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Re: [PATCH v35 10/13] target/avr: Add limited support for USART and 16 b


From: Michael Rolnik
Subject: Re: [PATCH v35 10/13] target/avr: Add limited support for USART and 16 bit timer peripherals
Date: Thu, 5 Dec 2019 21:46:34 +0200

Ok, understood. 

On Thu, Dec 5, 2019 at 8:45 PM Aleksandar Markovic <address@hidden> wrote:


On Tuesday, October 29, 2019, Michael Rolnik <address@hidden> wrote:
From: Sarah Harris <address@hidden>

These were designed to facilitate testing but should provide enough function to be useful in other contexts.
Only a subset of the functions of each peripheral is implemented, mainly due to the lack of a standard way to handle electrical connections (like GPIO pins).

Signed-off-by: Sarah Harris <address@hidden>
---

Apart from splitting this patch into three, Michael, please move "build" patch before this patch (of course, a little modified, without bits and pieces for USART and other devices, and then gradually update all Makefiles etc., within each patch that follows, until the end of the series.

This is important in case of board/soc/device reworking, which is likely.

Thanks,
Aleksandar


 
 hw/char/Kconfig                |   3 +
 hw/char/Makefile.objs          |   1 +
 hw/char/avr_usart.c            | 324 ++++++++++++++++++
 hw/misc/Kconfig                |   3 +
 hw/misc/Makefile.objs          |   2 +
 hw/misc/avr_mask.c             | 112 ++++++
 hw/timer/Kconfig               |   3 +
 hw/timer/Makefile.objs         |   2 +
 hw/timer/avr_timer16.c         | 605 +++++++++++++++++++++++++++++++++
 include/hw/char/avr_usart.h    |  97 ++++++
 include/hw/misc/avr_mask.h     |  47 +++
 include/hw/timer/avr_timer16.h |  97 ++++++
 12 files changed, 1296 insertions(+)
 create mode 100644 hw/char/avr_usart.c
 create mode 100644 hw/misc/avr_mask.c
 create mode 100644 hw/timer/avr_timer16.c
 create mode 100644 include/hw/char/avr_usart.h
 create mode 100644 include/hw/misc/avr_mask.h
 create mode 100644 include/hw/timer/avr_timer16.h

diff --git a/hw/char/Kconfig b/hw/char/Kconfig
index 40e7a8b8bb..331b20983f 100644
--- a/hw/char/Kconfig
+++ b/hw/char/Kconfig
@@ -46,3 +46,6 @@ config SCLPCONSOLE

 config TERMINAL3270
     bool
+
+config AVR_USART
+    bool
diff --git a/hw/char/Makefile.objs b/hw/char/Makefile.objs
index 02d8a66925..f05c1f5667 100644
--- a/hw/char/Makefile.objs
+++ b/hw/char/Makefile.objs
@@ -21,6 +21,7 @@ obj-$(CONFIG_PSERIES) += spapr_vty.o
 obj-$(CONFIG_DIGIC) += digic-uart.o
 obj-$(CONFIG_STM32F2XX_USART) += stm32f2xx_usart.o
 obj-$(CONFIG_RASPI) += bcm2835_aux.o
+common-obj-$(CONFIG_AVR_USART) += avr_usart.o

