[PATCH 19/20] hw/net/xilinx_ethlite: Map the RAM buffer as RAM memory region

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Rather than using I/O registers for RAM buffer, having to
swap endianness back and forth (because the core memory layer
automatically swaps endiannes for us), declare the buffers
as RAM regions. Remove the now unused s->regs[] array.

The memory flat view becomes:

  FlatView #0
   Root memory region: system
    0000000081000000-00000000810007f3 (prio 0, ram): ethlite.tx[0]buf
    00000000810007f4-00000000810007ff (prio 0, i/o): ethlite.tx[0]io
    0000000081000800-0000000081000ff3 (prio 0, ram): ethlite.tx[1]buf
    0000000081000ff4-0000000081000fff (prio 0, i/o): ethlite.tx[1]io
    0000000081001000-00000000810017f3 (prio 0, ram): ethlite.rx[0]buf
    00000000810017fc-00000000810017ff (prio 0, i/o): ethlite.rx[0]io
    0000000081001800-0000000081001ff3 (prio 0, ram): ethlite.rx[1]buf
    0000000081001ffc-0000000081001fff (prio 0, i/o): ethlite.rx[1]io

Mention the device datasheet in the file header.

Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/net/xilinx_ethlite.c | 79 +++++++++++------------------------------
 1 file changed, 20 insertions(+), 59 deletions(-)

diff --git a/hw/net/xilinx_ethlite.c b/hw/net/xilinx_ethlite.c
index f681b91769..da453465ca 100644
--- a/hw/net/xilinx_ethlite.c
+++ b/hw/net/xilinx_ethlite.c
@@ -2,6 +2,10 @@
  * QEMU model of the Xilinx Ethernet Lite MAC.
  *
  * Copyright (c) 2009 Edgar E. Iglesias.
+ * Copyright (c) 2024 Linaro, Ltd
+ *
+ * DS580: https://docs.amd.com/v/u/en-US/xps_ethernetlite
+ * LogiCORE IP XPS Ethernet Lite Media Access Controller
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -27,7 +31,6 @@
 #include "qemu/bitops.h"
 #include "qom/object.h"
 #include "qapi/error.h"
-#include "exec/tswap.h"
 #include "hw/sysbus.h"
 #include "hw/irq.h"
 #include "hw/qdev-properties.h"
@@ -46,7 +49,6 @@
 #define A_RX_BASE0    0x17fc
 #define R_RX_BUF1     (0x1800 / 4)
 #define A_RX_BASE1    0x1ffc
-#define R_MAX         (0x2000 / 4)
 
 #define RX_BUFSZ_MAX  0x07e0
 
@@ -72,6 +74,8 @@ typedef struct XlnxXpsEthLitePort
 {
     MemoryRegion txio;
     MemoryRegion rxio;
+    MemoryRegion txbuf;
+    MemoryRegion rxbuf;
 
     struct {
         uint32_t tx_len;
@@ -100,7 +104,6 @@ struct XlnxXpsEthLite
 
     UnimplementedDeviceState mdio;
     XlnxXpsEthLitePort port[2];
-    uint32_t regs[R_MAX];
 };
 
 static inline void eth_pulse_irq(XlnxXpsEthLite *s)
@@ -118,16 +121,12 @@ static unsigned addr_to_port_index(hwaddr addr)
 
 static void *txbuf_ptr(XlnxXpsEthLite *s, unsigned port_index)
 {
-    unsigned int rxbase = port_index * (0x800 / 4);
-
-    return &s->regs[rxbase + R_TX_BUF0];
+    return memory_region_get_ram_ptr(&s->port[port_index].txbuf);
 }
 
 static void *rxbuf_ptr(XlnxXpsEthLite *s, unsigned port_index)
 {
-    unsigned int rxbase = port_index * (0x800 / 4);
-
-    return &s->regs[rxbase + R_RX_BUF0];
+    return memory_region_get_ram_ptr(&s->port[port_index].rxbuf);
 }
 
 static uint64_t port_tx_read(void *opaque, hwaddr addr, unsigned int size)
@@ -252,53 +251,6 @@ static const MemoryRegionOps eth_portrx_ops = {
         },
 };
 
