[Qemu-devel] [PATCH arm-devs v2 1/2] hw/timer: Introduce ARM A9 Global Timer.

[peter . crosthwaite]

From: Peter Crosthwaite <address@hidden>

The ARM A9 MPCore has a timer that is global to all CPUs in the mpcore.
The timer is shared but each CPU has a private independent comparator
and interrupt.

Based on version contributed by Francois LEGAL.

Signed-off-by: François LEGAL <address@hidden>
[PC changes:
 * New commit message
 * Re-implemented as single timer model
 * Fixed backwards counting issue in polled mode
 * completed VMSD fields
 * macroified magic numbers (and headerified reg definitions)
 * split of as device-model-only patch
 * use bitops for 64 bit register access
 * Fixed auto increment mode to check condition properly
 * general cleanup (names etc).
]
Signed-off-by: Peter Crosthwaite <address@hidden>
---
Changed since v1:
Added /*< private >*/ to struct definition.
Pulled register definitions out into a header (AF review)
SOB Francois LEGAL with PC changes indicated.

 hw/timer/Makefile.objs      |   2 +-
 hw/timer/a9gtimer.c         | 412 ++++++++++++++++++++++++++++++++++++++++++++
 include/hw/timer/a9gtimer.h |  33 ++++
 3 files changed, 446 insertions(+), 1 deletion(-)
 create mode 100644 hw/timer/a9gtimer.c
 create mode 100644 include/hw/timer/a9gtimer.h

