Add the 64-bit free running timer. Do not model the COMPARE register
(no IRQ generated).
This timer is used by Linux kernel and recently U-Boot:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/clocksource/bcm2835_timer.c?h=v3.7
https://github.com/u-boot/u-boot/blob/v2019.07/include/configs/rpi.h#L19
Datasheet used:
https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
---
v2:
- Add status/compare* registers
- Add vmstate and reset handler
checkpatch warning:
WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
This is OK because the regex are:
F: hw/*/bcm283*
F: include/hw/*/bcm283*
---
hw/timer/Makefile.objs | 1 +
hw/timer/bcm2835_systmr.c | 166 ++++++++++++++++++++++++++++++
hw/timer/trace-events | 5 +
include/hw/timer/bcm2835_systmr.h | 33 ++++++
4 files changed, 205 insertions(+)
create mode 100644 hw/timer/bcm2835_systmr.c
create mode 100644 include/hw/timer/bcm2835_systmr.h
diff --git a/hw/timer/Makefile.objs b/hw/timer/Makefile.objs
index 123d92c969..696cda5905 100644
--- a/hw/timer/Makefile.objs
+++ b/hw/timer/Makefile.objs
@@ -47,3 +47,4 @@ common-obj-$(CONFIG_SUN4V_RTC) += sun4v-rtc.o
common-obj-$(CONFIG_CMSDK_APB_TIMER) += cmsdk-apb-timer.o
common-obj-$(CONFIG_CMSDK_APB_DUALTIMER) += cmsdk-apb-dualtimer.o
common-obj-$(CONFIG_MSF2) += mss-timer.o
+common-obj-$(CONFIG_RASPI) += bcm2835_systmr.o
diff --git a/hw/timer/bcm2835_systmr.c b/hw/timer/bcm2835_systmr.c
new file mode 100644
index 0000000000..49b40b55f9
--- /dev/null
+++ b/hw/timer/bcm2835_systmr.c
@@ -0,0 +1,166 @@
+/*
+ * BCM2835 SYS timer emulation
+ *
+ * Copyright (C) 2019 Philippe Mathieu-Daudé <address@hidden>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * Datasheet: BCM2835 ARM Peripherals (C6357-M-1398)
+ * https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
+ *
+ * Only the free running 64-bit counter is implemented.
+ * The 4 COMPARE registers and the interruption are not implemented.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "qemu/timer.h"
+#include "hw/timer/bcm2835_systmr.h"
+#include "hw/registerfields.h"
+#include "migration/vmstate.h"
+#include "trace.h"
+
+REG32(CTRL_STATUS, 0x00)
+REG32(COUNTER_LOW, 0x04)
+REG32(COUNTER_HIGH, 0x08)
+REG32(COMPARE0, 0x0c)
+REG32(COMPARE1, 0x10)
+REG32(COMPARE2, 0x14)
+REG32(COMPARE3, 0x18)
+
+static void bcm2835_systmr_update_irq(BCM2835SystemTimerState *s)
+{
+ bool enable = !!s->reg.status;
+
+ trace_bcm2835_systmr_irq(enable);
+ qemu_set_irq(s->irq, enable);
+}
+
+static void bcm2835_systmr_update_compare(BCM2835SystemTimerState *s,
+ unsigned timer_index)
+{
+ /* TODO fow now, since neither Linux nor U-boot use these timers. */
+ qemu_log_mask(LOG_UNIMP, "COMPARE register %u not implemented\n",
+ timer_index);
+}
+
+static uint64_t bcm2835_systmr_read(void *opaque, hwaddr offset,
+ unsigned size)
+{
+ BCM2835SystemTimerState *s = BCM2835_SYSTIMER(opaque);
+ uint64_t r = 0;
+
+ switch (offset) {
+ case A_CTRL_STATUS:
+ r = s->reg.status;
+ break;
+ case A_COMPARE0 ... A_COMPARE3:
+ r = s->reg.compare[(offset - A_COMPARE0) >> 2];
+ break;
+ case A_COUNTER_LOW:
+ case A_COUNTER_HIGH:
+ /* Free running counter at 1MHz */
+ r = qemu_clock_get_us(QEMU_CLOCK_VIRTUAL);
+ r >>= 8 * (offset - A_COUNTER_LOW);
+ r &= UINT32_MAX;
+ break;
+ default:
+ qemu_log_mask(LOG_GUEST_ERROR, "%s: bad offset 0x%" HWADDR_PRIx "\n",
+ __func__, offset);
+ break;
+ }
+ trace_bcm2835_systmr_read(offset, r);
+
+ return r;
+}
+
+static void bcm2835_systmr_write(void *opaque, hwaddr offset,
+ uint64_t value, unsigned size)
+{
+ BCM2835SystemTimerState *s = BCM2835_SYSTIMER(opaque);
+
+ trace_bcm2835_systmr_write(offset, value);
+ switch (offset) {
+ case A_CTRL_STATUS:
+ s->reg.status &= ~value; /* Ack */
+ bcm2835_systmr_update_irq(s);
+ break;
+ case A_COMPARE0 ... A_COMPARE3:
+ s->reg.compare[(offset - A_COMPARE0) >> 2] = value;
+ bcm2835_systmr_update_compare(s, (offset - A_COMPARE0) >> 2);
+ break;
+ case A_COUNTER_LOW:
+ case A_COUNTER_HIGH:
+ qemu_log_mask(LOG_GUEST_ERROR, "%s: read-only ofs 0x%" HWADDR_PRIx
"\n",
+ __func__, offset);
+ break;
+ default:
+ qemu_log_mask(LOG_GUEST_ERROR, "%s: bad offset 0x%" HWADDR_PRIx "\n",
+ __func__, offset);
+ break;
+ }
+}
+
+static const MemoryRegionOps bcm2835_systmr_ops = {
+ .read = bcm2835_systmr_read,
+ .write = bcm2835_systmr_write,
+ .endianness = DEVICE_LITTLE_ENDIAN,
+ .impl = {
+ .min_access_size = 4,
+ .max_access_size = 4,
+ },
+};
+
+static void bcm2835_systmr_reset(DeviceState *dev)
+{
+ BCM2835SystemTimerState *s = BCM2835_SYSTIMER(dev);
+
+ s->reg.status = 0;
+ for (size_t i = 0; i < ARRAY_SIZE(s->reg.compare); i++) {
+ s->reg.compare[i] = 0;
+ }