The implementation just allows Linux to determine date and time.
Signed-off-by: Bernhard Beschow <shen...@gmail.com>
---
MAINTAINERS | 1 +
hw/rtc/rs5c372.c | 227 ++++++++++++++++++++++++++++++++++++++++++++
hw/rtc/Kconfig | 5 +
hw/rtc/meson.build | 1 +
hw/rtc/trace-events | 4 +
5 files changed, 238 insertions(+)
create mode 100644 hw/rtc/rs5c372.c
diff --git a/MAINTAINERS b/MAINTAINERS
index ee837a3f6e..d87435adba 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -828,6 +828,7 @@ F: hw/arm/imx8mp-evk.c
F: hw/arm/fsl-imx8mp.c
F: hw/misc/imx8mp_*.c
F: hw/pci-host/fsl_imx8m_phy.c
+F: hw/rtc/rs5c372.c
F: include/hw/arm/fsl-imx8mp.h
F: include/hw/misc/imx8mp_*.h
F: include/hw/pci-host/fsl_imx8m_phy.h
diff --git a/hw/rtc/rs5c372.c b/hw/rtc/rs5c372.c
new file mode 100644
index 0000000000..d300f93e13
--- /dev/null
+++ b/hw/rtc/rs5c372.c
@@ -0,0 +1,227 @@
+/*
+ * Ricoh RS5C372, R222x I2C RTC
+ *
+ * Copyright (c) 2025 Bernhard Beschow <shen...@gmail.com>
+ *
+ * Based on hw/rtc/ds1338.c
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "hw/i2c/i2c.h"
+#include "migration/vmstate.h"
+#include "qemu/bcd.h"
+#include "qom/object.h"
+#include "system/rtc.h"
+#include "trace.h"
+
+#define NVRAM_SIZE 0x10
+
+/* Flags definitions */
+#define SECONDS_CH 0x80
+#define HOURS_PM 0x20
+#define CTRL2_24 0x20
+
+#define TYPE_RS5C372 "rs5c372"
+OBJECT_DECLARE_SIMPLE_TYPE(RS5C372State, RS5C372)
+
+struct RS5C372State {
+ I2CSlave parent_obj;
+
+ int64_t offset;
+ uint8_t wday_offset;
+ uint8_t nvram[NVRAM_SIZE];
+ uint8_t ptr;
+ uint8_t tx_format;
+ bool addr_byte;
+};
+
+static const VMStateDescription vmstate_rs5c372 = {
+ .name = "rs5c372",
+ .version_id = 1,
+ .minimum_version_id = 1,
+ .fields = (const VMStateField[]) {
+ VMSTATE_I2C_SLAVE(parent_obj, RS5C372State),
+ VMSTATE_INT64(offset, RS5C372State),
+ VMSTATE_UINT8_V(wday_offset, RS5C372State, 2),
+ VMSTATE_UINT8_ARRAY(nvram, RS5C372State, NVRAM_SIZE),
+ VMSTATE_UINT8(ptr, RS5C372State),
+ VMSTATE_UINT8(tx_format, RS5C372State),
+ VMSTATE_BOOL(addr_byte, RS5C372State),
+ VMSTATE_END_OF_LIST()
+ }
+};
+
+static void capture_current_time(RS5C372State *s)
+{
+ /*
+ * Capture the current time into the secondary registers which will be
+ * actually read by the data transfer operation.
+ */
+ struct tm now;
+ qemu_get_timedate(&now, s->offset);
+ s->nvram[0] = to_bcd(now.tm_sec);
+ s->nvram[1] = to_bcd(now.tm_min);
+ if (s->nvram[0xf] & CTRL2_24) {
+ s->nvram[2] = to_bcd(now.tm_hour);
+ } else {
+ int tmp = now.tm_hour;
+ if (tmp % 12 == 0) {
+ tmp += 12;
+ }
+ if (tmp <= 12) {
+ s->nvram[2] = to_bcd(tmp);
+ } else {
+ s->nvram[2] = HOURS_PM | to_bcd(tmp - 12);
+ }
+ }
+ s->nvram[3] = (now.tm_wday + s->wday_offset) % 7 + 1;
+ s->nvram[4] = to_bcd(now.tm_mday);
+ s->nvram[5] = to_bcd(now.tm_mon + 1);
+ s->nvram[6] = to_bcd(now.tm_year - 100);
+}
+
+static void inc_regptr(RS5C372State *s)
+{
+ s->ptr = (s->ptr + 1) & (NVRAM_SIZE - 1);
+}
+
+static int rs5c372_event(I2CSlave *i2c, enum i2c_event event)
+{
+ RS5C372State *s = RS5C372(i2c);
+
+ switch (event) {
+ case I2C_START_RECV:
+ /*
+ * In h/w, capture happens on any START condition, not just a
+ * START_RECV, but there is no need to actually capture on
+ * START_SEND, because the guest can't get at that data
+ * without going through a START_RECV which would overwrite it.
