Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755404Ab3CLNp3 (ORCPT ); Tue, 12 Mar 2013 09:45:29 -0400 Received: from mail.active-venture.com ([67.228.131.205]:65210 "EHLO mail.active-venture.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752204Ab3CLNp2 (ORCPT ); Tue, 12 Mar 2013 09:45:28 -0400 X-Originating-IP: 108.223.40.66 Date: Tue, 12 Mar 2013 06:45:28 -0700 From: Guenter Roeck To: Naveen Krishna Chatradhi Cc: linux-kernel@vger.kernel.org, lm-sensors@lm-sensors.org, devicetree-discuss@lists.ozlabs.org, khali@linux-fr.org, dianders@chromium.org, naveenkrishna.ch@gmail.com Subject: Re: [PATCH v2] hwmon: ntc: Add DT with IIO support to NTC thermistor driver Message-ID: <20130312134528.GA28019@roeck-us.net> References: <1363077566-6254-1-git-send-email-ch.naveen@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1363077566-6254-1-git-send-email-ch.naveen@samsung.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 12298 Lines: 387 On Tue, Mar 12, 2013 at 02:09:26PM +0530, Naveen Krishna Chatradhi wrote: > This patch adds DT support to NTC driver to parse the > platform data. > > Also adds the support to work as an iio device. > > During the probe ntc driver gets the respective channels of ADC > and uses iio_raw_read calls to get the ADC converted value. > > Signed-off-by: Naveen Krishna Chatradhi Much better, but I still have a couple of comments. > --- > Changes since v1: > 1. Combimed all the IIO and OF/device tree changes under CONFIG_OF > 2. parse_dt function now checks for of_node and iio_channels sanity > 3. merged both the patches to single, as they cant build independently > 4. used pdev_id for proper logging and support of DT and non DT based probing > 5. Rebased on linux git tree > 6. Added documentation for device tree bindings > > Sorry, for posting a patch rebased on local working branch. > Thanks Doug, for pointing out. > .../devicetree/bindings/hwmon/ntc_thermistor.txt | 29 +++++ > drivers/hwmon/ntc_thermistor.c | 133 +++++++++++++++++--- > include/linux/platform_data/ntc_thermistor.h | 6 +- You'll still need the conditional dependency on IIO in Kconfig. Something like depends on IIO if OF if that works, or alternatively select IIO if OF if that is acceptable. > 3 files changed, 148 insertions(+), 20 deletions(-) > create mode 100644 Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt > > diff --git a/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt > new file mode 100644 > index 0000000..731a78f > --- /dev/null > +++ b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt > @@ -0,0 +1,29 @@ > +NTC Thermistor hwmon sensors > +------------------------------- > + > +Requires node properties: > +- "compatible" value : one of > + "ntc,ncp15wb473" > + "ntc,ncp18wb473" > + "ntc,ncp21wb473" > + "ntc,ncp03wb473" > + "ntc,ncp15wl333" > +- "pullup-uV" Pull up voltage in micro volts > +- "pullup-ohm" Pull up resistor value in ohms > +- "pulldown-ohm" Pull down resistor value in ohms > +- "connected-positive" Always ON, If not specified. > + Status change is possible, value (1) is assigned. > +- "io-channels" Channel node of ADC to be used for > + conversion. > + > +Read more about iio bindings at > + Documentation/devicetree/bindings/iio/iio-bindings.txt > + > +Example: > + ncp15wb473@0 { > + compatible = "ntc,ncp15wb473"; > + pullup-uV = <1800000>; Is uV (uppercase) acceptable in dt bindings ? > + pullup-ohm = <47000>; > + pulldown-ohm = <0>; > + io-channels = <&adc 3>; > + }; > diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c > index b5f63f9..81d5bdc 100644 > --- a/drivers/hwmon/ntc_thermistor.c > +++ b/drivers/hwmon/ntc_thermistor.c > @@ -26,9 +26,16 @@ > #include > #include > #include > +#include > +#include > > #include > > +#include > +#include > +#include > +#include > + > #include > #include > > @@ -37,6 +44,15 @@ struct ntc_compensation { > unsigned int ohm; > }; > > +static const struct platform_device_id ntc_thermistor_id[] = { > + { "ncp15wb473", TYPE_NCPXXWB473 }, > + { "ncp18wb473", TYPE_NCPXXWB473 }, > + { "ncp21wb473", TYPE_NCPXXWB473 }, > + { "ncp03wb473", TYPE_NCPXXWB473 }, > + { "ncp15wl333", TYPE_NCPXXWL333 }, > + { }, > +}; > + > /* > * A compensation table should be sorted by the values of .ohm > * in descending order. > @@ -125,6 +141,76 @@ struct ntc_data { > char name[PLATFORM_NAME_SIZE]; > }; > > +#ifdef CONFIG_OF > +static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata) > +{ > + struct iio_channel *channel = pdata->chan; > + unsigned int result; > + int val, ret; > + > + ret = iio_read_channel_raw(channel, &val); > + if (ret < 0) { > + pr_err("read channel() error: %d\n", ret); > + return ret; > + } > + > + /* unit: mV */ > + result = pdata->pullup_uV * (s64) val; result is int, so the s64 typecast does not provide any value. Should result be s64 to avoid overflow errors ? > + result >>= 12; > + > + return result; > +} > + > +static const struct of_device_id ntc_match[] = { > + { .compatible = "ntc,ncp15wb473", > + .data = &ntc_thermistor_id[TYPE_NCPXXWB473] }, > + { .compatible = "ntc,ncp18wb473", > + .data = &ntc_thermistor_id[TYPE_NCPXXWB473] }, > + { .compatible = "ntc,ncp21wb473", > + .data = &ntc_thermistor_id[TYPE_NCPXXWB473] }, > + { .compatible = "ntc,ncp03wb473", > + .data = &ntc_thermistor_id[TYPE_NCPXXWB473] }, > + { .compatible = "ntc,ncp15wl333", > + .data = &ntc_thermistor_id[TYPE_NCPXXWL333] }, > + { }, > +}; > +MODULE_DEVICE_TABLE(of, ntc_match); > + > +static int ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata, > + struct platform_device *pdev) Common style is to align the second line with '('. Applies everywhere. > +{ > + struct iio_channel *chan; > + struct device_node *np = pdev->dev.of_node; > + > + if (!np) > + return -ENODEV; > + > + chan = iio_channel_get(&pdev->dev, NULL); > + if (IS_ERR(chan)) > + return IS_ERR(chan); return PTR_ERR(chann); > + > + of_property_read_u32(np, "pullup-uV", &pdata->pullup_uV); > + of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm); > + of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm); > + The above properties are mandatory, so you should check the return value of of_property_read_u32() and return an error if a property is not defined. > + if (of_find_property(np, "connected-positive", NULL)) > + pdata->connect = NTC_CONNECTED_POSITIVE; > + else /* status change should be possible if not always on. */ > + pdata->connect = NTC_CONNECTED_GROUND; > + > + pdata->chan = chan; > + pdata->read_uV = ntc_adc_iio_read; > + > + return 0; > +} > +#else > +static int ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata, > + struct platform_device *pdev) > +{ > + return -ENODEV; > +} > +#endif > + > static inline u64 div64_u64_safe(u64 dividend, u64 divisor) > { > if (divisor == 0 && dividend == 0) > @@ -259,7 +345,7 @@ static int ntc_thermistor_get_ohm(struct ntc_data *data) > return data->pdata->read_ohm(); > > if (data->pdata->read_uV) { > - read_uV = data->pdata->read_uV(); > + read_uV = data->pdata->read_uV(data->pdata); > if (read_uV < 0) > return read_uV; > return get_ohm_of_thermistor(data, read_uV); > @@ -311,9 +397,22 @@ static const struct attribute_group ntc_attr_group = { > > static int ntc_thermistor_probe(struct platform_device *pdev) > { > + const struct of_device_id *of_id = > + of_match_device(of_match_ptr(ntc_match), &pdev->dev); > + const struct platform_device_id *pdev_id; > + struct ntc_thermistor_platform_data *pdata; > struct ntc_data *data; > - struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data; > - int ret = 0; > + int ret; > + > + pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); > + if (!pdata) > + return -ENOMEM; > + That allocation should really be in ntc_thermistor_parse_dt, otherwise it is wasted in the non-OF case. ntc_thermistor_parse_dt can return a pointer to it or ERR_PTR on failure or NULL in the non-OF case (or if np is NULL). Then you don't need to check for -EPROBE_DEFER but can just use pdata = ntc_thermistor_parse_dt(pdev); if (IS_ERR(pdata)) return PTR_ERR(pdata); if (pdata == NULL) pdata = pdev->dev.platform_data; This way you also catch other errors returned by iio_channel_get(). > + ret = ntc_thermistor_parse_dt(pdata, pdev); > + if (ret == -EPROBE_DEFER) > + return ret; > + else if (ret < 0) else is unnecessary here. > + pdata = pdev->dev.platform_data; > > if (!pdata) { > dev_err(&pdev->dev, "No platform init data supplied.