[RFC PATCH 08/18] hw/pci-host/bonito: Remap PCI "lo" regions when PCIMAP reg is modified

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

Per the datasheet (Chapter 5.7.1. "PCI address regions"),
the PCIMAP register:

  Map the 64Mbyte regions marked "PCI_Lo" in the CPU's memory map,
  each of which can be assigned to any 64 Mbyte-aligned region of
  PCI memory. The address appearing on the PCI bus consists of the
  low 26 bits of the CPU physical address, with the high 6 bits
  coming from the appropriate base6 field. Each of the three regions
  is an independent window onto PCI memory, and can be positioned on
  any 64Mbyte boundary in PCI space.

Remap the 3 regions on reset and when PCIMAP is updated.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
RFC: memory_region_is_mapped() is probably not the best call to check
     if this is the first call.

 hw/pci-host/bonito.c | 49 ++++++++++++++++++++++++++++++++------------
 1 file changed, 36 insertions(+), 13 deletions(-)

diff --git a/hw/pci-host/bonito.c b/hw/pci-host/bonito.c
index 29c0294d289..a091ef15d27 100644
--- a/hw/pci-host/bonito.c
+++ b/hw/pci-host/bonito.c
@@ -138,6 +138,10 @@ FIELD(BONGENCFG, PCIQUEUE,      12, 1)
 
 /* 4. PCI address map control */
 #define BONITO_PCIMAP           (0x10 >> 2)      /* 0x110 */
+FIELD(PCIMAP, LO0,               0, 6)
+FIELD(PCIMAP, LO1,               6, 6)
+FIELD(PCIMAP, LO2,              12, 6)
+FIELD(PCIMAP, 2G,               18, 1)
 #define BONITO_PCIMEMBASECFG    (0x14 >> 2)      /* 0x114 */
 #define BONITO_PCIMAP_CFG       (0x18 >> 2)      /* 0x118 */
 
@@ -232,6 +236,7 @@ struct BonitoState {
     qemu_irq *pic;
     PCIBonitoState *pci_dev;
     MemoryRegion pci_mem;
+    MemoryRegion pcimem_lo_alias[3];
 };
 
 #define TYPE_BONITO_PCI_HOST_BRIDGE "Bonito-pcihost"
@@ -240,6 +245,31 @@ OBJECT_DECLARE_SIMPLE_TYPE(BonitoState, BONITO_PCI_HOST_BRIDGE)
 #define TYPE_PCI_BONITO "Bonito"
 OBJECT_DECLARE_SIMPLE_TYPE(PCIBonitoState, PCI_BONITO)
 
+static void bonito_remap(PCIBonitoState *s)
+{
+    static const char *const region_name[3] = {
+        "pci.lomem0", "pci.lomem1", "pci.lomem2"
+    };
+    BonitoState *bs = BONITO_PCI_HOST_BRIDGE(s->pcihost);
+
+    for (size_t i = 0; i < 3; i++) {
+        uint32_t offset = extract32(s->regs[BONITO_PCIMAP], 6 * i, 6) << 26;
+
+        if (memory_region_is_mapped(&bs->pcimem_lo_alias[i])) {
+            memory_region_del_subregion(get_system_memory(),
+                                        &bs->pcimem_lo_alias[i]);
+            object_unparent(OBJECT(&bs->pcimem_lo_alias[i]));
+        }
+
+        memory_region_init_alias(&bs->pcimem_lo_alias[i], OBJECT(s),
+                                 region_name[i], &bs->pci_mem,
+                                 offset, 64 * MiB);
+        memory_region_add_subregion(get_system_memory(),
+                                    BONITO_PCILO_BASE + i * 64 * MiB,
+                                    &bs->pcimem_lo_alias[i]);
+    }
+}
+
 static void bonito_writel(void *opaque, hwaddr addr,
                           uint64_t val, unsigned size)
 {
@@ -253,7 +283,6 @@ static void bonito_writel(void *opaque, hwaddr addr,
     switch (saddr) {
     case BONITO_IODEVCFG:
     case BONITO_SDCFG:
-    case BONITO_PCIMAP:
     case BONITO_PCIMEMBASECFG:
     case BONITO_PCIMAP_CFG:
     case BONITO_GPIODATA:
@@ -275,6 +304,10 @@ static void bonito_writel(void *opaque, hwaddr addr,
     case BONITO_MEMSIZE:
         s->regs[saddr] = val;
         break;
+    case BONITO_PCIMAP:
+        s->regs[saddr] = val;
+        bonito_remap(s);
+        break;
     case BONITO_BONGENCFG:
         if (!FIELD_EX32(s->regs[saddr], BONGENCFG, CPUSELFRESET)
                 && FIELD_EX32(val, BONGENCFG, CPUSELFRESET)) {
@@ -603,6 +636,8 @@ static void bonito_reset(void *opaque)
     s->regs[BONITO_DQCFG] = 0x8;
     s->regs[BONITO_MEMSIZE] = 0x10000000;
     s->regs[BONITO_PCIMAP] = 0x6140;
+
+    bonito_remap(s);
 }
 
 static const VMStateDescription vmstate_bonito = {
@@ -619,7 +654,6 @@ static void bonito_pcihost_realize(DeviceState *dev, Error **errp)
 {
     PCIHostState *phb = PCI_HOST_BRIDGE(dev);
     BonitoState *bs = BONITO_PCI_HOST_BRIDGE(dev);
-    MemoryRegion *pcimem_lo_alias = g_new(MemoryRegion, 3);
 
     memory_region_init(&bs->pci_mem, OBJECT(dev), "pci.mem", BONITO_PCIHI_SIZE);
     phb->bus = pci_register_root_bus(dev, "pci",
@@ -627,17 +661,6 @@ static void bonito_pcihost_realize(DeviceState *dev, Error **errp)
                                      dev, &bs->pci_mem, get_system_io(),
                                      PCI_DEVFN(5, 0), 32, TYPE_PCI_BUS);
 
-    for (size_t i = 0; i < 3; i++) {
-        char *name = g_strdup_printf("pci.lomem%zu", i);
-
-        memory_region_init_alias(&pcimem_lo_alias[i], NULL, name,
-                                 &bs->pci_mem, i * 64 * MiB, 64 * MiB);
-        memory_region_add_subregion(get_system_memory(),
-                                    BONITO_PCILO_BASE + i * 64 * MiB,
-                                    &pcimem_lo_alias[i]);
-        g_free(name);
-    }
-
     create_unimplemented_device("pci.io", BONITO_PCIIO_BASE, 1 * MiB);
 }
 
-- 
2.26.2