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iio: gts: Simplify available scale table build
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Make available scale building more clear. This hurts the performance
quite a bit by looping throgh the scales many times instead of doing
everything in one loop. It however simplifies logic by:
 - decoupling the gain and scale allocations & computations
 - keeping the temporary 'per_time_gains' table inside the
   per_time_scales computation function.
 - separating building the 'all scales' table in own function and doing
   it based on the already computed per-time scales.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Tested-by: subhajit.ghosh@tweaklogic.com
Link: https://patch.msgid.link/Z1_rRXqdhxhL6wBw@mva-rohm
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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Matti Vaittinen authored and Jonathan Cameron committed Feb 3, 2025
1 parent 6eaf49f commit 32f80e2
Showing 1 changed file with 174 additions and 98 deletions.
272 changes: 174 additions & 98 deletions drivers/iio/industrialio-gts-helper.c
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Original file line number Diff line number Diff line change
Expand Up @@ -160,16 +160,123 @@ static void iio_gts_purge_avail_scale_table(struct iio_gts *gts)
gts->num_avail_all_scales = 0;
}

static int scale_eq(int *sc1, int *sc2)
{
return sc1[0] == sc2[0] && sc1[1] == sc2[1];
}

static int scale_smaller(int *sc1, int *sc2)
{
if (sc1[0] != sc2[0])
return sc1[0] < sc2[0];

/* If integer parts are equal, fixp parts */
return sc1[1] < sc2[1];
}

/*
* Do a single table listing all the unique scales that any combination of
* supported gains and times can provide.
*/
static int do_combined_scaletable(struct iio_gts *gts,
size_t all_scales_tbl_bytes)
{
int t_idx, i, new_idx;
int **scales = gts->per_time_avail_scale_tables;
int *all_scales = kcalloc(gts->num_itime, all_scales_tbl_bytes,
GFP_KERNEL);

if (!all_scales)
return -ENOMEM;
/*
* Create table containing all of the supported scales by looping
* through all of the per-time scales and copying the unique scales
* into one sorted table.
*
* We assume all the gains for same integration time were unique.
* It is likely the first time table had greatest time multiplier as
* the times are in the order of preference and greater times are
* usually preferred. Hence we start from the last table which is likely
* to have the smallest total gains.
*/
t_idx = gts->num_itime - 1;
memcpy(all_scales, scales[t_idx], all_scales_tbl_bytes);
new_idx = gts->num_hwgain * 2;

while (t_idx-- > 0) {
for (i = 0; i < gts->num_hwgain ; i++) {
int *candidate = &scales[t_idx][i * 2];
int chk;

if (scale_smaller(candidate, &all_scales[new_idx - 2])) {
all_scales[new_idx] = candidate[0];
all_scales[new_idx + 1] = candidate[1];
new_idx += 2;

continue;
}
for (chk = 0; chk < new_idx; chk += 2)
if (!scale_smaller(candidate, &all_scales[chk]))
break;

if (scale_eq(candidate, &all_scales[chk]))
continue;

memmove(&all_scales[chk + 2], &all_scales[chk],
(new_idx - chk) * sizeof(int));
all_scales[chk] = candidate[0];
all_scales[chk + 1] = candidate[1];
new_idx += 2;
}
}

gts->num_avail_all_scales = new_idx / 2;
gts->avail_all_scales_table = all_scales;

return 0;
}

static void iio_gts_free_int_table_array(int **arr, int num_tables)
{
int i;

for (i = 0; i < num_tables; i++)
kfree(arr[i]);

kfree(arr);
}

static int iio_gts_alloc_int_table_array(int ***arr, int num_tables, int num_table_items)
{
int i, **tmp;

tmp = kcalloc(num_tables, sizeof(**arr), GFP_KERNEL);
if (!tmp)
return -ENOMEM;

for (i = 0; i < num_tables; i++) {
tmp[i] = kcalloc(num_table_items, sizeof(int), GFP_KERNEL);
if (!tmp[i])
goto err_free;
}

*arr = tmp;

return 0;
err_free:
iio_gts_free_int_table_array(tmp, i);

return -ENOMEM;
}

static int iio_gts_gain_cmp(const void *a, const void *b)
{
return *(int *)a - *(int *)b;
}

static int gain_to_scaletables(struct iio_gts *gts, int **gains, int **scales)
static int fill_and_sort_scaletables(struct iio_gts *gts, int **gains, int **scales)
{
int i, j, new_idx, time_idx, ret = 0;
int *all_gains;
size_t gain_bytes;
int i, j, ret;

for (i = 0; i < gts->num_itime; i++) {
/*
Expand All @@ -189,71 +296,69 @@ static int gain_to_scaletables(struct iio_gts *gts, int **gains, int **scales)
}
}

gain_bytes = array_size(gts->num_hwgain, sizeof(int));
all_gains = kcalloc(gts->num_itime, gain_bytes, GFP_KERNEL);
if (!all_gains)
return -ENOMEM;
return 0;
}

static void compute_per_time_gains(struct iio_gts *gts, int **gains)
{
int i, j;

for (i = 0; i < gts->num_itime; i++) {
for (j = 0; j < gts->num_hwgain; j++)
gains[i][j] = gts->hwgain_table[j].gain *
gts->itime_table[i].mul;
}
}

static int compute_per_time_tables(struct iio_gts *gts, int **scales)
{
int **per_time_gains;
int ret;

