Re: [PATCH 2/3] iio: adc: add support for Allwinner SoCs ADC
From: Jonathan Cameron
Date: Sun Jul 03 2016 - 08:49:13 EST
On 03/07/16 12:54, Jonathan Cameron wrote:
> On 28/06/16 09:18, Quentin Schulz wrote:
>> The Allwinner SoCs all have an ADC that can also act as a touchscreen
>> controller and a thermal sensor. This patch adds the ADC driver which is
>> based on the MFD for the same SoCs ADC.
>>
>> This also registers the thermal adc channel in the iio map array so
>> iio_hwmon could use it without modifying the Device Tree.
>>
>> This driver probes on three different platform_device_id to take into
>> account slight differences between Allwinner SoCs ADCs.
>>
>> Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxx>
> Hi Quentin.
>
> I'm a bit in two minds about some of this. That temperature sensor is
> so obviously meant for hwmon purposes, I'm tempted to suggest it might
> actually make sense to put it directly in hwmon rather than using the
> bridge. That obviously makes it less flexible in some ways (i.e. for
> use within the thermal subsystem at some point).
>
> Guenter, what do you think?
>
> I'm guessing detailed docs for this part aren't avaiable publicly? :(
>
> So the rest of my comments are kind of predicated on me having roughtly
> understood how this device works from the structure of the driver.
>
> The temperature sensor is really effectively as separate ADC?
> The main interest in this is for key detection?
Ah, I'm talking garbage, wrong ADC for the chip... I'd crossed the two
threads. Ignore that stuff.
>
> Anyhow, if the data flow for the temperatures sensor is not synced with
> the other ADC channels, adding buffered (pushed) output from the driver in
> future will be fiddly and with a 250Hz device you'll probably want it.
> Basically IIO buffered supports assumes each iio device will sample data
> at a particular frequency. If channels are not synchronized in that fashion
> then you have to register multiple devices or only pick a subset of channels
> to export.
>
> For the key detection you have already observed that IIO needs some
> additions to be able to have consumers of what we term 'events' e.g. threshold
> interrupts.
>
> Looking at the lradc-keys driver in tree, it looks like we only really have
> really simple threshold interrups - configured to detect a very low voltage?
> + only one per channel.
>
> So not too nasty a case, but you are right some work is needed in IIO as
> we simply don't have a means of passing these on as yet or configuring them
> from in kernel consumers.
> If we take the easy route and don't demux incoming events then it shouldn't
> be too hard to add (demux can follow later). Hence any client device can try
> to enable events it wants, but may get events that other client devices wanted
> as well.
>
> Config interface should be much the same as the write support for channels.
> Data flow marginally harder, but pretty much a list of callbacks within
> iio_push_event.
>
> Not trivial, but not too tricky either.
>
> The events subsystem has a few 'limitations' we need to address long term
> but as this is in kernel interface only, we can do this now and fix stuff
> up in future without any ABI breakage. (limitations are things like only
> one event of a given type and direction per channel - main challenge on
> that is finding a way of doing it without abi breakage).
>
> Anyhow, sounds fun - wish I had the time to do it myself!
>
> Otherwise, your remove is never going to work as indio_dev is always NULL.
>
> Jonathan
>
>> ---
>> drivers/iio/adc/Kconfig | 12 ++
>> drivers/iio/adc/Makefile | 1 +
>> drivers/iio/adc/sunxi-gpadc-iio.c | 371 ++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 384 insertions(+)
>> create mode 100644 drivers/iio/adc/sunxi-gpadc-iio.c
>>
>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>> index 82c718c..b7b566a 100644
>> --- a/drivers/iio/adc/Kconfig
>> +++ b/drivers/iio/adc/Kconfig
>> @@ -328,6 +328,18 @@ config NAU7802
>> To compile this driver as a module, choose M here: the
>> module will be called nau7802.
>>
>> +config SUNXI_ADC
>> + tristate "ADC driver for sunxi platforms"
>> + depends on IIO
>> + depends on MFD_SUNXI_ADC
>> + help
>> + Say yes here to build support for Allwinner SoCs (A10, A13 and A31)
>> + SoCs ADC. This ADC provides 4 channels which can be used as an ADC or
>> + as a touchscreen input and one channel for thermal sensor.
>> +
>> + To compile this driver as a module, choose M here: the
>> + module will be called sunxi-gpadc-iio.
