Re: [PATCH v8 6/6] IIO: Ingenic JZ47xx: Add touchscreen mode.

From: Jonathan Cameron
Date: Mon Jul 20 2020 - 07:49:19 EST

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On Sun, 12 Jul 2020 22:16:04 +0200
Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote:

> Hi Jonathan,
>
> Le dim. 12 juil. 2020 Ã 14:19, Jonathan Cameron <jic23@xxxxxxxxxx> a
> Ãcrit :
> > On Thu, 9 Jul 2020 17:22:00 +0200
> > Artur Rojek <contact@xxxxxxxxxxxxxx> wrote:
> >
> >> The SADC component in JZ47xx SoCs provides support for touchscreen
> >> operations (pen position and pen down pressure) in single-ended and
> >> differential modes.
> >>
> >> The touchscreen component of SADC takes a significant time to
> >> stabilize
> >> after first receiving the clock and a delay of 50ms has been
> >> empirically
> >> proven to be a safe value before data sampling can begin.
> >>
> >> Of the known hardware to use this controller, GCW Zero and Anbernic
> >> RG-350
> >> utilize the touchscreen mode by having their joystick(s) attached
> >> to the
> >> X/Y positive/negative input pins.
> >>
> >> JZ4770 and later SoCs introduce a low-level command feature. With
> >> it, up
> >> to 32 commands can be programmed, each one corresponding to a
> >> sampling
> >> job. It allows to change the low-voltage reference, the high-voltage
> >> reference, have them connected to VCC, GND, or one of the X-/X+ or
> >> Y-/Y+
> >> pins.
> >>
> >> This patch introduces support for 6 stream-capable channels:
> >> - channel #0 samples X+/GND
> >> - channel #1 samples Y+/GND
> >> - channel #2 samples X-/GND
> >> - channel #3 samples Y-/GND
> >> - channel #4 samples X+/X-
> >> - channel #5 samples Y+/Y-
> >
> > The one thing I noticed on this read was that we are slightly
> > stretching
> > the normal IIO channel definitions. The claim is that each of these
> > channels
> > is a POSITIONREALTIVE channel, whereas that isn't really true. They
> > are
> > related to the position, but as I understand it not directly
> > measuring it
> > (particularly X+ - X-) which is pretty much a reference voltage (I
> > think!)
> >
> > We might be better off just describing these as voltage channels, with
> > 4 and 5 described as differential voltage channels. The problem there
> > being that it doesn't describe the fact that the measurements are with
> > particular voltages also being applied to the touch screen.
> >
> > Perhaps we are best off just leaving it as you have it and being a bit
> > 'odd'. What do you think? Having written this down I think perhaps
> > leaving
> > it alone is the best plan :(
>
> That's up to you really. These ADC channels will measure voltage, but
> they are supposed to be used with a touchscreen, that's why we went
> with POSITIONRELATIVE. However, with the kind of devices we're working
> with, they are never used as such, so using VOLTAGE would work too.
I've picked up v9 as I don't think this matters hugely one way or the other.
If it becomes an issue in the long run I'm not that bothered if we end up
with one driver with a legacy and a new interface.

Thanks,

Jonathan

>
> > Otherwise this all looks fine to me.
> >
> > Thanks,
> >
> > Jonathan
> >
> >>
> >> Being able to sample X-/GND and Y-/GND is useful on some devices,
> >> where
> >> one joystick is connected to the X+/Y+ pins, and a second joystick
> >> is
> >> connected to the X-/Y- pins.
> >>
> >> All the boards which probe this driver have the interrupt provided
> >> from
> >> Device Tree, with no need to handle a case where the IRQ was not
> >> provided.
