From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from saturn.retrosnub.co.uk ([178.18.118.26]:36769 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754491Ab3JITL7 (ORCPT ); Wed, 9 Oct 2013 15:11:59 -0400 Message-ID: <5255B8AD.3040109@kernel.org> Date: Wed, 09 Oct 2013 21:12:29 +0100 From: Jonathan Cameron MIME-Version: 1.0 To: Josh Wu , dmitry.torokhov@gmail.com CC: linux-iio@vger.kernel.org, linux-arm-kernel@lists.infradead.org, maxime.ripard@free-electrons.com, plagnioj@jcrosoft.com, nicolas.ferre@atmel.com, thomas.petazzoni@free-electrons.com, mark.rutland@arm.com, b.brezillon@overkiz.com Subject: Re: [PATCH 1/3] iio: at91: ADC start-up time calculation changed since at91sam9x5 References: <1381204136-32322-1-git-send-email-josh.wu@atmel.com> <1381204136-32322-2-git-send-email-josh.wu@atmel.com> In-Reply-To: <1381204136-32322-2-git-send-email-josh.wu@atmel.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 10/08/13 04:48, Josh Wu wrote: > 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 > Acked-by: Maxime Ripard Applied to the togreg branch of iio.git Thanks > --- > 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 = / 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, >