diff --git a/hw/timer/Makefile.objs b/hw/timer/Makefile.objs
index eca5905..42d96df 100644
--- a/hw/timer/Makefile.objs
+++ b/hw/timer/Makefile.objs
@@ -1,5 +1,5 @@
 common-obj-$(CONFIG_ARM_TIMER) += arm_timer.o
-common-obj-$(CONFIG_ARM_MPTIMER) += arm_mptimer.o
+common-obj-$(CONFIG_ARM_MPTIMER) += arm_mptimer.o a9gtimer.o
 common-obj-$(CONFIG_CADENCE) += cadence_ttc.o
 common-obj-$(CONFIG_DS1338) += ds1338.o
 common-obj-$(CONFIG_HPET) += hpet.o
diff --git a/hw/timer/a9gtimer.c b/hw/timer/a9gtimer.c
new file mode 100644
index 0000000..72ebeba
--- /dev/null
+++ b/hw/timer/a9gtimer.c
@@ -0,0 +1,412 @@
+/*
+ * Global peripheral timer block for ARM A9MP
+ *
+ * (C) 2013 Xilinx Inc.
+ *
+ * Written by François LEGAL
+ * Written by Peter Crosthwaite <address@hidden>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "hw/sysbus.h"
+#include "qemu/timer.h"
+#include "qemu/bitops.h"
+#include "qemu/log.h"
+
+#include "hw/timer/a9gtimer.h"
+
+#ifndef ARM_GTIMER_ERR_DEBUG
+#define ARM_GTIMER_ERR_DEBUG 0
+#endif
+
+#define DB_PRINT_L(level, ...) do { \
+    if (ARM_GTIMER_ERR_DEBUG > (level)) { \
+        fprintf(stderr,  ": %s: ", __func__); \
+        fprintf(stderr, ## __VA_ARGS__); \
+    } \
+} while (0);
+
+#define DB_PRINT(...) DB_PRINT_L(0, ## __VA_ARGS__)
+
+#define MAX_CPUS 4
+
+typedef struct A9GlobalTimerPerCPU A9GlobalTimerPerCPU;
+typedef struct A9GlobalTimerState A9GlobalTimerState;
+
+struct A9GlobalTimerPerCPU {
+    A9GlobalTimerState *parent;
+
+    uint32_t control; /* only per cpu banked bits valid */
+    uint64_t compare;
+    uint32_t status;
+    uint32_t inc;
+
+    MemoryRegion iomem;
+    qemu_irq irq; /* PPI interrupts */
+};
+
+struct A9GlobalTimerState {
+    /*< private >*/
+    SysBusDevice parent_obj;
+    /*< public >*/
+
+    MemoryRegion iomem;
+    /* static props */
+    uint32_t num_cpu;
+
+    QEMUTimer *timer;
+
+    uint64_t counter; /* current timer value */
+
+    uint64_t ref_counter;
+    uint64_t cpu_ref_time; /* the cpu time as of last update of ref_counter */
+    uint32_t control; /* only non per cpu banked bits valid */
+
+    A9GlobalTimerPerCPU per_cpu[MAX_CPUS];
+};
+
+typedef struct A9GTimerUpdate {
+    uint64_t now;
+    uint64_t new;
+} A9GTimerUpdate;
+
+static inline int a9_gtimer_get_current_cpu(A9GlobalTimerState *s)
+{
+    if (current_cpu->cpu_index >= s->num_cpu) {
+        hw_error("arm_mptimer: num-cpu %d but this cpu is %d!\n",
+                 s->num_cpu, current_cpu->cpu_index);
+    }
+    return current_cpu->cpu_index;
+}
+
+static inline uint64_t a9_gtimer_get_conv(A9GlobalTimerState *s)
+{
+    uint64_t prescale = extract32(s->control, R_CONTROL_PRESCALER_SHIFT,
+                                  R_CONTROL_PRESCALER_LEN);
+
+    return (prescale + 1) * 100;
+}
+
+static A9GTimerUpdate a9_gtimer_get_update(A9GlobalTimerState *s)
+{
+    A9GTimerUpdate ret;
+
+    ret.now = qemu_get_clock_ns(vm_clock);
+    ret.new = s->ref_counter +
+              (ret.now - s->cpu_ref_time) / a9_gtimer_get_conv(s);
+    return ret;
+}
+
+static void a9_gtimer_update(A9GlobalTimerState *s, bool sync)
+{
+
+    A9GTimerUpdate update = a9_gtimer_get_update(s);
+    int i;
+    int64_t next_cdiff = 0;
+
+    for (i = 0; i < s->num_cpu; ++i) {
+        A9GlobalTimerPerCPU *gtb = &s->per_cpu[i];
+        int64_t cdiff = 0;
+
+        if ((s->control & R_CONTROL_TIMER_ENABLE) &&
+                (gtb->control & R_CONTROL_COMP_ENABLE)) {
+            /* R2p0+, where the compare function is > */
+            while (gtb->compare < update.new) {
+                DB_PRINT("Compare event happened for CPU %d\n", i);
+                gtb->status = 1;
+                if (gtb->control & R_CONTROL_AUTO_INCREMENT) {
+                    DB_PRINT("Auto incrementing timer compare by %" PRId32 
"\n",
+                             gtb->inc);
+                    gtb->compare += gtb->inc;
+                } else {
+                    break;
+                }
+            }
+            cdiff = (int64_t)gtb->compare - (int64_t)update.new + 1;
+            if (cdiff > 0 && (cdiff < next_cdiff || !next_cdiff)) {
+                next_cdiff = cdiff;
+            }
+        }
+
+        qemu_set_irq(gtb->irq,
+                     gtb->status && (gtb->control & R_CONTROL_IRQ_ENABLE));
+    }
+
+    qemu_del_timer(s->timer);
+    if (next_cdiff) {
+        DB_PRINT("scheduling qemu_timer to fire again in %"
+                 PRIx64 " cycles\n", next_cdiff);
