Re: [PATCH v3] iio: adc: rockchip_saradc: Add support iio buffers

Heiko Stübner
2020-04-13T16:55:24Z

Hi Jonathan,

Am Montag, 13. April 2020, 18:44:34 CEST schrieb Jonathan Cameron:
> On Mon, 13 Apr 2020 00:42:51 +0200
> Heiko Stuebner <heiko@sntech.de> wrote:
>
> > From: Simon Xue <xxm@rock-chips.com>
> >
> > Add the ability to also support access via (triggered) buffers
> > next to the existing direct mode.
> >
> > Device in question is the Odroid Go Advance that connects a joystick
> > to two of the saradc channels for X and Y axis and the new (and still
> > pending) adc joystick driver of course wants to use triggered buffers
> > from the iio subsystem.
> >
> > Signed-off-by: Simon Xue <xxm@rock-chips.com>
> > [some simplifications and added commit description]
> > Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
>
> Comments inline.
>
> The issue with mixing managed and unmanaged allocations needs tidying up.
> Sorry if I missed that one before; I probably didn't open up the current
> driver to sanity check it :(
>
> Jonathan
>
> > ---
> > changes in v3:
> > - split buffer struct into values and timestamp area similar to dln2-adc
> > and make sure timestamp gets 8-byte aligned - ALIGN uses 4 as it aligns
> > u16 elements not bytes - hopefully I got it right this time ;-)
> > changes in v2:
> > - use devm_iio_triggered_buffer_setup
> > - calculate data array size from channel number (curtesy of at91-sama5d2_adc)
> >
> > drivers/iio/adc/Kconfig | 2 +
> > drivers/iio/adc/rockchip_saradc.c | 146 ++++++++++++++++++++++--------
> > 2 files changed, 112 insertions(+), 36 deletions(-)
> >
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index 12bb8b7ca1ff..8d2dd60614c6 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -809,6 +809,8 @@ config ROCKCHIP_SARADC
> > tristate "Rockchip SARADC driver"
> > depends on ARCH_ROCKCHIP || (ARM && COMPILE_TEST)
> > depends on RESET_CONTROLLER
> > + select IIO_BUFFER
> > + select IIO_TRIGGERED_BUFFER
> > help
> > Say yes here to build support for the SARADC found in SoCs from
> > Rockchip.
> > diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
> > index 582ba047c4a6..0713363a4b43 100644
> > --- a/drivers/iio/adc/rockchip_saradc.c
> > +++ b/drivers/iio/adc/rockchip_saradc.c
> > @@ -15,7 +15,11 @@
> > #include <linux/delay.h>
> > #include <linux/reset.h>
> > #include <linux/regulator/consumer.h>
> > +#include <linux/iio/buffer.h>
> > #include <linux/iio/iio.h>
> > +#include <linux/iio/trigger.h>
> > +#include <linux/iio/trigger_consumer.h>
> > +#include <linux/iio/triggered_buffer.h>
> >
> > #define SARADC_DATA 0x00
> >
> > @@ -32,9 +36,12 @@
> > #define SARADC_DLY_PU_SOC_MASK 0x3f
> >
> > #define SARADC_TIMEOUT msecs_to_jiffies(100)
> > +#define SARADC_MAX_CHANNELS 6
> > +
> > +/* buffer elements are u16, timestamp needs to be 8-byte aligned */
> > +#define SARADC_BUFFER_NUM_U16 ALIGN(SARADC_MAX_CHANNELS, 4)
> I may be going crazy but I think that will get you the 'start' of the
> timestamp, not the length including it.
>
> We should be seeing 24 bytes here = 12 u16s. Sanity check the value.
>
> Running through the stack of defines.
> #define ALIGN(x, a) __ALIGN_KERNEL((x), (a))
> #define __ALIGN_KERNEL(x, a) __ALIGN_KERNEL_MASK(x, (typeof(x))(a) - 1)
> #define __ALIGN_KERNEL_MASK(x, mask) (((x) + (mask)) & ~(mask))
>
> ALIGN(6, 4) == __ALIGN_KERNEL(6, 4)
> == __ALIGN_KERNEL_MASK(6, 3)
> == (((6 + 3) & ~3)
> which is 9 with the bottom two bits masked or b1001 & b1100 = 8 not 12
>
> So I think you are looking for
> ALIGN(SARADC_MAX_CHANNELS + sizeof(u64) / sizeof(u16), 4)
> which will be ((10 + 3) & ~3) b1101 & b1100 = 12

