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

Jonathan Cameron
2020-04-13T16:44:42Z

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

>
> 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.

> + }
> +
> 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.

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