slotid: add slot id capability

This capability makes it possible for the guest to
report a unique chassis identifier to the user.

The spec also recommends making chassis indentifier
persist in eeprom.
This isn't implemented.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

3 files changed, 57 insertions, 0 deletions

diff --git a/hw/pci.h b/hw/pci.h
index dc4d9d10a7..8d0aa498e5 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -129,6 +129,8 @@ enum {
     /* Standard hot plug controller. */
 #define QEMU_PCI_SHPC_BITNR 5
     QEMU_PCI_CAP_SHPC = (1 << QEMU_PCI_SHPC_BITNR),
+#define QEMU_PCI_SLOTID_BITNR 6
+    QEMU_PCI_CAP_SLOTID = (1 << QEMU_PCI_SLOTID_BITNR),
 };
 
 #define TYPE_PCI_DEVICE "pci-device"
diff --git a/hw/slotid_cap.c b/hw/slotid_cap.c
new file mode 100644
index 0000000000..01064521a9
--- /dev/null
+++ b/hw/slotid_cap.c
@@ -0,0 +1,44 @@
+#include "slotid_cap.h"
+#include "pci.h"
+
+#define SLOTID_CAP_LENGTH 4
+#define SLOTID_NSLOTS_SHIFT (ffs(PCI_SID_ESR_NSLOTS) - 1)
+
+int slotid_cap_init(PCIDevice *d, int nslots,
+                    uint8_t chassis,
+                    unsigned offset)
+{
+    int cap;
+    if (!chassis) {
+        error_report("Bridge chassis not specified. Each bridge is required "
+                     "to be assigned a unique chassis id > 0.");
+        return -EINVAL;
+    }
+    if (nslots < 0 || nslots > (PCI_SID_ESR_NSLOTS >> SLOTID_NSLOTS_SHIFT)) {
+        /* TODO: error report? */
+        return -EINVAL;
+    }
+
+    cap = pci_add_capability(d, PCI_CAP_ID_SLOTID, offset, SLOTID_CAP_LENGTH);
+    if (cap < 0) {
+        return cap;
+    }
+    /* We make each chassis unique, this way each bridge is First in Chassis */
+    d->config[cap + PCI_SID_ESR] = PCI_SID_ESR_FIC |
+        (nslots << SLOTID_NSLOTS_SHIFT);
+    d->cmask[cap + PCI_SID_ESR] = 0xff;
+    d->config[cap + PCI_SID_CHASSIS_NR] = chassis;
+    /* Note: Chassis number register is non-volatile,
+       so we don't reset it. */
+    /* TODO: store in eeprom? */
+    d->wmask[cap + PCI_SID_CHASSIS_NR] = 0xff;
+
+    d->cap_present |= QEMU_PCI_CAP_SLOTID;
+    return 0;
+}
+
+void slotid_cap_cleanup(PCIDevice *d)
+{
+    /* TODO: cleanup config space? */
+    d->cap_present &= ~QEMU_PCI_CAP_SLOTID;
+}
diff --git a/hw/slotid_cap.h b/hw/slotid_cap.h
new file mode 100644
index 0000000000..70db0470b0
--- /dev/null
+++ b/hw/slotid_cap.h
@@ -0,0 +1,11 @@
+#ifndef PCI_SLOTID_CAP_H
+#define PCI_SLOTID_CAP_H
+
+#include "qemu-common.h"
+
+int slotid_cap_init(PCIDevice *dev, int nslots,
+                    uint8_t chassis,
+                    unsigned offset);
+void slotid_cap_cleanup(PCIDevice *dev);
+
+#endif