hmm, getting the start of the timestamp was actually what I intended ;-)
The dln2-adc driver did that fancy struct definition for its data. which
I stole, see the part from blow:

> > + struct {
> > + u16 values[SARADC_BUFFER_NUM_U16];
> > + int64_t timestamp;
> > + } data;

So SARADC_BUFFER_NUM really is meant to only contain the
number of actual buffer data - I guess I should explain that out better
in the comment. Because defining this separate makes this so much
more readable when we're not trying to implicitly add the timestamp
space.

And a size_of(data) for that struct then returned nicely these 24 bytes
in my tests.

> >
> > struct rockchip_saradc_data {
> > - int num_bits;
> > const struct iio_chan_spec *channels;
> > int num_channels;
> > unsigned long clk_rate;
> > @@ -49,8 +56,37 @@ struct rockchip_saradc {
> > struct reset_control *reset;
> > const struct rockchip_saradc_data *data;
> > u16 last_val;
> > + const struct iio_chan_spec *last_chan;
> > };
> >
> > +static void rockchip_saradc_power_down(struct rockchip_saradc *info)
> > +{
> > + /* Clear irq & power down adc */
> > + writel_relaxed(0, info->regs + SARADC_CTRL);
> > +}
> > +
> > +static int rockchip_saradc_conversion(struct rockchip_saradc *info,
> > + struct iio_chan_spec const *chan)
> > +{
> > + reinit_completion(&info->completion);
> > +
> > + /* 8 clock periods as delay between power up and start cmd */
> > + writel_relaxed(8, info->regs + SARADC_DLY_PU_SOC);
> > +
> > + info->last_chan = chan;
> > +
> > + /* Select the channel to be used and trigger conversion */
> > + writel(SARADC_CTRL_POWER_CTRL
> > + | (chan->channel & SARADC_CTRL_CHN_MASK)
> > + | SARADC_CTRL_IRQ_ENABLE,
> > + info->regs + SARADC_CTRL);
> > +
> > + if (!wait_for_completion_timeout(&info->completion, SARADC_TIMEOUT))
> > + return -ETIMEDOUT;
> > +
> > + return 0;
> > +}
> > +
> > static int rockchip_saradc_read_raw(struct iio_dev *indio_dev,
> > struct iio_chan_spec const *chan,
> > int *val, int *val2, long mask)
> > @@ -62,24 +98,12 @@ static int rockchip_saradc_read_raw(struct iio_dev *indio_dev,
> > case IIO_CHAN_INFO_RAW:
> > mutex_lock(&indio_dev->mlock);
> >
> > - reinit_completion(&info->completion);
> > -
> > - /* 8 clock periods as delay between power up and start cmd */
> > - writel_relaxed(8, info->regs + SARADC_DLY_PU_SOC);
> > -
> > - /* Select the channel to be used and trigger conversion */
> > - writel(SARADC_CTRL_POWER_CTRL
> > - | (chan->channel & SARADC_CTRL_CHN_MASK)
> > - | SARADC_CTRL_IRQ_ENABLE,
> > - info->regs + SARADC_CTRL);
> > -
> > - if (!wait_for_completion_timeout(&info->completion,
> > - SARADC_TIMEOUT)) {
> > - writel_relaxed(0, info->regs + SARADC_CTRL);
> > + ret = rockchip_saradc_conversion(info, chan);
> > + if (ret) {
> > + rockchip_saradc_power_down(info);
> > mutex_unlock(&indio_dev->mlock);
> > - return -ETIMEDOUT;
> > + return ret;
> > }
> > -
> > *val = info->last_val;
> > mutex_unlock(&indio_dev->mlock);
> > return IIO_VAL_INT;
> > @@ -91,7 +115,7 @@ static int rockchip_saradc_read_raw(struct iio_dev *indio_dev,
> > }
> >
> > *val = ret / 1000;
> > - *val2 = info->data->num_bits;
> > + *val2 = chan->scan_type.realbits;
> > return IIO_VAL_FRACTIONAL_LOG2;
> > default:
> > return -EINVAL;
> > @@ -104,10 +128,9 @@ static irqreturn_t rockchip_saradc_isr(int irq, void *dev_id)
> >
> > /* Read value */
> > info->last_val = readl_relaxed(info->regs + SARADC_DATA);
> > - info->last_val &= GENMASK(info->data->num_bits - 1, 0);
> > + info->last_val &= GENMASK(info->last_chan->scan_type.realbits - 1, 0);
> >
> > - /* Clear irq & power down adc */
> > - writel_relaxed(0, info->regs + SARADC_CTRL);
> > + rockchip_saradc_power_down(info);
> >
> > complete(&info->completion);
> >
> > @@ -118,51 +141,55 @@ static const struct iio_info rockchip_saradc_iio_info = {