>> +
>> config PALMAS_GPADC
>> tristate "TI Palmas General Purpose ADC"
>> depends on MFD_PALMAS
>> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
>> index 0cb7921..2996a5b 100644
>> --- a/drivers/iio/adc/Makefile
>> +++ b/drivers/iio/adc/Makefile
>> @@ -32,6 +32,7 @@ obj-$(CONFIG_MCP3422) += mcp3422.o
>> obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
>> obj-$(CONFIG_MXS_LRADC) += mxs-lradc.o
>> obj-$(CONFIG_NAU7802) += nau7802.o
>> +obj-$(CONFIG_SUNXI_ADC) += sunxi-gpadc-iio.o
>> obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
>> obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
>> obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
>> diff --git a/drivers/iio/adc/sunxi-gpadc-iio.c b/drivers/iio/adc/sunxi-gpadc-iio.c
>> new file mode 100644
>> index 0000000..5840f43
>> --- /dev/null
>> +++ b/drivers/iio/adc/sunxi-gpadc-iio.c
>> @@ -0,0 +1,371 @@
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/io.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/clk.h>
>> +#include <linux/completion.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/iio/machine.h>
>> +#include <linux/iio/driver.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/mfd/sunxi-gpadc-mfd.h>
>> +#include <linux/regmap.h>
>> +
> I'm fussy about this: Please prefix all defines as some of these
> are generic enough they may well end up defined in an included header
> sometime in the future.
>
>> +#define TP_CTRL0 0x00
>> +#define TP_CTRL1 0x04
>> +#define TP_CTRL2 0x08
>> +#define TP_CTRL3 0x0c
>> +#define TP_TPR 0x18
>> +#define TP_CDAT 0x1c
>> +#define TEMP_DATA 0x20
>> +#define TP_DATA 0x24
>> +
>> +/* TP_CTRL0 bits */
>> +#define ADC_FIRST_DLY(x) ((x) << 24) /* 8 bits */
>> +#define ADC_FIRST_DLY_MODE BIT(23)
>> +#define ADC_CLK_SELECT BIT(22)
>> +#define ADC_CLK_DIVIDER(x) ((x) << 20) /* 2 bits */
>> +#define FS_DIV(x) ((x) << 16) /* 4 bits */
>> +#define T_ACQ(x) ((x) << 0) /* 16 bits*/
>> +
>> +/* TP_CTRL1 bits */
>> +#define STYLUS_UP_DEBOUNCE(x) ((x) << 12) /* 8 bits */
>> +#define STYLUS_UP_DEBOUNCE_EN BIT(9)
>> +#define TOUCH_PAN_CALI_EN BIT(6)
>> +#define TP_DUAL_EN BIT(5)
>> +#define TP_MODE_EN BIT(4)
>> +#define TP_ADC_SELECT BIT(3)
>> +#define ADC_CHAN_SELECT(x) ((x) << 0) /* 3 bits */
>> +
>> +/* TP_CTRL1 bits for sun6i SOCs */
>> +#define SUN6I_TOUCH_PAN_CALI_EN BIT(7)
>> +#define SUN6I_TP_DUAL_EN BIT(6)
>> +#define SUN6I_TP_MODE_EN BIT(5)
>> +#define SUN6I_TP_ADC_SELECT BIT(4)
>> +#define SUN6I_ADC_CHAN_SELECT(x) BIT(x) /* 4 bits */
>> +
>> +/* TP_CTRL2 bits */
>> +#define TP_SENSITIVE_ADJUST(x) ((x) << 28) /* 4 bits */
>> +#define TP_MODE_SELECT(x) ((x) << 26) /* 2 bits */
>> +#define PRE_MEA_EN BIT(24)
>> +#define PRE_MEA_THRE_CNT(x) ((x) << 0) /* 24 bits*/
>> +
>> +/* TP_CTRL3 bits */
>> +#define FILTER_EN BIT(2)
>> +#define FILTER_TYPE(x) ((x) << 0) /* 2 bits */
>> +
>> +/* TP_INT_FIFOC irq and fifo mask / control bits */
>> +#define TEMP_IRQ_EN BIT(18)
>> +#define TP_OVERRUN_IRQ_EN BIT(17)
>> +#define TP_DATA_IRQ_EN BIT(16)
>> +#define TP_DATA_XY_CHANGE BIT(13)
>> +#define TP_FIFO_TRIG_LEVEL(x) ((x) << 8) /* 5 bits */
>> +#define TP_DATA_DRQ_EN BIT(7)
>> +#define TP_FIFO_FLUSH BIT(4)
>> +#define TP_UP_IRQ_EN BIT(1)
>> +#define TP_DOWN_IRQ_EN BIT(0)
>> +
>> +/* TP_INT_FIFOS irq and fifo status bits */
>> +#define TEMP_DATA_PENDING BIT(18)
>> +#define FIFO_OVERRUN_PENDING BIT(17)
>> +#define FIFO_DATA_PENDING BIT(16)
>> +#define TP_IDLE_FLG BIT(2)
