Date:	Fri, 14 Dec 2012 10:42:11 +0100
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Alexander Holler <holler@...oftware.de>
CC:	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
	Jonathan Cameron <jic23@....ac.uk>, rtc-linux@...glegroups.com,
	Alessandro Zummo <a.zummo@...ertech.it>,
	srinivas pandruvada <srinivas.pandruvada@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 4/4 v4] rtc: add rtc-driver for HID sensors of type time

On 12/12/2012 12:11 PM, Alexander Holler wrote:
> This driver makes the time from HID sensors (hubs) which are offering
> such available like any other RTC does.
> 
> Currently the time can only be read. Setting the time must be done
> through sending a report, which currently isn't supported by
> hid-sensor-hub. (I've planned to submit patches.)
> 
> It is necessary that all values like year, month etc, are send as
> 8bit values (1 byte each) and all of them in 1 report. Also the
> spec HUTRR39b doesn't define the range of the year field, we
> tread it as 0 - 99 because that's what most RTCs I know about are
> offering.
> 
> Signed-off-by: Alexander Holler <holler@...oftware.de>

Hi,

sorry for the delay. There is still the __devinit in front of
hid_time_remove left.

And another thing I've overlooked before:
wait_for_completion_interruptible_timeout can either return a positive
number when the completion was completed, 0 in case of an timeout, or a
negative error code in case it was interrupted. You need to handle all
three. E.g. something like this.

ret = wait_for_completion_interruptible_timeout(...)
if (ret == 0)
	return -EIO;
if (ret < 0)
	return ret


Otherwise it looks fine now. Maybe add a prefix to attrib_name() to avoid
potential clashes with the global namespace. E.g. hid_time_attrib_name()
Same goes for rtc_ops, hid_time_rtc_ops would be a better name.

