Date:	Mon, 17 Aug 2015 19:26:06 +0530
From:	maitysanchayan@...il.com
To:	Jonathan Cameron <jic23@...nel.org>
Cc:	linux-iio@...r.kernel.org, stefan@...er.ch, B38611@...escale.com,
	pmeerw@...erw.net, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3] iio: adc: vf610: Add IIO buffer support for Vybrid ADC

Hello Jonathan,

On 15-08-15 21:24:01, Jonathan Cameron wrote:
> On 11/08/15 10:05, Sanchayan Maity wrote:
> > This patch adds support for IIO buffer to the Vybrid ADC driver.
> > IIO triggered buffer infrastructure along with iio sysfs trigger
> > is used to leverage continuous sampling support provided by the
> > ADC block.
> > 
> > Signed-off-by: Sanchayan Maity <maitysanchayan@...il.com>
> Hi Sanchayan,
> 
> Very nearly there. One little point to do with the buffer handling.
> Basically I don't think you want anything in the preenable or
> postdisable hooks, just in the 'internal' ones.
> 
> Jonathan
> > ---
> >  drivers/iio/adc/Kconfig     |   2 +
> >  drivers/iio/adc/vf610_adc.c | 102 +++++++++++++++++++++++++++++++++++++++++---
> >  2 files changed, 97 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index 7c55658..660f790 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -337,6 +337,8 @@ config TWL6030_GPADC
> >  config VF610_ADC
> >  	tristate "Freescale vf610 ADC driver"
> >  	depends on OF
> > +	select IIO_BUFFER
> > +	select IIO_TRIGGERED_BUFFER
> >  	help
> >  	  Say yes here to support for Vybrid board analog-to-digital converter.
> >  	  Since the IP is used for i.MX6SLX, the driver also support i.MX6SLX.
> > diff --git a/drivers/iio/adc/vf610_adc.c b/drivers/iio/adc/vf610_adc.c
> > index 23b8fb9..de62c48 100644
> > --- a/drivers/iio/adc/vf610_adc.c
> > +++ b/drivers/iio/adc/vf610_adc.c
> > @@ -34,8 +34,11 @@
> >  #include <linux/err.h>
> >  
> >  #include <linux/iio/iio.h>
> > +#include <linux/iio/buffer.h>
> >  #include <linux/iio/sysfs.h>
> > -#include <linux/iio/driver.h>
> > +#include <linux/iio/trigger.h>
> > +#include <linux/iio/trigger_consumer.h>
> > +#include <linux/iio/triggered_buffer.h>
> >  
> >  /* This will be the driver name the kernel reports */
> >  #define DRIVER_NAME "vf610-adc"
> > @@ -170,6 +173,7 @@ struct vf610_adc {
> >  	u32 sample_freq_avail[5];
> >  
> >  	struct completion completion;
> > +	u16 buffer[8];
> >  };
> >  
> >  static const u32 vf610_hw_avgs[] = { 1, 4, 8, 16, 32 };
> > @@ -505,12 +509,24 @@ static const struct iio_chan_spec_ext_info vf610_ext_info[] = {
> >  	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |	\
> >  				BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
> >  	.ext_info = vf610_ext_info,				\
> > +	.scan_index = (_idx),			\
> > +	.scan_type = {					\
> > +		.sign = 'u',				\
> > +		.realbits = 12,				\
> > +		.storagebits = 16,			\
> > +	},						\
> >  }
> >  
> >  #define VF610_ADC_TEMPERATURE_CHAN(_idx, _chan_type) {	\
> >  	.type = (_chan_type),	\
> >  	.channel = (_idx),		\
> >  	.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),	\
> > +	.scan_index = (_idx),					\
> > +	.scan_type = {						\
> > +		.sign = 'u',					\
> > +		.realbits = 12,					\
> > +		.storagebits = 16,				\
> > +	},							\
> >  }
> >  
> >  static const struct iio_chan_spec vf610_adc_iio_channels[] = {
> > @@ -531,6 +547,7 @@ static const struct iio_chan_spec vf610_adc_iio_channels[] = {
> >  	VF610_ADC_CHAN(14, IIO_VOLTAGE),
> >  	VF610_ADC_CHAN(15, IIO_VOLTAGE),
> >  	VF610_ADC_TEMPERATURE_CHAN(26, IIO_TEMP),
> > +	IIO_CHAN_SOFT_TIMESTAMP(32),
> >  	/* sentinel */
> >  };
> >  
> > @@ -559,13 +576,20 @@ static int vf610_adc_read_data(struct vf610_adc *info)
> >  
> >  static irqreturn_t vf610_adc_isr(int irq, void *dev_id)
> >  {
> > -	struct vf610_adc *info = (struct vf610_adc *)dev_id;
> > +	struct iio_dev *indio_dev = (struct iio_dev *)dev_id;
> > +	struct vf610_adc *info = iio_priv(indio_dev);
> >  	int coco;
> >  
> >  	coco = readl(info->regs + VF610_REG_ADC_HS);
> >  	if (coco & VF610_ADC_HS_COCO0) {
> >  		info->value = vf610_adc_read_data(info);
> > -		complete(&info->completion);
> > +		if (iio_buffer_enabled(indio_dev)) {
> > +			info->buffer[0] = info->value;
> > +			iio_push_to_buffers_with_timestamp(indio_dev,
> > +					info->buffer, iio_get_time_ns());
> > +			iio_trigger_notify_done(indio_dev->trig);
> > +		} else
> > +			complete(&info->completion);
> >  	}
> >  
> >  	return IRQ_HANDLED;
> > @@ -613,8 +637,12 @@ static int vf610_read_raw(struct iio_dev *indio_dev,
> >  	case IIO_CHAN_INFO_RAW:
> >  	case IIO_CHAN_INFO_PROCESSED:
> >  		mutex_lock(&indio_dev->mlock);
> > -		reinit_completion(&info->completion);
> > +		if (iio_buffer_enabled(indio_dev)) {
> > +			mutex_unlock(&indio_dev->mlock);
> > +			return -EBUSY;
> > +		}
> >  
> > +		reinit_completion(&info->completion);
> >  		hc_cfg = VF610_ADC_ADCHC(chan->channel);
> >  		hc_cfg |= VF610_ADC_AIEN;
> >  		writel(hc_cfg, info->regs + VF610_REG_ADC_HC0);
> > @@ -694,6 +722,57 @@ static int vf610_write_raw(struct iio_dev *indio_dev,
> >  	return -EINVAL;
> >  }
> >  
> > +static int vf610_adc_buffer_postenable(struct iio_dev *indio_dev)
> > +{
> > +	struct vf610_adc *info = iio_priv(indio_dev);
> > +	unsigned int channel;
> > +	int ret;
> > +	int val;
> > +
> > +	ret = iio_triggered_buffer_postenable(indio_dev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	val = readl(info->regs + VF610_REG_ADC_GC);
> > +	val |= VF610_ADC_ADCON;
> > +	writel(val, info->regs + VF610_REG_ADC_GC);
> > +
> > +	channel = find_first_bit(indio_dev->active_scan_mask,
> > +						indio_dev->masklength);
> > +
> > +	val = VF610_ADC_ADCHC(channel);
> > +	val |= VF610_ADC_AIEN;
> > +
> > +	writel(val, info->regs + VF610_REG_ADC_HC0);
> > +
> > +	return 0;
> > +}
> > +
> 
> These are suppose to be pair wise matched, so anything set up
> in postenable has to be torn down in predisable.
> Likewise, preenable setup torn down in postdisable.
> 
> The distinction is meant to be that a query will return that the
> buffer is enabled from a point between the pre and post enable
> and return that it is disabled from a point between the pre and
> post disable.  Actually locks are held so there may no longer
> be a window where it matters, but best to keep to convention.
> 
> I think you want the postdisable -> predisable and then call the
> standard predisable from there.