>> +#define TP_UP_PENDING BIT(1)
>> +#define TP_DOWN_PENDING BIT(0)
>> +
>> +/* TP_TPR bits */
>> +#define TEMP_ENABLE(x) ((x) << 16)
>> +#define TEMP_PERIOD(x) ((x) << 0) /*t = x * 256 * 16 / clkin*/
>> +
>> +#define ARCH_SUN4I BIT(0)
>> +#define ARCH_SUN5I BIT(1)
>> +#define ARCH_SUN6I BIT(2)
>> +
>> +struct sunxi_gpadc_dev {
>> + void __iomem *regs;
>> + struct completion completion;
>> + int temp_data;
>> + u32 adc_data;
>> + struct regmap *regmap;
>> + unsigned int fifo_data_irq;
>> + unsigned int temp_data_irq;
>> + unsigned int flags;
>> +};
>> +
>> +#define ADC_CHANNEL(_channel, _name) { \
>> + .type = IIO_VOLTAGE, \
>> + .indexed = 1, \
>> + .channel = _channel, \
>> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
>> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
>> + .datasheet_name = _name, \
>> +}
>> +
>> +static struct iio_map sunxi_gpadc_hwmon_maps[] = {
>> + {
>> + .adc_channel_label = "temp_adc",
>> + .consumer_dev_name = "iio_hwmon.0",
>> + },
>> + {},
>> +};
>> +
>> +static const struct iio_chan_spec sunxi_gpadc_channels[] = {
>> + ADC_CHANNEL(0, "adc_chan0"),
>> + ADC_CHANNEL(1, "adc_chan1"),
>> + ADC_CHANNEL(2, "adc_chan2"),
>> + ADC_CHANNEL(3, "adc_chan3"),
>> + {
>> + .type = IIO_TEMP,
>> + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
>> + .datasheet_name = "temp_adc",
>> + },
>> +};
>> +
>> +static int sunxi_gpadc_adc_read(struct iio_dev *indio_dev, int channel)
>> +{
>> + struct sunxi_gpadc_dev *info = iio_priv(indio_dev);
>> + int val = 0;
>> +
>> + mutex_lock(&indio_dev->mlock);
>> +
>> + reinit_completion(&info->completion);
>> + regmap_write(info->regmap, TP_CTRL1, SUN6I_TP_MODE_EN |
>> + SUN6I_TP_ADC_SELECT |
>> + SUN6I_ADC_CHAN_SELECT(channel));
>> + regmap_write(info->regmap, TP_INT_FIFOC, TP_FIFO_TRIG_LEVEL(1) |
>> + TP_FIFO_FLUSH);
>> + enable_irq(info->fifo_data_irq);
>> +
>> + if (!wait_for_completion_timeout(&info->completion,
>> + msecs_to_jiffies(100))) {
>> + disable_irq(info->fifo_data_irq);
>> + mutex_unlock(&indio_dev->mlock);
>> + return -ETIMEDOUT;
>> + }
>> +
>> + val = info->adc_data;
>> + disable_irq(info->fifo_data_irq);
>> + mutex_unlock(&indio_dev->mlock);
>> +
>> + return val;
>> +}
>> +
>> +static int sunxi_gpadc_temp_read(struct iio_dev *indio_dev)
>> +{
>> + struct sunxi_gpadc_dev *info = iio_priv(indio_dev);
>> + int val = 0;
>> +
>> + mutex_lock(&indio_dev->mlock);
>> +
>> + reinit_completion(&info->completion);
>> +
>> + regmap_write(info->regmap, TP_INT_FIFOC, TP_FIFO_TRIG_LEVEL(1) |
>> + TP_FIFO_FLUSH);
>> + regmap_write(info->regmap, TP_CTRL1, SUN6I_TP_MODE_EN);
>> + enable_irq(info->temp_data_irq);
>> +
>> + if (!wait_for_completion_timeout(&info->completion,
>> + msecs_to_jiffies(100))) {
>> + disable_irq(info->temp_data_irq);
>> + mutex_unlock(&indio_dev->mlock);
>> + return -ETIMEDOUT;
>> + }
>> +
>> + if (info->flags & ARCH_SUN4I)
>> + val = info->temp_data * 133 - 257000;
>> + else if (info->flags & ARCH_SUN5I)
>> + val = info->temp_data * 100 - 144700;
>> + else if (info->flags & ARCH_SUN6I)
>> + val = info->temp_data * 167 - 271000;
>> +
>> + disable_irq(info->temp_data_irq);
>> + mutex_unlock(&indio_dev->mlock);
>> + return val;
>> +}
>> +
>> +static int sunxi_gpadc_read_raw(struct iio_dev *indio_dev,
>> + struct iio_chan_spec const *chan,
>> + int *val, int *val2, long mask)
>> +{
>> + switch (mask) {
>> + case IIO_CHAN_INFO_PROCESSED:
>> + *val = sunxi_gpadc_temp_read(indio_dev);
>> + if (*val < 0)