+        qemu_mod_timer(s->timer,
+                       update.now + next_cdiff * a9_gtimer_get_conv(s));
+    }
+
+    if (s->control & R_CONTROL_TIMER_ENABLE) {
+        s->counter = update.new;
+    }
+
+    if (sync) {
+        s->cpu_ref_time = update.now;
+        s->ref_counter = s->counter;
+    }
+}
+
+static void a9_gtimer_update_no_sync(void *opaque)
+{
+    A9GlobalTimerState *s = ARM_GTIMER(opaque);
+
+    return a9_gtimer_update(s, false);
+}
+
+static uint64_t a9_gtimer_read(void *opaque, hwaddr addr, unsigned size)
+{
+    A9GlobalTimerPerCPU *gtb = (A9GlobalTimerPerCPU *)opaque;
+    A9GlobalTimerState *s = gtb->parent;
+    A9GTimerUpdate update;
+    uint64_t ret = 0;
+    int shift = 0;
+
+    switch (addr) {
+    case R_COUNTER_HI:
+        shift = 32;
+        /* fallthrough */
+    case R_COUNTER_LO:
+        update = a9_gtimer_get_update(s);
+        ret = extract64(update.new, shift, 32);
+        break;
+    case R_CONTROL:
+        ret = s->control | gtb->control;
+        break;
+    case R_INTERRUPT_STATUS:
+        ret = gtb->status;
+        break;
+    case R_COMPARATOR_HI:
+        shift = 32;
+        /* fallthrough */
+    case R_COMPARATOR_LO:
+        ret = extract64(gtb->compare, shift, 32);
+        break;
+    case R_AUTO_INCREMENT:
+        ret =  gtb->inc;
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "bad a9gtimer register: %x\n",
+                      (unsigned)addr);
+        return 0;
+    }
+
+    DB_PRINT("addr:%#x data:%#08" PRIx64 "\n", (unsigned)addr, ret);
+    return ret;
+}
+
+static void a9_gtimer_write(void *opaque, hwaddr addr, uint64_t value,
+                            unsigned size)
+{
+    A9GlobalTimerPerCPU *gtb = (A9GlobalTimerPerCPU *)opaque;
+    A9GlobalTimerState *s = gtb->parent;
+    int shift = 0;
+
+    DB_PRINT("addr:%#x data:%#08" PRIx64 "\n", (unsigned)addr, value);
+
+    switch (addr) {
+    case R_COUNTER_HI:
+        shift = 32;
+        /* fallthrough */
+    case R_COUNTER_LO:
+        /*
+         * Keep it simple - ARM docco explicitly says to disable timer before
+         * modding it, so dont bother trying to do all the difficult on the fly
+         * timer modifications - (if they even work in real hardware??).
+         */
+        if (s->control & R_CONTROL_TIMER_ENABLE) {
+            qemu_log_mask(LOG_GUEST_ERROR, "Cannot mod running ARM gtimer\n");
+            return;
+        }
+        s->counter = deposit64(s->counter, shift, 32, value);
+        return;
+    case R_CONTROL:
+        a9_gtimer_update(s, (value ^ s->control) & R_CONTROL_NEEDS_SYNC);
+        gtb->control = value & R_CONTROL_BANKED;
+        s->control = value & ~R_CONTROL_BANKED;
+        break;
+    case R_INTERRUPT_STATUS:
+        a9_gtimer_update(s, false);
+        gtb->status &= ~value;
+        break;
+    case R_COMPARATOR_HI:
+        shift = 32;
+        /* fallthrough */
+    case R_COMPARATOR_LO:
+        a9_gtimer_update(s, false);
+        gtb->compare = deposit64(gtb->compare, shift, 32, value);
+        break;
+    case R_AUTO_INCREMENT:
+        gtb->inc = value;
+        return;
+    default:
+        return;
+    }
+
+    a9_gtimer_update(s, false);
+}
+
+/* Wrapper functions to implement the "read global timer for
+ * the current CPU" memory regions.
+ */
+static uint64_t a9_gtimer_this_read(void *opaque, hwaddr addr,
+                                    unsigned size)
+{
+    A9GlobalTimerState *s = ARM_GTIMER(opaque);
+    int id = a9_gtimer_get_current_cpu(s);
+
+    /* no \n so concatenates with message from read fn */
+    DB_PRINT("CPU:%d:", id);
+
+    return a9_gtimer_read(&s->per_cpu[id], addr, size);
+}
+
+static void a9_gtimer_this_write(void *opaque, hwaddr addr,
+                                 uint64_t value, unsigned size)
+{
+    A9GlobalTimerState *s = ARM_GTIMER(opaque);
+    int id = a9_gtimer_get_current_cpu(s);
+
+    /* no \n so concatentates with message from write fn */
+    DB_PRINT("CPU:%d:", id);
+
+    a9_gtimer_write(&s->per_cpu[id], addr, value, size);
+}
+
+static const MemoryRegionOps a9_gtimer_this_ops = {
+    .read = a9_gtimer_this_read,
+    .write = a9_gtimer_this_write,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
+    .endianness = DEVICE_NATIVE_ENDIAN,
+};
+
+static const MemoryRegionOps a9_gtimer_ops = {
+    .read = a9_gtimer_read,
+    .write = a9_gtimer_write,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
+    .endianness = DEVICE_NATIVE_ENDIAN,