 common-obj-$(CONFIG_CMSDK_APB_UART) += cmsdk-apb-uart.o
 common-obj-$(CONFIG_ETRAXFS) += etraxfs_ser.o
diff --git a/hw/char/avr_usart.c b/hw/char/avr_usart.c
new file mode 100644
index 0000000000..9ca3c2a1cd
--- /dev/null
+++ b/hw/char/avr_usart.c
@@ -0,0 +1,324 @@
+/*
+ * AVR USART
+ *
+ * Copyright (c) 2018 University of Kent
+ * Author: Sarah Harris
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/char/avr_usart.h"
+#include "qemu/log.h"
+#include "hw/irq.h"
+#include "hw/qdev-properties.h"
+
+static int avr_usart_can_receive(void *opaque)
+{
+    AVRUsartState *usart = opaque;
+
+    if (usart->data_valid || !(usart->csrb & USART_CSRB_RXEN)) {
+        return 0;
+    }
+    return 1;
+}
+
+static void avr_usart_receive(void *opaque, const uint8_t *buffer, int size)
+{
+    AVRUsartState *usart = opaque;
+    assert(size == 1);
+    assert(!usart->data_valid);
+    usart->data = ""> +    usart->data_valid = true;
+    usart->csra |= USART_CSRA_RXC;
+    if (usart->csrb & USART_CSRB_RXCIE) {
+        qemu_set_irq(usart->rxc_irq, 1);
+    }
+}
+
+static void update_char_mask(AVRUsartState *usart)
+{
+    uint8_t mode = ((usart->csrc & USART_CSRC_CSZ0) ? 1 : 0) |
+        ((usart->csrc & USART_CSRC_CSZ1) ? 2 : 0) |
+        ((usart->csrb & USART_CSRB_CSZ2) ? 4 : 0);
+    switch (mode) {
+    case 0:
+        usart->char_mask = 0b11111;
+        break;
+    case 1:
+        usart->char_mask = 0b111111;
+        break;
+    case 2:
+        usart->char_mask = 0b1111111;
+        break;
+    case 3:
+        usart->char_mask = 0b11111111;
+        break;
+    case 4:
+        /* Fallthrough. */
+    case 5:
+        /* Fallthrough. */
+    case 6:
+        qemu_log_mask(
+            LOG_GUEST_ERROR,
+            "%s: Reserved character size 0x%x\n",
+            __func__,
+            mode);
+        break;
+    case 7:
+        qemu_log_mask(
+            LOG_GUEST_ERROR,
+            "%s: Nine bit character size not supported (forcing eight)\n",
+            __func__);
+        usart->char_mask = 0b11111111;
+        break;
+    default:
+        assert(0);
+    }
+}
+
+static void avr_usart_reset(DeviceState *dev)
+{
+    AVRUsartState *usart = AVR_USART(dev);
+    usart->data_valid = false;
+    usart->csra = 0b00100000;
+    usart->csrb = 0b00000000;
+    usart->csrc = 0b00000110;
+    usart->brrl = 0;
+    usart->brrh = 0;
+    update_char_mask(usart);
+    qemu_set_irq(usart->rxc_irq, 0);
+    qemu_set_irq(usart->txc_irq, 0);
+    qemu_set_irq(usart->dre_irq, 0);
+}
+
+static uint64_t avr_usart_read(void *opaque, hwaddr addr, unsigned int size)
+{
+    AVRUsartState *usart = opaque;
+    uint8_t data;
+    assert(size == 1);
+
+    if (!usart->enabled) {
+        return 0;
+    }
+
+    switch (addr) {
+    case USART_DR:
+        if (!(usart->csrb & USART_CSRB_RXEN)) {
+            /* Receiver disabled, ignore. */
+            return 0;
+        }
+        if (usart->data_valid) {
+            data = "" & usart->char_mask;
+            usart->data_valid = false;
+        } else {
+            data = ""> +        }
+        usart->csra &= 0xff ^ USART_CSRA_RXC;
+        qemu_set_irq(usart->rxc_irq, 0);
+        qemu_chr_fe_accept_input(&usart->chr);
+        return data;
+    case USART_CSRA:
+        return usart->csra;
+    case USART_CSRB:
+        return usart->csrb;
+    case USART_CSRC:
+        return usart->csrc;
+    case USART_BRRL:
+        return usart->brrl;
+    case USART_BRRH:
+        return usart->brrh;
+    default:
+        qemu_log_mask(
+            LOG_GUEST_ERROR,
+            "%s: Bad offset 0x%"HWADDR_PRIx"\n",
+            __func__,
+            addr);
+    }
+    return 0;
+}
+
+static void avr_usart_write(void *opaque, hwaddr addr, uint64_t value,
+                                unsigned int size)
+{
+    AVRUsartState *usart = opaque;
+    uint8_t mask;
+    uint8_t data;
+    assert((value & 0xff) == value);
+    assert(size == 1);
+
+    if (!usart->enabled) {
+        return;
+    }
+
+    switch (addr) {
+    case USART_DR:
+        if (!(usart->csrb & USART_CSRB_TXEN)) {
+            /* Transmitter disabled, ignore. */
+            return;
+        }
+        usart->csra |= USART_CSRA_TXC;
+        usart->csra |= USART_CSRA_DRE;
+        if (usart->csrb & USART_CSRB_TXCIE) {
+            qemu_set_irq(usart->txc_irq, 1);
+            usart->csra &= 0xff ^ USART_CSRA_TXC;
+        }
+        if (usart->csrb & USART_CSRB_DREIE) {
+            qemu_set_irq(usart->dre_irq, 1);
+        }
+        data = ""> +        qemu_chr_fe_write_all(&usart->chr, &data, 1);
