[RFC PATCH v2 1/4] pci: add handling of Enable bit in ATS Control Register

[Viktor Prutyanov <viktor@daynix.com>]

According to PCIe Address Translation Services specification 5.1.3.,
ATS Control Register has Enable bit to enable/disable ATS.
A trigger function is called at the Enable bit change, so that PCIe
devices can handle ATS enable/disable.

Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
---
 hw/pci/pcie.c         | 22 ++++++++++++++++++++++
 include/hw/pci/pcie.h |  5 +++++
 2 files changed, 27 insertions(+)

diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index b8c24cf45f..14ac1b0fb9 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -1063,6 +1063,28 @@ void pcie_ats_init(PCIDevice *dev, uint16_t offset, bool aligned)
     pci_set_word(dev->wmask + dev->exp.ats_cap + PCI_ATS_CTRL, 0x800f);
 }
 
+void pcie_ats_config_write(PCIDevice *dev, uint32_t address,
+                           uint32_t val, int len,
+                           void (*trigger_func)(PCIDevice *dev, bool enable))
+{
+    uint32_t off;
+    uint16_t ats_cap = dev->exp.ats_cap;
+
+    if (!ats_cap || address < ats_cap) {
+        return;
+    }
+    off = address - ats_cap;
+    if (off >= PCI_EXT_CAP_ATS_SIZEOF) {
+        return;
+    }
+
+    if (range_covers_byte(off, len, PCI_ATS_CTRL + 1)) {
+        if (trigger_func) {
+            trigger_func(dev, !!(val & PCI_ATS_CTRL_ENABLE));
+        }
+    }
+}
+
 /* ACS (Access Control Services) */
 void pcie_acs_init(PCIDevice *dev, uint16_t offset)
 {
diff --git a/include/hw/pci/pcie.h b/include/hw/pci/pcie.h
index 3cc2b15957..f5571527d3 100644
--- a/include/hw/pci/pcie.h
+++ b/include/hw/pci/pcie.h
@@ -146,4 +146,9 @@ void pcie_cap_slot_unplug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
                              Error **errp);
 void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
                                      DeviceState *dev, Error **errp);
+
+void pcie_ats_config_write(PCIDevice *dev, uint32_t address,
+                           uint32_t val, int len,
+                           void (*trigger_func)(PCIDevice *dev, bool enable));
+
 #endif /* QEMU_PCIE_H */
-- 
2.35.1