Re: [PATCH v3 2/2] iio: twl6030-gpadc: TWL6030, TWL6032 GPADC driver

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Hi All,

I have a question regarding this patch and IIO in general
- Does IIO provide sync mechanism with system wide suspend/resume or this should be handled by each driver itself?

What if during system suspend iio_read_channel_raw() (or any other consumer API) will be called after gpadc driver have been suspended already? (I did some investigation and seems it's possible - Am I right?)

If no, could "info_exist_lock" be reused for such purposes?

Regards,
-grygorii


On 07/12/2013 10:56 PM, Lars-Peter Clausen wrote:

A couple of comments inline.

On 07/12/2013 09:18 AM, Oleksandr Kozaruk wrote:
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index ab0767e6..87d699e 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -157,4 +157,12 @@ config VIPERBOARD_ADC
        Say yes here to access the ADC part of the Nano River
        Technologies Viperboard.

+config TWL6030_GPADC
+    tristate "TWL6030 GPADC (General Purpose A/D Convertor) Support"
+    depends on TWL4030_CORE
+    default n
+    help
+      Say yes here if you want support for the TWL6030 General Purpose
+      A/D Convertor.
+

Keep it in alphabetical order

  endmenu
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 0a825be..8b05633 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -17,3 +17,4 @@ obj-$(CONFIG_MAX1363) += max1363.o
  obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
  obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
  obj-$(CONFIG_VIPERBOARD_ADC) += viperboard_adc.o
+obj-$(CONFIG_TWL6030_GPADC) += twl6030-gpadc.o

Same here.

diff --git a/drivers/iio/adc/twl6030-gpadc.c
b/drivers/iio/adc/twl6030-gpadc.c
new file mode 100644
index 0000000..6ceb789
--- /dev/null
+++ b/drivers/iio/adc/twl6030-gpadc.c
@@ -0,0 +1,1019 @@
[...]
+static u8 twl6032_channel_to_reg(int channel)
+{
+    return TWL6032_GPADC_GPCH0_LSB;

There is more than one channel, isn't there?

[...]
 > +static int twl6030_gpadc_read_raw(struct iio_dev *indio_dev,
 > +                 const struct iio_chan_spec *chan,
 > +                 int *val, int *val2, long mask)
 > +{
 > +    struct twl6030_gpadc_data *gpadc = iio_priv(indio_dev);
 > +    int ret = -EINVAL;
 > +
 > +    mutex_lock(&gpadc->lock);
 > +
 > +    ret = gpadc->pdata->start_conversion(chan->channel);
 > +    if (ret) {
 > +        dev_err(gpadc->dev, "failed to start conversion\n");
 > +        goto err;
 > +    }
 > +    /* wait for conversion to complete */
 > +    wait_for_completion_interruptible_timeout(&gpadc->irq_complete,
 > +                        msecs_to_jiffies(5000));

wait_for_completion_interruptible_timeout() can return either a negative
error code if it was interrupted, 0 if it timed out, or a positive value
if it was successfully completed. You need to handle all three cases.
Have a look at other existing drivers to see how to do this properly.

 > +
 > +    switch (mask) {
 > +    case IIO_CHAN_INFO_RAW:
 > +        ret = twl6030_gpadc_get_raw(gpadc, chan->channel, val);
 > +        ret = ret ? -EIO : IIO_VAL_INT;
 > +        break;
 > +
 > +    case IIO_CHAN_INFO_PROCESSED:
 > +        ret = twl6030_gpadc_get_processed(gpadc, chan->channel, val);
 > +        ret = ret ? -EIO : IIO_VAL_INT;
 > +        break;
 > +
 > +    default:
 > +        break;
 > +    }
 > +err:
 > +    mutex_unlock(&gpadc->lock);
 > +
 > +    return ret;
 > +}

