Since in at91sam9x5, sama5d3x chip. the start up time calucation is changed.
This patch can choose different start up time calculation formula for different
chips.
Signed-off-by: Josh Wu <josh.wu@xxxxxxxxx>
Acked-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
---
drivers/iio/adc/at91_adc.c | 53 ++++++++++++++++++++++++++++++++++++++------
1 file changed, 46 insertions(+), 7 deletions(-)
diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
index 0f16b55..cee04a4 100644
--- a/drivers/iio/adc/at91_adc.c
+++ b/drivers/iio/adc/at91_adc.c
@@ -40,6 +40,9 @@
(writel_relaxed(val, st->reg_base + reg))
struct at91_adc_caps {
+ /* startup time calculate function */
+ u32 (*calc_startup_ticks)(u8 startup_time, u32 adc_clk_khz);
+
struct at91_adc_reg_desc registers;
};
@@ -434,6 +437,45 @@ ret:
return ret;
}
+static u32 calc_startup_ticks_9260(u8 startup_time, u32 adc_clk_khz)
+{
+ /*
+ * Number of ticks needed to cover the startup time of the ADC
+ * as defined in the electrical characteristics of the board,
+ * divided by 8. The formula thus is :
+ * Startup Time = (ticks + 1) * 8 / ADC Clock
+ */
+ return round_up((startup_time * adc_clk_khz / 1000) - 1, 8) / 8;
+}
+
+static u32 calc_startup_ticks_9x5(u8 startup_time, u32 adc_clk_khz)
+{
+ /*
+ * For sama5d3x and at91sam9x5, the formula changes to:
+ * Startup Time = <lookup_table_value> / ADC Clock
+ */
+ const int startup_lookup[] = {
+ 0 , 8 , 16 , 24 ,
+ 64 , 80 , 96 , 112,
+ 512, 576, 640, 704,
+ 768, 832, 896, 960
+ };
+ int i, size = ARRAY_SIZE(startup_lookup);
+ unsigned int ticks;
+
+ ticks = startup_time * adc_clk_khz / 1000;
+ for (i = 0; i < size; i++)
+ if (ticks < startup_lookup[i])
+ break;
+
+ ticks = i;
+ if (ticks == size)
+ /* Reach the end of lookup table */
+ ticks = size - 1;
+
+ return ticks;
+}
+
static const struct of_device_id at91_adc_dt_ids[];
static int at91_adc_probe_dt(struct at91_adc_state *st,
@@ -657,15 +699,9 @@ static int at91_adc_probe(struct platform_device *pdev)
ret = -EINVAL;
goto error_disable_adc_clk;
}
+ ticks = (*st->caps->calc_startup_ticks)(st->startup_time, adc_clk_khz);
/*
- * Number of ticks needed to cover the startup time of the ADC as
- * defined in the electrical characteristics of the board, divided by 8.
- * The formula thus is : Startup Time = (ticks + 1) * 8 / ADC Clock
- */
- ticks = round_up((st->startup_time * adc_clk_khz /
- 1000) - 1, 8) / 8;
- /*
* a minimal Sample and Hold Time is necessary for the ADC to guarantee
* the best converted final value between two channels selection
* The formula thus is : Sample and Hold Time = (shtim + 1) / ADCClock
@@ -742,6 +778,7 @@ static int at91_adc_remove(struct platform_device *pdev)
#ifdef CONFIG_OF
static struct at91_adc_caps at91sam9260_caps = {
+ .calc_startup_ticks = calc_startup_ticks_9260,
.registers = {
.channel_base = AT91_ADC_CHR(0),
.drdy_mask = AT91_ADC_DRDY,
@@ -753,6 +790,7 @@ static struct at91_adc_caps at91sam9260_caps = {
};
static struct at91_adc_caps at91sam9g45_caps = {
+ .calc_startup_ticks = calc_startup_ticks_9260, /* same as 9260 */
.registers = {
.channel_base = AT91_ADC_CHR(0),
.drdy_mask = AT91_ADC_DRDY,
@@ -764,6 +802,7 @@ static struct at91_adc_caps at91sam9g45_caps = {
};
static struct at91_adc_caps at91sam9x5_caps = {
+ .calc_startup_ticks = calc_startup_ticks_9x5,
.registers = {
.channel_base = AT91_ADC_CDR0_9X5,
.drdy_mask = AT91_ADC_SR_DRDY_9X5,
--
1.7.9.5
--
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