This replaces the current-to-lux look up table with some
integer math using int_pow() from <linux/kernel.h>.
Drop the unused <linux/math64.h> in the process.
Cc: Jonathan Bakker <xc-racer2@xxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
I would appreciate testing that this give the right
result. Using math does look a lot better.
---
drivers/iio/light/gp2ap002.c | 94 +++---------------------------------
1 file changed, 7 insertions(+), 87 deletions(-)
diff --git a/drivers/iio/light/gp2ap002.c b/drivers/iio/light/gp2ap002.c
index 433907619268..153ae0a163ab 100644
--- a/drivers/iio/light/gp2ap002.c
+++ b/drivers/iio/light/gp2ap002.c
@@ -33,7 +33,6 @@
#include <linux/pm_runtime.h>
#include <linux/interrupt.h>
#include <linux/bits.h>
-#include <linux/math64.h>
#include <linux/pm.h>
#define GP2AP002_PROX_CHANNEL 0
@@ -205,71 +204,10 @@ static irqreturn_t gp2ap002_prox_irq(int irq, void *d)
return IRQ_HANDLED;
}
-struct gp2ap002_illuminance {
- unsigned int curr;
- unsigned int lux;
-};
-
-/*
- * This array maps current and lux.
- *
- * Ambient light sensing range is 3 to 55000 lux.
- *
- * This mapping is based on the following formula.
- * illuminance = 10 ^ (current / 10)
- */
-static const struct gp2ap002_illuminance gp2ap002_illuminance_table[] = {
- { .curr = 5, .lux = 3 },
- { .curr = 6, .lux = 4 },
- { .curr = 7, .lux = 5 },
- { .curr = 8, .lux = 6 },
- { .curr = 9, .lux = 8 },
- { .curr = 10, .lux = 10 },
- { .curr = 11, .lux = 12 },
- { .curr = 12, .lux = 16 },
- { .curr = 13, .lux = 20 },
- { .curr = 14, .lux = 25 },
- { .curr = 15, .lux = 32 },
- { .curr = 16, .lux = 40 },
- { .curr = 17, .lux = 50 },
- { .curr = 18, .lux = 63 },
- { .curr = 19, .lux = 79 },
- { .curr = 20, .lux = 100 },
- { .curr = 21, .lux = 126 },
- { .curr = 22, .lux = 158 },
- { .curr = 23, .lux = 200 },
- { .curr = 24, .lux = 251 },
- { .curr = 25, .lux = 316 },
- { .curr = 26, .lux = 398 },
- { .curr = 27, .lux = 501 },
- { .curr = 28, .lux = 631 },
- { .curr = 29, .lux = 794 },
- { .curr = 30, .lux = 1000 },
- { .curr = 31, .lux = 1259 },
- { .curr = 32, .lux = 1585 },
- { .curr = 33, .lux = 1995 },
- { .curr = 34, .lux = 2512 },
- { .curr = 35, .lux = 3162 },
- { .curr = 36, .lux = 3981 },
- { .curr = 37, .lux = 5012 },
- { .curr = 38, .lux = 6310 },
- { .curr = 39, .lux = 7943 },
- { .curr = 40, .lux = 10000 },
- { .curr = 41, .lux = 12589 },
- { .curr = 42, .lux = 15849 },
- { .curr = 43, .lux = 19953 },
- { .curr = 44, .lux = 25119 },
- { .curr = 45, .lux = 31623 },
- { .curr = 46, .lux = 39811 },
- { .curr = 47, .lux = 50119 },
-};
-
static int gp2ap002_get_lux(struct gp2ap002 *gp2ap002)
{
- const struct gp2ap002_illuminance *ill1;
- const struct gp2ap002_illuminance *ill2;
int ret, res;
- int i;
+ u64 lux;
ret = iio_read_channel_processed(gp2ap002->alsout, &res);
if (ret < 0)
@@ -277,31 +215,13 @@ static int gp2ap002_get_lux(struct gp2ap002 *gp2ap002)
dev_dbg(gp2ap002->dev, "read %d mA from ADC\n", res);
- ill1 = &gp2ap002_illuminance_table[0];
- if (res < ill1->curr) {
- dev_dbg(gp2ap002->dev, "total darkness\n");
- return 0;
- }
- for (i = 0; i < ARRAY_SIZE(gp2ap002_illuminance_table) - 1; i++) {
- ill1 = &gp2ap002_illuminance_table[i];
- ill2 = &gp2ap002_illuminance_table[i + 1];
-
- if (res > ill2->curr)
- continue;
- if ((res <= ill1->curr) && (res >= ill2->curr))
- break;
+ lux = int_pow(10, (res/10));
+ if (lux > INT_MAX) {
+ dev_err(gp2ap002->dev, "lux overflow, capped\n");
+ lux = INT_MAX;
}
- if (res > ill2->curr) {
- dev_info_once(gp2ap002->dev, "max current overflow\n");
- return ill2->curr;
- }
- /* Interpolate and return */
- dev_dbg(gp2ap002->dev, "interpolate index %d and %d\n", i, i + 1);
- /* How many steps along the curve */
- i = res - ill1->curr; /* x - x0 */
- /* Linear interpolation */
- return ill1->lux + i *
- ((ill2->lux - ill1->lux) / (ill2->curr - ill1->curr));
+
+ return (int)lux;
}
static int gp2ap002_read_raw(struct iio_dev *indio_dev,
--
2.21.1
