[PATCH v0 5/6] ACPI: TAD: Add RTC class device interface

["Rafael J. Wysocki" <rafael@kernel.org>]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Add an RTC class device interface allowing to read and set the real time
value and providing a procfs callback to the ACPI TAD driver.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/acpi_tad.c |   85 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 83 insertions(+), 2 deletions(-)

--- a/drivers/acpi/acpi_tad.c
+++ b/drivers/acpi/acpi_tad.c
@@ -25,6 +25,7 @@
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/rtc.h>
 #include <linux/suspend.h>
 
 MODULE_DESCRIPTION("ACPI Time and Alarm (TAD) Device Driver");
@@ -51,6 +52,7 @@ MODULE_AUTHOR("Rafael J. Wysocki");
 
 /* ACPI TAD RTC */
 #define ACPI_TAD_TZ_UNSPEC	2047
+#define ACPI_TAD_TIME_ISDST	3
 
 struct acpi_tad_driver_data {
 	u32 capabilities;
@@ -164,6 +166,8 @@ static int acpi_tad_get_real_time(struct
 	return 0;
 }
 
+/* sysfs interface */
+
 static char *acpi_tad_rt_next_field(char *s, int *val)
 {
 	char *p;
@@ -579,6 +583,77 @@ static const struct attribute_group acpi
 	.is_visible = acpi_tad_attr_is_visible,
 };
 
+/* RTC class device interface */
+
+static int acpi_tad_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct acpi_tad_rt rt;
+
+	rt.year = tm->tm_year + 1900;
+	rt.month = tm->tm_mon + 1;
+	rt.day = tm->tm_mday;
+	rt.hour = tm->tm_hour;
+	rt.minute = tm->tm_min;
+	rt.second = tm->tm_sec;
+	rt.tz = ACPI_TAD_TZ_UNSPEC;
+	rt.daylight = ACPI_TAD_TIME_ISDST * !!tm->tm_isdst;
+
+	return acpi_tad_set_real_time(dev, &rt);
+}
+
+static int acpi_tad_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct acpi_tad_rt rt;
+	int ret;
+
+	ret = acpi_tad_get_real_time(dev, &rt);
+	if (ret)
+		return ret;
+
+	tm->tm_year = rt.year - 1900;
+	tm->tm_mon = rt.month - 1;
+	tm->tm_mday = rt.day;
+	tm->tm_hour = rt.hour;
+	tm->tm_min = rt.minute;
+	tm->tm_sec = rt.second;
+	tm->tm_isdst = rt.daylight == ACPI_TAD_TIME_ISDST;
+
+	return 0;
+}
+
+static int acpi_tad_rtc_procfs(struct device *dev, struct seq_file *seq)
+{
+	struct acpi_tad_rt rt;
+	int ret;
+
+	ret = acpi_tad_get_real_time(dev, &rt);
+	if (ret)
+		return ret;
+
+	seq_printf(seq,
+		   "Time\t\t: %u:%u:%u\n"
+		   "Date\t\t: %u-%u-%u\n"
+		   "Daylight\t: %s\n",
+		   rt.hour, rt.minute, rt.second,
+		   rt.year, rt.month, rt.day,
+		   str_yes_no(rt.daylight == ACPI_TAD_TIME_ISDST));
+
+	if (rt.tz == ACPI_TAD_TZ_UNSPEC)
+		seq_puts(seq, "Timezone\t: unspecified\n");
+	else
+		seq_printf(seq, "Timezone\t: %d\n", rt.tz);
+
+	return 0;
+}
+
+static const struct rtc_class_ops acpi_tad_rtc_ops = {
+	.read_time = acpi_tad_rtc_read_time,
+	.set_time = acpi_tad_rtc_set_time,
+	.proc = acpi_tad_rtc_procfs,
+};
+
+/* Platform driver interface */
+
 static int acpi_tad_disable_timer(struct device *dev, u32 timer_id)
 {
 	return acpi_tad_wake_set(dev, "_STV", timer_id, ACPI_TAD_WAKE_DISABLED);
@@ -655,10 +730,16 @@ static int acpi_tad_probe(struct platfor
 	pm_runtime_suspend(dev);
 
 	ret = sysfs_create_group(&dev->kobj, &acpi_tad_attr_group);
-	if (ret)
+	if (ret) {
 		acpi_tad_remove(pdev);
+		return ret;
+	}
 
-	return ret;
+	if (caps & ACPI_TAD_RT)
+		devm_rtc_device_register(dev, "acpi-tad-rtc", &acpi_tad_rtc_ops,
+					 THIS_MODULE);
+
+	return 0;
 }
 
 static const struct acpi_device_id acpi_tad_ids[] = {