From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from newsmtp5.atmel.com ([204.2.163.5]:34471 "EHLO sjogate2.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753129Ab3HKLH2 (ORCPT ); Sun, 11 Aug 2013 07:07:28 -0400 From: Josh Wu To: jic23@cam.ac.uk Cc: linux-arm-kernel@lists.infradead.org, linux-iio@vger.kernel.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, Josh Wu Subject: [PATCH v2 3/4] iio: at91: ADC start-up time calculation changed since at91sam9x5 Date: Sun, 11 Aug 2013 19:04:30 +0800 Message-Id: <1376219071-29946-4-git-send-email-josh.wu@atmel.com> In-Reply-To: <1376219071-29946-1-git-send-email-josh.wu@atmel.com> References: <1376219071-29946-1-git-send-email-josh.wu@atmel.com> Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org 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 --- v1 --> v2: add a new variable for different start_time calculation. drivers/iio/adc/at91_adc.c | 42 +++++++++++++++++++++++++++++++++++------- 1 file changed, 35 insertions(+), 7 deletions(-) diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c index b41eb60..9b0ffff 100644 --- a/drivers/iio/adc/at91_adc.c +++ b/drivers/iio/adc/at91_adc.c @@ -40,6 +40,7 @@ (writel_relaxed(val, st->reg_base + reg)) struct at91_adc_caps { + bool start_time_use_lookup_tab; u32 mr_prescal_mask; u32 mr_startup_mask; }; @@ -700,13 +701,39 @@ 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->start_time_use_lookup_tab) { + /* + * 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 = / 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 @@ -798,6 +825,7 @@ static struct at91_adc_caps at91sam9g45_caps = { }; static struct at91_adc_caps at91sam9x5_caps = { + .start_time_use_lookup_tab = true, .mr_prescal_mask = AT91_ADC_PRESCAL_9G45, /* same as 9G45 */ .mr_startup_mask = AT91_ADC_STARTUP_9X5, }; -- 1.7.10