hw/arm/digic: add UART support

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 1387188908-754-5-git-send-email-antonynpavlov@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 195 insertions, 0 deletions

diff --git a/hw/char/digic-uart.c b/hw/char/digic-uart.c
new file mode 100644
index 0000000000..fd8e07713d
--- /dev/null
+++ b/hw/char/digic-uart.c
@@ -0,0 +1,195 @@
+/*
+ * QEMU model of the Canon DIGIC UART block.
+ *
+ * Copyright (C) 2013 Antony Pavlov <antonynpavlov@gmail.com>
+ *
+ * This model is based on reverse engineering efforts
+ * made by CHDK (http://chdk.wikia.com) and
+ * Magic Lantern (http://www.magiclantern.fm) projects
+ * contributors.
+ *
+ * See "Serial terminal" docs here:
+ *   http://magiclantern.wikia.com/wiki/Register_Map#Misc_Registers
+ *
+ * The QEMU model of the Milkymist UART block by Michael Walle
+ * is used as a template.
+ *
+ * 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.
+ *
+ */
+
+#include "hw/hw.h"
+#include "hw/sysbus.h"
+#include "sysemu/char.h"
+
+#include "hw/char/digic-uart.h"
+
+enum {
+    ST_RX_RDY = (1 << 0),
+    ST_TX_RDY = (1 << 1),
+};
+
+static uint64_t digic_uart_read(void *opaque, hwaddr addr,
+                                unsigned size)
+{
+    DigicUartState *s = opaque;
+    uint64_t ret = 0;
+
+    addr >>= 2;
+
+    switch (addr) {
+    case R_RX:
+        s->reg_st &= ~(ST_RX_RDY);
+        ret = s->reg_rx;
+        break;
+
+    case R_ST:
+        ret = s->reg_st;
+        break;
+
+    default:
+        qemu_log_mask(LOG_UNIMP,
+                      "digic-uart: read access to unknown register 0x"
+                      TARGET_FMT_plx, addr << 2);
+    }
+
+    return ret;
+}
+
+static void digic_uart_write(void *opaque, hwaddr addr, uint64_t value,
+                             unsigned size)
+{
+    DigicUartState *s = opaque;
+    unsigned char ch = value;
+
+    addr >>= 2;
+
+    switch (addr) {
+    case R_TX:
+        if (s->chr) {
+            qemu_chr_fe_write_all(s->chr, &ch, 1);
+        }
+        break;
+
+    case R_ST:
+        /*
+         * Ignore write to R_ST.
+         *
+         * The point is that this register is actively used
+         * during receiving and transmitting symbols,
+         * but we don't know the function of most of bits.
+         *
+         * Ignoring writes to R_ST is only a simplification
+         * of the model. It has no perceptible side effects
+         * for existing guests.
+         */
+        break;
+
+    default:
+        qemu_log_mask(LOG_UNIMP,
+                      "digic-uart: write access to unknown register 0x"
+                      TARGET_FMT_plx, addr << 2);
+    }
+}
+
+static const MemoryRegionOps uart_mmio_ops = {
+    .read = digic_uart_read,
+    .write = digic_uart_write,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
+    .endianness = DEVICE_NATIVE_ENDIAN,
+};
+
+static int uart_can_rx(void *opaque)
+{
+    DigicUartState *s = opaque;
+
+    return !(s->reg_st & ST_RX_RDY);
+}
+
+static void uart_rx(void *opaque, const uint8_t *buf, int size)
+{
+    DigicUartState *s = opaque;
+
+    assert(uart_can_rx(opaque));
+
+    s->reg_st |= ST_RX_RDY;
+    s->reg_rx = *buf;
+}
+
+static void uart_event(void *opaque, int event)
+{
+}
+
+static void digic_uart_reset(DeviceState *d)
+{
+    DigicUartState *s = DIGIC_UART(d);
+
+    s->reg_rx = 0;
+    s->reg_st = ST_TX_RDY;
+}
+
+static void digic_uart_realize(DeviceState *dev, Error **errp)
+{
+    DigicUartState *s = DIGIC_UART(dev);
+
+    s->chr = qemu_char_get_next_serial();
+    if (s->chr) {
+        qemu_chr_add_handlers(s->chr, uart_can_rx, uart_rx, uart_event, s);
+    }
+}
+
+static void digic_uart_init(Object *obj)
+{
+    DigicUartState *s = DIGIC_UART(obj);
+
+    memory_region_init_io(&s->regs_region, OBJECT(s), &uart_mmio_ops, s,
+                          TYPE_DIGIC_UART, 0x18);
+    sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->regs_region);
+}
+
+static const VMStateDescription vmstate_digic_uart = {
+    .name = "digic-uart",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(reg_rx, DigicUartState),
+        VMSTATE_UINT32(reg_st, DigicUartState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void digic_uart_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->realize = digic_uart_realize;
+    dc->reset = digic_uart_reset;
+    dc->vmsd = &vmstate_digic_uart;
+}
+
+static const TypeInfo digic_uart_info = {
+    .name = TYPE_DIGIC_UART,
+    .parent = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(DigicUartState),
+    .instance_init = digic_uart_init,
+    .class_init = digic_uart_class_init,
+};
+
+static void digic_uart_register_types(void)
+{
+    type_register_static(&digic_uart_info);
+}
+
+type_init(digic_uart_register_types)