fsl-imx: add simple RTC emulation for i.MX6 and i.MX7 boards

Signed-off-by: Nikita Ostrenkov <n.ostrenkov@gmail.com>
Message-id: 20231216133408.2884-1-n.ostrenkov@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/misc/imx7_snvs.c

@@ -13,29 +13,101 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/bitops.h"
+#include "qemu/timer.h"
+#include "migration/vmstate.h"
 #include "hw/misc/imx7_snvs.h"
+#include "qemu/cutils.h"
 #include "qemu/module.h"
+#include "sysemu/sysemu.h"
+#include "sysemu/rtc.h"
 #include "sysemu/runstate.h"
 #include "trace.h"
 
+#define RTC_FREQ    32768ULL
+
+static const VMStateDescription vmstate_imx7_snvs = {
+    .name = TYPE_IMX7_SNVS,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(tick_offset, IMX7SNVSState),
+        VMSTATE_UINT64(lpcr, IMX7SNVSState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static uint64_t imx7_snvs_get_count(IMX7SNVSState *s)
+{
+    uint64_t ticks = muldiv64(qemu_clock_get_ns(rtc_clock), RTC_FREQ,
+                              NANOSECONDS_PER_SECOND);
+    return s->tick_offset + ticks;
+}
+
 static uint64_t imx7_snvs_read(void *opaque, hwaddr offset, unsigned size)
 {
-    trace_imx7_snvs_read(offset, 0);
+    IMX7SNVSState *s = IMX7_SNVS(opaque);
+    uint64_t ret = 0;
 
-    return 0;
+    switch (offset) {
+    case SNVS_LPSRTCMR:
+        ret = extract64(imx7_snvs_get_count(s), 32, 15);
+        break;
+    case SNVS_LPSRTCLR:
+        ret = extract64(imx7_snvs_get_count(s), 0, 32);
+        break;
+    case SNVS_LPCR:
+        ret = s->lpcr;
+        break;
+    }
+
+    trace_imx7_snvs_read(offset, ret, size);
+
+    return ret;
+}
+
+static void imx7_snvs_reset(DeviceState *dev)
+{
+    IMX7SNVSState *s = IMX7_SNVS(dev);
+
+    s->lpcr = 0;
 }
 
 static void imx7_snvs_write(void *opaque, hwaddr offset,
                             uint64_t v, unsigned size)
 {
-    const uint32_t value = v;
+    trace_imx7_snvs_write(offset, v, size);
+
+    IMX7SNVSState *s = IMX7_SNVS(opaque);
+
+    uint64_t new_value = 0, snvs_count = 0;
+
+    if (offset == SNVS_LPSRTCMR || offset == SNVS_LPSRTCLR) {
+        snvs_count = imx7_snvs_get_count(s);
+    }
+
+    switch (offset) {
+    case SNVS_LPSRTCMR:
+        new_value = deposit64(snvs_count, 32, 32, v);
+        break;
+    case SNVS_LPSRTCLR:
+        new_value = deposit64(snvs_count, 0, 32, v);
+        break;
+    case SNVS_LPCR: {
+        s->lpcr = v;
+
         const uint32_t mask  = SNVS_LPCR_TOP | SNVS_LPCR_DP_EN;
 
-    trace_imx7_snvs_write(offset, value);
-
-    if (offset == SNVS_LPCR && ((value & mask) == mask)) {
+        if ((v & mask) == mask) {
             qemu_system_shutdown_request(SHUTDOWN_CAUSE_GUEST_SHUTDOWN);
         }
+        break;
+    }
+    }
+
+    if (offset == SNVS_LPSRTCMR || offset == SNVS_LPSRTCLR) {
+        s->tick_offset += new_value - snvs_count;
+    }
 }
 
 static const struct MemoryRegionOps imx7_snvs_ops = {
@@ -59,17 +131,24 @@ static void imx7_snvs_init(Object *obj)
 {
     SysBusDevice *sd = SYS_BUS_DEVICE(obj);
     IMX7SNVSState *s = IMX7_SNVS(obj);
+    struct tm tm;
 
     memory_region_init_io(&s->mmio, obj, &imx7_snvs_ops, s,
                           TYPE_IMX7_SNVS, 0x1000);
 
     sysbus_init_mmio(sd, &s->mmio);
+
+    qemu_get_timedate(&tm, 0);
+    s->tick_offset = mktimegm(&tm) -
+        qemu_clock_get_ns(rtc_clock) / NANOSECONDS_PER_SECOND;
 }
 
 static void imx7_snvs_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
 
+    dc->reset = imx7_snvs_reset;
+    dc->vmsd = &vmstate_imx7_snvs;
     dc->desc  = "i.MX7 Secure Non-Volatile Storage Module";
 }
 

hw/misc/trace-events

@@ -116,8 +116,8 @@ imx7_gpr_read(uint64_t offset) "addr 0x%08" PRIx64
 imx7_gpr_write(uint64_t offset, uint64_t value) "addr 0x%08" PRIx64 "value 0x%08" PRIx64
 
 # imx7_snvs.c
-imx7_snvs_read(uint64_t offset, uint32_t value) "addr 0x%08" PRIx64 "value 0x%08" PRIx32
-imx7_snvs_write(uint64_t offset, uint32_t value) "addr 0x%08" PRIx64 "value 0x%08" PRIx32
+imx7_snvs_read(uint64_t offset, uint64_t value, unsigned size) "i.MX SNVS read: offset 0x%08" PRIx64 " value 0x%08" PRIx64 " size %u"
+imx7_snvs_write(uint64_t offset, uint64_t value, unsigned size) "i.MX SNVS write: offset 0x%08" PRIx64 " value 0x%08" PRIx64 " size %u"
 
 # mos6522.c
 mos6522_set_counter(int index, unsigned int val) "T%d.counter=%d"

include/hw/misc/imx7_snvs.h

@@ -20,7 +20,9 @@
 enum IMX7SNVSRegisters {
     SNVS_LPCR = 0x38,
     SNVS_LPCR_TOP   = BIT(6),
-    SNVS_LPCR_DP_EN = BIT(5)
+    SNVS_LPCR_DP_EN = BIT(5),
+    SNVS_LPSRTCMR = 0x050, /* Secure Real Time Counter MSB Register */
+    SNVS_LPSRTCLR = 0x054, /* Secure Real Time Counter LSB Register */
 };
 
 #define TYPE_IMX7_SNVS "imx7.snvs"
@@ -31,6 +33,9 @@ struct IMX7SNVSState {
     SysBusDevice parent_obj;
 
     MemoryRegion mmio;
+
+    uint64_t tick_offset;
+    uint64_t lpcr;
 };
 
 #endif /* IMX7_SNVS_H */