rtc: add rtc-driver for HID sensors of type time

This driver makes the time from HID sensors (hubs) which are offering
such available like any other RTC does.

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.

Currently the time can only be read. Setting the time must be done
through sending a report (or a feature). The spec currently doesn't
define how and I'm not sure if I just should define something by myself.

Signed-off-by: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 308 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index d0cea02b5dfc..eed335c16cb0 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1165,4 +1165,20 @@ 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 c3f62c80dc06..63be277d9ff6 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -52,6 +52,7 @@ 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 000000000000..25cac6ec374d
--- /dev/null
+++ b/drivers/rtc/rtc-hid-sensor-time.c
@@ -0,0 +1,291 @@
+/*
+ * 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 *hid_time_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",
+                                hid_time_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",
+                                hid_time_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",
+                                hid_time_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));
+        int ret;
+
+        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) */
+        ret = wait_for_completion_killable_timeout(
+                        &time_state->comp_last_time, HZ*6);
+        if (ret > 0) {
+                /* no error */
+                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;
+        }
+        if (!ret)
+                return -EIO; /* timeouted */
+        return ret; /* killed (-ERESTARTSYS) */
+}
+
+static const struct rtc_class_ops hid_time_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, &hid_time_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 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@ahsoftware.de>");
+MODULE_LICENSE("GPL");