> >>
> >> Co-developed-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >> Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >> Signed-off-by: Artur Rojek <contact@xxxxxxxxxxxxxx>
> >> ---
> >>
> >> Changes:
> >>
> >> v2: - improve description of the touchscreen mode,
> >> - get rid of the unneeded kfifo,
> >> - drop IIO_BUFFER_CB from Kconfig,
> >> - remove extended names from the touchscreen channels
> >>
> >> v3: remove unneeded `linux/iio/kfifo_buf.h` include
> >>
> >> v4: clarify irq provider source in the patch description
> >>
> >> v5: no change
> >>
> >> v6: - correct the spelling of Device Tree and IRQ in commit message
> >> - don't omit trailing commas from initializer lists
> >> - error check `clk_enable`
> >> - remove redundant `dev_err` from `platform_get_irq` error
> >> check
> >>
> >> v7: no change
> >>
> >> v8: add support for ADCMD low-level command feature
> >>
> >> drivers/iio/adc/Kconfig | 1 +
> >> drivers/iio/adc/ingenic-adc.c | 250
> >> +++++++++++++++++++++++++++++++++-
> >> 2 files changed, 249 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> >> index ff3569635ce0..5b57437cef75 100644
> >> --- a/drivers/iio/adc/Kconfig
> >> +++ b/drivers/iio/adc/Kconfig
> >> @@ -500,6 +500,7 @@ config INA2XX_ADC
> >> config INGENIC_ADC
> >> tristate "Ingenic JZ47xx SoCs ADC driver"
> >> depends on MIPS || COMPILE_TEST
> >> + select IIO_BUFFER
> >> help
> >> Say yes here to build support for the Ingenic JZ47xx SoCs ADC
> >> unit.
> >>
> >> diff --git a/drivers/iio/adc/ingenic-adc.c
> >> b/drivers/iio/adc/ingenic-adc.c
> >> index 0233a9055c86..976aea46fede 100644
> >> --- a/drivers/iio/adc/ingenic-adc.c
> >> +++ b/drivers/iio/adc/ingenic-adc.c
> >> @@ -8,7 +8,9 @@
> >>
> >> #include <dt-bindings/iio/adc/ingenic,adc.h>
> >> #include <linux/clk.h>
> >> +#include <linux/iio/buffer.h>
> >> #include <linux/iio/iio.h>
> >> +#include <linux/interrupt.h>
> >> #include <linux/io.h>
> >> #include <linux/iopoll.h>
> >> #include <linux/kernel.h>
> >> @@ -20,19 +22,46 @@
> >> #define JZ_ADC_REG_CFG 0x04
> >> #define JZ_ADC_REG_CTRL 0x08
> >> #define JZ_ADC_REG_STATUS 0x0c
> >> +#define JZ_ADC_REG_ADSAME 0x10
> >> +#define JZ_ADC_REG_ADWAIT 0x14
> >> #define JZ_ADC_REG_ADTCH 0x18
> >> #define JZ_ADC_REG_ADBDAT 0x1c
> >> #define JZ_ADC_REG_ADSDAT 0x20
> >> +#define JZ_ADC_REG_ADCMD 0x24
> >> #define JZ_ADC_REG_ADCLK 0x28
> >>
> >> #define JZ_ADC_REG_ENABLE_PD BIT(7)
