| Message ID | 20200204101008.11411-3-olivier.moysan@st.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iio: adc: stm32-dfsdm: add scale and offset support | expand |
On Tue, 4 Feb 2020 11:10:06 +0100 Olivier Moysan <olivier.moysan@st.com> wrote: > Add scale support to sigma delta modulator. > > Signed-off-by: Olivier Moysan <olivier.moysan@st.com> I note below that there are probably some complexities around whether vref is used as you have it here or not. A few other bits inline around a race condition introduced in probe / remove. Thanks, Jonathan > --- > drivers/iio/adc/sd_adc_modulator.c | 108 ++++++++++++++++++++++++++--- > 1 file changed, 100 insertions(+), 8 deletions(-) > > diff --git a/drivers/iio/adc/sd_adc_modulator.c b/drivers/iio/adc/sd_adc_modulator.c > index 560d8c7d9d86..a83f35832050 100644 > --- a/drivers/iio/adc/sd_adc_modulator.c > +++ b/drivers/iio/adc/sd_adc_modulator.c > @@ -10,8 +10,7 @@ > #include <linux/iio/triggered_buffer.h> > #include <linux/module.h> > #include <linux/of_device.h> > - > -static const struct iio_info iio_sd_mod_iio_info; > +#include <linux/regulator/consumer.h> > > static const struct iio_chan_spec iio_sd_mod_ch = { > .type = IIO_VOLTAGE, > @@ -21,34 +20,126 @@ static const struct iio_chan_spec iio_sd_mod_ch = { > .realbits = 1, > .shift = 0, > }, > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), This relies on generic sigma delta modulators using an external vref. They might have an internal always on regulator... I would suggest we only support scale for devices with explicitly defined compatibles where we can know what regulators are used etc. For many devices, there will be a single powersupply called vdd-supply or similar in DT. It may also provide a reference voltage. > +}; > + > +static const struct iio_chan_spec iio_sd_mod_ch_ads = { > + .type = IIO_VOLTAGE, > + .indexed = 1, > + .scan_type = { > + .sign = 'u', > + .realbits = 1, > + .shift = 0, > + }, > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), > + .differential = 1, > +}; > + > +struct iio_sd_mod_priv { > + struct regulator *vref; > + int vref_mv; > +}; > + > +static int iio_sd_mod_read_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, int *val, > + int *val2, long mask) > +{ > + struct iio_sd_mod_priv *priv = iio_priv(indio_dev); > + > + switch (mask) { > + case IIO_CHAN_INFO_SCALE: > + *val = priv->vref_mv; > + *val2 = chan->scan_type.realbits; > + return IIO_VAL_INT; > + } > + > + return -EINVAL; > +} > + > +static const struct iio_info iio_sd_mod_iio_info = { > + .read_raw = iio_sd_mod_read_raw, > }; > > static int iio_sd_mod_probe(struct platform_device *pdev) > { > struct device *dev = &pdev->dev; > + struct iio_sd_mod_priv *priv; > struct iio_dev *iio; > + int ret; > > - iio = devm_iio_device_alloc(dev, 0); > + iio = devm_iio_device_alloc(dev, sizeof(*priv)); > if (!iio) > return -ENOMEM; > > + iio->channels = (const struct iio_chan_spec *) > + of_device_get_match_data(&pdev->dev); > + > + priv = iio_priv(iio); > + > iio->dev.parent = dev; > iio->dev.of_node = dev->of_node; > iio->name = dev_name(dev); > iio->info = &iio_sd_mod_iio_info; > iio->modes = INDIO_BUFFER_HARDWARE; > - > iio->num_channels = 1; > - iio->channels = &iio_sd_mod_ch; > > platform_set_drvdata(pdev, iio); > > - return devm_iio_device_register(&pdev->dev, iio); > + priv->vref = devm_regulator_get_optional(dev, "vref"); > + if (IS_ERR(priv->vref)) { > + ret = PTR_ERR(priv->vref); > + if (ret != -ENODEV) { > + if (ret != -EPROBE_DEFER) > + dev_err(dev, "vref get failed, %d\n", ret); > + return ret; > + } > + } > + > + if (!IS_ERR(priv->vref)) { > + ret = regulator_enable(priv->vref); > + if (ret < 0) { > + dev_err(dev, "vref enable failed %d\n", ret); > + return ret; > + } > + > + ret = regulator_get_voltage(priv->vref); > + if (ret < 0) { > + dev_err(dev, "vref get failed, %d\n", ret); > + goto