/*
* We assume all the gains for same integration time were unique.
* It is likely the first time table had greatest time multiplier as
* the times are in the order of preference and greater times are
* usually preferred. Hence we start from the last table which is likely
* to have the smallest total gains.
* Create a temporary array of the 'total gains' for each integration
* time.
*/
time_idx = gts->num_itime - 1;
memcpy(all_gains, gains[time_idx], gain_bytes);
new_idx = gts->num_hwgain;
ret = iio_gts_alloc_int_table_array(&per_time_gains, gts->num_itime,
gts->num_hwgain);
if (ret)
return ret;

while (time_idx-- > 0) {
for (j = 0; j < gts->num_hwgain; j++) {
int candidate = gains[time_idx][j];
int chk;
compute_per_time_gains(gts, per_time_gains);

if (candidate > all_gains[new_idx - 1]) {
all_gains[new_idx] = candidate;
new_idx++;
/* Convert the gains to scales and populate the scale tables */
ret = fill_and_sort_scaletables(gts, per_time_gains, scales);

continue;
}
for (chk = 0; chk < new_idx; chk++)
if (candidate <= all_gains[chk])
break;
iio_gts_free_int_table_array(per_time_gains, gts->num_itime);

if (candidate == all_gains[chk])
continue;
return ret;
}

memmove(&all_gains[chk + 1], &all_gains[chk],
(new_idx - chk) * sizeof(int));
all_gains[chk] = candidate;
new_idx++;
}
}
/*
* Create a table of supported scales for each supported integration time.
* This can be used as available_scales by drivers which don't allow scale
* setting to change the integration time to display correct set of scales
* depending on the used integration time.
*/
static int **create_per_time_scales(struct iio_gts *gts)
{
int **per_time_scales, ret;

gts->avail_all_scales_table = kcalloc(new_idx, 2 * sizeof(int),
GFP_KERNEL);
if (!gts->avail_all_scales_table) {
ret = -ENOMEM;
goto free_out;
}
gts->num_avail_all_scales = new_idx;
ret = iio_gts_alloc_int_table_array(&per_time_scales, gts->num_itime,
gts->num_hwgain * 2);
if (ret)
return ERR_PTR(ret);

for (i = 0; i < gts->num_avail_all_scales; i++) {
ret = iio_gts_total_gain_to_scale(gts, all_gains[i],
&gts->avail_all_scales_table[i * 2],
&gts->avail_all_scales_table[i * 2 + 1]);
ret = compute_per_time_tables(gts, per_time_scales);
if (ret)
goto err_out;

if (ret) {
kfree(gts->avail_all_scales_table);
gts->num_avail_all_scales = 0;
goto free_out;
}
}
return per_time_scales;

free_out:
kfree(all_gains);
err_out:
iio_gts_free_int_table_array(per_time_scales, gts->num_itime);

return ret;
return ERR_PTR(ret);
}

/**
Expand All @@ -275,55 +380,26 @@ static int gain_to_scaletables(struct iio_gts *gts, int **gains, int **scales)
*/
static int iio_gts_build_avail_scale_table(struct iio_gts *gts)
{
int **per_time_gains, **per_time_scales, i, j, ret = -ENOMEM;
int ret, all_scales_tbl_bytes;
int **per_time_scales;

per_time_gains = kcalloc(gts->num_itime, sizeof(*per_time_gains), GFP_KERNEL);
if (!per_time_gains)
return ret;

per_time_scales = kcalloc(gts->num_itime, sizeof(*per_time_scales), GFP_KERNEL);
if (!per_time_scales)
goto free_gains;

for (i = 0; i < gts->num_itime; i++) {
per_time_scales[i] = kcalloc(gts->num_hwgain, 2 * sizeof(int),
GFP_KERNEL);
if (!per_time_scales[i])
goto err_free_out;

per_time_gains[i] = kcalloc(gts->num_hwgain, sizeof(int),
GFP_KERNEL);
if (!per_time_gains[i]) {
kfree(per_time_scales[i]);
goto err_free_out;
}

for (j = 0; j < gts->num_hwgain; j++)
per_time_gains[i][j] = gts->hwgain_table[j].gain *
gts->itime_table[i].mul;
}
if (unlikely(check_mul_overflow(gts->num_hwgain, 2 * sizeof(int),
&all_scales_tbl_bytes)))
return -EOVERFLOW;

ret = gain_to_scaletables(gts, per_time_gains, per_time_scales);
if (ret)
goto err_free_out;
per_time_scales = create_per_time_scales(gts);
if (IS_ERR(per_time_scales))
return PTR_ERR(per_time_scales);

for (i = 0; i < gts->num_itime; i++)
kfree(per_time_gains[i]);
kfree(per_time_gains);
gts->per_time_avail_scale_tables = per_time_scales;

return 0;

err_free_out:
for (i--; i >= 0; i--) {
kfree(per_time_scales[i]);
kfree(per_time_gains[i]);
ret = do_combined_scaletable(gts, all_scales_tbl_bytes);
if (ret) {
iio_gts_free_int_table_array(per_time_scales, gts->num_itime);
return ret;
}
kfree(per_time_scales);
free_gains:
kfree(per_time_gains);

return ret;
return 0;
}

static void iio_gts_us_to_int_micro(int *time_us, int *int_micro_times,
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