diff options
Diffstat (limited to 'drivers/iio/adc')
| -rw-r--r-- | drivers/iio/adc/at91_adc.c | 53 |
1 files changed, 46 insertions, 7 deletions
diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c index 8b93295..abce01b 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; }; @@ -428,6 +431,45 @@ 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, @@ -651,15 +693,9 @@ 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 @@ -736,6 +772,7 @@ 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, @@ -747,6 +784,7 @@ 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, @@ -758,6 +796,7 @@ 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, |