err_regulator_disable; > + } > + > + priv->vref_mv = ret / 1000; > + dev_dbg(dev, "vref+=%dmV\n", priv->vref_mv); > + } > + > + ret = devm_iio_device_register(&pdev->dev, iio); This exposes the userspace and in kernel interfaces. Those are partly dependent on the regulator enable you have above. Using devm_ version fo this interface leaves you with a race in remove. The regulator is disabled before you have remove the interfaces that will only work if we assume it is still on. Hence, you should either use devm_add_action_or_reset magic to ensure we still do everything in the right order, or do it manually by using iio_device_register and iio_device_unregister. > + if (ret < 0) { > + dev_err(dev, "Failed to register sd-modulator, %d\n", ret); > + goto err_regulator_disable; > + } > + > + return 0; > + > +err_regulator_disable: > + regulator_disable(priv->vref); > + > + return ret; > +} > + > +static int iio_sd_mod_remove(struct platform_device *pdev) > +{ > + struct iio_dev *indio_dev = platform_get_drvdata(pdev); > + struct iio_sd_mod_priv *priv = iio_priv(indio_dev); > + > + if (priv->vref) > + return regulator_disable(priv->vref); > + > + return 0; > } > > static const struct of_device_id sd_adc_of_match[] = { > - { .compatible = "sd-modulator" }, > - { .compatible = "ads1201" }, > + { .compatible = "sd-modulator", .data = &iio_sd_mod_ch }, > + { .compatible = "ads1201", .data = &iio_sd_mod_ch_ads }, > { } > }; > MODULE_DEVICE_TABLE(of, sd_adc_of_match); > @@ -59,6 +150,7 @@ static struct platform_driver iio_sd_mod_adc = { > .of_match_table = of_match_ptr(sd_adc_of_match), > }, > .probe = iio_sd_mod_probe, > + .remove = iio_sd_mod_remove, > }; > > module_platform_driver(iio_sd_mod_adc);
Hi Jonathan, On 2/8/20 5:03 PM, Jonathan Cameron wrote: > On Tue, 4 Feb 2020 11:10:06 +0100 > Olivier Moysan <olivier.moysan@st.com> wrote: > >> Add scale support to sigma delta modulator. >> >> Signed-off-by: Olivier Moysan <olivier.moysan@st.com> > I note below that there are probably some complexities around > whether vref is used as you have it here or not. > > A few other bits inline around a race condition introduced in probe / remove. > > Thanks, > > Jonathan > >> --- >> drivers/iio/adc/sd_adc_modulator.c | 108 ++++++++++++++++++++++++++--- >> 1 file changed, 100 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/iio/adc/sd_adc_modulator.c b/drivers/iio/adc/sd_adc_modulator.c >> index 560d8c7d9d86..a83f35832050 100644 >> --- a/drivers/iio/adc/sd_adc_modulator.c >> +++ b/drivers/iio/adc/sd_adc_modulator.c >> @@ -10,8 +10,7 @@ >> #include <linux/iio/triggered_buffer.h> >> #include <linux/module.h> >> #include <linux/of_device.h> >> - >> -static const struct iio_info iio_sd_mod_iio_info; >> +#include <linux/regulator/consumer.h> >> >> static const struct iio_chan_spec iio_sd_mod_ch = { >> .type = IIO_VOLTAGE, >> @@ -21,34 +20,126 @@ static const struct iio_chan_spec iio_sd_mod_ch = { >> .realbits = 1, >> .shift = 0, >> }, >> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), > This relies on generic sigma delta modulators using an external vref. > They might have an internal always on regulator... > I would suggest we only support scale for devices with explicitly > defined compatibles where we can know what regulators are used etc. > > For many devices, there will be a single powersupply called vdd-supply > or similar in DT. It may also provide a reference voltage. I will remove scale support for generic sd-modulator, according to your comment on sd modulator bindings. The DFSDM driver expects scale attribute from sd-modulator. So, some rework of DFSDM driver will be required to also support raw data reading. >> +}; >> + >> +static const struct iio_chan_spec iio_sd_mod_ch_ads = { >> + .type = IIO_VOLTAGE, >> + .indexed = 1, >> + .scan_type = { >> + .sign = 'u', >> + .realbits = 1, >> + .shift = 