = &st->channels[i].cfg;
> +
> +             if (cfg->live)
> +                     slots[cfg->cfg_slot] = 1;

Worth maintaining a bitmap as we make use of configs
rather than computing this here?
Defintiely use a bitmap here if not and find_next_zero_bit() to
find an empty hole. 

> +     }
> +
> +     /* find a free one */
> +     for (i = 0; i < AD7124_MAX_CONFIGS; i++) {
> +             if (slots[i] == 0)
> +                     return i;
> +     }
> +
> +     return -1;
> +}
> +
> +static int ad7124_init_config_vref(struct ad7124_state *st, struct 
> ad7124_channel_config *cfg)
> +{
> +     unsigned int refsel = cfg->refsel;
> +
> +     switch (refsel) {
> +     case AD7124_REFIN1:
> +     case AD7124_REFIN2:
> +     case AD7124_AVDD_REF:
> +             if (IS_ERR(st->vref[refsel])) {
> +                     dev_err(&st->sd.spi->dev,
> +                             "Error, trying to use external voltage 
> reference without a %s regulator.\n",
> +                             ad7124_ref_names[refsel]);
> +                             return PTR_ERR(st->vref[refsel]);
> +             }
> +             cfg->vref_mv = regulator_get_voltage(st->vref[refsel]);
> +             /* Conversion from uV to mV */
> +             cfg->vref_mv /= 1000;
> +             break;
> +     case AD7124_INT_REF:
> +             cfg->vref_mv = 2500;
> +             st->adc_control &= ~AD7124_ADC_CTRL_REF_EN_MSK;
> +             st->adc_control |= AD7124_ADC_CTRL_REF_EN(1);
> +             return ad_sd_write_reg(&st->sd, AD7124_ADC_CONTROL,
> +                                   2, st->adc_control);
> +     default:
> +             dev_err(&st->sd.spi->dev, "Invalid reference %d\n", refsel);
> +             return -EINVAL;
> +     }
> +
> +     return 0;
Move this up to the the one break path above?  (trivial!)
> +}
> +
> +static int ad7124_write_config(struct ad7124_state *st, struct 
> ad7124_channel_config *cfg,
> +                            unsigned int cfg_slot)
> +{
> +     unsigned int tmp;
> +     unsigned int val;
> +     int ret;
> +
> +     cfg->cfg_slot = cfg_slot;
> +
> +     tmp = (cfg->buf_positive << 1) + cfg->buf_negative;
> +     val = AD7124_CONFIG_BIPOLAR(cfg->bipolar) | 
> AD7124_CONFIG_REF_SEL(cfg->refsel) |
> +           AD7124_CONFIG_IN_BUFF(tmp);
> +     ret = ad_sd_write_reg(&st->sd, AD7124_CONFIG(cfg->cfg_slot), 2, val);
> +     if (ret < 0)
> +             return ret;
> +
> +     tmp = AD7124_FILTER_TYPE_SEL(cfg->filter_type);
> +     ret = ad7124_spi_write_mask(st, AD7124_FILTER(cfg->cfg_slot), 
> AD7124_FILTER_TYPE_MSK,
> +                                 tmp, 3);
> +     if (ret < 0)
> +             return ret;
> +
> +     ret = ad7124_spi_write_mask(st, AD7124_FILTER(cfg->cfg_slot), 
> AD7124_FILTER_FS_MSK,
> +                                 AD7124_FILTER_FS(cfg->odr_sel_bits), 3);
> +     if (ret < 0)
> +             return ret;
> +
> +     return ad7124_spi_write_mask(st, AD7124_CONFIG(cfg->cfg_slot), 
> AD7124_CONFIG_PGA_MSK,
> +                                  AD7124_CONFIG_PGA(cfg->pga_bits), 2);
> +}
> +
> +static struct ad7124_channel_config *ad7124_pop_config(struct ad7124_state 
> *st)
> +{
> +     struct ad7124_channel_config *lru_cfg;
> +     struct ad7124_channel_config *cfg;
> +     int ret;
> +     int i;
> +
> +     /* pop least recently used config from the fifo