>> + return *val;
>> +
>> + return IIO_VAL_INT;
>> + case IIO_CHAN_INFO_RAW:
>> + *val = sunxi_gpadc_adc_read(indio_dev, chan->channel);
>> + if (*val < 0)
>> + return *val;
>> +
>> + return IIO_VAL_INT;
>> + default:
>> + break;
>> + }
>> +
>> + return -EINVAL;
>> +}
>> +
>> +static const struct iio_info sunxi_gpadc_iio_info = {
>> + .read_raw = sunxi_gpadc_read_raw,
>> + .driver_module = THIS_MODULE,
>> +};
>> +
>> +static irqreturn_t sunxi_gpadc_temp_data_irq_handler(int irq, void *dev_id)
>> +{
>> + struct sunxi_gpadc_dev *info = dev_id;
>> + int ret;
>> +
>> + ret = regmap_read(info->regmap, TEMP_DATA, &info->temp_data);
>> + if (ret == 0)
>> + complete(&info->completion);
>> +
>> + return IRQ_HANDLED;
>> +}
> Interesting that it's a separate data flow for the temperature sensor.
> That means that if you add buffered (pushed data) support in future either
> you'll need to split the device in two or not allow the temperature channel
> to go through the buffer interface.
>> +
>> +static irqreturn_t sunxi_gpadc_fifo_data_irq_handler(int irq, void *dev_id)
>> +{
>> + struct sunxi_gpadc_dev *info = dev_id;
>> + int ret;
>> +
>> + ret = regmap_read(info->regmap, TP_DATA, &info->adc_data);
>> + if (ret == 0)
>> + complete(&info->completion);
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static int sunxi_gpadc_probe(struct platform_device *pdev)
>> +{
>> + struct sunxi_gpadc_dev *info = NULL;
>> + struct iio_dev *indio_dev = NULL;
>> + int ret = 0;
>> + unsigned int irq;
>> + struct sunxi_gpadc_mfd_dev *sunxi_gpadc_mfd_dev;
>> +
>> + sunxi_gpadc_mfd_dev = dev_get_drvdata(pdev->dev.parent);
>> +
>> + indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*info));
>> + if (!indio_dev) {
>> + dev_err(&pdev->dev, "failed to allocate iio device.\n");
>> + return -ENOMEM;
>> + }
>> + info = iio_priv(indio_dev);
>> +
>> + info->regmap = sunxi_gpadc_mfd_dev->regmap;
>> + init_completion(&info->completion);
>> + indio_dev->name = dev_name(&pdev->dev);
>> + indio_dev->dev.parent = &pdev->dev;
>> + indio_dev->dev.of_node = pdev->dev.of_node;
>> + indio_dev->info = &sunxi_gpadc_iio_info;
>> + indio_dev->modes = INDIO_DIRECT_MODE;
>> + indio_dev->num_channels = ARRAY_SIZE(sunxi_gpadc_channels);
>> + indio_dev->channels = sunxi_gpadc_channels;
>> +
>> + info->flags = platform_get_device_id(pdev)->driver_data;
>> +
>> + regmap_write(info->regmap, TP_CTRL0, ADC_CLK_DIVIDER(2) |
>> + FS_DIV(7) |
>> + T_ACQ(63));
>> + regmap_write(info->regmap, TP_CTRL1, SUN6I_TP_MODE_EN);
>> + regmap_write(info->regmap, TP_CTRL3, FILTER_EN | FILTER_TYPE(1));
>> + regmap_write(info->regmap, TP_TPR, TEMP_ENABLE(1) | TEMP_PERIOD(1953));
>> +
>> + irq = platform_get_irq_byname(pdev, "TEMP_DATA_PENDING");
>> + if (irq < 0) {
>> + dev_err(&pdev->dev,
>> + "no TEMP_DATA_PENDING interrupt registered\n");
>> + return irq;
>> + }
>> +
>> + irq = regmap_irq_get_virq(sunxi_gpadc_mfd_dev->regmap_irqc, irq);
>> + ret = devm_request_any_context_irq(&pdev->dev, irq,
>> + sunxi_gpadc_temp_data_irq_handler,
>> + 0, "temp_data", info);
>> + if (ret < 0) {
>> + dev_err(&pdev->dev,
>> + "could not request TEMP_DATA_PENDING interrupt: %d\n",
>> + ret);
>> + return ret;
>> + }
>> +
>> + info->temp_data_irq = irq;
>> + disable_irq(irq);
>> +
>> + irq = platform_get_irq_byname(pdev, "FIFO_DATA_PENDING");
> hohum. A fifo? This part is getting more interesting ;) I'll have to
> dig out the datasheet at some point (if public).