> > .read_raw = rockchip_saradc_read_raw,
> > };
> >
> > -#define ADC_CHANNEL(_index, _id) { \
> > +#define ADC_CHANNEL(_index, _id, _res) { \
> > .type = IIO_VOLTAGE, \
> > .indexed = 1, \
> > .channel = _index, \
> > .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> > .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> > .datasheet_name = _id, \
> > + .scan_index = _index, \
> > + .scan_type = { \
> > + .sign = 'u', \
> > + .realbits = _res, \
> > + .storagebits = 16, \
> > + .endianness = IIO_LE, \
> > + }, \
> > }
> >
> > static const struct iio_chan_spec rockchip_saradc_iio_channels[] = {
> > - ADC_CHANNEL(0, "adc0"),
> > - ADC_CHANNEL(1, "adc1"),
> > - ADC_CHANNEL(2, "adc2"),
> > + ADC_CHANNEL(0, "adc0", 10),
> > + ADC_CHANNEL(1, "adc1", 10),
> > + ADC_CHANNEL(2, "adc2", 10),
> > };
> >
> > static const struct rockchip_saradc_data saradc_data = {
> > - .num_bits = 10,
> > .channels = rockchip_saradc_iio_channels,
> > .num_channels = ARRAY_SIZE(rockchip_saradc_iio_channels),
> > .clk_rate = 1000000,
> > };
> >
> > static const struct iio_chan_spec rockchip_rk3066_tsadc_iio_channels[] = {
> > - ADC_CHANNEL(0, "adc0"),
> > - ADC_CHANNEL(1, "adc1"),
> > + ADC_CHANNEL(0, "adc0", 12),
> > + ADC_CHANNEL(1, "adc1", 12),
> > };
> >
> > static const struct rockchip_saradc_data rk3066_tsadc_data = {
> > - .num_bits = 12,
> > .channels = rockchip_rk3066_tsadc_iio_channels,
> > .num_channels = ARRAY_SIZE(rockchip_rk3066_tsadc_iio_channels),
> > .clk_rate = 50000,
> > };
> >
> > static const struct iio_chan_spec rockchip_rk3399_saradc_iio_channels[] = {
> > - ADC_CHANNEL(0, "adc0"),
> > - ADC_CHANNEL(1, "adc1"),
> > - ADC_CHANNEL(2, "adc2"),
> > - ADC_CHANNEL(3, "adc3"),
> > - ADC_CHANNEL(4, "adc4"),
> > - ADC_CHANNEL(5, "adc5"),
> > + ADC_CHANNEL(0, "adc0", 10),
> > + ADC_CHANNEL(1, "adc1", 10),
> > + ADC_CHANNEL(2, "adc2", 10),
> > + ADC_CHANNEL(3, "adc3", 10),
> > + ADC_CHANNEL(4, "adc4", 10),
> > + ADC_CHANNEL(5, "adc5", 10),
> > };
> >
> > static const struct rockchip_saradc_data rk3399_saradc_data = {
> > - .num_bits = 10,
> > .channels = rockchip_rk3399_saradc_iio_channels,
> > .num_channels = ARRAY_SIZE(rockchip_rk3399_saradc_iio_channels),
> > .clk_rate = 1000000,
> > @@ -193,6 +220,42 @@ static void rockchip_saradc_reset_controller(struct reset_control *reset)
> > reset_control_deassert(reset);
> > }
> >
> > +static irqreturn_t rockchip_saradc_trigger_handler(int irq, void *p)
> > +{
> > + struct iio_poll_func *pf = p;
> > + struct iio_dev *i_dev = pf->indio_dev;
> > + struct rockchip_saradc *info = iio_priv(i_dev);
> > + struct {
> > + u16 values[SARADC_BUFFER_NUM_U16];
> > + int64_t timestamp;
> > + } data;
> > + int ret;
> > + int i, j = 0;
> > +
> > + mutex_lock(&i_dev->mlock);
> > +
> > + for_each_set_bit(i, i_dev->active_scan_mask, i_dev->masklength) {
> > + const struct iio_chan_spec *chan = &i_dev->channels[i];
> > +
> > + ret = rockchip_saradc_conversion(info, chan);
> > + if (ret) {
> > + rockchip_saradc_power_down(info);
> > + goto out;
> > + }
> > +
> > + data.values[j] = info->last_val;
> > + j++;
> > + }
> > +
> > + iio_push_to_buffers_with_timestamp(i_dev, &data, iio_get_time_ns(i_dev));
> > +out:
> > + mutex_unlock(&i_dev->mlock);
> > +
> > + iio_trigger_notify_done(i_dev->trig);
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > static int rockchip_saradc_probe(struct platform_device *pdev)
> > {
> > struct rockchip_saradc *info = NULL;
> > @@ -221,6 +284,11 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
> >
> > info->data = match->data;
> >
> > + if (info->data->num_channels > SARADC_MAX_CHANNELS) {
> > + dev_err(&pdev->dev, "max channels exceeded");
> > + return -EINVAL;
>
> How can that happen? Bug in the addition of a new device type?
> If it's just paranoia against future code, perhaps add a comment to
> say that.