/*
 * Pop

> +      * in order to make room for the new one
> +      */
> +     ret = kfifo_get(&st->live_cfgs_fifo, &lru_cfg);
> +     if (ret <= 0)
> +             return NULL;
> +
> +     lru_cfg->live = false;
> +
> +     /* invalidate all other configs that pointed to this one */
> +     for (i = 0; i < st->num_channels; i++) {
> +             cfg = &st->channels[i].cfg;
> +
> +             if (cfg->cfg_slot == lru_cfg->cfg_slot)
> +                     cfg->live = false;
>       }
>  
> -     return ad7124_set_channel_odr(st, channel, new_odr);
> +     return lru_cfg;
> +}
> +
> +static int ad7124_enable_channel(struct ad7124_state *st, struct 
> ad7124_channel *ch)
> +{
> +     ch->cfg.live = true;
> +     return ad_sd_write_reg(&st->sd, AD7124_CHANNEL(ch->nr), 2, ch->ain |
> +                           AD7124_CHANNEL_SETUP(ch->cfg.cfg_slot) | 
> AD7124_CHANNEL_EN(1));
>  }
>  
> +static int ad7124_prepare_read(struct ad7124_state *st, int address)
> +{
> +     struct ad7124_channel_config *cfg = &st->channels[address].cfg;
> +     struct ad7124_channel_config *live_cfg;
> +     struct ad7124_channel_config *lru_cfg;
> +     int free_cfg_slot;
> +     int ret;
> +
> +     /* Before doing any reads assign the channel a configuration.

