Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756738Ab3GQR1A (ORCPT ); Wed, 17 Jul 2013 13:27:00 -0400 Received: from mail-ee0-f47.google.com ([74.125.83.47]:60070 "EHLO mail-ee0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756714Ab3GQR06 (ORCPT ); Wed, 17 Jul 2013 13:26:58 -0400 From: Zubair Lutfullah To: jic23@cam.ac.uk Cc: linux-iio@vger.kernel.org, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, koen@dominion.thruhere.net, zubair.lutfullah@gmail.com Subject: [PATCH 02/21] IIO: ADC: ti_adc: Fix 1st sample read Date: Wed, 17 Jul 2013 18:26:31 +0100 Message-Id: <1374082010-28095-3-git-send-email-zubair.lutfullah@gmail.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1374082010-28095-1-git-send-email-zubair.lutfullah@gmail.com> References: <1374082010-28095-1-git-send-email-zubair.lutfullah@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3610 Lines: 122 Previously we tried to read data form ADC even before ADC sequencer finished sampling. This led to wrong samples. We now wait on ADC status register idle bit to be set. This patch is based on work in the 3.2 tree by TI Original Author is Patil Rachna Signed-off-by: Zubair Lutfullah --- drivers/iio/adc/ti_am335x_adc.c | 30 ++++++++++++++++++++++-------- include/linux/mfd/ti_am335x_tscadc.h | 16 ++++++++++++++++ 2 files changed, 38 insertions(+), 8 deletions(-) diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c index 4427e8e..1f83cf7 100644 --- a/drivers/iio/adc/ti_am335x_adc.c +++ b/drivers/iio/adc/ti_am335x_adc.c @@ -60,7 +60,6 @@ static void tiadc_step_config(struct tiadc_device *adc_dev) { unsigned int stepconfig; int i, steps; - u32 step_en; /* * There are 16 configurable steps and 8 analog input @@ -86,8 +85,7 @@ static void tiadc_step_config(struct tiadc_device *adc_dev) adc_dev->channel_step[i] = steps; steps++; } - step_en = get_adc_step_mask(adc_dev); - am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en); + } static const char * const chan_name_ain[] = { @@ -142,10 +140,22 @@ static int tiadc_read_raw(struct iio_dev *indio_dev, int *val, int *val2, long mask) { struct tiadc_device *adc_dev = iio_priv(indio_dev); - int i; - unsigned int fifo1count, read; + int i, map_val; + unsigned int fifo1count, read, stepid; u32 step = UINT_MAX; bool found = false; + u32 step_en; + unsigned long timeout = jiffies + usecs_to_jiffies + (IDLE_TIMEOUT * adc_dev->channels); + step_en = get_adc_step_mask(adc_dev); + am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en); + + /* Wait for ADC sequencer to complete sampling */ + while (tiadc_readl(adc_dev, REG_ADCFSM) & SEQ_STATUS) { + if (time_after(jiffies, timeout)) + return -EAGAIN; + } + map_val = chan->channel + TOTAL_CHANNELS; /* * When the sub-system is first enabled, @@ -170,12 +180,16 @@ static int tiadc_read_raw(struct iio_dev *indio_dev, fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT); for (i = 0; i < fifo1count; i++) { read = tiadc_readl(adc_dev, REG_FIFO1); - if (read >> 16 == step) { - *val = read & 0xfff; + stepid = read & FIFOREAD_CHNLID_MASK; + stepid = stepid >> 0x10; + + if (stepid == map_val) { + read = read & FIFOREAD_DATA_MASK; found = true; + *val = read; } } - am335x_tsc_se_update(adc_dev->mfd_tscadc); + if (found == false) return -EBUSY; return IIO_VAL_INT; diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h index 8d73fe2..db1791b 100644 --- a/include/linux/mfd/ti_am335x_tscadc.h +++ b/include/linux/mfd/ti_am335x_tscadc.h @@ -113,11 +113,27 @@ #define CNTRLREG_8WIRE CNTRLREG_AFE_CTRL(3) #define CNTRLREG_TSCENB BIT(7) +/* FIFO READ Register */ +#define FIFOREAD_DATA_MASK (0xfff << 0) +#define FIFOREAD_CHNLID_MASK (0xf << 16) + +/* Sequencer Status */ +#define SEQ_STATUS BIT(5) + #define ADC_CLK 3000000 #define MAX_CLK_DIV 7 #define TOTAL_STEPS 16 #define TOTAL_CHANNELS 8 +/* +* ADC runs at 3MHz, and it takes +* 15 cycles to latch one data output. +* Hence the idle time for ADC to +* process one sample data would be +* around 5 micro seconds. +*/ +#define IDLE_TIMEOUT 5 /* microsec */ + #define TSCADC_CELLS 2 struct ti_tscadc_dev { -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/