m68k: Instantiate the ESP SCSI controller for the NeXTcube machine

The NeXTcube uses a NCR 53C90 SCSI interface for its disks, so we should
be able to use the ESP controller from QEMU here. The code here has been
basically taken from Bryce Lanham's GSoC 2011 contribution, except for
the next_scsi_init() function which has been rewritte as a replacement
for the esp_init() function (that has been removed quite a while ago).

Note that SCSI is not working yet. The ESP code likely needs some more
fixes first and there still might be some bugs left in they way we wire
it up for the NeXT-Cube machine.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-ID: <20230930132351.30282-4-huth@tuxfamily.org>
Signed-off-by: Thomas Huth <huth@tuxfamily.org>

Author: huth

hw/m68k/next-cube.c

@@ -90,10 +90,13 @@ struct NeXTPC {
 
     uint32_t scr1;
     uint32_t scr2;
-    uint8_t scsi_csr_1;
-    uint8_t scsi_csr_2;
     uint32_t int_mask;
     uint32_t int_status;
+    uint8_t scsi_csr_1;
+    uint8_t scsi_csr_2;
+
+    qemu_irq scsi_reset;
+    qemu_irq scsi_dma;
 
     NextRtc rtc;
 };
@@ -466,7 +469,7 @@ static void scr_writeb(NeXTPC *s, hwaddr addr, uint32_t value)
             DPRINTF("SCSICSR FIFO Flush\n");
             /* will have to add another irq to the esp if this is needed */
             /* esp_puflush_fifo(esp_g); */
-            /* qemu_irq_pulse(s->scsi_dma); */
+            qemu_irq_pulse(s->scsi_dma);
         }
 
         if (value & SCSICSR_ENABLE) {
@@ -486,20 +489,21 @@ static void scr_writeb(NeXTPC *s, hwaddr addr, uint32_t value)
         if (value & SCSICSR_RESET) {
             DPRINTF("SCSICSR Reset\n");
             /* I think this should set DMADIR. CPUDMA and INTMASK to 0 */
-            /* qemu_irq_raise(s->scsi_reset); */
-            /* s->scsi_csr_1 &= ~(SCSICSR_INTMASK |0x80|0x1); */
-
+            qemu_irq_raise(s->scsi_reset);
+            s->scsi_csr_1 &= ~(SCSICSR_INTMASK | 0x80 | 0x1);
+            qemu_irq_lower(s->scsi_reset);
         }
         if (value & SCSICSR_DMADIR) {
             DPRINTF("SCSICSR DMAdir\n");
         }
         if (value & SCSICSR_CPUDMA) {
             DPRINTF("SCSICSR CPUDMA\n");
             /* qemu_irq_raise(s->scsi_dma); */
-
             s->int_status |= 0x4000000;
         } else {
+            /* fprintf(stderr,"SCSICSR CPUDMA disabled\n"); */
             s->int_status &= ~(0x4000000);
+            /* qemu_irq_lower(s->scsi_dma); */
         }
         if (value & SCSICSR_INTMASK) {
             DPRINTF("SCSICSR INTMASK\n");
@@ -828,6 +832,103 @@ static void next_irq(void *opaque, int number, int level)
     }
 }
 