\n"); > @@ -349,11 +448,13 @@ static int ntc_thermistor_probe(struct platform_device *pdev) > if (!data) > return -ENOMEM; > > + pdev_id = of_id ? of_id->data : platform_get_device_id(pdev); > + > data->dev = &pdev->dev; > data->pdata = pdata; > - strlcpy(data->name, pdev->id_entry->name, sizeof(data->name)); > + strncpy(data->name, pdev_id->name, sizeof(data->name)); Why strncpy instead of strlcpy ? That means there is no guarantee that data->name is 0 terminated. Not that I mind if you have a good reason for not using strlcpy, but I just don't see it. > > - switch (pdev->id_entry->driver_data) { > + switch (pdev_id->driver_data) { > case TYPE_NCPXXWB473: > data->comp = ncpXXwb473; > data->n_comp = ARRAY_SIZE(ncpXXwb473); > @@ -364,8 +465,7 @@ static int ntc_thermistor_probe(struct platform_device *pdev) > break; > default: > dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n", > - pdev->id_entry->driver_data, > - pdev->id_entry->name); > + pdev_id->driver_data, pdev_id->name); > return -EINVAL; > } > > @@ -384,39 +484,34 @@ static int ntc_thermistor_probe(struct platform_device *pdev) > goto err_after_sysfs; > } > > - dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n", > - pdev->name, pdev->id, pdev->id_entry->name, > - pdev->id_entry->driver_data); > + dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n", > + pdev->name); > + > return 0; > err_after_sysfs: > sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); > + iio_channel_release(pdata->chan); With that non-conditional, IIO would be mandatory. Also, iio_channel_release does not check if the parameter is NULL, so if it is (ie in the non-OF case) there will be a nice crash. I would suggest to add a helper function such as ntc_iio_channel_release() to be defined in the conditional OF code above. It would be an empty function for the non-OF case and otherwise call iio_channel_release(). To avoid such problems, you should try to build the driver with IIO disabled. > return ret; > } > > static int ntc_thermistor_remove(struct platform_device *pdev) > { > struct ntc_data *data = platform_get_drvdata(pdev); > + struct ntc_thermistor_platform_data *pdata = data->pdata; > > hwmon_device_unregister(data->hwmon_dev); > sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); > + iio_channel_release(pdata->chan); Same here. > platform_set_drvdata(pdev, NULL); > > return 0; > } > > -static const struct platform_device_id ntc_thermistor_id[] = { > - { "ncp15wb473", TYPE_NCPXXWB473 }, > - { "ncp18wb473", TYPE_NCPXXWB473 }, > - { "ncp21wb473", TYPE_NCPXXWB473 }, > - { "ncp03wb473", TYPE_NCPXXWB473 }, > - { "ncp15wl333", TYPE_NCPXXWL333 }, > - { }, > -}; > - > static struct platform_driver ntc_thermistor_driver = { > .driver = { > .name = "ntc-thermistor", > .owner = THIS_MODULE, > + .of_match_table = of_match_ptr(ntc_match), > }, > .probe = ntc_thermistor_probe, > .remove = ntc_thermistor_remove, > diff --git a/include/linux/platform_data/ntc_thermistor.h b/include/linux/platform_data/ntc_thermistor.h > index 88734e8..6cf5081 100644 > --- a/include/linux/platform_data/ntc_thermistor.h > +++ b/include/linux/platform_data/ntc_thermistor.h > @@ -39,13 +39,17 @@ struct ntc_thermistor_platform_data { > * described at Documentation/hwmon/ntc_thermistor > * > * pullup/down_ohm: 0 for infinite / not-connected > + * > + * chan: iio_channel pointer to communicate with the ADC which the > + * thermistor is using for conversion of the analog values. > */ > - int (*read_uV)(void); > + int (*read_uV)(struct ntc_thermistor_platform_data *); > unsigned int pullup_uV; > > unsigned int pullup_ohm; > unsigned int pulldown_ohm; > enum { NTC_CONNECTED_POSITIVE, NTC_CONNECTED_GROUND } connect; > + struct iio_channel *chan; Please specify struct iio_channel; at the beginning of the include file. > > int (*read_ohm)(void); > }; > -- > 1.7.9.5 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/