[PATCH v2 2/3] iio: adc: at91-sama5d2_adc: add hw trigger and buffer support
Jonathan Cameron
jic23 at kernel.org
Sun May 7 08:01:06 PDT 2017
On 04/05/17 13:13, Eugen Hristev wrote:
> Added support for the external hardware trigger on pin ADTRG,
> integrated the three possible edge triggers into the subsystem
> and created buffer management for data retrieval
>
> Signed-off-by: Eugen Hristev <eugen.hristev at microchip.com>
> ---
> Changes in v2:
> - Moved buffer allocation and freeing into the preenable and postdisable
> callbacks.
> We have a total of scan bytes that can vary a lot depending on each channel
> enabled at a certain point.
How much? Having dynamic allocations are likely to prove just as costly as you'll
almost always end up allocating a lot more than you ask for.
I'm counting worst case of 18x 2byte channels + timestamp = 48 bytes.
A quick google suggests you'll always allocate 32 bytes whatever with slab
(lower for slob). So not a huge saving...
Worth the hassle?
> - made the at91 trigger list part of state structure
> - made the iio trigger list preallocated in state structure
> - moved irq enabling/disabling into the try_reenable callback
I'd have liked a little explanation on why we need to explicitly disable
the irq. It will have little effect it if triggers too often as the
trigger consumers are all oneshot anyway.
> - on trigger disable must write disable registries as well
Basically looks good. A few questions inline.
Jonathan
>
> drivers/iio/adc/at91-sama5d2_adc.c | 231 ++++++++++++++++++++++++++++++++++++-
> 1 file changed, 228 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index e10dca3..11f5570 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -23,8 +23,15 @@
> #include <linux/platform_device.h>
> #include <linux/sched.h>
> #include <linux/wait.h>
> +#include <linux/slab.h>
> +
> #include <linux/iio/iio.h>
> #include <linux/iio/sysfs.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> +
> #include <linux/regulator/consumer.h>
>
> /* Control Register */
> @@ -132,6 +139,17 @@
> #define AT91_SAMA5D2_PRESSR 0xbc
> /* Trigger Register */
> #define AT91_SAMA5D2_TRGR 0xc0
> +/* Mask for TRGMOD field of TRGR register */
> +#define AT91_SAMA5D2_TRGR_TRGMOD_MASK GENMASK(2, 0)
> +/* No trigger, only software trigger can start conversions */
> +#define AT91_SAMA5D2_TRGR_TRGMOD_NO_TRIGGER 0
> +/* Trigger Mode external trigger rising edge */
> +#define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_RISE 1
> +/* Trigger Mode external trigger falling edge */
> +#define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_FALL 2
> +/* Trigger Mode external trigger any edge */
> +#define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_ANY 3
> +
> /* Correction Select Register */
> #define AT91_SAMA5D2_COSR 0xd0
> /* Correction Value Register */
> @@ -145,14 +163,20 @@
> /* Version Register */
> #define AT91_SAMA5D2_VERSION 0xfc
>
> +#define AT91_SAMA5D2_HW_TRIG_CNT 3
> +#define AT91_SAMA5D2_SINGLE_CHAN_CNT 12
> +#define AT91_SAMA5D2_DIFF_CHAN_CNT 6
> +
> #define AT91_SAMA5D2_CHAN_SINGLE(num, addr) \
> { \
> .type = IIO_VOLTAGE, \
> .channel = num, \
> .address = addr, \
> + .scan_index = num, \
> .scan_type = { \
> .sign = 'u', \
> .realbits = 12, \
> + .storagebits = 16, \
> }, \
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> @@ -168,9 +192,11 @@
> .channel = num, \
> .channel2 = num2, \
> .address = addr, \
> + .scan_index = num + AT91_SAMA5D2_SINGLE_CHAN_CNT, \
> .scan_type = { \
> .sign = 's', \
> .realbits = 12, \
> + .storagebits = 16, \
> }, \
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> @@ -188,18 +214,25 @@ struct at91_adc_soc_info {
> unsigned max_sample_rate;
> };
>
> +struct at91_adc_trigger {
> + char *name;
> + unsigned int trgmod_value;
> +};
> +
> struct at91_adc_state {
> void __iomem *base;
> int irq;
> struct clk *per_clk;
> struct regulator *reg;
> struct regulator *vref;
> + u16 *buffer;
> int vref_uv;
> const struct iio_chan_spec *chan;
> bool conversion_done;
> u32 conversion_value;
> struct at91_adc_soc_info soc_info;
> wait_queue_head_t wq_data_available;
> + struct iio_trigger *trig[AT91_SAMA5D2_HW_TRIG_CNT];
> /*
> * lock to prevent concurrent 'single conversion' requests through
> * sysfs.