>> + if (irq < 0) {
>> + dev_err(&pdev->dev,
>> + "no FIFO_DATA_PENDING interrupt registered\n");
>> + return irq;
>> + }
>> +
>> + irq = regmap_irq_get_virq(sunxi_gpadc_mfd_dev->regmap_irqc, irq);
>> + ret = devm_request_any_context_irq(&pdev->dev, irq,
>> + sunxi_gpadc_fifo_data_irq_handler,
>> + 0, "fifo_data", info);
>> + if (ret < 0) {
>> + dev_err(&pdev->dev,
>> + "could not request FIFO_DATA_PENDING interrupt: %d\n",
>> + ret);
>> + return ret;
>> + }
>> +
>> + info->fifo_data_irq = irq;
>> + disable_irq(irq);
>> +
>> + ret = iio_map_array_register(indio_dev, sunxi_gpadc_hwmon_maps);
> As mentioned for previous patch I think this should be described externally.
> Chances are that some of those other adc channels are also going to be
> in reality used for hwmon anyway so doing it in the device tree will give
> you more flexibility.
>
>> + if (ret < 0) {
>> + dev_err(&pdev->dev, "failed to register iio map array\n");
>> + return ret;
>> + }
>> +
>> + platform_set_drvdata(pdev, indio_dev);
>> +
>> + ret = iio_device_register(indio_dev);
>> + if (ret < 0) {
>> + dev_err(&pdev->dev, "could not register the device\n");
>> + iio_map_array_unregister(indio_dev);
>> + return ret;
>> + }
>> +
> This is kind of self evident when the device turns up so I'd not bother
> cluttering up the logs with it as no additional information is given.
>> + dev_info(&pdev->dev, "successfully loaded\n");
>> +
>> + return ret;
>> +}
>> +
>> +static int sunxi_gpadc_remove(struct platform_device *pdev)
>> +{
>> + struct iio_dev *indio_dev = NULL;
> ? If it's null the below isn't going to work as intended.
> Missing a platform_get_drvdata which I'd just roll into the above
> local variable definition.
>
>> + struct sunxi_gpadc_dev *info = NULL;
>> +
>> + iio_device_unregister(indio_dev);
>> + iio_map_array_unregister(indio_dev);
>> + info = iio_priv(indio_dev);
> I'd roll this into the local variable declaration above
> (it's only a trivial bit of pointer arithemetic after all.
> struct sunxi_gpadc_dev *info = iio_priv(indio_dev);
>
>> + regmap_write(info->regmap, TP_INT_FIFOC, 0);
>> +
>> + return 0;
>> +}
>> +
>> +static const struct platform_device_id sunxi_gpadc_id[] = {
>> + { "sun4i-a10-gpadc-iio", ARCH_SUN4I },
>> + { "sun5i-a13-gpadc-iio", ARCH_SUN5I },
>> + { "sun6i-a31-gpadc-iio", ARCH_SUN6I },
>> + { /*sentinel*/ },
>> +};
>> +
>> +static struct platform_driver sunxi_gpadc_driver = {
>> + .driver = {
>> + .name = "sunxi-gpadc-iio",
>> + },
>> + .id_table = sunxi_gpadc_id,
>> + .probe = sunxi_gpadc_probe,
>> + .remove = sunxi_gpadc_remove,
>> +};
>> +
>> +module_platform_driver(sunxi_gpadc_driver);
>> +
>> +MODULE_DESCRIPTION("ADC driver for sunxi platforms");
>> +MODULE_AUTHOR("Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxx>");
>> +MODULE_LICENSE("GPL v2");
>>
>
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