yep that is "paranoia" for the case someone adds a fancy new 20 channel
saradc variant and forgets to adapt the constant.

I'll add a comment.

>
> > + }
> > +
> > mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > info->regs = devm_ioremap_resource(&pdev->dev, mem);
> > if (IS_ERR(info->regs))
> > @@ -315,6 +383,12 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
> > indio_dev->channels = info->data->channels;
> > indio_dev->num_channels = info->data->num_channels;
> >
> > + ret = devm_iio_triggered_buffer_setup(&indio_dev->dev, indio_dev, NULL,
> > + rockchip_saradc_trigger_handler,
> > + NULL);
> > + if (ret)
> > + goto err_clk;
> > +
>
> Please avoid mixing an matching between device managed an unmanaged interfaces.
> It means the driver is not 'obviously correct' and hence harder to review.
>
> Two choices here. Either use devm_add_action_or_reset to automatically
> disable each clock + regulator in the managed release path, drop all the error
> handling and remove (note this should be a precursor patch), or use
> iio_triggered_buffer_setup and manually call iio_triggered_buffer_cleanup
> in the right place in the remove function.

I'll go with the devm_* approach, less complexity is better than adding more ;-)

Heiko

> > ret = iio_device_register(indio_dev);
> > if (ret)
> > goto err_clk;
>
>