ppc/pnv: move nest_regs_mr to PnvPHB4

We're now able to cleanly move nest_regs_mr to the PnvPHB4 device.

One thing of notice here is the need to use a phb->stack->pec pointer
because pnv_pec_stk_nest_xscom_write requires a PEC object. Another
thing that can be noticed in the use of 'stack->stack_no' that still
remains throughout the XSCOM code.

After moving all MemoryRegions to the PnvPHB4 object, this illustrates
what is the remaining role of the stack: provide a PEC pointer and the
'stack_no' information. If we can provide these in the PnvPHB4 object
instead (spoiler: we can, and we will), the PnvPhb4PecStack device will
be deprecated and can be removed.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20220113192952.911188-10-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

hw/pci-host/pnv_phb4.c

@@ -861,8 +861,7 @@ const MemoryRegionOps pnv_phb4_xscom_ops = {
 static uint64_t pnv_pec_stk_nest_xscom_read(void *opaque, hwaddr addr,
                                             unsigned size)
 {
-    PnvPhb4PecStack *stack = PNV_PHB4_PEC_STACK(opaque);
-    PnvPHB4 *phb = stack->phb;
+    PnvPHB4 *phb = PNV_PHB4(opaque);
     uint32_t reg = addr >> 3;
 
     /* TODO: add list of allowed registers and error out if not */
@@ -982,9 +981,8 @@ static void pnv_pec_stk_update_map(PnvPHB4 *phb)
 static void pnv_pec_stk_nest_xscom_write(void *opaque, hwaddr addr,
                                          uint64_t val, unsigned size)
 {
-    PnvPhb4PecStack *stack = PNV_PHB4_PEC_STACK(opaque);
-    PnvPHB4 *phb = stack->phb;
-    PnvPhb4PecState *pec = stack->pec;
+    PnvPHB4 *phb = PNV_PHB4(opaque);
+    PnvPhb4PecState *pec = phb->stack->pec;
     uint32_t reg = addr >> 3;
 
     switch (reg) {
@@ -1470,10 +1468,10 @@ static void pnv_phb4_xscom_realize(PnvPHB4 *phb)
     assert(pec);
 
     /* Initialize the XSCOM regions for the stack registers */
-    snprintf(name, sizeof(name), "xscom-pec-%d.%d-nest-stack-%d",
+    snprintf(name, sizeof(name), "xscom-pec-%d.%d-nest-phb-%d",
              pec->chip_id, pec->index, stack->stack_no);
-    pnv_xscom_region_init(&stack->nest_regs_mr, OBJECT(stack),
-                          &pnv_pec_stk_nest_xscom_ops, stack, name,
+    pnv_xscom_region_init(&phb->nest_regs_mr, OBJECT(phb),
+                          &pnv_pec_stk_nest_xscom_ops, phb, name,
                           PHB4_PEC_NEST_STK_REGS_COUNT);
 
     snprintf(name, sizeof(name), "xscom-pec-%d.%d-pci-phb-%d",
@@ -1494,7 +1492,7 @@ static void pnv_phb4_xscom_realize(PnvPHB4 *phb)
     /* Populate the XSCOM address space. */
     pnv_xscom_add_subregion(pec->chip,
                             pec_nest_base + 0x40 * (stack->stack_no + 1),
-                            &stack->nest_regs_mr);
+                            &phb->nest_regs_mr);
     pnv_xscom_add_subregion(pec->chip,
                             pec_pci_base + 0x40 * (stack->stack_no + 1),
                             &phb->pci_regs_mr);

include/hw/pci-host/pnv_phb4.h

@@ -115,6 +115,7 @@ struct PnvPHB4 {
     /* Nest registers */
 #define PHB4_PEC_NEST_STK_REGS_COUNT  0x17
     uint64_t nest_regs[PHB4_PEC_NEST_STK_REGS_COUNT];
+    MemoryRegion nest_regs_mr;
 
     /* Memory windows from PowerBus to PHB */
     MemoryRegion phbbar;
@@ -169,8 +170,6 @@ struct PnvPhb4PecStack {
     /* My own stack number */
     uint32_t stack_no;
 
-    MemoryRegion nest_regs_mr;
-
     /* PHB pass-through XSCOM */
     MemoryRegion phb_regs_mr;