/*
 * Before

> +      * Check if channel's config is on the device
> +      */
> +     if (!cfg->live) {
> +             /* check if config matches another one */
> +             live_cfg = ad7124_find_similar_live_cfg(st, cfg);
> +             if (!live_cfg) {
> +                     free_cfg_slot = ad7124_find_free_config_slot(st);
> +                     if (free_cfg_slot >= 0) {
> +                             ret = ad7124_write_config(st, cfg, 
> free_cfg_slot);
> +                             if (ret < 0)
> +                                     return ret;
> +
> +                             /* push the new config in configs queue */
> +                             cfg->cfg_slot = free_cfg_slot;
> +                             kfifo_put(&st->live_cfgs_fifo, cfg);
> +                     } else {
> +                             lru_cfg = ad7124_pop_config(st);
> +                             if (!lru_cfg)
> +                                     return -EINVAL;
> +
> +                             /* push the new config in configs queue */
> +                             cfg->cfg_slot = lru_cfg->cfg_slot;
> +                             kfifo_put(&st->live_cfgs_fifo, cfg);
> +                     }
> +             } else {
> +                     cfg->cfg_slot = live_cfg->cfg_slot;
> +             }
> +     }
> +
> +     /* point channel to the config slot and enable */
> +     return ad7124_enable_channel(st, &st->channels[address]);
> +}
> +
> +static int ad7124_set_channel(struct ad_sigma_delta *sd, unsigned int 
> channel)
> +{
> +     struct ad7124_state *st = container_of(sd, struct ad7124_state, sd);
> +     int ret;
> +
> +     mutex_lock(&st->cfgs_lock);
> +     ret = ad7124_prepare_read(st, channel);
> +     mutex_unlock(&st->cfgs_lock);
> +
> +     return ret;
> +}
> +
> +static const struct ad_sigma_delta_info ad7124_sigma_delta_info = {
> +     .set_channel = ad7124_set_channel,
> +     .set_mode = ad7124_set_mode,
> +     .has_registers = true,
> +     .addr_shift = 0,
> +     .read_mask = BIT(6),
> +     .data_reg = AD7124_DATA,
> +     .irq_flags = IRQF_TRIGGER_FALLING
> +};
> +
>  static int ad7124_read_raw(struct iio_dev *indio_dev,
>                          struct iio_chan_spec const *chan,
>                          int *val, int *val2, long info)
> @@ -378,36 +546,44 @@ static int ad7124_read_raw(struct iio_dev *indio_dev,
>                       return ret;
>  
>               /* After the conversion is performed, disable the channel */
> -             ret = ad_sd_write_reg(&st->sd,
> -                                   AD7124_CHANNEL(chan->address), 2,
> -                                   st->channel_config[chan->address].ain |
> -                                   AD7124_CHANNEL_EN(0));
> +             ret = ad_sd_write_reg(&st->sd, AD7124_CHANNEL(chan->address), 2,
> +                                   st->channels[chan->address].ain | 
> AD7124_CHANNEL_EN(0));
>               if (ret < 0)
>                       return ret;
>  
>               return IIO_VAL_INT;
>       case IIO_CHAN_INFO_SCALE:
> -             idx = st->channel_config[chan->address].pga_bits;
> -             *val = st->channel_config[chan->address].vref_mv;
> -             if (st->channel_config[chan->address].bipolar)
> +             mutex_lock(&st->cfgs_lock);
> +
> +             idx = st->channels[chan->address].cfg.pga_bits;
> +             *val = st->channels[chan->address].cfg.vref_mv;
> +             if (st->channels[chan->address].cfg.bipolar)
>                       *val2 = chan->scan_type.realbits - 1 + idx;
>               else
>                       *val2 = chan->scan_type.realbits + idx;
>  
> +             mutex_unlock(&st->cfgs_lock);
>               return IIO_VAL_FRACTIONAL_LOG2;
>       case IIO_CHAN_INFO_OFFSET:
> -             if (st->channel_config[chan->address].bipolar)
> +             mutex_lock(&st->cfgs_lock);
> +             if (st->channels[chan->address].cfg.bipolar)
>                       *val = -(1 << (chan->scan_type.realbits - 1));
>               else
>                       *val = 0;
>  
> +             mutex_unlock(&st->cfgs_lock);
>               return IIO_VAL_INT;
>       case IIO_CHAN_INFO_SAMP_FREQ:
> -             *val = st->channel_config[chan->address].odr;
> +             mutex_lock(&st->cfgs_lock);
> +             *val = st->channels[chan->address].cfg.odr;
> +             mutex_unlock(&st->cfgs_lock);
>  
>               return IIO_VAL_INT;
>       case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> +             mutex_lock(&st->cfgs_lock);
>               *val = ad7124_get_3db_filter_freq(st, chan->scan_index);
> +             mutex_unlock(&st->cfgs_lock);
> +
>               return IIO_VAL_INT;
>       default:
>               return -EINVAL;
> @@ -421,32 +597,53 @@ static int ad7124_write_raw(struct iio_dev *indio_dev,
>       struct ad7124_state *st = iio_priv(indio_dev);
>       unsigned int res, gain, full_scale, vref;
>  
> +     mutex_lock(&st->cfgs_lock);

Taking a lock outside of a switch but then always unlocking it
in the case statements is a little unintuitive.
Can we move a 
        goto err;
        or
        break; as appropriate.


err:
        mutex_unlock() path and move the unlock out of the switch
as well?



> +     /* any change to the configs will make them different to

/*
 * Any change...

> +      * the ones written on the device
> +      */

Technically we don't yet know it is a change. - Could be a rewrite
of the existing config.  It might be worth identifying that there
is an actual change before we do this.

