1 files changed, 100 insertions, 0 deletions
diff --git a/roms/skiboot/hw/fake-rtc.c b/roms/skiboot/hw/fake-rtc.c
new file mode 100644
index 000000000..3f083050c
--- /dev/null
+++ b/roms/skiboot/hw/fake-rtc.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+/* Copyright 2013-2017 IBM Corp. */
+
+#include <skiboot.h>
+#include <opal.h>
+#include <mem_region.h>
+#include <device.h>
+#include <timebase.h>
+#include <time-utils.h>
+#include <lock.h>
+
+/* timebase when tm_offset was assigned */
+static unsigned long tb_synctime;
+
+/*
+ * Absolute time that was last assigned.
+ * Current rtc value is calculated from this.
+*/
+static struct tm tm_offset;
+
+/* protects tm_offset & tb_synctime */
+static struct lock emulation_lock;
+
+static int64_t fake_rtc_write(uint32_t ymd, uint64_t hmsm)
+{
+
+	lock(&emulation_lock);
+
+	datetime_to_tm(ymd, hmsm, &tm_offset);
+	tb_synctime = mftb();
+
+	unlock(&emulation_lock);
+
+	return OPAL_SUCCESS;
+}
+
+static int64_t fake_rtc_read(__be32 *__ymd, __be64 *__hmsm)
+{
+
+	time_t sec;
+	struct tm tm_calculated;
+	uint32_t ymd;
+	uint64_t hmsm;
+
+	if (!__ymd || !__hmsm)
+		return OPAL_PARAMETER;
+
+	/* Compute the emulated clock value */
+	lock(&emulation_lock);
+
+	sec = tb_to_secs(mftb() - tb_synctime) + mktime(&tm_offset);
+	gmtime_r(&sec, &tm_calculated);
+	tm_to_datetime(&tm_calculated, &ymd, &hmsm);
+
+	unlock(&emulation_lock);
+
+	*__ymd = cpu_to_be32(ymd);
+	*__hmsm = cpu_to_be64(hmsm);
+
+	return OPAL_SUCCESS;
+}
+
+void fake_rtc_init(void)
+{
+	struct mem_region *rtc_region = NULL;
+	uint32_t *rtc = NULL, *fake_ymd;
+	uint64_t *fake_hmsm;
+	struct dt_node *np;
+
+	/* Read initial values from reserved memory */
+	rtc_region = find_mem_region("ibm,fake-rtc");
+
+	/* Should we register anyway? */
+	if (!rtc_region) {
+		prlog(PR_TRACE, "No initial RTC value found\n");
+		return;
+	}
+
+	init_lock(&emulation_lock);
+
+	/* Fetch the initial rtc values */
+	rtc = (uint32_t *) rtc_region->start;
+
+	fake_ymd = rtc;
+	fake_hmsm = ((uint64_t *) &rtc[1]);
+
+	fake_rtc_write(*fake_ymd, *fake_hmsm);
+
+	/* Register opal calls */
+	opal_register(OPAL_RTC_READ, fake_rtc_read, 2);
+	opal_register(OPAL_RTC_WRITE, fake_rtc_write, 2);
+
+	/* add the fake rtc dt node */
+	np = dt_new(opal_node, "rtc");
+	dt_add_property_strings(np, "compatible", "ibm,opal-rtc");
+
+	prlog(PR_TRACE, "Init fake RTC to Date:%d-%d-%d Time:%d-%d-%d\n",
+	      tm_offset.tm_mon, tm_offset.tm_mday, tm_offset.tm_year,
+	      tm_offset.tm_hour, tm_offset.tm_min, tm_offset.tm_sec);
+}