From: josh.wu@atmel•com (Josh Wu)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 3/5] iio: at91: ADC start-up time calculation changed since at91sam9x5
Date: Thu, 25 Jul 2013 15:35:56 +0800 [thread overview]
Message-ID: <51F0D55C.90709@atmel.com> (raw)
In-Reply-To: <51EA5AC5.30400@kernel.org>
On 7/20/2013 5:39 PM, Jonathan Cameron wrote:
> On 07/14/2013 09:04 AM, Josh Wu wrote:
>> Since in at91sam9x5, sama5d3x chip. the start up time calucation is changed.
>> And these two chips also have TSMR, so we check whether ADC has TSMR, then
>> choose different start up time calculation formula.
> If this doesn't have anything directly to do with the TSMR and this is just
> coincidence, then do this separately with it's own flag as it will be
> easier to maintain in the long run.
Agreed. I will fix it in next version.
Best Regards,
Josh Wu
>
> Jonathan
>> Signed-off-by: Josh Wu <josh.wu@atmel•com>
>> ---
>> drivers/iio/adc/at91_adc.c | 40 +++++++++++++++++++++++++++++++++-------
>> 1 file changed, 33 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
>> index 14e99ba..e93a075 100644
>> --- a/drivers/iio/adc/at91_adc.c
>> +++ b/drivers/iio/adc/at91_adc.c
>> @@ -733,13 +733,39 @@ static int at91_adc_probe(struct platform_device *pdev)
>> goto error_disable_adc_clk;
>> }
>>
>> - /*
>> - * 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;
>> + if (!st->caps.has_tsmr) {
>> + /*
>> + * 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;
>> + } else {
>> + /*
>> + * 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);
>> + ticks = st->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;
>> + }
>> +
>> /*
>> * a minimal Sample and Hold Time is necessary for the ADC to guarantee
>> * the best converted final value between two channels selection
>>
next prev parent reply other threads:[~2013-07-25 7:35 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-14 8:04 [PATCH 0/5] iio: at91: Add touch screen support in at91 adc Josh Wu
2013-07-14 8:04 ` [PATCH 1/5] iio: at91: use adc_clk_khz to make the calculation not easy to large than u32 Josh Wu
2013-07-15 12:52 ` Maxime Ripard
2013-07-16 7:54 ` Josh Wu
2013-07-14 8:04 ` [PATCH 2/5] iio: at91: Use different prescal, startup mask in MR for different IP Josh Wu
2013-07-15 12:58 ` Maxime Ripard
2013-07-16 8:35 ` Josh Wu
2013-07-16 8:46 ` Nicolas Ferre
2013-07-16 11:20 ` Maxime Ripard
2013-07-16 11:30 ` Thomas Petazzoni
2013-07-16 19:03 ` Jonathan Cameron
2013-07-16 19:17 ` Thomas Petazzoni
2013-07-17 8:23 ` Nicolas Ferre
2013-07-17 8:12 ` Nicolas Ferre
2013-07-17 9:07 ` Josh Wu
2013-07-17 15:40 ` Maxime Ripard
2013-07-17 7:58 ` Nicolas Ferre
2013-07-17 10:09 ` Josh Wu
2013-07-20 9:35 ` Jonathan Cameron
2013-07-14 8:04 ` [PATCH 3/5] iio: at91: ADC start-up time calculation changed since at91sam9x5 Josh Wu
2013-07-20 9:39 ` Jonathan Cameron
2013-07-25 7:35 ` Josh Wu [this message]
2013-07-14 8:04 ` [PATCH 4/5] iio: at91: add an optional dt property for for adc clock hz Josh Wu
2013-07-15 13:06 ` Maxime Ripard
2013-07-16 7:55 ` Josh Wu
2013-07-16 10:30 ` Maxime Ripard
2013-07-16 11:16 ` Lars-Peter Clausen
2013-07-25 7:29 ` Josh Wu
2013-07-25 12:01 ` boris brezillon
2013-07-25 12:11 ` boris brezillon
2013-07-14 8:04 ` [PATCH 5/5] iio: at91: introduce touch screen support in iio adc driver Josh Wu
2013-07-15 13:15 ` Maxime Ripard
2013-07-16 9:09 ` Josh Wu
2013-07-16 11:43 ` Maxime Ripard
2013-07-20 9:57 ` Jonathan Cameron
2013-07-22 13:17 ` Mark Rutland
2013-07-25 7:56 ` Josh Wu
2013-07-25 16:45 ` Mark Rutland
2013-08-06 10:24 ` Josh Wu
2013-08-08 13:40 ` Mark Rutland
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