- Lars

> ---
>  drivers/rtc/Kconfig               |   16 ++
>  drivers/rtc/Makefile              |    1 +
>  drivers/rtc/rtc-hid-sensor-time.c |  283 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 300 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/rtc/rtc-hid-sensor-time.c
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 19c03ab..e0d29b5 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -1144,4 +1144,20 @@ config RTC_DRV_SNVS
>  	   This driver can also be built as a module, if so, the module
>  	   will be called "rtc-snvs".
>  
> +comment "HID Sensor RTC drivers"
> +
> +config RTC_DRV_HID_SENSOR_TIME
> +	tristate "HID Sensor Time"
> +	depends on USB_HID
> +	select IIO
> +	select HID_SENSOR_HUB
> +	select HID_SENSOR_IIO_COMMON
> +	help
> +	  Say yes here to build support for the HID Sensors of type Time.
> +	  This drivers makes such sensors available as RTCs.
> +
> +	  If this driver is compiled as a module, it will be named
> +	  rtc-hid-sensor-time.
> +
> +
>  endif # RTC_CLASS
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 56297f0..9d1658a 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -51,6 +51,7 @@ obj-$(CONFIG_RTC_DRV_EM3027)	+= rtc-em3027.o
>  obj-$(CONFIG_RTC_DRV_EP93XX)	+= rtc-ep93xx.o
>  obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o
>  obj-$(CONFIG_RTC_DRV_GENERIC)	+= rtc-generic.o
> +obj-$(CONFIG_RTC_DRV_HID_SENSOR_TIME) += rtc-hid-sensor-time.o
>  obj-$(CONFIG_RTC_DRV_IMXDI)	+= rtc-imxdi.o
>  obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
>  obj-$(CONFIG_RTC_DRV_ISL12022)	+= rtc-isl12022.o
> diff --git a/drivers/rtc/rtc-hid-sensor-time.c b/drivers/rtc/rtc-hid-sensor-time.c
> new file mode 100644
> index 0000000..41bc011
> --- /dev/null
> +++ b/drivers/rtc/rtc-hid-sensor-time.c
> @@ -0,0 +1,283 @@
> +/*
> + * HID Sensor Time Driver
> + * Copyright (c) 2012, Alexander Holler.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program; if not, write to the Free Software Foundation, Inc.,
> + * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
> + *
> + */
> +#include <linux/device.h>
> +#include <linux/platform_device.h>
> +#include <linux/module.h>
> +#include <linux/hid-sensor-hub.h>
> +#include <linux/iio/iio.h>
> +#include <linux/rtc.h>
> +
> +/* Format: HID-SENSOR-usage_id_in_hex */
> +/* Usage ID from spec for Time: 0x2000A0 */
> +#define DRIVER_NAME "HID-SENSOR-2000a0" /* must be lowercase */
> +
> +enum hid_time_channel {
> +	CHANNEL_SCAN_INDEX_YEAR,
> +	CHANNEL_SCAN_INDEX_MONTH,
> +	CHANNEL_SCAN_INDEX_DAY,
> +	CHANNEL_SCAN_INDEX_HOUR,
> +	CHANNEL_SCAN_INDEX_MINUTE,
> +	CHANNEL_SCAN_INDEX_SECOND,
> +	TIME_RTC_CHANNEL_MAX,
> +};
> +
> +struct hid_time_state {
> +	struct hid_sensor_hub_callbacks callbacks;
> +	struct hid_sensor_iio_common common_attributes;
> +	struct hid_sensor_hub_attribute_info info[TIME_RTC_CHANNEL_MAX];
> +	struct rtc_time last_time;
> +	spinlock_t lock_last_time;
> +	struct completion comp_last_time;
> +	struct rtc_time time_buf;
> +	struct rtc_device *rtc;
> +};
> +
> +static const u32 hid_time_addresses[TIME_RTC_CHANNEL_MAX] = {
> +	HID_USAGE_SENSOR_TIME_YEAR,
> +	HID_USAGE_SENSOR_TIME_MONTH,
> +	HID_USAGE_SENSOR_TIME_DAY,
> +	HID_USAGE_SENSOR_TIME_HOUR,
> +	HID_USAGE_SENSOR_TIME_MINUTE,
> +	HID_USAGE_SENSOR_TIME_SECOND,
> +};
> +
> +/* Channel names for verbose error messages */
> +static const char * const hid_time_channel_names[TIME_RTC_CHANNEL_MAX] = {
> +	"year", "month", "day", "hour", "minute", "second",
> +};
> +
> +/* Callback handler to send event after all samples are received and captured */
> +static int hid_time_proc_event(struct hid_sensor_hub_device *hsdev,
> +				unsigned usage_id, void *priv)
> +{
> +	unsigned long flags;
> +	struct hid_time_state *time_state = platform_get_drvdata(priv);
> +
> +	spin_lock_irqsave(&time_state->lock_last_time, flags);
> +	time_state->last_time = time_state->time_buf;
> +	spin_unlock_irqrestore(&time_state->lock_last_time, flags);
> +	complete(&time_state->comp_last_time);
> +	return 0;
> +}
> +
> +static int hid_time_capture_sample(struct hid_sensor_hub_device *hsdev,
> +				unsigned usage_id, size_t raw_len,
> +				char *raw_data, void *priv)
> +{
> +	struct hid_time_state *time_state = platform_get_drvdata(priv);
> +	struct rtc_time *time_buf = &time_state->time_buf;
> +
> +	switch (usage_id) {
> +	case HID_USAGE_SENSOR_TIME_YEAR:
> +		time_buf->tm_year = *(u8 *)raw_data;
> +		if (time_buf->tm_year < 70)
> +			/* assume we are in 1970...2069 */
> +			time_buf->tm_year += 100;
> +		break;
> +	case HID_USAGE_SENSOR_TIME_MONTH:
> +		/* sensor sending the month as 1-12, we need 0-11 */
> +		time_buf->tm_mon = *(u8 *)raw_data-1;
> +		break;
> +	case HID_USAGE_SENSOR_TIME_DAY:
> +		time_buf->tm_mday = *(u8 *)raw_data;
> +		break;
> +	case HID_USAGE_SENSOR_TIME_HOUR:
> +		time_buf->tm_hour = *(u8 *)raw_data;
> +		break;
> +	case HID_USAGE_SENSOR_TIME_MINUTE:
> +		time_buf->tm_min = *(u8 *)raw_data;
> +		break;
> +	case HID_USAGE_SENSOR_TIME_SECOND:
> +		time_buf->tm_sec = *(u8 *)raw_data;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
> +/* small helper, haven't found any other way */
> +static const char *attrib_name(u32 attrib_id)
> +{
> +	static const char unknown[] = "unknown";
> +	unsigned i;
