[PATCH 1/2] hw/pci-host/pam: Free PAMMemoryRegion from Intel-specific bit handling

[Bernhard Beschow]

The PAM bit extraction is currently spread across pam.c and the northbridge
device models, making the extraction logic harder to comprehend. Also note how
pam_update() deals with PAM_REGIONS_COUNT, even though it handles exactly one
region. Fix this (at the cost of minor code duplication) by moving the bit
extraction into the northbridge device models. As a side effect, pam_update()
becomes less Intel-specific which would allow it to be reused e.g. in VIA
northbridges.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
---
 include/hw/pci-host/pam.h |  7 +++----
 hw/pci-host/i440fx.c      |  7 +++++--
 hw/pci-host/pam.c         | 14 +++++++-------
 hw/pci-host/q35.c         |  5 +++--
 4 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/include/hw/pci-host/pam.h b/include/hw/pci-host/pam.h
index 005916f826..b9b33aecc8 100644
--- a/include/hw/pci-host/pam.h
+++ b/include/hw/pci-host/pam.h
@@ -70,7 +70,6 @@
 /* PAM registers: log nibble and high nibble*/
 #define PAM_ATTR_WE     ((uint8_t)2)
 #define PAM_ATTR_RE     ((uint8_t)1)
-#define PAM_ATTR_MASK   ((uint8_t)3)
 
 /* SMRAM register */
 #define SMRAM_D_OPEN           ((uint8_t)(1 << 6))
@@ -83,13 +82,13 @@
 #define PAM_REGIONS_COUNT       13
 
 typedef struct PAMMemoryRegion {
-    MemoryRegion alias[4];  /* index = PAM value */
-    unsigned current;
+    MemoryRegion alias[4];  /* index = mode value */
+    uint8_t mode;
 } PAMMemoryRegion;
 
 void init_pam(PAMMemoryRegion *mem, Object *owner, MemoryRegion *ram,
               MemoryRegion *system, MemoryRegion *pci,
               uint32_t start, uint32_t size);
-void pam_update(PAMMemoryRegion *mem, int idx, uint8_t val);
+void pam_update(PAMMemoryRegion *mem, uint8_t mode);
 
 #endif /* QEMU_PAM_H */
diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c
index 4f0a0438d7..cddd506ab0 100644
--- a/hw/pci-host/i440fx.c
+++ b/hw/pci-host/i440fx.c
@@ -64,6 +64,8 @@ struct I440FXState {
 #define I440FX_PAM_SIZE 7
 #define I440FX_SMRAM    0x72
 
+#define I440FX_PAM_ATTR_MASK ((uint8_t)3)
+
 /* Keep it 2G to comply with older win32 guests */
 #define I440FX_PCI_HOST_HOLE64_SIZE_DEFAULT (1ULL << 31)
 
@@ -88,8 +90,9 @@ static void i440fx_update_memory_mappings(PCII440FXState *d)
 
     memory_region_transaction_begin();
     for (i = 0; i < ARRAY_SIZE(d->pam_regions); i++) {
-        pam_update(&d->pam_regions[i], i,
-                   pd->config[I440FX_PAM + DIV_ROUND_UP(i, 2)]);
+        uint8_t reg = pd->config[I440FX_PAM + DIV_ROUND_UP(i, 2)];
+        pam_update(&d->pam_regions[i],
+                   (reg >> ((!(i & 1)) * 4)) & I440FX_PAM_ATTR_MASK);
     }
     memory_region_set_enabled(&d->smram_region,
                               !(pd->config[I440FX_SMRAM] & SMRAM_D_OPEN));
diff --git a/hw/pci-host/pam.c b/hw/pci-host/pam.c
index 68e9884d27..29c0db097a 100644
--- a/hw/pci-host/pam.c
+++ b/hw/pci-host/pam.c
@@ -51,20 +51,20 @@ void init_pam(PAMMemoryRegion *mem, Object *owner, 
MemoryRegion *ram_memory,
                              start, size);
 
     memory_region_transaction_begin();
-    for (i = 0; i < 4; ++i) {
+    for (i = 0; i < ARRAY_SIZE(mem->alias); ++i) {
         memory_region_set_enabled(&mem->alias[i], false);
         memory_region_add_subregion_overlap(system_memory, start,
                                             &mem->alias[i], 1);
     }
     memory_region_transaction_commit();
-    mem->current = 0;
+    mem->mode = 0;
 }
 
-void pam_update(PAMMemoryRegion *pam, int idx, uint8_t val)
+void pam_update(PAMMemoryRegion *pam, uint8_t mode)
 {
-    assert(0 <= idx && idx < PAM_REGIONS_COUNT);
+    g_assert(mode < ARRAY_SIZE(pam->alias));
 
-    memory_region_set_enabled(&pam->alias[pam->current], false);
-    pam->current = (val >> ((!(idx & 1)) * 4)) & PAM_ATTR_MASK;
-    memory_region_set_enabled(&pam->alias[pam->current], true);
+    memory_region_set_enabled(&pam->alias[pam->mode], false);
+    pam->mode = mode;
+    memory_region_set_enabled(&pam->alias[pam->mode], true);
 }
diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index 0d7d4e3f08..947d9aa9c4 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -330,8 +330,9 @@ static void mch_update_pam(MCHPCIState *mch)
 
     memory_region_transaction_begin();
     for (i = 0; i < 13; i++) {
-        pam_update(&mch->pam_regions[i], i,
-                   pd->config[MCH_HOST_BRIDGE_PAM0 + DIV_ROUND_UP(i, 2)]);
+        uint8_t reg = pd->config[MCH_HOST_BRIDGE_PAM0 + DIV_ROUND_UP(i, 2)];
+        pam_update(&mch->pam_regions[i],
+                   (reg >> ((!(i & 1)) * 4)) & MCH_HOST_BRIDGE_PAM_MASK);
     }
     memory_region_transaction_commit();
 }
-- 
2.44.0