> >> #define JZ_ADC_REG_CFG_AUX_MD (BIT(0) | BIT(1))
> >> #define JZ_ADC_REG_CFG_BAT_MD BIT(4)
> >> +#define JZ_ADC_REG_CFG_SAMPLE_NUM(n) ((n) << 10)
> >> +#define JZ_ADC_REG_CFG_PULL_UP(n) ((n) << 16)
> >> +#define JZ_ADC_REG_CFG_CMD_SEL BIT(22)
> >> +#define JZ_ADC_REG_CFG_TOUCH_OPS_MASK (BIT(31) | GENMASK(23, 10))
> >> #define JZ_ADC_REG_ADCLK_CLKDIV_LSB 0
> >> #define JZ4725B_ADC_REG_ADCLK_CLKDIV10US_LSB 16
> >> #define JZ4770_ADC_REG_ADCLK_CLKDIV10US_LSB 8
> >> #define JZ4770_ADC_REG_ADCLK_CLKDIVMS_LSB 16
> >>
> >> +#define JZ_ADC_REG_ADCMD_YNADC BIT(7)
> >> +#define JZ_ADC_REG_ADCMD_YPADC BIT(8)
> >> +#define JZ_ADC_REG_ADCMD_XNADC BIT(9)
> >> +#define JZ_ADC_REG_ADCMD_XPADC BIT(10)
> >> +#define JZ_ADC_REG_ADCMD_VREFPYP BIT(11)
> >> +#define JZ_ADC_REG_ADCMD_VREFPXP BIT(12)
> >> +#define JZ_ADC_REG_ADCMD_VREFPXN BIT(13)
> >> +#define JZ_ADC_REG_ADCMD_VREFPAUX BIT(14)
> >> +#define JZ_ADC_REG_ADCMD_VREFPVDD33 BIT(15)
> >> +#define JZ_ADC_REG_ADCMD_VREFNYN BIT(16)
> >> +#define JZ_ADC_REG_ADCMD_VREFNXP BIT(17)
> >> +#define JZ_ADC_REG_ADCMD_VREFNXN BIT(18)
> >> +#define JZ_ADC_REG_ADCMD_VREFAUX BIT(19)
> >> +#define JZ_ADC_REG_ADCMD_YNGRU BIT(20)
> >> +#define JZ_ADC_REG_ADCMD_XNGRU BIT(21)
> >> +#define JZ_ADC_REG_ADCMD_XPGRU BIT(22)
> >> +#define JZ_ADC_REG_ADCMD_YPSUP BIT(23)
> >> +#define JZ_ADC_REG_ADCMD_XNSUP BIT(24)
> >> +#define JZ_ADC_REG_ADCMD_XPSUP BIT(25)
> >> +
> >> #define JZ_ADC_AUX_VREF 3300
> >> #define JZ_ADC_AUX_VREF_BITS 12
> >> #define JZ_ADC_BATTERY_LOW_VREF 2500
> >> @@ -44,6 +73,14 @@
> >> #define JZ4770_ADC_BATTERY_VREF 6600
> >> #define JZ4770_ADC_BATTERY_VREF_BITS 12
> >>
> >> +#define JZ_ADC_IRQ_AUX BIT(0)
> >> +#define JZ_ADC_IRQ_BATTERY BIT(1)
> >> +#define JZ_ADC_IRQ_TOUCH BIT(2)
> >> +#define JZ_ADC_IRQ_PEN_DOWN BIT(3)
> >> +#define JZ_ADC_IRQ_PEN_UP BIT(4)
> >> +#define JZ_ADC_IRQ_PEN_DOWN_SLEEP BIT(5)
> >> +#define JZ_ADC_IRQ_SLEEP BIT(7)
> >> +
> >> struct ingenic_adc;
> >>
> >> struct ingenic_adc_soc_data {
> >> @@ -69,6 +106,61 @@ struct ingenic_adc {
> >> bool low_vref_mode;
> >> };
> >>
> >> +static void ingenic_adc_set_adcmd(struct iio_dev *iio_dev,
> >> unsigned long mask)
> >> +{
> >> + struct ingenic_adc *adc = iio_priv(iio_dev);
> >> +
> >> + mutex_lock(&adc->lock);
> >> +
> >> + /* Init ADCMD */
> >> + readl(adc->base + JZ_ADC_REG_ADCMD);
> >> +
> >> + if (mask & 0x3) {