> +     st->channels[chan->address].cfg.live = false;
> +
>       switch (info) {
>       case IIO_CHAN_INFO_SAMP_FREQ:
> -             if (val2 != 0)
> +             if (val2 != 0) {
> +                     mutex_unlock(&st->cfgs_lock);
>                       return -EINVAL;
> +             }
>  
> -             return ad7124_set_channel_odr(st, chan->address, val);
> +             ad7124_set_channel_odr(st, chan->address, val);
> +
> +             mutex_unlock(&st->cfgs_lock);
> +             return 0;
>       case IIO_CHAN_INFO_SCALE:
> -             if (val != 0)
> +             if (val != 0) {
> +                     mutex_unlock(&st->cfgs_lock);
>                       return -EINVAL;
> +             }
>  
> -             if (st->channel_config[chan->address].bipolar)
> +             if (st->channels[chan->address].cfg.bipolar)
>                       full_scale = 1 << (chan->scan_type.realbits - 1);
>               else
>                       full_scale = 1 << chan->scan_type.realbits;
>  
> -             vref = st->channel_config[chan->address].vref_mv * 1000000LL;
> +             vref = st->channels[chan->address].cfg.vref_mv * 1000000LL;
>               res = DIV_ROUND_CLOSEST(vref, full_scale);
>               gain = DIV_ROUND_CLOSEST(res, val2);
> +             res = ad7124_find_closest_match(ad7124_gain, 
> ARRAY_SIZE(ad7124_gain), gain);
> +             st->channels[chan->address].cfg.pga_bits = res;
>  
> -             return ad7124_set_channel_gain(st, chan->address, gain);
> +             mutex_unlock(&st->cfgs_lock);
> +             return 0;
>       case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> -             if (val2 != 0)
> +             if (val2 != 0) {
> +                     mutex_unlock(&st->cfgs_lock);
>                       return -EINVAL;
> +             }
>  
> -             return ad7124_set_3db_filter_freq(st, chan->address, val);
> +             ad7124_set_3db_filter_freq(st, chan->address, val);
> +             mutex_unlock(&st->cfgs_lock);
> +             return 0;
>       default:
> +             mutex_unlock(&st->cfgs_lock);
>               return -EINVAL;
>       }
>  }
> @@ -547,47 +744,14 @@ static int ad7124_check_chip_id(struct ad7124_state *st)
>       return 0;
>  }
>  
> -static int ad7124_init_channel_vref(struct ad7124_state *st,
> -                                 unsigned int channel_number)
> -{
> -     unsigned int refsel = st->channel_config[channel_number].refsel;
> -
> -     switch (refsel) {
> -     case AD7124_REFIN1:
> -     case AD7124_REFIN2:
> -     case AD7124_AVDD_REF:
> -             if (IS_ERR(st->vref[refsel])) {
> -                     dev_err(&st->sd.spi->dev,
> -                             "Error, trying to use external voltage 
> reference without a %s regulator.\n",
> -                             ad7124_ref_names[refsel]);
> -                     return PTR_ERR(st->vref[refsel]);
> -             }
> -             st->channel_config[channel_number].vref_mv =
> -                     regulator_get_voltage(st->vref[refsel]);
> -             /* Conversion from uV to mV */
> -             st->channel_config[channel_number].vref_mv /= 1000;
> -             break;
> -     case AD7124_INT_REF:
> -             st->channel_config[channel_number].vref_mv = 2500;
> -             st->adc_control &= ~AD7124_ADC_CTRL_REF_EN_MSK;
> -             st->adc_control |= AD7124_ADC_CTRL_REF_EN(1);
> -             return ad_sd_write_reg(&st->sd, AD7124_ADC_CONTROL,
> -                                   2, st->adc_control);
> -     default:
> -             dev_err(&st->sd.spi->dev, "Invalid reference %d\n", refsel);
> -             return -EINVAL;
> -     }
> -
> -     return 0;
> -}
> -
>  static int ad7124_of_parse_channel_config(struct iio_dev *indio_dev,
>                                         struct device_node *np)
>  {
>       struct ad7124_state *st = iio_priv(indio_dev);
> +     struct ad7124_channel_config *cfg;
> +     struct ad7124_channel *channels;
>       struct device_node *child;
>       struct iio_chan_spec *chan;
> -     struct ad7124_channel_config *chan_config;
>       unsigned int ain[2], channel = 0, tmp;
>       int ret;
>  
> @@ -602,16 +766,18 @@ static int ad7124_of_parse_channel_config(struct 
> iio_dev *indio_dev,
>       if (!chan)
>               return -ENOMEM;
>  
