[PATCH 5/5] iio: at91: introduce touch screen support in iio adc driver
Maxime Ripard
maxime.ripard at free-electrons.com
Tue Jul 16 07:43:05 EDT 2013
Hi Josh,
On Tue, Jul 16, 2013 at 05:09:32PM +0800, Josh Wu wrote:
> On 7/15/2013 9:15 PM, Maxime Ripard wrote:
> >Hi Josh,
> >
> >On Sun, Jul 14, 2013 at 04:04:29PM +0800, Josh Wu wrote:
> >>AT91 ADC hardware integrate touch screen support. So this patch add touch
> >>screen support for at91 adc iio driver.
> >>To enable touch screen support in adc, you need to add the dt parameters:
> >> which type of touch are used? (4 or 5 wires), sample period time,
> >> pen detect debounce time, average samples and pen detect resistor.
> >>
> >>In the meantime, since touch screen will use a interal period trigger of adc,
> >>so it is conflict to other hardware triggers. Driver will disable the hardware
> >>trigger support if touch screen is enabled.
> >>
> >>This driver has been tested in AT91SAM9X5-EK and SAMA5D3x-EK.
> >>
> >>Signed-off-by: Josh Wu <josh.wu at atmel.com>
> >>Cc: Dmitry Torokhov <dmitry.torokhov at gmail.com>
> >>---
> >> .../devicetree/bindings/arm/atmel-adc.txt | 13 +
> >> arch/arm/mach-at91/include/mach/at91_adc.h | 34 ++
> >> drivers/iio/adc/at91_adc.c | 389 ++++++++++++++++++--
> >> 3 files changed, 412 insertions(+), 24 deletions(-)
> >>
> >>diff --git a/Documentation/devicetree/bindings/arm/atmel-adc.txt b/Documentation/devicetree/bindings/arm/atmel-adc.txt
> >>index 0db2945..925d656 100644
> >>--- a/Documentation/devicetree/bindings/arm/atmel-adc.txt
> >>+++ b/Documentation/devicetree/bindings/arm/atmel-adc.txt
> >>@@ -29,6 +29,19 @@ Optional properties:
> >> - atmel,adc-sample-hold-time: Sample and Hold Time in microseconds
> >> - atmel,adc-clock-rate: ADC clock rate. If not specified, use the default
> >> adc_op_clk.
> >>+ - atmel,adc-touchscreen-wires: Number of touch screen wires. Only support
> >>+ 4 and 5 wires touch screen.
> >>+ NOTE: when adc touch screen enabled, the adc hardware trigger will be
> >>+ disabled. Since touch screen will occupied the trigger register.
> >>+ - atmel,adc-ts-pendet-debounce: Debounce time in microsecond for touch pen
> >>+ detect.
> >>+ - atmel,adc-ts-sample-period-time: Sample Period Time in microsecond for
> >>+ touch screen
> >>+ - atmel,adc-ts-filter-average: Numbers of sampling data will be averaged.
> >>+ 0 means no average. 1 means average two samples. 2 means average four
> >>+ samples. 3 means average eight samples.
> >>+ - atmel,adc-ts-pendet-sensitivity: Pen Detection input pull-up resistor.
> >>+ It can be 0, 1, 2, 3.
> >Could you expand a bit on what are these properties for? Are they
> >board-specific? IP-specific?
>
> + - atmel,adc-touchscreen-wires: Number of touch screen wires. Only support
> + 4 and 5 wires touch screen.
> + NOTE: when adc touch screen enabled, the adc hardware trigger will be
> + disabled. Since touch screen will occupied the trigger register.
>
> It is board specific. Currently in AT91SAM9M10G45EK, AT91SAM9X5-EK,
> SAMA5D3x-EK all use 4 wire touch.
> Now the driver not support 5 wire yet.
I see, maybe you should add this in the documentation then
> + - atmel,adc-ts-pendet-debounce: Debounce time in microsecond for
> touch pen
> + detect.
>
> de-glitch time for pen detect. Board specific.
>
> + - atmel,adc-ts-sample-period-time: Sample Period Time in microsecond for
> + touch screen
>
> The period to sample a touch data after pen is touched. Board specific.
>
> + - atmel,adc-ts-filter-average: Numbers of sampling data will be averaged.
> + 0 means no average. 1 means average two samples. 2 means average four
> + samples. 3 means average eight samples.
> + - atmel,adc-ts-pendet-sensitivity: Pen Detection input pull-up resistor.
> + It can be 0, 1, 2, 3.
>
> Above two properties only supported in SAM9X5, SAMA5D3 IP.
Ok, that should go to the documentation as well. What do the values of
atmel,adc-ts-pendet-sensitivity correspond to?
> >>@@ -104,14 +140,10 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
> >> return IRQ_HANDLED;
> >> }
> >>-static irqreturn_t at91_adc_eoc_trigger(int irq, void *private)
> >>+/* Handler for classic adc channel eoc trigger */
> >>+void handle_adc_eoc_trigger(int irq, struct iio_dev *idev)
> >> {
> >>- struct iio_dev *idev = private;
> >> struct at91_adc_state *st = iio_priv(idev);
> >>- u32 status = at91_adc_readl(st, st->registers->status_register);
> >>-
> >>- if (!(status & st->registers->drdy_mask))
> >>- return IRQ_HANDLED;
> >Why are you changing the prototype and remove most of the useful part
> >out of the handler?
>
> I change the protype because I make it as a sub interrupt handler.
> Since I just add a new interrupt handler which will check the
> interrupt type, if DRDY interrupt is coming, it will call your
> original handler.
> Otherwise use touch screen interrupt handler code.
>
> Following is the new interrupt handler code in this patch:
>
> +static irqreturn_t at91_adc_interrupt(int irq, void *private)
> +{
> + struct iio_dev *idev = private;
> + struct at91_adc_state *st = iio_priv(idev);
> + u32 status = at91_adc_readl(st, st->registers->status_register);
> + const uint32_t ts_data_irq_mask =
> + AT91_ADC_IER_XRDY |
> + AT91_ADC_IER_YRDY |
> + AT91_ADC_IER_PRDY;
> +
> + if (status & st->registers->drdy_mask)
> + handle_adc_eoc_trigger(irq, idev);
>
> ^
> |
> here we call original trigger handler.
>
> +
> + if (status & AT91_ADC_IER_PEN) {
> + at91_adc_writel(st, AT91_ADC_IDR, AT91_ADC_IER_PEN);
> + at91_adc_writel(st, AT91_ADC_IER, AT91_ADC_IER_NOPEN |
> + ts_data_irq_mask);
> + /* Set up period trigger for sampling */
> + at91_adc_writel(st, st->registers->trigger_register,
> + AT91_ADC_TRGR_MOD_PERIOD_TRIG |
> + AT91_ADC_TRGR_TRGPER_(st->ts_sample_period_val));
> + } else if (status & AT91_ADC_IER_NOPEN) {
> + at91_adc_writel(st, st->registers->trigger_register, 0);
> + at91_adc_writel(st, AT91_ADC_IDR, AT91_ADC_IER_NOPEN |
> + ts_data_irq_mask);
> + at91_adc_writel(st, AT91_ADC_IER, AT91_ADC_IER_PEN);
> +
> + input_report_key(st->ts_input, BTN_TOUCH, 0);
> + input_sync(st->ts_input);
> + } else if ((status & ts_data_irq_mask) == ts_data_irq_mask) {
>
> Those code will handle for the Touch screen interrupt.
Ah, right.
Thanks!
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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