> >> + /* Second channel (INGENIC_ADC_TOUCH_YP): sample YP vs. GND */
> >> + writel(JZ_ADC_REG_ADCMD_XNGRU
> >> + | JZ_ADC_REG_ADCMD_VREFNXN | JZ_ADC_REG_ADCMD_VREFPVDD33
> >> + | JZ_ADC_REG_ADCMD_YPADC,
> >> + adc->base + JZ_ADC_REG_ADCMD);
> >> +
> >> + /* First channel (INGENIC_ADC_TOUCH_XP): sample XP vs. GND */
> >> + writel(JZ_ADC_REG_ADCMD_YNGRU
> >> + | JZ_ADC_REG_ADCMD_VREFNYN | JZ_ADC_REG_ADCMD_VREFPVDD33
> >> + | JZ_ADC_REG_ADCMD_XPADC,
> >> + adc->base + JZ_ADC_REG_ADCMD);
> >> + }
> >> +
> >> + if (mask & 0xc) {
> >> + /* Fourth channel (INGENIC_ADC_TOUCH_YN): sample YN vs. GND */
> >> + writel(JZ_ADC_REG_ADCMD_XNGRU
> >> + | JZ_ADC_REG_ADCMD_VREFNXN | JZ_ADC_REG_ADCMD_VREFPVDD33
> >> + | JZ_ADC_REG_ADCMD_YNADC,
> >> + adc->base + JZ_ADC_REG_ADCMD);
> >> +
> >> + /* Third channel (INGENIC_ADC_TOUCH_XN): sample XN vs. GND */
> >> + writel(JZ_ADC_REG_ADCMD_YNGRU
> >> + | JZ_ADC_REG_ADCMD_VREFNYN | JZ_ADC_REG_ADCMD_VREFPVDD33
> >> + | JZ_ADC_REG_ADCMD_XNADC,
> >> + adc->base + JZ_ADC_REG_ADCMD);
> >> + }
> >> +
> >> + if (mask & 0x30) {
> >> + /* Sixth channel (INGENIC_ADC_TOUCH_YD): sample YP vs. YN */
> >> + writel(JZ_ADC_REG_ADCMD_VREFNYN | JZ_ADC_REG_ADCMD_VREFPVDD33
> >> + | JZ_ADC_REG_ADCMD_YPADC,
> >> + adc->base + JZ_ADC_REG_ADCMD);
> >> +
> >> + /* Fifth channel (INGENIC_ADC_TOUCH_XD): sample XP vs. XN */
> >> + writel(JZ_ADC_REG_ADCMD_VREFNXN | JZ_ADC_REG_ADCMD_VREFPVDD33
> >> + | JZ_ADC_REG_ADCMD_XPADC,
> >> + adc->base + JZ_ADC_REG_ADCMD);
> >> + }
> >> +
> >> + /* We're done */
> >> + writel(0, adc->base + JZ_ADC_REG_ADCMD);
> >> +
> >> + mutex_unlock(&adc->lock);
> >> +}
> >> +
> >> static void ingenic_adc_set_config(struct ingenic_adc *adc,
> >> uint32_t mask,
> >> uint32_t val)
> >> @@ -288,6 +380,72 @@ static const struct iio_chan_spec
> >> jz4740_channels[] = {
> >> };
> >>
> >> static const struct iio_chan_spec jz4770_channels[] = {
> >> + {
> >> + .type = IIO_POSITIONRELATIVE,
> >> + .indexed = 1,
> >> + .channel = INGENIC_ADC_TOUCH_XP,
> >
> > Ah. sorry. I should have noticed this much earlier.
> >
> > These aren't position channels as such. They are channels
> > that are then processed into position in combination.
> >
> > Problem is I'm not sure how we 'should' describe then.
> >
> > Perhaps this is the best we can do.
>
> We could have the two differencial channels as IIO_POSITIONRELATIVE,
> and the four single-ended ones as IIO_VOLTAGE.