+        break;
+    case USART_CSRA:
+        mask = 0b01000011;
+        /* Mask read-only bits. */
+        value = (value & mask) | (usart->csra & (0xff ^ mask));
+        usart->csra = value;
+        if (value & USART_CSRA_TXC) {
+            usart->csra ^= USART_CSRA_TXC;
+            qemu_set_irq(usart->txc_irq, 0);
+        }
+        if (value & USART_CSRA_MPCM) {
+            qemu_log_mask(
+                LOG_GUEST_ERROR,
+                "%s: MPCM not supported by USART\n",
+                __func__);
+        }
+        break;
+    case USART_CSRB:
+        mask = 0b11111101;
+        /* Mask read-only bits. */
+        value = (value & mask) | (usart->csrb & (0xff ^ mask));
+        usart->csrb = value;
+        if (!(value & USART_CSRB_RXEN)) {
+            /* Receiver disabled, flush input buffer. */
+            usart->data_valid = false;
+        }
+        qemu_set_irq(usart->rxc_irq,
+            ((value & USART_CSRB_RXCIE) &&
+            (usart->csra & USART_CSRA_RXC)) ? 1 : 0);
+        qemu_set_irq(usart->txc_irq,
+            ((value & USART_CSRB_TXCIE) &&
+            (usart->csra & USART_CSRA_TXC)) ? 1 : 0);
+        qemu_set_irq(usart->dre_irq,
+            ((value & USART_CSRB_DREIE) &&
+            (usart->csra & USART_CSRA_DRE)) ? 1 : 0);
+        update_char_mask(usart);
+        break;
+    case USART_CSRC:
+        usart->csrc = value;
+        if ((value & USART_CSRC_MSEL1) && (value & USART_CSRC_MSEL0)) {
+            qemu_log_mask(
+                LOG_GUEST_ERROR,
+                "%s: SPI mode not supported by USART\n",
+                __func__);
+        }
+        if ((value & USART_CSRC_MSEL1) && !(value & USART_CSRC_MSEL0)) {
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad USART mode\n", __func__);
+        }
+        if (!(value & USART_CSRC_PM1) && (value & USART_CSRC_PM0)) {
+            qemu_log_mask(
+                LOG_GUEST_ERROR,
+                "%s: Bad USART parity mode\n",
+                __func__);
+        }
+        update_char_mask(usart);
+        break;
+    case USART_BRRL:
+        usart->brrl = value;
+        break;
+    case USART_BRRH:
+        usart->brrh = value & 0b00001111;
+        break;
+    default:
+        qemu_log_mask(
+            LOG_GUEST_ERROR,
+            "%s: Bad offset 0x%"HWADDR_PRIx"\n",
+            __func__,
+            addr);
+    }
+}
+
+static const MemoryRegionOps avr_usart_ops = {
+    .read = avr_usart_read,
+    .write = avr_usart_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {.min_access_size = 1, .max_access_size = 1}
+};
+
+static Property avr_usart_properties[] = {
+    DEFINE_PROP_CHR("chardev", AVRUsartState, chr),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void avr_usart_pr(void *opaque, int irq, int level)
+{
+    AVRUsartState *s = AVR_USART(opaque);
+
+    s->enabled = !level;
+
+    if (!s->enabled) {
+        avr_usart_reset(DEVICE(s));
+    }
+}
+
+static void avr_usart_init(Object *obj)
+{
+    AVRUsartState *s = AVR_USART(obj);
+    sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->rxc_irq);
+    sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->dre_irq);
+    sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->txc_irq);
+    memory_region_init_io(&s->mmio, obj, &avr_usart_ops, s, TYPE_AVR_USART, 8);
+    sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
+    qdev_init_gpio_in(DEVICE(s), avr_usart_pr, 1);
+    s->enabled = true;
+}
+
+static void avr_usart_realize(DeviceState *dev, Error **errp)
+{
+    AVRUsartState *s = AVR_USART(dev);
+    qemu_chr_fe_set_handlers(&s->chr, avr_usart_can_receive,
+                             avr_usart_receive, NULL, NULL,
+                             s, NULL, true);
+    avr_usart_reset(dev);
+}
+
+static void avr_usart_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->reset = avr_usart_reset;
+    dc->props = avr_usart_properties;
+    dc->realize = avr_usart_realize;
+}
+
+static const TypeInfo avr_usart_info = {
+    .name          = TYPE_AVR_USART,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(AVRUsartState),
+    .instance_init = avr_usart_init,
+    .class_init    = avr_usart_class_init,
+};
+
+static void avr_usart_register_types(void)
+{
+    type_register_static(&avr_usart_info);
+}
+
+type_init(avr_usart_register_types)
diff --git a/hw/misc/Kconfig b/hw/misc/Kconfig
index 2164646553..e79841e3a4 100644
--- a/hw/misc/Kconfig
+++ b/hw/misc/Kconfig
@@ -125,4 +125,7 @@ config MAC_VIA
     select MOS6522
     select ADB

