From 41e484b3d6f182947adabfb738c2c27f65bda4a2 Mon Sep 17 00:00:00 2001
From: patrick <patrick@openbsd.org>
Date: Sat, 22 Jul 2023 22:48:35 +0000
Subject: [PATCH] Use the PMIC SDAM scratch-register blocks to manage the RTC
 offset instead of accessing UEFI variables through the qcscm(4) TEE
 interface.

ok kettenis@
---
 sys/dev/fdt/qcrtc.c | 25 +++++++++++++++----------
 sys/dev/fdt/qcscm.c | 10 ++++++++--
 2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/sys/dev/fdt/qcrtc.c b/sys/dev/fdt/qcrtc.c
index bc1e78dbc45..22783cd82db 100644
--- a/sys/dev/fdt/qcrtc.c
+++ b/sys/dev/fdt/qcrtc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: qcrtc.c,v 1.2 2023/01/16 20:12:38 patrick Exp $	*/
+/*	$OpenBSD: qcrtc.c,v 1.3 2023/07/22 22:48:35 patrick Exp $	*/
 /*
  * Copyright (c) 2022 Patrick Wildt <patrick@blueri.se>
  *
@@ -25,6 +25,7 @@
 #include <dev/fdt/spmivar.h>
 
 #include <dev/ofw/openfirm.h>
+#include <dev/ofw/ofw_misc.h>
 #include <dev/ofw/fdt.h>
 
 #include <dev/clock_subr.h>
@@ -114,12 +115,14 @@ qcrtc_gettime(struct todr_chip_handle *handle, struct timeval *tv)
 		return error;
 	}
 
-	/* Retrieve RTC offset stored in UEFI. */
-	if (qcscm_uefi_rtc_get(&off) != 0)
-		return EIO;
+	/* Retrieve RTC offset from either NVRAM or UEFI. */
+	error = nvmem_read_cell(sc->sc_node, "offset", &off, sizeof(off));
+	if (error == ENXIO || (!error && off == 0))
+		error = qcscm_uefi_rtc_get(&off);
+	if (error)
+		return error;
 
-	/* Add RTC counter and 10y+1w to get seconds from epoch. */
-	tv->tv_sec = off + (reg + (10 * 365 * 86400 + 7 * 86400));
+	tv->tv_sec = off + reg;
 	tv->tv_usec = 0;
 	return 0;
 }
@@ -138,9 +141,11 @@ qcrtc_settime(struct todr_chip_handle *handle, struct timeval *tv)
 		return error;
 	}
 
-	/* Subtract RTC counter and 10y+1w to get offset for UEFI. */
-	off = tv->tv_sec - (reg + (10 * 365 * 86400 + 7 * 86400));
+	/* Store RTC offset in either NVRAM or UEFI. */
+	off = tv->tv_sec - reg;
+	error = nvmem_write_cell(sc->sc_node, "offset", &off, sizeof(off));
+	if (error == ENXIO)
+		error = qcscm_uefi_rtc_set(off);
 
-	/* Store offset in UEFI. */
-	return qcscm_uefi_rtc_set(off);
+	return error;
 }
diff --git a/sys/dev/fdt/qcscm.c b/sys/dev/fdt/qcscm.c
index c5d2daa9d30..1e39742e38b 100644
--- a/sys/dev/fdt/qcscm.c
+++ b/sys/dev/fdt/qcscm.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: qcscm.c,v 1.4 2023/05/17 23:12:04 patrick Exp $ */
+/* $OpenBSD: qcscm.c,v 1.5 2023/07/22 22:48:35 patrick Exp $ */
 /*
  * Copyright (c) 2022 Patrick Wildt <patrick@blueri.se>
  *
@@ -90,6 +90,8 @@
 #define EFI_VARIABLE_BOOTSERVICE_ACCESS	0x00000002
 #define EFI_VARIABLE_RUNTIME_ACCESS	0x00000004
 
+#define UNIX_GPS_EPOCH_OFFSET		315964800
+
 struct qcscm_dmamem {
 	bus_dmamap_t		qdm_map;
 	bus_dma_segment_t	qdm_seg;
@@ -703,7 +705,8 @@ qcscm_uefi_rtc_get(uint32_t *off)
 	    &rtcinfosize) != 0)
 		return EIO;
 
-	*off = rtcinfo[0];
+	/* UEFI stores the offset based on GPS epoch */
+	*off = rtcinfo[0] + UNIX_GPS_EPOCH_OFFSET;
 	return 0;
 }
 
@@ -722,6 +725,9 @@ qcscm_uefi_rtc_set(uint32_t off)
 	    &rtcinfosize) != 0)
 		return EIO;
 
+	/* UEFI stores the offset based on GPS epoch */
+	off -= UNIX_GPS_EPOCH_OFFSET;
+
 	/* No need to set if we're not changing anything */
 	if (rtcinfo[0] == off)
 		return 0;
-- 
2.20.1