>
> Cheers,
> -Paul
>
> >> + .scan_index = 0,
> >> + .scan_type = {
> >> + .sign = 'u',
> >> + .realbits = 12,
> >> + .storagebits = 16,
> >> + },
> >> + },
> >> + {
> >> + .type = IIO_POSITIONRELATIVE,
> >> + .indexed = 1,
> >> + .channel = INGENIC_ADC_TOUCH_YP,
> >> + .scan_index = 1,
> >> + .scan_type = {
> >> + .sign = 'u',
> >> + .realbits = 12,
> >> + .storagebits = 16,
> >> + },
> >> + },
> >> + {
> >> + .type = IIO_POSITIONRELATIVE,
> >> + .indexed = 1,
> >> + .channel = INGENIC_ADC_TOUCH_XN,
> >> + .scan_index = 2,
> >> + .scan_type = {
> >> + .sign = 'u',
> >> + .realbits = 12,
> >> + .storagebits = 16,
> >> + },
> >> + },
> >> + {
> >> + .type = IIO_POSITIONRELATIVE,
> >> + .indexed = 1,
> >> + .channel = INGENIC_ADC_TOUCH_YN,
> >> + .scan_index = 3,
> >> + .scan_type = {
> >> + .sign = 'u',
> >> + .realbits = 12,
> >> + .storagebits = 16,
> >> + },
> >> + },
> >> + {
> >> + .type = IIO_POSITIONRELATIVE,
> >> + .indexed = 1,
> >> + .channel = INGENIC_ADC_TOUCH_XD,
> >> + .scan_index = 4,
> >> + .scan_type = {
> >> + .sign = 'u',
> >> + .realbits = 12,
> >> + .storagebits = 16,
> >> + },
> >> + },
> >> + {
> >> + .type = IIO_POSITIONRELATIVE,
> >> + .indexed = 1,
> >> + .channel = INGENIC_ADC_TOUCH_YD,
> >> + .scan_index = 5,
> >> + .scan_type = {
> >> + .sign = 'u',
> >> + .realbits = 12,
> >> + .storagebits = 16,
> >> + },
> >> + },
> >> {
> >> .extend_name = "aux",
> >> .type = IIO_VOLTAGE,
> >> @@ -490,13 +648,89 @@ static const struct iio_info ingenic_adc_info
> >> = {
> >> .of_xlate = ingenic_adc_of_xlate,
> >> };
> >>
> >> +static int ingenic_adc_buffer_enable(struct iio_dev *iio_dev)
> >> +{
> >> + struct ingenic_adc *adc = iio_priv(iio_dev);
> >> + int ret;
> >> +
> >> + ret = clk_enable(adc->clk);
> >> + if (ret) {
> >> + dev_err(iio_dev->dev.parent, "Failed to enable clock: %d\n",
> >> + ret);
> >> + return ret;
> >> + }
> >> +
> >> + /* It takes significant time for the touchscreen hw to stabilize.
