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Message-ID: <54C7FCF8.80703@kernel.org>
Date: Tue, 27 Jan 2015 21:02:48 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Stefan Agner <stefan@...er.ch>
CC: shawn.guo@...aro.org, B38611@...escale.com,
maitysanchayan@...il.com, linux-iio@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] iio: adc: vf610: implement configurable conversion
modes
On 20/01/15 16:02, Stefan Agner wrote:
> Support configureable conversion mode through sysfs. So far, the
> mode used was low-power, which is enabled by default now. Beside
> that, the modes normal and high-speed are selectable as well.
>
> Use the new device tree property which specifies the maximum ADC
> conversion clock frequencies. Depending on the mode used, the
> available resulting conversion frequency are calcaulated
> dynamically.
>
> Signed-off-by: Stefan Agner <stefan@...er.ch>
We have the extinfo stuff to cut down on the boiler plate, particularly
with enum type items like this. See the various IIO_ENUM() etc in iio.h
> ---
> drivers/iio/adc/vf610_adc.c | 92 ++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 86 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iio/adc/vf610_adc.c b/drivers/iio/adc/vf610_adc.c
> index e63b8e7..fd41d91c 100644
> --- a/drivers/iio/adc/vf610_adc.c
> +++ b/drivers/iio/adc/vf610_adc.c
> @@ -118,15 +118,21 @@ enum average_sel {
> VF610_ADC_SAMPLE_32,
> };
>
> +enum conversion_mode_sel {
> + VF610_ADC_CONV_NORMAL,
> + VF610_ADC_CONV_HIGH_SPEED,
> + VF610_ADC_CONV_LOW_POWER,
> +};
> +
> struct vf610_adc_feature {
> enum clk_sel clk_sel;
> enum vol_ref vol_ref;
> + enum conversion_mode_sel conv_mode;
>
> int clk_div;
> int sample_rate;
> int res_mode;
>
> - bool lpm;
> bool calibration;
> bool ovwren;
> };
> @@ -139,6 +145,8 @@ struct vf610_adc {
> u32 vref_uv;
> u32 value;
> struct regulator *vref;
> +
> + u32 max_adck_rate[3];
> struct vf610_adc_feature adc_feature;
>
> u32 sample_freq_avail[5];
> @@ -146,6 +154,8 @@ struct vf610_adc {
> struct completion completion;
> };
>
> +static const char * const vf610_conv_modes[] = { "normal", "high-speed",
> + "low-power" };
> static const u32 vf610_hw_avgs[] = { 1, 4, 8, 16, 32 };
>
> #define VF610_ADC_CHAN(_idx, _chan_type) { \
> @@ -186,8 +196,20 @@ static const struct iio_chan_spec vf610_adc_iio_channels[] = {
>
> static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
> {
> + struct vf610_adc_feature *adc_feature = &info->adc_feature;
> unsigned long adck_rate, ipg_rate = clk_get_rate(info->clk);
> - int i;
> + int divisor, i;
> +
> + adck_rate = info->max_adck_rate[adc_feature->conv_mode];
> +
> + if (adck_rate) {
> + /* calculate clk divider which is within specification */
> + divisor = ipg_rate / adck_rate;
> + adc_feature->clk_div = 1 << fls(divisor + 1);
> + } else {
> + /* fall-back value using a safe divisor */
> + adc_feature->clk_div = 8;
> + }
>
> /*
> * Calculate ADC sample frequencies
> @@ -219,10 +241,8 @@ static inline void vf610_adc_cfg_init(struct vf610_adc *info)
>
> adc_feature->res_mode = 12;
> adc_feature->sample_rate = 1;
> - adc_feature->lpm = true;
>
> - /* Use a save ADCK which is below 20MHz on all devices */
> - adc_feature->clk_div = 8;
> + adc_feature->conv_mode = VF610_ADC_CONV_LOW_POWER;
>
> vf610_adc_calculate_rates(info);
> }
> @@ -307,10 +327,12 @@ static void vf610_adc_cfg_set(struct vf610_adc *info)
> cfg_data = readl(info->regs + VF610_REG_ADC_CFG);
>
> cfg_data &= ~VF610_ADC_ADLPC_EN;
> - if (adc_feature->lpm)
> + if (adc_feature->conv_mode == VF610_ADC_CONV_LOW_POWER)
> cfg_data |= VF610_ADC_ADLPC_EN;
>
> cfg_data &= ~VF610_ADC_ADHSC_EN;
> + if (adc_feature->conv_mode == VF610_ADC_CONV_HIGH_SPEED)
> + cfg_data |= VF610_ADC_ADHSC_EN;
>
> writel(cfg_data, info->regs + VF610_REG_ADC_CFG);
> }
> @@ -466,10 +488,65 @@ static ssize_t vf610_show_samp_freq_avail(struct device *dev,
> return len;
> }
>
> +static ssize_t vf610_read_mode(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> + struct vf610_adc *info = iio_priv(indio_dev);
> +
> + return sprintf(buf, "%s\n",
> + vf610_conv_modes[info->adc_feature.conv_mode]);
> +}
> +
> +
> +static ssize_t vf610_write_mode(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf,
> + size_t len)
> +{
> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> + struct vf610_adc *info = iio_priv(indio_dev);
> + int i, mode = -EINVAL;
> +
> + mutex_lock(&indio_dev->mlock);
> + if (iio_buffer_enabled(indio_dev)) {
> + mutex_unlock(&indio_dev->mlock);
> + return -EBUSY;
> + }
> + mutex_unlock(&indio_dev->mlock);
> +
> + for (i = 0; i < ARRAY_SIZE(vf610_conv_modes); i++) {
> + if (!strcmp(vf610_conv_modes[i], buf)) {
> + mode = i;
> + break;
> + }
> + }
> +
> + if (mode < 0)
> + return mode;
> +
> + mutex_lock(&indio_dev->mlock);
> + info->adc_feature.conv_mode = mode;
> + vf610_adc_calculate_rates(info);
> + vf610_adc_hw_init(info);
> + mutex_unlock(&indio_dev->mlock);
> +
> + return len;
> +}
> +
> static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(vf610_show_samp_freq_avail);
>
> +static IIO_CONST_ATTR_NAMED(conversion_mode_available,
> + conversion_mode_available, "normal high-speed low-power");
> +
> +IIO_DEVICE_ATTR(conversion_mode, S_IWUSR | S_IRUGO, vf610_read_mode,
> + vf610_write_mode, 0);
> +
> static struct attribute *vf610_attributes[] = {
> &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
> + &iio_const_attr_conversion_mode_available.dev_attr.attr,
> + &iio_dev_attr_conversion_mode.dev_attr.attr,
> NULL
> };
>
> @@ -654,6 +731,9 @@ static int vf610_adc_probe(struct platform_device *pdev)
>
> info->vref_uv = regulator_get_voltage(info->vref);
>
> + of_property_read_u32_array(pdev->dev.of_node, "fsl,adck-max-frequency",
> + info->max_adck_rate, 3);
> +
> platform_set_drvdata(pdev, indio_dev);
>
> init_completion(&info->completion);
>
--
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