> @@ -207,6 +240,21 @@ struct at91_adc_state {
> struct mutex lock;
> };
>
> +static const struct at91_adc_trigger at91_adc_trigger_list[] = {
> + {
> + .name = "external-rising",
> + .trgmod_value = AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_RISE,
> + },
> + {
> + .name = "external-falling",
> + .trgmod_value = AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_FALL,
> + },
> + {
> + .name = "external-any",
> + .trgmod_value = AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_ANY,
> + },
Hmm. Should this be a userspace configurable option? Feels rather like
it is an element of the hardware - reflecting the characteristics of some
hardware device sat on the pin.
> +};
> +
> static const struct iio_chan_spec at91_adc_channels[] = {
> AT91_SAMA5D2_CHAN_SINGLE(0, 0x50),
> AT91_SAMA5D2_CHAN_SINGLE(1, 0x54),
> @@ -226,8 +274,168 @@ static const struct iio_chan_spec at91_adc_channels[] = {
> AT91_SAMA5D2_CHAN_DIFF(6, 7, 0x68),
> AT91_SAMA5D2_CHAN_DIFF(8, 9, 0x70),
> AT91_SAMA5D2_CHAN_DIFF(10, 11, 0x78),
> + IIO_CHAN_SOFT_TIMESTAMP(AT91_SAMA5D2_SINGLE_CHAN_CNT
> + + AT91_SAMA5D2_DIFF_CHAN_CNT + 1),
> };
>
> +static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
> +{
> + struct iio_dev *indio = iio_trigger_get_drvdata(trig);
> + struct at91_adc_state *st = iio_priv(indio);
> + u32 status = at91_adc_readl(st, AT91_SAMA5D2_TRGR);
> + u8 bit;
> + int i;
> +
> + /* clear TRGMOD */
> + status &= ~AT91_SAMA5D2_TRGR_TRGMOD_MASK;
> +
> + if (state)
> + for (i = 0; i < AT91_SAMA5D2_HW_TRIG_CNT; i++) {
> + if (!strstr(trig->name,
> + at91_adc_trigger_list[i].name)) {
> + status |= at91_adc_trigger_list[i].trgmod_value;
> + break;
> + }
> + }
> +
> + /* set/unset hw trigger */
> + at91_adc_writel(st, AT91_SAMA5D2_TRGR, status);
> +
> + for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
> + struct iio_chan_spec const *chan = indio->channels + bit;
> +
> + if (state) {
> + at91_adc_writel(st, AT91_SAMA5D2_CHER,
> + BIT(chan->channel));
> + at91_adc_writel(st, AT91_SAMA5D2_IER,
> + BIT(chan->channel));
> + } else {
> + at91_adc_writel(st, AT91_SAMA5D2_IDR,
> + BIT(chan->channel));
> + at91_adc_writel(st, AT91_SAMA5D2_CHDR,
> + BIT(chan->channel));
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int at91_adc_reenable_trigger(struct iio_trigger *trig)
> +{
> + struct iio_dev *indio = iio_trigger_get_drvdata(trig);
> + struct at91_adc_state *st = iio_priv(indio);
> +
> + enable_irq(st->irq);
> + return 0;
> +}
> +
> +static const struct iio_trigger_ops at91_adc_trigger_ops = {
> + .owner = THIS_MODULE,
> + .set_trigger_state = &at91_adc_configure_trigger,
> + .try_reenable = &at91_adc_reenable_trigger,
> +};
> +
> +static int at91_adc_buffer_preenable(struct iio_dev *indio_dev)
> +{
> + struct at91_adc_state *st = iio_priv(indio_dev);
> +
> + st->buffer = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);Why allocate it here? Presumably the biggest it can get is fairly
small? Unless very large, just make sure you allocate enough
directly in st in the first place.