+config AVR_MASK
+    bool
+
 source macio/Kconfig
diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
index ba898a5781..3a8093be6a 100644
--- a/hw/misc/Makefile.objs
+++ b/hw/misc/Makefile.objs
@@ -82,3 +82,5 @@ common-obj-$(CONFIG_NRF51_SOC) += nrf51_rng.o
 obj-$(CONFIG_MAC_VIA) += mac_via.o

 common-obj-$(CONFIG_GRLIB) += grlib_ahb_apb_pnp.o
+
+obj-$(CONFIG_AVR_MASK) += avr_mask.o
diff --git a/hw/misc/avr_mask.c b/hw/misc/avr_mask.c
new file mode 100644
index 0000000000..3af82ed9c1
--- /dev/null
+++ b/hw/misc/avr_mask.c
@@ -0,0 +1,112 @@
+/*
+ * AVR Power Reduction
+ *
+ * Copyright (c) 2019 Michael Rolnik
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/misc/avr_mask.h"
+#include "qemu/log.h"
+#include "hw/qdev-properties.h"
+#include "hw/irq.h"
+
+#define DB_PRINT(fmt, args...) /* Nothing */
+/*#define DB_PRINT(fmt, args...) printf("%s: " fmt "\n", __func__, ## args)*/
+
+static void avr_mask_reset(DeviceState *dev)
+{
+    AVRMaskState *s = AVR_MASK(dev);
+
+    s->val = 0x00;
+
+    for (int i = 0; i < 8; i++) {
+        qemu_set_irq(s->irq[i], 0);
+    }
+}
+
+static uint64_t avr_mask_read(void *opaque, hwaddr offset, unsigned size)
+{
+    assert(size == 1);
+    assert(offset == 0);
+    AVRMaskState *s = opaque;
+
+    return (uint64_t)s->val;
+}
+
+static void avr_mask_write(void *opaque, hwaddr offset,
+                              uint64_t val64, unsigned size)
+{
+    assert(size == 1);
+    assert(offset == 0);
+    AVRMaskState *s = opaque;
+    uint8_t val8 = val64;
+
+    DB_PRINT("write %d to offset %d", val8, (uint8_t)offset);
+
+    s->val = val8;
+    for (int i = 0; i < 8; i++) {
+        qemu_set_irq(s->irq[i], (val8 & (1 << i)) != 0);
+    }
+}
+
+static const MemoryRegionOps avr_mask_ops = {
+    .read = avr_mask_read,
+    .write = avr_mask_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {.max_access_size = 1}
+};
+
+static void avr_mask_init(Object *dev)
+{
+    AVRMaskState *s = AVR_MASK(dev);
+    SysBusDevice *busdev = SYS_BUS_DEVICE(dev);
+
+    memory_region_init_io(&s->iomem, dev, &avr_mask_ops, s, TYPE_AVR_MASK,
+            0x01);
+    sysbus_init_mmio(busdev, &s->iomem);
+
+    for (int i = 0; i < 8; i++) {
+        sysbus_init_irq(busdev, &s->irq[i]);
+    }
+    s->val = 0x00;
+}
+
+static void avr_mask_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->reset = avr_mask_reset;
+}
+
+static const TypeInfo avr_mask_info = {
+    .name          = TYPE_AVR_MASK,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(AVRMaskState),
+    .class_init    = avr_mask_class_init,
+    .instance_init = avr_mask_init,
+};
+
+static void avr_mask_register_types(void)
+{
+    type_register_static(&avr_mask_info);
+}
+
+type_init(avr_mask_register_types)
diff --git a/hw/timer/Kconfig b/hw/timer/Kconfig
index a990f9fe35..4343bc23f3 100644
--- a/hw/timer/Kconfig
+++ b/hw/timer/Kconfig
