[PATCH v5 1/2] PCI: add AMD PCIe quirk for nvme shutdown opt

[Prike Liang <Prike.Liang@amd.com>]

In the NVMe controller default suspend-resume seems only save/restore the
NVMe link state by APST opt and the NVMe remains in D0 during this time.
Then the NVMe device will be shutdown by SMU firmware in the s2idle entry
and then will lost the NVMe power context during s2idle resume.Finally,
the NVMe command queue request will be processed abnormally and result
in access timeout.This issue can be settled by using PCIe power set with
simple suspend-resume process path instead of APST get/set opt.

In this patch prepare a PCIe RC bus flag to identify the platform whether
need the quirk.

Cc: <stable@vger.kernel.org> # 5.10+
Signed-off-by: Prike Liang <Prike.Liang@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
[ck: split patches for nvme and pcie]
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Suggested-by: Keith Busch <kbusch@kernel.org>
Acked-by: Keith Busch <kbusch@kernel.org>
---
Changes in v2:
Fix the patch format and check chip root complex DID instead of PCIe RP
to avoid the storage device plugged in internal PCIe RP by USB adaptor.

Changes in v3:
According to Christoph Hellwig do NVME PCIe related identify opt better in
PCIe quirk driver rather than in NVME module.

Changes in v4:
Split the fix to PCIe and NVMe part and then call the pci_dev_put() put
the device reference count and finally refine the commit info.

Changes in v5:
According to Christoph Hellwig and Keith Busch better use a passthrough device(bus)
gloable flag to identify the NVMe shutdown opt rather than look up the device BDF.
---
 drivers/pci/probe.c  | 5 ++++-
 drivers/pci/quirks.c | 7 +++++++
 include/linux/pci.h  | 2 ++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 953f15a..34ba691e 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -558,10 +558,13 @@ static struct pci_bus *pci_alloc_bus(struct pci_bus *parent)
 	INIT_LIST_HEAD(&b->resources);
 	b->max_bus_speed = PCI_SPEED_UNKNOWN;
 	b->cur_bus_speed = PCI_SPEED_UNKNOWN;
+	if (parent) {
 #ifdef CONFIG_PCI_DOMAINS_GENERIC
-	if (parent)
 		b->domain_nr = parent->domain_nr;
 #endif
+		if (parent->bus_flags & PCI_BUS_FLAGS_DISABLE_ON_S2I)
+			b->bus_flags |= PCI_BUS_FLAGS_DISABLE_ON_S2I;
+	}
 	return b;
 }
 
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 653660e3..7c4bb8e 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -312,6 +312,13 @@ static void quirk_nopciamd(struct pci_dev *dev)
 }
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD,	PCI_DEVICE_ID_AMD_8151_0,	quirk_nopciamd);
 
+static void quirk_amd_s2i_fixup(struct pci_dev *dev)
+{
+	dev->bus->bus_flags |= PCI_BUS_FLAGS_DISABLE_ON_S2I;
+	pci_info(dev, "AMD simple suspend opt enabled\n");
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_AMD, 0x1630, quirk_amd_s2i_fixup);
+
 /* Triton requires workarounds to be used by the drivers */
 static void quirk_triton(struct pci_dev *dev)
 {
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 53f4904..dc65219 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -240,6 +240,8 @@ enum pci_bus_flags {
 	PCI_BUS_FLAGS_NO_MMRBC	= (__force pci_bus_flags_t) 2,
 	PCI_BUS_FLAGS_NO_AERSID	= (__force pci_bus_flags_t) 4,
 	PCI_BUS_FLAGS_NO_EXTCFG	= (__force pci_bus_flags_t) 8,
+	/* Driver must pci_disable_device() for suspend-to-idle */
+	PCI_BUS_FLAGS_DISABLE_ON_S2I	= (__force pci_bus_flags_t) 16,
 };
 
 /* Values from Link Status register, PCIe r3.1, sec 7.8.8 */
-- 
2.7.4