> +
> +	for (i = 0; i < TIME_RTC_CHANNEL_MAX; ++i) {
> +		if (hid_time_addresses[i] == attrib_id)
> +			return hid_time_channel_names[i];
> +	}
> +	return unknown; /* should never happen */
> +}
> +
> +static int hid_time_parse_report(struct platform_device *pdev,
> +				struct hid_sensor_hub_device *hsdev,
> +				unsigned usage_id,
> +				struct hid_time_state *time_state)
> +{
> +	int report_id, i;
> +
> +	for (i = 0; i < TIME_RTC_CHANNEL_MAX; ++i)
> +		if (sensor_hub_input_get_attribute_info(hsdev,
> +				HID_INPUT_REPORT, usage_id,
> +				hid_time_addresses[i],
> +				&time_state->info[i]) < 0)
> +			return -EINVAL;
> +	/* Check the (needed) attributes for sanity */
> +	report_id = time_state->info[0].report_id;
> +	if (report_id < 0) {
> +		dev_err(&pdev->dev, "bad report ID!\n");
> +		return -EINVAL;
> +	}
> +	for (i = 0; i < TIME_RTC_CHANNEL_MAX; ++i) {
> +		if (time_state->info[i].report_id != report_id) {
> +			dev_err(&pdev->dev,
> +				"not all needed attributes inside the same report!\n");
> +			return -EINVAL;
> +		}
> +		if (time_state->info[i].size != 1) {
> +			dev_err(&pdev->dev,
> +				"attribute '%s' not 8 bits wide!\n",
> +				attrib_name(time_state->info[i].attrib_id));
> +			return -EINVAL;
> +		}
> +		if (time_state->info[i].units !=
> +				HID_USAGE_SENSOR_UNITS_NOT_SPECIFIED &&
> +				/* allow attribute seconds with unit seconds */
> +				!(time_state->info[i].attrib_id ==
> +				HID_USAGE_SENSOR_TIME_SECOND &&
> +				time_state->info[i].units ==
> +				HID_USAGE_SENSOR_UNITS_SECOND)) {
> +			dev_err(&pdev->dev,
> +				"attribute '%s' hasn't a unit of type 'none'!\n",
> +				attrib_name(time_state->info[i].attrib_id));
> +			return -EINVAL;
> +		}
> +		if (time_state->info[i].unit_expo) {
> +			dev_err(&pdev->dev,
> +				"attribute '%s' hasn't a unit exponent of 1!\n",
> +				attrib_name(time_state->info[i].attrib_id));
> +			return -EINVAL;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int hid_rtc_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +	unsigned long flags;
> +	struct hid_time_state *time_state =
> +		platform_get_drvdata(to_platform_device(dev));
> +
> +	INIT_COMPLETION(time_state->comp_last_time);
> +	/* get a report with all values through requesting one value */
> +	sensor_hub_input_attr_get_raw_value(time_state->common_attributes.hsdev,
> +			HID_USAGE_SENSOR_TIME, hid_time_addresses[0],
> +			time_state->info[0].report_id);
> +	/* wait for all values (event) */
> +	if (!wait_for_completion_interruptible_timeout(
> +			&time_state->comp_last_time, HZ*6))
> +		return -EIO;
> +	spin_lock_irqsave(&time_state->lock_last_time, flags);
> +	*tm = time_state->last_time;
> +	spin_unlock_irqrestore(&time_state->lock_last_time, flags);
> +
> +	return 0;
> +}
> +
> +static const struct rtc_class_ops rtc_ops = {
> +	.read_time = hid_rtc_read_time,
> +};
> +
> +static int hid_time_probe(struct platform_device *pdev)
> +{
> +	int ret = 0;
> +	struct hid_sensor_hub_device *hsdev = pdev->dev.platform_data;
> +	struct hid_time_state *time_state = devm_kzalloc(&pdev->dev,
> +		sizeof(struct hid_time_state), GFP_KERNEL);
> +
> +	if (time_state == NULL)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, time_state);
> +
> +	init_completion(&time_state->comp_last_time);
> +	time_state->common_attributes.hsdev = hsdev;
> +	time_state->common_attributes.pdev = pdev;
> +
> +	ret = hid_sensor_parse_common_attributes(hsdev,
> +				HID_USAGE_SENSOR_TIME,
> +				&time_state->common_attributes);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to setup common attributes!\n");
> +		return ret;
> +	}
> +
> +	ret = hid_time_parse_report(pdev, hsdev, HID_USAGE_SENSOR_TIME,
> +					time_state);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to setup attributes!\n");
> +		return ret;
> +	}
> +
> +	time_state->callbacks.send_event = hid_time_proc_event;
> +	time_state->callbacks.capture_sample = hid_time_capture_sample;
> +	time_state->callbacks.pdev = pdev;
> +	ret = sensor_hub_register_callback(hsdev, HID_USAGE_SENSOR_TIME,
> +					&time_state->callbacks);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "register callback failed!\n");
> +		return ret;
> +	}
> +
> +	time_state->rtc = rtc_device_register("hid-sensor-time",
> +				&pdev->dev, &rtc_ops, THIS_MODULE);
> +
> +	if (IS_ERR(time_state->rtc)) {
> +		dev_err(&pdev->dev, "rtc device register failed!\n");
> +		return PTR_ERR(time_state->rtc);
> +	}
> +
> +	return ret;
> +}
> +
> +static int __devinit hid_time_remove(struct platform_device *pdev)
> +{
> +	struct hid_sensor_hub_device *hsdev = pdev->dev.platform_data;
> +	struct hid_time_state *time_state = platform_get_drvdata(pdev);
> +
> +	rtc_device_unregister(time_state->rtc);
> +	sensor_hub_remove_callback(hsdev, HID_USAGE_SENSOR_TIME);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver hid_time_platform_driver = {
> +	.driver = {
> +		.name	= DRIVER_NAME,
> +		.owner	= THIS_MODULE,
> +	},
> +	.probe		= hid_time_probe,
> +	.remove		= hid_time_remove,
> +};
> +module_platform_driver(hid_time_platform_driver);
> +
> +MODULE_DESCRIPTION("HID Sensor Time");
> +MODULE_AUTHOR("Alexander Holler <holler@...oftware.de>");
> +MODULE_LICENSE("GPL");

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