+static void nextdma_write(void *opaque, uint8_t *buf, int size, int type)
+{
+    uint32_t base_addr;
+    int irq = 0;
+    uint8_t align = 16;
+    NeXTState *next_state = NEXT_MACHINE(qdev_get_machine());
+
+    if (type == NEXTDMA_ENRX || type == NEXTDMA_ENTX) {
+        align = 32;
+    }
+    /* Most DMA is supposedly 16 byte aligned */
+    if ((size % align) != 0) {
+        size -= size % align;
+        size += align;
+    }
+
+    /*
+     * prom sets the dma start using initbuf while the bootloader uses next
+     * so we check to see if initbuf is 0
+     */
+    if (next_state->dma[type].next_initbuf == 0) {
+        base_addr = next_state->dma[type].next;
+    } else {
+        base_addr = next_state->dma[type].next_initbuf;
+    }
+
+    cpu_physical_memory_write(base_addr, buf, size);
+
+    next_state->dma[type].next_initbuf = 0;
+
+    /* saved limit is checked to calculate packet size by both, rom and netbsd */
+    next_state->dma[type].saved_limit = (next_state->dma[type].next + size);
+    next_state->dma[type].saved_next  = (next_state->dma[type].next);
+
+    /*
+     * 32 bytes under savedbase seems to be some kind of register
+     * of which the purpose is unknown as of yet
+     */
+    /* stl_phys(s->rx_dma.base-32,0xFFFFFFFF); */
+
+    if (!(next_state->dma[type].csr & DMA_SUPDATE)) {
+        next_state->dma[type].next  = next_state->dma[type].start;
+        next_state->dma[type].limit = next_state->dma[type].stop;
+    }
+
+    /* Set dma registers and raise an irq */
+    next_state->dma[type].csr |= DMA_COMPLETE; /* DON'T CHANGE THIS! */
+
+    switch (type) {
+    case NEXTDMA_SCSI:
+        irq = NEXT_SCSI_DMA_I;
+        break;
+    }
+
+    next_irq(opaque, irq, 1);
+    next_irq(opaque, irq, 0);
+}
+
+static void nextscsi_read(void *opaque, uint8_t *buf, int len)
+{
+    DPRINTF("SCSI READ: %x\n", len);
+    abort();
+}
+
+static void nextscsi_write(void *opaque, uint8_t *buf, int size)
+{
+    DPRINTF("SCSI WRITE: %i\n", size);
+    nextdma_write(opaque, buf, size, NEXTDMA_SCSI);
+}
+
+static void next_scsi_init(DeviceState *pcdev, M68kCPU *cpu)
+{
+    struct NeXTPC *next_pc = NEXT_PC(pcdev);
+    DeviceState *dev;
+    SysBusDevice *sysbusdev;
+    SysBusESPState *sysbus_esp;
+    ESPState *esp;
+
+    dev = qdev_new(TYPE_SYSBUS_ESP);
+    sysbus_esp = SYSBUS_ESP(dev);
+    esp = &sysbus_esp->esp;
+    esp->dma_memory_read = nextscsi_read;
+    esp->dma_memory_write = nextscsi_write;
+    esp->dma_opaque = pcdev;
+    sysbus_esp->it_shift = 0;
+    esp->dma_enabled = 1;
+    sysbusdev = SYS_BUS_DEVICE(dev);
+    sysbus_realize_and_unref(sysbusdev, &error_fatal);
+    sysbus_connect_irq(sysbusdev, 0, qdev_get_gpio_in(pcdev, NEXT_SCSI_I));
+    sysbus_mmio_map(sysbusdev, 0, 0x2114000);
+
+    next_pc->scsi_reset = qdev_get_gpio_in(dev, 0);
+    next_pc->scsi_dma = qdev_get_gpio_in(dev, 1);
+
+    scsi_bus_legacy_handle_cmdline(&esp->bus);
+}
+
 static void next_escc_init(DeviceState *pcdev)
 {
     DeviceState *dev;
@@ -1021,6 +1122,7 @@ static void next_cube_init(MachineState *machine)
     /* TODO: */
     /* Network */
     /* SCSI */
+    next_scsi_init(pcdev, cpu);
 
     /* DMA */
     memory_region_init_io(dmamem, NULL, &dma_ops, machine, "next.dma", 0x5000);
@@ -1033,6 +1135,7 @@ static void next_machine_class_init(ObjectClass *oc, void *data)
 
     mc->desc = "NeXT Cube";
     mc->init = next_cube_init;
+    mc->block_default_type = IF_SCSI;
     mc->default_ram_size = RAM_SIZE;
     mc->default_ram_id = "next.ram";
     mc->default_cpu_type = M68K_CPU_TYPE_NAME("m68040");