@@ -34,3 +34,6 @@ config CMSDK_APB_TIMER
 config CMSDK_APB_DUALTIMER
     bool
     select PTIMER
+
+config AVR_TIMER16
+    bool
diff --git a/hw/timer/Makefile.objs b/hw/timer/Makefile.objs
index dece235fd7..af0913ca3b 100644
--- a/hw/timer/Makefile.objs
+++ b/hw/timer/Makefile.objs
@@ -35,3 +35,5 @@ 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
+
+obj-$(CONFIG_AVR_TIMER16) += avr_timer16.o
diff --git a/hw/timer/avr_timer16.c b/hw/timer/avr_timer16.c
new file mode 100644
index 0000000000..ac6ef73e77
--- /dev/null
+++ b/hw/timer/avr_timer16.c
@@ -0,0 +1,605 @@
+/*
+ * AVR 16 bit timer
+ *
+ * Copyright (c) 2018 University of Kent
+ * Author: Ed Robbins
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+/*
+ * Driver for 16 bit timers on 8 bit AVR devices.
+ * Note:
+ * ATmega640/V-1280/V-1281/V-2560/V-2561/V timers 1, 3, 4 and 5 are 16 bit
+ */
+
+/*
+ * XXX TODO: Power Reduction Register support
+ *           prescaler pause support
+ *           PWM modes, GPIO, output capture pins, input compare pin
+ */
+
+#include "qemu/osdep.h"
+#include "hw/timer/avr_timer16.h"
+#include "qemu/log.h"
+#include "hw/irq.h"
+#include "hw/qdev-properties.h"
+
+/* Register offsets */
+#define T16_CRA     0x0
+#define T16_CRB     0x1
+#define T16_CRC     0x2
+#define T16_CNTL    0x4
+#define T16_CNTH    0x5
+#define T16_ICRL    0x6
+#define T16_ICRH    0x7
+#define T16_OCRAL   0x8
+#define T16_OCRAH   0x9
+#define T16_OCRBL   0xa
+#define T16_OCRBH   0xb
+#define T16_OCRCL   0xc
+#define T16_OCRCH   0xd
+
+/* Field masks */
+#define T16_CRA_WGM01   0x3
+#define T16_CRA_COMC    0xc
+#define T16_CRA_COMB    0x30
+#define T16_CRA_COMA    0xc0
+#define T16_CRA_OC_CONF \
+    (T16_CRA_COMA | T16_CRA_COMB | T16_CRA_COMC)
+
+#define T16_CRB_CS      0x7
+#define T16_CRB_WGM23   0x18
+#define T16_CRB_ICES    0x40
+#define T16_CRB_ICNC    0x80
+
+#define T16_CRC_FOCC    0x20
+#define T16_CRC_FOCB    0x40
+#define T16_CRC_FOCA    0x80
+
+/* Fields masks both TIMSK and TIFR (interrupt mask/flag registers) */
+#define T16_INT_TOV    0x1 /* Timer overflow */
+#define T16_INT_OCA    0x2 /* Output compare A */
+#define T16_INT_OCB    0x4 /* Output compare B */
+#define T16_INT_OCC    0x8 /* Output compare C */
+#define T16_INT_IC     0x20 /* Input capture */
+
+/* Clock source values */
+#define T16_CLKSRC_STOPPED     0
+#define T16_CLKSRC_DIV1        1
+#define T16_CLKSRC_DIV8        2
+#define T16_CLKSRC_DIV64       3
+#define T16_CLKSRC_DIV256      4
+#define T16_CLKSRC_DIV1024     5
+#define T16_CLKSRC_EXT_FALLING 6
+#define T16_CLKSRC_EXT_RISING  7
+
+/* Timer mode values (not including PWM modes) */
+#define T16_MODE_NORMAL     0
+#define T16_MODE_CTC_OCRA   4
+#define T16_MODE_CTC_ICR    12
+
+/* Accessors */
+#define CLKSRC(t16) (t16->crb & T16_CRB_CS)
+#define MODE(t16)   (((t16->crb & T16_CRB_WGM23) >> 1) | \
+                     (t16->cra & T16_CRA_WGM01))
