pci: implement RW1C register framework.

Implement RW1C register framework.
With this patch, it would be easy to implement
W1C(Write 1 to Clear) register by just setting w1cmask.
Later RW1C register will be used by pcie.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

2 files changed, 8 insertions, 0 deletions

diff --git a/hw/pci.c b/hw/pci.c
index 97a7b232ac..abddc6d239 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -627,6 +627,7 @@ static void pci_config_alloc(PCIDevice *pci_dev)
     pci_dev->config = qemu_mallocz(config_size);
     pci_dev->cmask = qemu_mallocz(config_size);
     pci_dev->wmask = qemu_mallocz(config_size);
+    pci_dev->w1cmask = qemu_mallocz(config_size);
     pci_dev->used = qemu_mallocz(config_size);
 }
 
@@ -635,6 +636,7 @@ static void pci_config_free(PCIDevice *pci_dev)
     qemu_free(pci_dev->config);
     qemu_free(pci_dev->cmask);
     qemu_free(pci_dev->wmask);
+    qemu_free(pci_dev->w1cmask);
     qemu_free(pci_dev->used);
 }
 
@@ -997,7 +999,10 @@ void pci_default_write_config(PCIDevice *d, uint32_t addr, uint32_t val, int l)
 
     for (i = 0; i < l && addr + i < config_size; val >>= 8, ++i) {
         uint8_t wmask = d->wmask[addr + i];
+        uint8_t w1cmask = d->w1cmask[addr + i];
+        assert(!(wmask & w1cmask));
         d->config[addr + i] = (d->config[addr + i] & ~wmask) | (val & wmask);
+        d->config[addr + i] &= ~(val & w1cmask); /* W1C: Write 1 to Clear */
     }
     if (ranges_overlap(addr, l, PCI_BASE_ADDRESS_0, 24) ||
         ranges_overlap(addr, l, PCI_ROM_ADDRESS, 4) ||
diff --git a/hw/pci.h b/hw/pci.h
index 1c6075eb40..d8b399f4d5 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -129,6 +129,9 @@ struct PCIDevice {
     /* Used to implement R/W bytes */
     uint8_t *wmask;
 
+    /* Used to implement RW1C(Write 1 to Clear) bytes */
+    uint8_t *w1cmask;
+
     /* Used to allocate config space for capabilities. */
     uint8_t *used;