Ok. I guess I understood. So the postdisable code actually should
go into predisable and while taking care of mutex locking.

The way I was reasoning wanting to enable the continuous sampling
after the buffer is enabled and then after buffer is disabled,
stopping it. With your explanation it makes sense that I should
have it in predisable.

Thank you for the feedback. I will incoporate the above change
and send the new version.

- Sanchayan.

> 
> > +static int vf610_adc_buffer_postdisable(struct iio_dev *indio_dev)
> > +{
> > +	struct vf610_adc *info = iio_priv(indio_dev);
> > +	unsigned int hc_cfg = 0;
> > +	int val;
> > +
> > +	val = readl(info->regs + VF610_REG_ADC_GC);
> > +	val &= ~VF610_ADC_ADCON;
> > +	writel(val, info->regs + VF610_REG_ADC_GC);
> > +
> > +	hc_cfg |= VF610_ADC_CONV_DISABLE;
> > +	hc_cfg &= ~VF610_ADC_AIEN;
> > +
> > +	writel(hc_cfg, info->regs + VF610_REG_ADC_HC0);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct iio_buffer_setup_ops iio_triggered_buffer_setup_ops = {
> > +	.postenable = &vf610_adc_buffer_postenable,
> > +	.predisable = &iio_triggered_buffer_predisable,
> > +	.postdisable = &vf610_adc_buffer_postdisable,
> > +	.validate_scan_mask = &iio_validate_scan_mask_onehot,
> > +};
> > +
> >  static int vf610_adc_reg_access(struct iio_dev *indio_dev,
> >  			unsigned reg, unsigned writeval,
> >  			unsigned *readval)
> > @@ -753,7 +832,7 @@ static int vf610_adc_probe(struct platform_device *pdev)
> >  
> >  	ret = devm_request_irq(info->dev, irq,
> >  				vf610_adc_isr, 0,
> > -				dev_name(&pdev->dev), info);
> > +				dev_name(&pdev->dev), indio_dev);
> >  	if (ret < 0) {
> >  		dev_err(&pdev->dev, "failed requesting irq, irq = %d\n", irq);
> >  		return ret;
> > @@ -806,15 +885,23 @@ static int vf610_adc_probe(struct platform_device *pdev)
> >  	vf610_adc_cfg_init(info);
> >  	vf610_adc_hw_init(info);
> >  
> > +	ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
> > +					NULL, &iio_triggered_buffer_setup_ops);
> > +	if (ret < 0) {
> > +		dev_err(&pdev->dev, "Couldn't initialise the buffer\n");
> > +		goto error_iio_device_register;
> > +	}
> > +
> >  	ret = iio_device_register(indio_dev);
> >  	if (ret) {
> >  		dev_err(&pdev->dev, "Couldn't register the device.\n");
> > -		goto error_iio_device_register;
> > +		goto error_adc_buffer_init;
> >  	}
> >  
> >  	return 0;
> >  
> > -
> > +error_adc_buffer_init:
> > +	iio_triggered_buffer_cleanup(indio_dev);
> >  error_iio_device_register:
> >  	clk_disable_unprepare(info->clk);
> >  error_adc_clk_enable:
> > @@ -829,6 +916,7 @@ static int vf610_adc_remove(struct platform_device *pdev)
> >  	struct vf610_adc *info = iio_priv(indio_dev);
> >  
> >  	iio_device_unregister(indio_dev);
> > +	iio_triggered_buffer_cleanup(indio_dev);
> >  	regulator_disable(info->vref);
> >  	clk_disable_unprepare(info->clk);
> >  
> > 
> 
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