0, >> + }, >> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), >> + .differential = 1, >> +}; >> + >> +struct iio_sd_mod_priv { >> + struct regulator *vref; >> + int vref_mv; >> +}; >> + >> +static int iio_sd_mod_read_raw(struct iio_dev *indio_dev, >> + struct iio_chan_spec const *chan, int *val, >> + int *val2, long mask) >> +{ >> + struct iio_sd_mod_priv *priv = iio_priv(indio_dev); >> + >> + switch (mask) { >> + case IIO_CHAN_INFO_SCALE: >> + *val = priv->vref_mv; >> + *val2 = chan->scan_type.realbits; >> + return IIO_VAL_INT; >> + } >> + >> + return -EINVAL; >> +} >> + >> +static const struct iio_info iio_sd_mod_iio_info = { >> + .read_raw = iio_sd_mod_read_raw, >> }; >> >> static int iio_sd_mod_probe(struct platform_device *pdev) >> { >> struct device *dev = &pdev->dev; >> + struct iio_sd_mod_priv *priv; >> struct iio_dev *iio; >> + int ret; >> >> - iio = devm_iio_device_alloc(dev, 0); >> + iio = devm_iio_device_alloc(dev, sizeof(*priv)); >> if (!iio) >> return -ENOMEM; >> >> + iio->channels = (const struct iio_chan_spec *) >> + of_device_get_match_data(&pdev->dev); >> + >> + priv = iio_priv(iio); >> + >> iio->dev.parent = dev; >> iio->dev.of_node = dev->of_node; >> iio->name = dev_name(dev); >> iio->info = &iio_sd_mod_iio_info; >> iio->modes = INDIO_BUFFER_HARDWARE; >> - >> iio->num_channels = 1; >> - iio->channels = &iio_sd_mod_ch; >> >> platform_set_drvdata(pdev, iio); >> >> - return devm_iio_device_register(&pdev->dev, iio); >> + priv->vref = devm_regulator_get_optional(dev, "vref"); >> + if (IS_ERR(priv->vref)) { >> + ret = PTR_ERR(priv->vref); >> + if (ret != -ENODEV) { >> + if (ret != -EPROBE_DEFER) >> + dev_err(dev, "vref get failed, %d\n", ret); >> + return ret; >> + } >> + } >> + >> + if (!IS_ERR(priv->vref)) { >> + ret = regulator_enable(priv->vref); >> + if (ret < 0) { >> + dev_err(dev, "vref enable failed %d\n", ret); >> + return ret; >> + } >> + >> + ret = regulator_get_voltage(priv->vref); >> + if (ret < 0) { >> + dev_err(dev, "vref get failed, %d\n", ret); >> + goto err_regulator_disable; >> + } >> + >> + priv->vref_mv = ret / 1000; >> + dev_dbg(dev, "vref+=%dmV\n", priv->vref_mv); >> + } >> + >> + ret = devm_iio_device_register(&pdev->dev, iio); > This exposes the userspace and in kernel interfaces. Those > are partly dependent on the regulator enable you have above. > > Using devm_ version fo this interface leaves you with a race in remove. > The regulator is disabled before you have remove the interfaces that > will only work if we assume it is still on. > > Hence, you should either use devm_add_action_or_reset magic > to ensure we still do everything in the right order, or do it > manually by using iio_device_register and iio_device_unregister. > I will fix this in v2. Regards Olivier >> + if (ret < 0) { >> + dev_err(dev, "Failed to register sd-modulator, %d\n", ret); >> + goto err_regulator_disable; >> + } >> + >> + return 0; >> + >> +err_regulator_disable: >> + regulator_disable(priv->vref); >> + >> + return ret; >> +} >> + >> +static int iio_sd_mod_remove(struct platform_device *pdev) >> +{ >> + struct iio_dev *indio_dev = platform_get_drvdata(pdev); >> + struct iio_sd_mod_priv *priv = iio_priv(indio_dev); >> + >> + if (priv->vref) >> + return regulator_disable(priv->vref); >> + >> + return 0; >> } >> >> static const struct of_device_id sd_adc_of_match[] = { >> - { .compatible = "sd-modulator" }, >> - { .compatible = "ads1201" }, >> + { .compatible = "sd-modulator", .data = &iio_sd_mod_ch }, >> + { .compatible = "ads1201", .data = &iio_sd_mod_ch_ads }, >> { } >> }; >> MODULE_DEVICE_TABLE(of, sd_adc_of_match); >> @@ -59,6 +150,7 @@ static struct platform_driver iio_sd_mod_adc = { >> .of_match_table = of_match_ptr(sd_adc_of_match), >> }, >> .probe = iio_sd_mod_probe, >> + .remove = iio_sd_mod_remove, >> }; >> >> module_platform_driver(iio_sd_mod_adc);