+#define CNT(t16)    VAL16(t16->cntl, t16->cnth)
+#define OCRA(t16)   VAL16(t16->ocral, t16->ocrah)
+#define OCRB(t16)   VAL16(t16->ocrbl, t16->ocrbh)
+#define OCRC(t16)   VAL16(t16->ocrcl, t16->ocrch)
+#define ICR(t16)    VAL16(t16->icrl, t16->icrh)
+
+/* Helper macros */
+#define VAL16(l, h) ((h << 8) | l)
+#define ERROR(fmt, args...) \
+    qemu_log_mask(LOG_GUEST_ERROR, "%s: " fmt "\n", __func__, ## args)
+#define DB_PRINT(fmt, args...) /* Nothing */
+/*#define DB_PRINT(fmt, args...) printf("%s: " fmt "\n", __func__, ## args)*/
+
+static inline int64_t avr_timer16_ns_to_ticks(AVRTimer16State *t16, int64_t t)
+{
+    if (t16->period_ns == 0) {
+        return 0;
+    }
+    return t / t16->period_ns;
+}
+
+static void avr_timer16_update_cnt(AVRTimer16State *t16)
+{
+    uint16_t cnt;
+    cnt = avr_timer16_ns_to_ticks(t16, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) -
+                                       t16->reset_time_ns);
+    t16->cntl = (uint8_t)(cnt & 0xff);
+    t16->cnth = (uint8_t)((cnt & 0xff00) >> 8);
+}
+
+static inline void avr_timer16_recalc_reset_time(AVRTimer16State *t16)
+{
+    t16->reset_time_ns = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) -
+                         CNT(t16) * t16->period_ns;
+}
+
+static void avr_timer16_clock_reset(AVRTimer16State *t16)
+{
+    t16->cntl = 0;
+    t16->cnth = 0;
+    t16->reset_time_ns = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+}
+
+static void avr_timer16_clksrc_update(AVRTimer16State *t16)
+{
+    uint16_t divider = 0;
+    switch (CLKSRC(t16)) {
+    case T16_CLKSRC_EXT_FALLING:
+    case T16_CLKSRC_EXT_RISING:
+        ERROR("external clock source unsupported");
+        goto end;
+    case T16_CLKSRC_STOPPED:
+        goto end;
+    case T16_CLKSRC_DIV1:
+        divider = 1;
+        break;
+    case T16_CLKSRC_DIV8:
+        divider = 8;
+        break;
+    case T16_CLKSRC_DIV64:
+        divider = 64;
+        break;
+    case T16_CLKSRC_DIV256:
+        divider = 256;
+        break;
+    case T16_CLKSRC_DIV1024:
+        divider = 1024;
+        break;
+    default:
+        goto end;
+    }
+    t16->freq_hz = t16->cpu_freq_hz / divider;
+    t16->period_ns = 1000000000ULL / t16->freq_hz;
+    DB_PRINT("Timer frequency %" PRIu64 " hz, period %" PRIu64 " ns (%f s)",
+             t16->freq_hz, t16->period_ns, 1 / (double)t16->freq_hz);
+end:
+    return;
+}
+
+static void avr_timer16_set_alarm(AVRTimer16State *t16)
+{
+    if (CLKSRC(t16) == T16_CLKSRC_EXT_FALLING ||
+        CLKSRC(t16) == T16_CLKSRC_EXT_RISING ||
+        CLKSRC(t16) == T16_CLKSRC_STOPPED) {
+        /* Timer is disabled or set to external clock source (unsupported) */
+        goto end;
+    }
+
+    uint64_t alarm_offset = 0xffff;
+    enum NextInterrupt next_interrupt = OVERFLOW;
+
+    switch (MODE(t16)) {
+    case T16_MODE_NORMAL:
