Hi Heiner,
thanks for this patch!
I have some questions since I don't have access to my boards until
Saturday - I added them inline below.
On Tue, Feb 14, 2017 at 10:58 PM, Heiner Kallweit <hkallweit1@xxxxxxxxx> wrote:
> Switch from polling to interrupt mode.
>
> Successfully tested on a S905GXBB-based Odroid C2.
>
> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
> ---
> drivers/iio/adc/meson_saradc.c | 46 +++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 41 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
> index 89def603..dbd56bcc 100644
> --- a/drivers/iio/adc/meson_saradc.c
> +++ b/drivers/iio/adc/meson_saradc.c
> @@ -18,7 +18,9 @@
> #include <linux/io.h>
> #include <linux/iio/iio.h>
> #include <linux/module.h>
> +#include <linux/interrupt.h>
> #include <linux/of.h>
> +#include <linux/of_irq.h>
> #include <linux/of_device.h>
> #include <linux/platform_device.h>
> #include <linux/regmap.h>
> @@ -163,6 +165,7 @@
> #define MESON_SAR_ADC_REG13_12BIT_CALIBRATION_MASK GENMASK(13, 8)
>
> #define MESON_SAR_ADC_MAX_FIFO_SIZE 32
> +#define MESON_SAR_ADC_TIMEOUT 100 /* ms */
>
> #define MESON_SAR_ADC_CHAN(_chan) { \
> .type = IIO_VOLTAGE, \
> @@ -229,6 +232,7 @@ struct meson_sar_adc_priv {
> struct clk_gate clk_gate;
> struct clk *adc_div_clk;
> struct clk_divider clk_div;
> + struct completion done;
> };
>
> static const struct regmap_config meson_sar_adc_regmap_config = {
> @@ -274,11 +278,11 @@ static int meson_sar_adc_read_raw_sample(struct iio_dev *indio_dev,
> int *val)
> {
> struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
> - int ret, regval, fifo_chan, fifo_val, sum = 0, count = 0;
> + int regval, fifo_chan, fifo_val, sum = 0, count = 0;
>
> - ret = meson_sar_adc_wait_busy_clear(indio_dev);
> - if (ret)
> - return ret;
> + if(!wait_for_completion_timeout(&priv->done,
> + msecs_to_jiffies(MESON_SAR_ADC_TIMEOUT)))
> + return -ETIMEDOUT;
>
> while (meson_sar_adc_get_fifo_count(indio_dev) > 0 &&
> count < MESON_SAR_ADC_MAX_FIFO_SIZE) {
> @@ -456,6 +460,7 @@ static int meson_sar_adc_get_sample(struct iio_dev *indio_dev,
> enum meson_sar_adc_num_samples avg_samples,
> int *val)
> {
> + struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
> int ret;
>
> ret = meson_sar_adc_lock(indio_dev);
> @@ -465,6 +470,11 @@ static int meson_sar_adc_get_sample(struct iio_dev *indio_dev,
> /* clear the FIFO to make sure we're not reading old values */
> meson_sar_adc_clear_fifo(indio_dev);
>
> + reinit_completion(&priv->done);
> + regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
> + MESON_SAR_ADC_REG0_FIFO_IRQ_EN,
> + MESON_SAR_ADC_REG0_FIFO_IRQ_EN);
> +
can't we add this to meson_sar_adc_start_sample_engine()?
> meson_sar_adc_set_averaging(indio_dev, chan, avg_mode, avg_samples);
>
> meson_sar_adc_enable_channel(indio_dev, chan);
> @@ -473,6 +483,9 @@ static int meson_sar_adc_get_sample(struct iio_dev *indio_dev,
> ret = meson_sar_adc_read_raw_sample(indio_dev, chan, val);
> meson_sar_adc_stop_sample_engine(indio_dev);
>
> + regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
> + MESON_SAR_ADC_REG0_FIFO_IRQ_EN, 0);
> +
similar to enabling the IRQ above, can't we add this to
meson_sar_adc_stop_sample_engine()?
> meson_sar_adc_unlock(indio_dev);
>
> if (ret) {
> @@ -577,6 +590,9 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
> */
> meson_sar_adc_set_chan7_mux(indio_dev, CHAN7_MUX_CH7_INPUT);
>
> + regval = FIELD_PREP(MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, 1);
> + regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
> + MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, regval);
I'm wondering whether we should do this in meson_sar_adc_hw_enable()
in case u-boot is involved in the "return from suspend" process then
doing it in _init() might be a problem since the vendor u-boot
overwrites REG0, see [0]
please note that this is an actual question, not some kind of
suggestion in question form
> /*
> * leave sampling delay and the input clocks as configured by BL30 to
> * make sure BL30 gets the values it expects when reading the
> @@ -728,6 +744,16 @@ static int meson_sar_adc_hw_disable(struct iio_dev *indio_dev)
> return 0;
> }
>
> +static irqreturn_t meson_sar_adc_irq(int irq, void *data)
> +{
> + struct iio_dev *indio_dev = data;
> + struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
> +
> + complete(&priv->done);
> +
> + return IRQ_HANDLED;
would it make sense to return IRQ_NONE when
meson_sar_adc_get_fifo_count() returns 0?
> +}
> +
> static const struct iio_info meson_sar_adc_iio_info = {
> .read_raw = meson_sar_adc_iio_info_read_raw,
> .driver_module = THIS_MODULE,
> @@ -770,7 +796,7 @@ static int meson_sar_adc_probe(struct platform_device *pdev)
> struct resource *res;
> void __iomem *base;
> const struct of_device_id *match;
> - int ret;
> + int irq, ret;
>
> indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*priv));
> if (!indio_dev) {
> @@ -779,6 +805,7 @@ static int meson_sar_adc_probe(struct platform_device *pdev)
> }
>
> priv = iio_priv(indio_dev);
> + init_completion(&priv->done);
>
> match = of_match_device(meson_sar_adc_of_match, &pdev->dev);
> priv->data = match->data;
> @@ -797,6 +824,15 @@ static int meson_sar_adc_probe(struct platform_device *pdev)
> if (IS_ERR(base))
> return PTR_ERR(base);
>
> + irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
Documentation/devicetree/bindings/iio/adc/amlogic,meson-saradc.txt
should also be updated to reflect that the IRQ is now required (the
.dts already contains the IRQ, so no change is required on that side).
> + if (!irq)
> + return -EINVAL;
> +
> + ret = devm_request_irq(&pdev->dev, irq, meson_sar_adc_irq, 0,
> + dev_name(&pdev->dev), indio_dev);
> + if (ret)
> + return ret;
> +
> priv->regmap = devm_regmap_init_mmio(&pdev->dev, base,
> &meson_sar_adc_regmap_config);
> if (IS_ERR(priv->regmap))
> --
> 2.11.1
>
Regards,
Martin
[0] https://github.com/khadas/u-boot/blob/d09ed9f0c69054e46af45a7aed2b3cb0f6eaa3bc/drivers/adc/saradc.c#L191
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