From 101ca8d05913b7d1e6e8b9dd792193d4082fff86 Mon Sep 17 00:00:00 2001
From: Shanker Donthineni <sdonthineni@nvidia.com>
Date: Mon, 2 Jan 2023 17:06:30 -0600
Subject: [PATCH] rtc: efi: Enable SET/GET WAKEUP services as optional
Git-commit: 101ca8d05913b7d1e6e8b9dd792193d4082fff86
Patch-mainline: v6.2-rc7
References: bsc#1213116

[ backport note: the patch slightly modified, only clearing
  RTC_FEATURE_ALARM feature bit, and skip RTC_FEATURE_ALARM_WAKEUP_ONLY
  bit, as the latter isn't defined in SLE15-SP5.
  Also, rtc->uie_unsupported setup is kept as is. -- tiwai ]

The current implementation of rtc-efi is expecting all the 4
time services GET{SET}_TIME{WAKEUP} must be supported by UEFI
firmware. As per the EFI_RT_PROPERTIES_TABLE, the platform
specific implementations can choose to enable selective time
services based on the RTC device capabilities.

This patch does the following changes to provide GET/SET RTC
services on platforms that do not support the WAKEUP feature.

1) Relax time services cap check when creating a platform device.
2) Clear RTC_FEATURE_ALARM bit in the absence of WAKEUP services.
3) Conditional alarm entries in '/proc/driver/rtc'.

Cc: <stable@vger.kernel.org> # v6.0+
Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com>
Link: https://lore.kernel.org/r/20230102230630.192911-1-sdonthineni@nvidia.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/rtc/rtc-efi.c |   45 +++++++++++++++++++++++++--------------------
 include/linux/efi.h   |    3 ++-
 2 files changed, 27 insertions(+), 21 deletions(-)

--- a/drivers/rtc/rtc-efi.c
+++ b/drivers/rtc/rtc-efi.c
@@ -188,9 +188,10 @@ static int efi_set_time(struct device *d
 
 static int efi_procfs(struct device *dev, struct seq_file *seq)
 {
-	efi_time_t      eft, alm;
-	efi_time_cap_t  cap;
-	efi_bool_t      enabled, pending;
+	efi_time_t        eft, alm;
+	efi_time_cap_t    cap;
+	efi_bool_t        enabled, pending;
+	struct rtc_device *rtc = dev_get_drvdata(dev);
 
 	memset(&eft, 0, sizeof(eft));
 	memset(&alm, 0, sizeof(alm));
@@ -213,23 +214,25 @@ static int efi_procfs(struct device *dev
 		/* XXX fixme: convert to string? */
 		seq_printf(seq, "Timezone\t: %u\n", eft.timezone);
 
-	seq_printf(seq,
-		   "Alarm Time\t: %u:%u:%u.%09u\n"
-		   "Alarm Date\t: %u-%u-%u\n"
-		   "Alarm Daylight\t: %u\n"
-		   "Enabled\t\t: %s\n"
-		   "Pending\t\t: %s\n",
-		   alm.hour, alm.minute, alm.second, alm.nanosecond,
-		   alm.year, alm.month, alm.day,
-		   alm.daylight,
-		   enabled == 1 ? "yes" : "no",
-		   pending == 1 ? "yes" : "no");
-
-	if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
-		seq_puts(seq, "Timezone\t: unspecified\n");
-	else
-		/* XXX fixme: convert to string? */
-		seq_printf(seq, "Timezone\t: %u\n", alm.timezone);
+	if (test_bit(RTC_FEATURE_ALARM, rtc->features)) {
+		seq_printf(seq,
+			   "Alarm Time\t: %u:%u:%u.%09u\n"
+			   "Alarm Date\t: %u-%u-%u\n"
+			   "Alarm Daylight\t: %u\n"
+			   "Enabled\t\t: %s\n"
+			   "Pending\t\t: %s\n",
+			   alm.hour, alm.minute, alm.second, alm.nanosecond,
+			   alm.year, alm.month, alm.day,
+			   alm.daylight,
+			   enabled == 1 ? "yes" : "no",
+			   pending == 1 ? "yes" : "no");
+
+		if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
+			seq_puts(seq, "Timezone\t: unspecified\n");
+		else
+			/* XXX fixme: convert to string? */
+			seq_printf(seq, "Timezone\t: %u\n", alm.timezone);
+	}
 
 	/*
 	 * now prints the capabilities
@@ -269,6 +272,8 @@ static int __init efi_rtc_probe(struct p
 
 	rtc->ops = &efi_rtc_ops;
 	rtc->uie_unsupported = 1;
+	if (!efi_rt_services_supported(EFI_RT_SUPPORTED_WAKEUP_SERVICES))
+		clear_bit(RTC_FEATURE_ALARM, rtc->features);
 
 	device_init_wakeup(&dev->dev, true);
 
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -651,7 +651,8 @@ extern struct efi {
 
 #define EFI_RT_SUPPORTED_ALL					0x3fff
 
-#define EFI_RT_SUPPORTED_TIME_SERVICES				0x000f
+#define EFI_RT_SUPPORTED_TIME_SERVICES				0x0003
+#define EFI_RT_SUPPORTED_WAKEUP_SERVICES			0x000c
 #define EFI_RT_SUPPORTED_VARIABLE_SERVICES			0x0070
 
 extern struct mm_struct efi_mm;