+};
+
+static void a9_gtimer_reset(DeviceState *dev)
+{
+    A9GlobalTimerState *s = ARM_GTIMER(dev);
+    int i;
+
+    s->counter = 0;
+    s->control = 0;
+
+    for (i = 0; i < s->num_cpu; i++) {
+        A9GlobalTimerPerCPU *gtb = &s->per_cpu[i];
+
+        gtb->control = 0;
+        gtb->status = 0;
+        gtb->compare = 0;
+    }
+    a9_gtimer_update(s, false);
+}
+
+static void a9_gtimer_realize(DeviceState *dev, Error **errp)
+{
+    A9GlobalTimerState *s = ARM_GTIMER(dev);
+    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
+    int i;
+
+    if (s->num_cpu < 1 || s->num_cpu > MAX_CPUS) {
+        error_setg(errp, "%s: num-cpu must be between 1 and %d\n",
+                   __func__, MAX_CPUS);
+    }
+
+    memory_region_init_io(&s->iomem, OBJECT(dev), &a9_gtimer_this_ops, s,
+                          "MMIO shared", 0x20);
+    sysbus_init_mmio(sbd, &s->iomem);
+    s->timer = qemu_new_timer_ns(vm_clock, a9_gtimer_update_no_sync, s);
+
+    for (i = 0; i < s->num_cpu; i++) {
+        A9GlobalTimerPerCPU *gtb = &s->per_cpu[i];
+
+        gtb->parent = s;
+        sysbus_init_irq(sbd, &gtb->irq);
+        memory_region_init_io(&gtb->iomem, OBJECT(dev), &a9_gtimer_ops, gtb,
+                              "MMIO per cpu", 0x20);
+        sysbus_init_mmio(sbd, &gtb->iomem);
+    }
+}
+
+static const VMStateDescription vmstate_a9_gtimer_per_cpu = {
+    .name = "arm.cortex-a9-global-timer.percpu",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(control, A9GlobalTimerPerCPU),
+        VMSTATE_UINT64(compare, A9GlobalTimerPerCPU),
+        VMSTATE_UINT32(status, A9GlobalTimerPerCPU),
+        VMSTATE_UINT32(inc, A9GlobalTimerPerCPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription vmstate_a9_gtimer = {
+    .name = "arm.cortex-a9-global-timer",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_TIMER(timer, A9GlobalTimerState),
+        VMSTATE_UINT64(counter, A9GlobalTimerState),
+        VMSTATE_UINT64(cpu_ref_time, A9GlobalTimerState),
+        VMSTATE_STRUCT_VARRAY_UINT32(per_cpu, A9GlobalTimerState, num_cpu,
+                                     1, vmstate_a9_gtimer_per_cpu,
+                                     A9GlobalTimerPerCPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static Property a9_gtimer_properties[] = {
+    DEFINE_PROP_UINT32("num-cpu", A9GlobalTimerState, num_cpu, 0),
+    DEFINE_PROP_END_OF_LIST()
+};
+
+static void a9_gtimer_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->realize = a9_gtimer_realize;
+    dc->vmsd = &vmstate_a9_gtimer;
+    dc->reset = a9_gtimer_reset;
+    dc->no_user = 1;
+    dc->props = a9_gtimer_properties;
+}
+
+static const TypeInfo a9_gtimer_info = {
+    .name          = TYPE_ARM_GTIMER,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(A9GlobalTimerState),
+    .class_init    = a9_gtimer_class_init,
+};
+
+static void a9_gtimer_register_types(void)
+{
+    type_register_static(&a9_gtimer_info);
+}
+
+type_init(a9_gtimer_register_types)
diff --git a/include/hw/timer/a9gtimer.h b/include/hw/timer/a9gtimer.h
new file mode 100644
index 0000000..f4c1499
--- /dev/null
+++ b/include/hw/timer/a9gtimer.h
@@ -0,0 +1,33 @@
+#ifndef A9GTIMER_H
+#define A9GTIMER_H
+
+#include "qom/object.h"
+
+#define TYPE_ARM_GTIMER "arm.cortex-a9-global-timer"
+#define ARM_GTIMER(obj) OBJECT_CHECK(A9GlobalTimerState, (obj), 
TYPE_ARM_GTIMER)
+
+#define R_COUNTER_LO                0x00
+#define R_COUNTER_HI                0x04
+
+#define R_CONTROL                   0x08
+#define R_CONTROL_TIMER_ENABLE      (1 << 0)
+#define R_CONTROL_COMP_ENABLE       (1 << 1)
+#define R_CONTROL_IRQ_ENABLE        (1 << 2)
+#define R_CONTROL_AUTO_INCREMENT    (1 << 2)
+#define R_CONTROL_PRESCALER_SHIFT   8
+#define R_CONTROL_PRESCALER_LEN     8
+#define R_CONTROL_PRESCALER_MASK    (((1 << R_CONTROL_PRESCALER_LEN) - 1) << \
+                                     R_CONTROL_PRESCALER_SHIFT)
+
+#define R_CONTROL_BANKED            (R_CONTROL_COMP_ENABLE | \
+                                     R_CONTROL_IRQ_ENABLE | \
+                                     R_CONTROL_AUTO_INCREMENT)
+#define R_CONTROL_NEEDS_SYNC        (R_CONTROL_TIMER_ENABLE | \
+                                     R_CONTROL_PRESCALER_MASK)
+
+#define R_INTERRUPT_STATUS          0x0C
+#define R_COMPARATOR_LO             0x10
+#define R_COMPARATOR_HI             0x14
+#define R_AUTO_INCREMENT            0x18
+
+#endif /* #ifdef A9GTIMER_H */
-- 
1.8.3.rc1.44.gb387c77.dirty