> +
> + if (!st->buffer)
> + return -ENOMEM;
> +
> + return 0;
> +}
> +
> +static int at91_adc_buffer_postdisable(struct iio_dev *indio_dev)
> +{
> + struct at91_adc_state *st = iio_priv(indio_dev);
> +
> + kfree(st->buffer);
> +
> + return 0;
> +}
> +
> +static const struct iio_buffer_setup_ops at91_buffer_setup_ops = {
> + .preenable = &at91_adc_buffer_preenable,
> + .postenable = &iio_triggered_buffer_postenable,
> + .predisable = &iio_triggered_buffer_predisable,
> + .postdisable = &at91_adc_buffer_postdisable,
> +};
> +
> +static struct iio_trigger *at91_adc_allocate_trigger(struct iio_dev *indio,
> + char *trigger_name)
> +{
> + struct iio_trigger *trig;
> + int ret;
> +
> + trig = devm_iio_trigger_alloc(&indio->dev, "%s-dev%d-%s", indio->name,
> + indio->id, trigger_name);
> + if (!trig)
> + return NULL;
> +
> + trig->dev.parent = indio->dev.parent;
> + iio_trigger_set_drvdata(trig, indio);
> + trig->ops = &at91_adc_trigger_ops;
> +
> + ret = devm_iio_trigger_register(&indio->dev, trig);
> +
> + if (ret)
> + return NULL;
> +
> + return trig;
> +}
> +
> +static int at91_adc_trigger_init(struct iio_dev *indio)
> +{
> + struct at91_adc_state *st = iio_priv(indio);
> + int i;
> +
> + for (i = 0; i < AT91_SAMA5D2_HW_TRIG_CNT; i++) {
> + st->trig[i] = at91_adc_allocate_trigger(indio,
> + at91_adc_trigger_list[i].name);
> + if (!st->trig[i]) {
> + dev_err(&indio->dev,
> + "could not allocate trigger %d\n", i);
> + return -ENOMEM;
> + }
> + }
> +
> + return 0;
> +}
> +
> +static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
> +{
> + struct iio_poll_func *pf = p;
> + struct iio_dev *indio = pf->indio_dev;
> + struct at91_adc_state *st = iio_priv(indio);
> + int i = 0;
> + u8 bit;
> +
> + for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
> + struct iio_chan_spec const *chan = indio->channels + bit;
> +
> + st->buffer[i] = at91_adc_readl(st, chan->address);
> + i++;
> + }
> +
> + iio_push_to_buffers_with_timestamp(indio, st->buffer, pf->timestamp);
> +
> + iio_trigger_notify_done(indio->trig);
> +
> + /* Needed to ACK the DRDY interruption */
> + at91_adc_readl(st, AT91_SAMA5D2_LCDR);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int at91_adc_buffer_init(struct iio_dev *indio)
> +{
> + return devm_iio_triggered_buffer_setup(&indio->dev, indio,
> + &iio_pollfunc_store_time,
> + &at91_adc_trigger_handler, &at91_buffer_setup_ops);
> +}
> +
> static unsigned at91_adc_startup_time(unsigned startup_time_min,
> unsigned adc_clk_khz)
> {
> @@ -293,14 +501,19 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
> u32 status = at91_adc_readl(st, AT91_SAMA5D2_ISR);
> u32 imr = at91_adc_readl(st, AT91_SAMA5D2_IMR);
>
> - if (status & imr) {
> + if (!(status & imr))
> + return IRQ_NONE;
> +
> + if (iio_buffer_enabled(indio)) {
> + disable_irq_nosync(irq);
> + iio_trigger_poll(indio->trig);
> + } else {
> st->conversion_value = at91_adc_readl(st, st->chan->address);
> st->conversion_done = true;
> wake_up_interruptible(&st->wq_data_available);
> - return IRQ_HANDLED;
> }
>
> - return IRQ_NONE;
> + return IRQ_HANDLED;
> }
>
> static int at91_adc_read_raw(struct iio_dev *indio_dev,
> @@ -499,6 +712,18 @@ static int at91_adc_probe(struct platform_device *pdev)
>
> platform_set_drvdata(pdev, indio_dev);
>
> + ret = at91_adc_buffer_init(indio_dev);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "couldn't initialize the buffer.\n");
> + goto per_clk_disable_unprepare;
> + }
> +
> + ret = at91_adc_trigger_init(indio_dev);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "couldn't setup the triggers.\n");
> + goto per_clk_disable_unprepare;
> + }
> +
> ret = iio_device_register(indio_dev);
> if (ret < 0)
> goto per_clk_disable_unprepare;
>
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