+ */
+ capture_current_time(s);
+ s->ptr = 0xf;
+ break;
+ case I2C_START_SEND:
+ s->addr_byte = true;
+ break;
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+static uint8_t rs5c372_recv(I2CSlave *i2c)
+{
+ RS5C372State *s = RS5C372(i2c);
+ uint8_t res;
+
+ res = s->nvram[s->ptr];
+
+ trace_rs5c372_recv(s->ptr, res);
+
+ inc_regptr(s);
+ return res;
+}
+
+static int rs5c372_send(I2CSlave *i2c, uint8_t data)
+{
+ RS5C372State *s = RS5C372(i2c);
+
+ if (s->addr_byte) {
+ s->ptr = data >> 4;
+ s->tx_format = data & 0xf;
+ s->addr_byte = false;
+ return 0;
+ }
+
+ trace_rs5c372_send(s->ptr, data);
+
+ if (s->ptr < 7) {
+ /* Time register. */
+ struct tm now;
+ qemu_get_timedate(&now, s->offset);
+ switch (s->ptr) {
+ case 0:
+ now.tm_sec = from_bcd(data & 0x7f);
+ break;
+ case 1:
+ now.tm_min = from_bcd(data & 0x7f);
+ break;
+ case 2:
+ if (s->nvram[0xf] & CTRL2_24) {
+ now.tm_hour = from_bcd(data & 0x3f);
+ } else {
+ int tmp = from_bcd(data & (HOURS_PM - 1));
+ if (data & HOURS_PM) {
+ tmp += 12;
+ }
+ if (tmp % 12 == 0) {
+ tmp -= 12;
+ }
+ now.tm_hour = tmp;
+ }
+ break;
+ case 3:
+ {
+ /*
+ * The day field is supposed to contain a value in the range
+ * 1-7. Otherwise behavior is undefined.
+ */
+ int user_wday = (data & 7) - 1;
+ s->wday_offset = (user_wday - now.tm_wday + 7) % 7;
+ }
+ break;
+ case 4:
+ now.tm_mday = from_bcd(data & 0x3f);
+ break;
+ case 5:
+ now.tm_mon = from_bcd(data & 0x1f) - 1;
+ break;
+ case 6:
+ now.tm_year = from_bcd(data) + 100;
+ break;
+ }
+ s->offset = qemu_timedate_diff(&now);
+ } else {
+ s->nvram[s->ptr] = data;
+ }
+ inc_regptr(s);
+ return 0;
+}
+
+static void rs5c372_reset(DeviceState *dev)
+{
+ RS5C372State *s = RS5C372(dev);
+
+ /* The clock is running and synchronized with the host */
+ s->offset = 0;
+ s->wday_offset = 0;
+ memset(s->nvram, 0, NVRAM_SIZE);
+ s->ptr = 0;
+ s->addr_byte = false;
+}
+
+static void rs5c372_class_init(ObjectClass *klass, void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(klass);
+ I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
+
+ k->event = rs5c372_event;
+ k->recv = rs5c372_recv;
+ k->send = rs5c372_send;
+ device_class_set_legacy_reset(dc, rs5c372_reset);
+ dc->vmsd = &vmstate_rs5c372;
+}
+
+static const TypeInfo rs5c372_types[] = {
+ {
+ .name = TYPE_RS5C372,
+ .parent = TYPE_I2C_SLAVE,
+ .instance_size = sizeof(RS5C372State),
+ .class_init = rs5c372_class_init,
+ },
+};
+
+DEFINE_TYPES(rs5c372_types)
diff --git a/hw/rtc/Kconfig b/hw/rtc/Kconfig
index 2fe04ec1d0..315b0e4ecc 100644
--- a/hw/rtc/Kconfig
+++ b/hw/rtc/Kconfig
@@ -26,3 +26,8 @@ config GOLDFISH_RTC
config LS7A_RTC
bool
+
+config RS5C372_RTC
+ bool
+ depends on I2C
+ default y if I2C_DEVICES
diff --git a/hw/rtc/meson.build b/hw/rtc/meson.build
index 8ecc2d792c..6c87864dc0 100644
--- a/hw/rtc/meson.build
+++ b/hw/rtc/meson.build
@@ -13,3 +13,4 @@ system_ss.add(when: 'CONFIG_GOLDFISH_RTC', if_true:
files('goldfish_rtc.c'))
system_ss.add(when: 'CONFIG_LS7A_RTC', if_true: files('ls7a_rtc.c'))
system_ss.add(when: 'CONFIG_ALLWINNER_H3', if_true: files('allwinner-rtc.c'))
system_ss.add(when: 'CONFIG_MC146818RTC', if_true: files('mc146818rtc.c'))
+system_ss.add(when: 'CONFIG_RS5C372_RTC', if_true: files('rs5c372.c'))
diff --git a/hw/rtc/trace-events b/hw/rtc/trace-events
index 8012afe102..b9f2852d35 100644
--- a/hw/rtc/trace-events
+++ b/hw/rtc/trace-events
@@ -35,3 +35,7 @@ m48txx_nvram_mem_write(uint32_t addr, uint32_t value) "mem
write addr:0x%04x val
# goldfish_rtc.c
goldfish_rtc_read(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value
0x%08" PRIx64
goldfish_rtc_write(uint64_t addr, uint64_t value) "addr 0x%02" PRIx64 " value
0x%08" PRIx64
+
+# rs5c372.c
+rs5c372_recv(uint32_t addr, uint8_t value) "[0x%" PRIx32 "] -> 0x%02" PRIx8
+rs5c372_send(uint32_t addr, uint8_t value) "[0x%" PRIx32 "] <- 0x%02" PRIx8
--
2.48.1