-static uint64_t
-eth_read(void *opaque, hwaddr addr, unsigned int size)
-{
-    XlnxXpsEthLite *s = opaque;
-    uint32_t r = 0;
-
-    addr >>= 2;
-
-    switch (addr)
-    {
-        default:
-            r = tswap32(s->regs[addr]);
-            break;
-    }
-    return r;
-}
-
-static void
-eth_write(void *opaque, hwaddr addr,
-          uint64_t val64, unsigned int size)
-{
-    XlnxXpsEthLite *s = opaque;
-    uint32_t value = val64;
-
-    addr >>= 2;
-    switch (addr) 
-    {
-        default:
-            s->regs[addr] = tswap32(value);
-            break;
-    }
-}
-
-static const MemoryRegionOps eth_ops = {
-    .read = eth_read,
-    .write = eth_write,
-    .endianness = DEVICE_NATIVE_ENDIAN,
-    .impl = {
-        .min_access_size = 4,
-        .max_access_size = 4,
-    },
-    .valid = {
-        .min_access_size = 4,
-        .max_access_size = 4
-    }
-};
-
 static bool eth_can_rx(NetClientState *nc)
 {
     XlnxXpsEthLite *s = qemu_get_nic_opaque(nc);
@@ -354,6 +306,9 @@ static void xilinx_ethlite_realize(DeviceState *dev, Error **errp)
 {
     XlnxXpsEthLite *s = XILINX_ETHLITE(dev);
 
+    memory_region_init(&s->mmio, OBJECT(dev),
+                       "xlnx.xps-ethernetlite", 0x2000);
+
     object_initialize_child(OBJECT(dev), "ethlite.mdio", &s->mdio,
                            TYPE_UNIMPLEMENTED_DEVICE);
     qdev_prop_set_string(DEVICE(&s->mdio), "name", "ethlite.mdio");
@@ -363,6 +318,10 @@ static void xilinx_ethlite_realize(DeviceState *dev, Error **errp)
                             sysbus_mmio_get_region(SYS_BUS_DEVICE(&s->mdio), 0));
 
     for (unsigned i = 0; i < 2; i++) {
+        memory_region_init_ram(&s->port[i].txbuf, OBJECT(dev),
+                               i ? "ethlite.tx[1]buf" : "ethlite.tx[0]buf",
+                               0x07f4, &error_abort);
+        memory_region_add_subregion(&s->mmio, 0x0800 * i, &s->port[i].txbuf);
         memory_region_init_io(&s->port[i].txio, OBJECT(dev),
                               &eth_porttx_ops, s,
                               i ? "ethlite.tx[1]io" : "ethlite.tx[0]io",
@@ -370,6 +329,11 @@ static void xilinx_ethlite_realize(DeviceState *dev, Error **errp)
         memory_region_add_subregion(&s->mmio, i ? A_TX_BASE1 : A_TX_BASE0,
                                     &s->port[i].txio);
 
+        memory_region_init_ram(&s->port[i].rxbuf, OBJECT(dev),
+                               i ? "ethlite.rx[1]buf" : "ethlite.rx[0]buf",
+                               0x07f4, &error_abort);
+        memory_region_add_subregion(&s->mmio, 0x1000 + 0x0800 * i,
+                                    &s->port[i].rxbuf);
         memory_region_init_io(&s->port[i].rxio, OBJECT(dev),
                               &eth_portrx_ops, s,
                               i ? "ethlite.rx[1]io" : "ethlite.rx[0]io",
@@ -390,9 +354,6 @@ static void xilinx_ethlite_init(Object *obj)
     XlnxXpsEthLite *s = XILINX_ETHLITE(obj);
 
     sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->irq);
-
-    memory_region_init_io(&s->mmio, obj, &eth_ops, s,
-                          "xlnx.xps-ethernetlite", R_MAX * 4);
     sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
 }
 
-- 
2.45.2