diff --git a/drivers/iio/adc/sd_adc_modulator.c b/drivers/iio/adc/sd_adc_modulator.c index 560d8c7d9d86..a83f35832050 100644 --- a/drivers/iio/adc/sd_adc_modulator.c +++ b/drivers/iio/adc/sd_adc_modulator.c @@ -10,8 +10,7 @@ #include <linux/iio/triggered_buffer.h> #include <linux/module.h> #include <linux/of_device.h> - -static const struct iio_info iio_sd_mod_iio_info; +#include <linux/regulator/consumer.h> static const struct iio_chan_spec iio_sd_mod_ch = { .type = IIO_VOLTAGE, @@ -21,34 +20,126 @@ static const struct iio_chan_spec iio_sd_mod_ch = { .realbits = 1, .shift = 0, }, + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), +}; + +static const struct iio_chan_spec iio_sd_mod_ch_ads = { + .type = IIO_VOLTAGE, + .indexed = 1, + .scan_type = { + .sign = 'u', + .realbits = 1, + .shift = 0, + }, + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), + .differential = 1, +}; + +struct iio_sd_mod_priv { + struct regulator *vref; + int vref_mv; +}; + +static int iio_sd_mod_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, int *val, + int *val2, long mask) +{ + struct iio_sd_mod_priv *priv = iio_priv(indio_dev); + + switch (mask) { + case IIO_CHAN_INFO_SCALE: + *val = priv->vref_mv; + *val2 = chan->scan_type.realbits; + return IIO_VAL_INT; + } + + return -EINVAL; +} + +static const struct iio_info iio_sd_mod_iio_info = { + .read_raw = iio_sd_mod_read_raw, }; static int iio_sd_mod_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; + struct iio_sd_mod_priv *priv; struct iio_dev *iio; + int ret; - iio = devm_iio_device_alloc(dev, 0); + iio = devm_iio_device_alloc(dev, sizeof(*priv)); if (!iio) return -ENOMEM; + iio->channels = (const struct iio_chan_spec *) + of_device_get_match_data(&pdev->dev); + + priv = iio_priv(iio); + iio->dev.parent = dev; iio->dev.of_node = dev->of_node; iio->name = dev_name(dev); iio->info = &iio_sd_mod_iio_info; iio->modes = INDIO_BUFFER_HARDWARE; - iio->num_channels = 1; - iio->channels = &iio_sd_mod_ch; platform_set_drvdata(pdev, iio); - return devm_iio_device_register(&pdev->dev, iio); + priv->vref = devm_regulator_get_optional(dev, "vref"); + if (IS_ERR(priv->vref)) { + ret = PTR_ERR(priv->vref); + if (ret != -ENODEV) { + if (ret != -EPROBE_DEFER) + dev_err(dev, "vref get failed, %d\n", ret); + return ret; + } + } + + if (!IS_ERR(priv->vref)) { + ret = regulator_enable(priv->vref); + if (ret < 0) { + dev_err(dev, "vref enable failed %d\n", ret); + return ret; + } + + ret = regulator_get_voltage(priv->vref); + if (ret < 0) { + dev_err(dev, "vref get failed, %d\n", ret); + goto err_regulator_disable; + } + + priv->vref_mv = ret / 1000; + dev_dbg(dev, "vref+=%dmV\n", priv->vref_mv); + } + + ret = devm_iio_device_register(&pdev->dev, iio); + if (ret < 0) { + dev_err(dev, "Failed to register sd-modulator, %d\n", ret); + goto err_regulator_disable; + } + + return 0; + +err_regulator_disable: + regulator_disable(priv->vref); + + return ret; +} + +static int iio_sd_mod_remove(struct platform_device *pdev) +{ + struct iio_dev *indio_dev = platform_get_drvdata(pdev); + struct iio_sd_mod_priv *priv = iio_priv(indio_dev); + + if (priv->vref) + return regulator_disable(priv->vref); + + return 0; } static const struct of_device_id sd_adc_of_match[] = { - { .compatible = "sd-modulator" }, - { .compatible = "ads1201" }, + { .compatible = "sd-modulator", .data = &iio_sd_mod_ch }, + { .compatible = "ads1201", .data = &iio_sd_mod_ch_ads }, { } }; MODULE_DEVICE_TABLE(of, sd_adc_of_match); @@ -59,6 +150,7 @@ static struct platform_driver iio_sd_mod_adc = { .of_match_table = of_match_ptr(sd_adc_of_match), }, .probe = iio_sd_mod_probe, + .remove = iio_sd_mod_remove, }; module_platform_driver(iio_sd_mod_adc);
Add scale support to sigma delta modulator. Signed-off-by: Olivier Moysan <olivier.moysan@st.com> --- drivers/iio/adc/sd_adc_modulator.c | 108 ++++++++++++++++++++++++++--- 1 file changed, 100 insertions(+), 8 deletions(-)