[PATCH 10/19] hw/timer/bcm2835: Add the BCM2835 SYS_timer

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

Add the 64-bit free running timer. Do not model the COMPARE register
(no IRQ generated).
This timer is used by U-Boot and recent Linux kernels:
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 <f4bug@amsat.org>
---
Since which kernels? 4.19 seems to use it.

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         | 100 ++++++++++++++++++++++++++++++
 hw/timer/trace-events             |   4 ++
 include/hw/timer/bcm2835_systmr.h |  30 +++++++++
 4 files changed, 135 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..c4d2b488bd
--- /dev/null
+++ b/hw/timer/bcm2835_systmr.c
@@ -0,0 +1,100 @@
+/*
+ * BCM2835 SYS timer emulation
+ *
+ * Copyright (C) 2019 Philippe Mathieu-Daudé <f4bug@amsat.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 or
+ * (at your option) any later version.
+ *
+ * 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/timer.h"
+#include "qemu/log.h"
+#include "hw/registerfields.h"
+#include "hw/timer/bcm2835_systmr.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 uint64_t bcm2835_sys_timer_read(void *opaque, hwaddr offset,
+                                       unsigned size)
+{
+    uint64_t r = 0;
+
+    switch (offset) {
+    case A_CTRL_STATUS:
+    case A_COMPARE0 ... A_COMPARE3:
+        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_sys_timer_read(offset, r);
+
+    return r;
+}
+
+static void bcm2835_sys_timer_write(void *opaque, hwaddr offset,
+                                    uint64_t value, unsigned size)
+{
+    trace_bcm2835_sys_timer_write(offset, value);
+
+    qemu_log_mask(LOG_UNIMP, "%s: bad offset 0x%" HWADDR_PRIx "\n",
+                  __func__, offset);
+}
+
+static const MemoryRegionOps bcm2835_sys_timer_ops = {
+    .read = bcm2835_sys_timer_read,
+    .write = bcm2835_sys_timer_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
+};
+
+static void bcm2835_sys_timer_init(Object *obj)
+{
+    SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
+    BCM2835SysTimerState *s = BCM2835_SYSTIMER(obj);
+
+    memory_region_init_io(&s->iomem, obj, &bcm2835_sys_timer_ops,
+                          s, "bcm2835-sys-timer", 0x20);
+    sysbus_init_mmio(sbd, &s->iomem);
+    sysbus_init_irq(sbd, &s->irq);
+}
+
+static const TypeInfo bcm2835_sys_timer_info = {
+    .name = TYPE_BCM2835_SYSTIMER,
+    .parent = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(BCM2835SysTimerState),
+    .instance_init = bcm2835_sys_timer_init,
+};
+
+static void bcm2835_sys_timer_register_types(void)
+{
+    type_register_static(&bcm2835_sys_timer_info);
+}
+
+type_init(bcm2835_sys_timer_register_types);
diff --git a/hw/timer/trace-events b/hw/timer/trace-events
index db02a9142c..81967a1a19 100644
--- a/hw/timer/trace-events
+++ b/hw/timer/trace-events
@@ -87,3 +87,7 @@ pl031_read(uint32_t addr, uint32_t value) "addr 0x%08x value 0x%08x"
 pl031_write(uint32_t addr, uint32_t value) "addr 0x%08x value 0x%08x"
 pl031_alarm_raised(void) "alarm raised"
 pl031_set_alarm(uint32_t ticks) "alarm set for %u ticks"
+
+# bcm2835_systmr.c
+bcm2835_sys_timer_read(uint64_t offset, uint64_t data) "timer read: offset 0x%" PRIx64 " data 0x%" PRIx64
+bcm2835_sys_timer_write(uint64_t offset, uint64_t data) "timer write: offset 0x%" PRIx64 " data 0x%" PRIx64
diff --git a/include/hw/timer/bcm2835_systmr.h b/include/hw/timer/bcm2835_systmr.h
new file mode 100644
index 0000000000..6ac7f8ec5a
--- /dev/null
+++ b/include/hw/timer/bcm2835_systmr.h
@@ -0,0 +1,30 @@
+/*
+ * BCM2835 SYS timer emulation
+ *
+ * Copyright (c) 2019 Philippe Mathieu-Daudé <f4bug@amsat.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 or
+ *  (at your option) any later version.
+ */
+
+#ifndef BCM2835_SYSTIMER_H
+#define BCM2835_SYSTIMER_H
+
+#include "hw/sysbus.h"
+#include "hw/irq.h"
+
+#define TYPE_BCM2835_SYSTIMER "bcm2835-sys-timer"
+#define BCM2835_SYSTIMER(obj) \
+    OBJECT_CHECK(BCM2835SysTimerState, (obj), TYPE_BCM2835_SYSTIMER)
+
+typedef struct {
+    /*< private >*/
+    SysBusDevice parent_obj;
+
+    /*< public >*/
+    MemoryRegion iomem;
+    qemu_irq irq;
+} BCM2835SysTimerState;
+
+#endif
-- 
2.20.1