> -     chan_config = devm_kcalloc(indio_dev->dev.parent, st->num_channels,
> -                                sizeof(*chan_config), GFP_KERNEL);
> -     if (!chan_config)
> +     channels = devm_kcalloc(indio_dev->dev.parent, st->num_channels, 
> sizeof(*channels),
> +                             GFP_KERNEL);
> +     if (!channels)
>               return -ENOMEM;
>  
>       indio_dev->channels = chan;
>       indio_dev->num_channels = st->num_channels;
> -     st->channel_config = chan_config;
> +     st->channels = channels;
>  
>       for_each_available_child_of_node(np, child) {
> +             cfg = &st->channels[channel].cfg;
> +
>               ret = of_property_read_u32(child, "reg", &channel);
>               if (ret)
>                       goto err;
> @@ -621,21 +787,20 @@ static int ad7124_of_parse_channel_config(struct 
> iio_dev *indio_dev,
>               if (ret)
>                       goto err;
>  
> -             st->channel_config[channel].ain = AD7124_CHANNEL_AINP(ain[0]) |
> +             st->channels[channel].nr = channel;
> +             st->channels[channel].ain = AD7124_CHANNEL_AINP(ain[0]) |
>                                                 AD7124_CHANNEL_AINM(ain[1]);
> -             st->channel_config[channel].bipolar =
> -                     of_property_read_bool(child, "bipolar");
> +
> +             cfg->bipolar = of_property_read_bool(child, "bipolar");
>  
>               ret = of_property_read_u32(child, "adi,reference-select", &tmp);
>               if (ret)
> -                     st->channel_config[channel].refsel = AD7124_INT_REF;
> +                     cfg->refsel = AD7124_INT_REF;
>               else
> -                     st->channel_config[channel].refsel = tmp;
> +                     cfg->refsel = tmp;
>  
> -             st->channel_config[channel].buf_positive =
> -                     of_property_read_bool(child, "adi,buffered-positive");
> -             st->channel_config[channel].buf_negative =
> -                     of_property_read_bool(child, "adi,buffered-negative");
> +             cfg->buf_positive = of_property_read_bool(child, 
> "adi,buffered-positive");
> +             cfg->buf_negative = of_property_read_bool(child, 
> "adi,buffered-negative");
>  
>               chan[channel] = ad7124_channel_template;
>               chan[channel].address = channel;
> @@ -654,7 +819,7 @@ static int ad7124_of_parse_channel_config(struct iio_dev 
> *indio_dev,
>  static int ad7124_setup(struct ad7124_state *st)
>  {
>       unsigned int val, fclk, power_mode;
> -     int i, ret, tmp;
> +     int i, ret;
>  
>       fclk = clk_get_rate(st->mclk);
>       if (!fclk)
> @@ -677,31 +842,21 @@ static int ad7124_setup(struct ad7124_state *st)
>       if (ret < 0)
>               return ret;
>  
> +     mutex_init(&st->cfgs_lock);
> +     INIT_KFIFO(st->live_cfgs_fifo);
>       for (i = 0; i < st->num_channels; i++) {
> -             val = st->channel_config[i].ain | AD7124_CHANNEL_SETUP(i);
> -             ret = ad_sd_write_reg(&st->sd, AD7124_CHANNEL(i), 2, val);
> -             if (ret < 0)
> -                     return ret;
> +             val = st->channels[i].ain;
>  
> -             ret = ad7124_init_channel_vref(st, i);
> +             ret = ad7124_init_config_vref(st, &st->channels[i].cfg);
>               if (ret < 0)
>                       return ret;
>  
> -             tmp = (st->channel_config[i].buf_positive << 1)  +
> -                     st->channel_config[i].buf_negative;
> -
> -             val = AD7124_CONFIG_BIPOLAR(st->channel_config[i].bipolar) |
> -                   AD7124_CONFIG_REF_SEL(st->channel_config[i].refsel) |
> -                   AD7124_CONFIG_IN_BUFF(tmp);
> -             ret = ad_sd_write_reg(&st->sd, AD7124_CONFIG(i), 2, val);
> -             if (ret < 0)
> -                     return ret;
>               /*
>                * 9.38 SPS is the minimum output data rate supported
>                * regardless of the selected power mode. Round it up to 10 and
> -              * set all the enabled channels to this default value.
> +              * set all channels to this default value.
>                */
> -             ret = ad7124_set_channel_odr(st, i, 10);
> +             ad7124_set_channel_odr(st, i, 10);
>       }
>  
>       return ret;

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