> >> */
> >> + msleep(50);
> >> + ingenic_adc_set_config(adc, JZ_ADC_REG_CFG_TOUCH_OPS_MASK,
> >> + JZ_ADC_REG_CFG_SAMPLE_NUM(4) |
> >> + JZ_ADC_REG_CFG_PULL_UP(4));
> >> +
> >> + writew(80, adc->base + JZ_ADC_REG_ADWAIT);
> >> + writew(2, adc->base + JZ_ADC_REG_ADSAME);
> >> + writeb((u8)~JZ_ADC_IRQ_TOUCH, adc->base + JZ_ADC_REG_CTRL);
> >> + writel(0, adc->base + JZ_ADC_REG_ADTCH);
> >> +
> >> + ingenic_adc_set_config(adc, JZ_ADC_REG_CFG_CMD_SEL,
> >> + JZ_ADC_REG_CFG_CMD_SEL);
> >> + ingenic_adc_set_adcmd(iio_dev, iio_dev->active_scan_mask[0]);
> >> +
> >> + ingenic_adc_enable(adc, 2, true);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static int ingenic_adc_buffer_disable(struct iio_dev *iio_dev)
> >> +{
> >> + struct ingenic_adc *adc = iio_priv(iio_dev);
> >> +
> >> + ingenic_adc_enable(adc, 2, false);
> >> +
> >> + ingenic_adc_set_config(adc, JZ_ADC_REG_CFG_CMD_SEL, 0);
> >> +
> >> + writeb(0xff, adc->base + JZ_ADC_REG_CTRL);
> >> + writeb(0xff, adc->base + JZ_ADC_REG_STATUS);
> >> + ingenic_adc_set_config(adc, JZ_ADC_REG_CFG_TOUCH_OPS_MASK, 0);
> >> + writew(0, adc->base + JZ_ADC_REG_ADSAME);
> >> + writew(0, adc->base + JZ_ADC_REG_ADWAIT);
> >> + clk_disable(adc->clk);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static const struct iio_buffer_setup_ops ingenic_buffer_setup_ops
> >> = {
> >> + .postenable = &ingenic_adc_buffer_enable,
> >> + .predisable = &ingenic_adc_buffer_disable
> >> +};
> >> +
> >> +static irqreturn_t ingenic_adc_irq(int irq, void *data)
> >> +{
> >> + struct iio_dev *iio_dev = data;
> >> + struct ingenic_adc *adc = iio_priv(iio_dev);
> >> + unsigned long mask = iio_dev->active_scan_mask[0];
> >> + unsigned int i;
> >> + u32 tdat[3];
> >> +
> >> + for (i = 0; i < ARRAY_SIZE(tdat); mask >>= 2, i++) {
> >> + if (mask & 0x3)
> >> + tdat[i] = readl(adc->base + JZ_ADC_REG_ADTCH);
> >> + else
> >> + tdat[i] = 0;
> >> + }
> >> +
> >> + iio_push_to_buffers(iio_dev, tdat);
> >> + writeb(JZ_ADC_IRQ_TOUCH, adc->base + JZ_ADC_REG_STATUS);
> >> +
> >> + return IRQ_HANDLED;
> >> +}
> >> +
> >> static int ingenic_adc_probe(struct platform_device *pdev)
> >> {
> >> struct device *dev = &pdev->dev;
> >> struct iio_dev *iio_dev;
> >> struct ingenic_adc *adc;
> >> const struct ingenic_adc_soc_data *soc_data;
> >> - int ret;
> >> + int irq, ret;
> >>
> >> soc_data = device_get_match_data(dev);
> >> if (!soc_data)
> >> @@ -511,6 +745,17 @@ static int ingenic_adc_probe(struct
> >> platform_device *pdev)
> >> mutex_init(&adc->aux_lock);
> >> adc->soc_data = soc_data;
> >>
> >> + irq = platform_get_irq(pdev, 0);
> >> + if (irq < 0)
> >> + return irq;
> >> +
> >> + ret = devm_request_irq(dev, irq, ingenic_adc_irq, 0,
> >> + dev_name(dev), iio_dev);
> >> + if (ret < 0) {
> >> + dev_err(dev, "Failed to request irq: %d\n", ret);
> >> + return ret;
> >> + }
> >> +
> >> adc->base = devm_platform_ioremap_resource(pdev, 0);
> >> if (IS_ERR(adc->base))
> >> return PTR_ERR(adc->base);
> >> @@ -550,7 +795,8 @@ static int ingenic_adc_probe(struct
> >> platform_device *pdev)
> >>
> >> iio_dev->dev.parent = dev;
> >> iio_dev->name = "jz-adc";
> >> - iio_dev->modes = INDIO_DIRECT_MODE;
> >> + iio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
> >> + iio_dev->setup_ops = &ingenic_buffer_setup_ops;
> >> iio_dev->channels = soc_data->channels;
> >> iio_dev->num_channels = soc_data->num_channels;
> >> iio_dev->info = &ingenic_adc_info;
> >
>
>

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