+}
+
[...]
+static int twl6030_gpadc_probe(struct platform_device *pdev)
+{
+    struct device *dev = &pdev->dev;
+    struct twl6030_gpadc_data *gpadc;
+    const struct twl6030_gpadc_platform_data *pdata;
+    const struct of_device_id *match;
+    struct iio_dev *indio_dev;
+    int irq;
+    int ret = 0;
+
+    match = of_match_device(of_match_ptr(of_twl6030_match_tbl), dev);
+    pdata = match ? match->data : dev->platform_data;
+
+    if (!pdata)
+        return -EINVAL;
+
+    indio_dev = iio_device_alloc(sizeof(struct twl6030_gpadc_data));

sizeof(*gpadc)

+    if (!indio_dev) {
+        dev_err(dev, "failed allocating iio device\n");
+        ret = -ENOMEM;
+    }
+
+    gpadc = iio_priv(indio_dev);
+
+    gpadc->twl6030_cal_tbl = devm_kzalloc(dev,
+                    sizeof(struct twl6030_chnl_calib) *
+                    pdata->nchannels, GFP_KERNEL);
+    if (!gpadc->twl6030_cal_tbl)
+        goto err;
+
+    gpadc->dev = dev;
+    gpadc->pdata = pdata;
+
+    platform_set_drvdata(pdev, indio_dev);
+    mutex_init(&gpadc->lock);
+    init_completion(&gpadc->irq_complete);
+
+    ret = pdata->calibrate(gpadc);
+    if (ret < 0) {
+        dev_err(&pdev->dev, "failed to read calibration registers\n");
+        goto err;
+    }
+
+    irq = platform_get_irq(pdev, 0);
+    if (irq < 0) {
+        dev_err(&pdev->dev, "failed to get irq\n");
+        goto err;
+    }
+
+    ret = devm_request_threaded_irq(dev, irq, NULL,
+                    twl6030_gpadc_irq_handler,
+                    IRQF_ONESHOT, "twl6030_gpadc", gpadc);

You access memory in the interrupt handler which is freed before the
interrupt handler is freed.

+    if (ret) {
+        dev_dbg(&pdev->dev, "could not request irq\n");
+        goto err;
+    }
+
+    ret = twl6030_gpadc_enable_irq(TWL6030_GPADC_RT_SW1_EOC_MASK);
+    if (ret < 0) {
+        dev_err(&pdev->dev, "failed to enable GPADC interrupt\n");
+        goto err;
+    }
+    ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, TWL6030_GPADCS,
+                    TWL6030_REG_TOGGLE1);
+    if (ret < 0) {
+        dev_err(&pdev->dev, "failed to enable GPADC module\n");
+        goto err;
+    }
+
+    indio_dev->name = DRIVER_NAME;
+    indio_dev->dev.parent = dev;
+    indio_dev->info = &twl6030_gpadc_iio_info;
+    indio_dev->modes = INDIO_DIRECT_MODE;
+    indio_dev->channels = pdata->iio_channels;
+    indio_dev->num_channels = pdata->nchannels;
+
+    ret = iio_device_register(indio_dev);
+    if (ret)
+        goto err;
+
+    return ret;
+err:
+    iio_device_free(indio_dev);
+    return ret;
+}
+
[...]
+static int twl6030_gpadc_suspend(struct device *pdev)
+{
+    int ret;
+
+    ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, TWL6030_GPADCR,
+                TWL6030_REG_TOGGLE1);
+    if (ret)
+        dev_err(pdev, "error reseting GPADC (%d)!\n", ret);
+
+    return 0;
+};
+
+static int twl6030_gpadc_resume(struct device *pdev)
+{
+    int ret;
+
+    ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, TWL6030_GPADCS,
+                TWL6030_REG_TOGGLE1);
+    if (ret)
+        dev_err(pdev, "error setting GPADC (%d)!\n", ret);
+
+    return 0;
+};
+
+static const struct dev_pm_ops twl6030_gpadc_pm_ops = {
+    .suspend = twl6030_gpadc_suspend,
+    .resume = twl6030_gpadc_resume,
+};

SIMPLE_DEV_PM_OPS?

[...]
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