+        /* Normal mode */
+        if (OCRA(t16) < alarm_offset && OCRA(t16) > CNT(t16) &&
+            (t16->imsk & T16_INT_OCA)) {
+            alarm_offset = OCRA(t16);
+            next_interrupt = COMPA;
+        }
+        break;
+    case T16_MODE_CTC_OCRA:
+        /* CTC mode, top = ocra */
+        if (OCRA(t16) < alarm_offset && OCRA(t16) > CNT(t16)) {
+            alarm_offset = OCRA(t16);
+            next_interrupt = COMPA;
+        }
+       break;
+    case T16_MODE_CTC_ICR:
+        /* CTC mode, top = icr */
+        if (ICR(t16) < alarm_offset && ICR(t16) > CNT(t16)) {
+            alarm_offset = ICR(t16);
+            next_interrupt = CAPT;
+        }
+        if (OCRA(t16) < alarm_offset && OCRA(t16) > CNT(t16) &&
+            (t16->imsk & T16_INT_OCA)) {
+            alarm_offset = OCRA(t16);
+            next_interrupt = COMPA;
+        }
+        break;
+    default:
+        ERROR("pwm modes are unsupported");
+        goto end;
+    }
+    if (OCRB(t16) < alarm_offset && OCRB(t16) > CNT(t16) &&
+        (t16->imsk & T16_INT_OCB)) {
+        alarm_offset = OCRB(t16);
+        next_interrupt = COMPB;
+    }
+    if (OCRC(t16) < alarm_offset && OCRB(t16) > CNT(t16) &&
+        (t16->imsk & T16_INT_OCC)) {
+        alarm_offset = OCRB(t16);
+        next_interrupt = COMPC;
+    }
+    alarm_offset -= CNT(t16);
+
+    t16->next_interrupt = next_interrupt;
+    uint64_t alarm_ns =
+        t16->reset_time_ns + ((CNT(t16) + alarm_offset) * t16->period_ns);
+    timer_mod(t16->timer, alarm_ns);
+
+    DB_PRINT("next alarm %" PRIu64 " ns from now",
+        alarm_offset * t16->period_ns);
+
+end:
+    return;
+}
+
+static void avr_timer16_interrupt(void *opaque)
+{
+    AVRTimer16State *t16 = opaque;
+    uint8_t mode = MODE(t16);
+
+    avr_timer16_update_cnt(t16);
+
+    if (CLKSRC(t16) == T16_CLKSRC_EXT_FALLING ||
+        CLKSRC(t16) == T16_CLKSRC_EXT_RISING ||
+        CLKSRC(t16) == T16_CLKSRC_STOPPED) {
+        /* Timer is disabled or set to external clock source (unsupported) */
+        return;
+    }
+
+    DB_PRINT("interrupt, cnt = %d", CNT(t16));
+
+    /* Counter overflow */
+    if (t16->next_interrupt == OVERFLOW) {
+        DB_PRINT("0xffff overflow");
+        avr_timer16_clock_reset(t16);
+        if (t16->imsk & T16_INT_TOV) {
+            t16->ifr |= T16_INT_TOV;
+            qemu_set_irq(t16->ovf_irq, 1);
+        }
+    }
+    /* Check for ocra overflow in CTC mode */
+    if (mode == T16_MODE_CTC_OCRA && t16->next_interrupt == COMPA) {
+        DB_PRINT("CTC OCRA overflow");
+        avr_timer16_clock_reset(t16);
+    }
+    /* Check for icr overflow in CTC mode */
+    if (mode == T16_MODE_CTC_ICR && t16->next_interrupt == CAPT) {
+        DB_PRINT("CTC ICR overflow");--
2.17.2 (Apple Git-113)



--
Best Regards,
Michael Rolnik

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