powerpc/pseries: Make 32-bit MSI quirk work on systems lacking firmware support

Recent commit e61133dda480062d221f09e4fc18f66763f8ecd0 added support for a new firmware feature to force an adapter to use 32 bit MSIs. However, this firmware is not available for all systems. The hack below allows devices needing 32 bit MSIs to work on these systems as well. It is careful to only enable this on Gen2 slots, which should limit this to configurations where this hack is needed and tested to work. [Small change to factor out the hack into a separate function -- BenH] Signed-off-by: Brian King <brking@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/pseries: Make 32-bit MSI quirk work on systems lacking firmware support
Recent commit e61133dda480062d221f09e4fc18f66763f8ecd0 added support for a new firmware feature to force an adapter to use 32 bit MSIs. However, this firmware is not available for all systems. The hack below allows devices needing 32 bit MSIs to work on these systems as well. It is careful to only enable this on Gen2 slots, which should limit this to configurations where this hack is needed and tested to work. [Small change to factor out the hack into a separate function -- BenH] Signed-off-by: Brian King <brking@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Brian King · Benjamin Herrenschmidt
1 parent 83920c498e
Showing 1 changed file with 37 additions and 3 deletions Side-by-side Diff
arch/powerpc/platforms/pseries/msi.c
@@ -374,6 +374,23 @@
 	return 0;
 }
  
+static void rtas_hack_32bit_msi_gen2(struct pci_dev *pdev)
+{
+	u32 addr_hi, addr_lo;
+
+	/*
+	 * We should only get in here for IODA1 configs. This is based on the
+	 * fact that we using RTAS for MSIs, we don't have the 32 bit MSI RTAS
+	 * support, and we are in a PCIe Gen2 slot.
+	 */
+	dev_info(&pdev->dev,
+		 "rtas_msi: No 32 bit MSI firmware support, forcing 32 bit MSI\n");
+	pci_read_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, &addr_hi);
+	addr_lo = 0xffff0000 | ((addr_hi >> (48 - 32)) << 4);
+	pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_LO, addr_lo);
+	pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, 0);
+}
+
 static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec_in, int type)
 {
 	struct pci_dn *pdn;
@@ -381,6 +398,7 @@
 	struct msi_desc *entry;
 	struct msi_msg msg;
 	int nvec = nvec_in;
+	int use_32bit_msi_hack = 0;
  
 	pdn = pci_get_pdn(pdev);
 	if (!pdn)
  
  
  
@@ -408,15 +426,31 @@
 	 */
 again:
 	if (type == PCI_CAP_ID_MSI) {
-		if (pdn->force_32bit_msi)
+		if (pdn->force_32bit_msi) {
 			rc = rtas_change_msi(pdn, RTAS_CHANGE_32MSI_FN, nvec);
-		else
+			if (rc < 0) {
+				/*
+				 * We only want to run the 32 bit MSI hack below if
+				 * the max bus speed is Gen2 speed
+				 */
+				if (pdev->bus->max_bus_speed != PCIE_SPEED_5_0GT)
+					return rc;
+
+				use_32bit_msi_hack = 1;
+			}
+		} else
+			rc = -1;
+
+		if (rc < 0)
 			rc = rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, nvec);
  
-		if (rc < 0 && !pdn->force_32bit_msi) {
+		if (rc < 0) {
 			pr_debug("rtas_msi: trying the old firmware call.\n");
 			rc = rtas_change_msi(pdn, RTAS_CHANGE_FN, nvec);
 		}
+
+		if (use_32bit_msi_hack && rc > 0)
+			rtas_hack_32bit_msi_gen2(pdev);
 	} else
 		rc = rtas_change_msi(pdn, RTAS_CHANGE_MSIX_FN, nvec);
...	...	@@ -374,6 +374,23 @@
374	374	return 0;
375	375	}
376	376
	377	+static void rtas_hack_32bit_msi_gen2(struct pci_dev *pdev)
	378	+{
	379	+ u32 addr_hi, addr_lo;
	380	+
	381	+ /*
	382	+ * We should only get in here for IODA1 configs. This is based on the
	383	+ * fact that we using RTAS for MSIs, we don't have the 32 bit MSI RTAS
	384	+ * support, and we are in a PCIe Gen2 slot.
	385	+ */
	386	+ dev_info(&pdev->dev,
	387	+ "rtas_msi: No 32 bit MSI firmware support, forcing 32 bit MSI\n");
	388	+ pci_read_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, &addr_hi);
	389	+ addr_lo = 0xffff0000 \| ((addr_hi >> (48 - 32)) << 4);
	390	+ pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_LO, addr_lo);
	391	+ pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, 0);
	392	+}
	393	+
377	394	static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec_in, int type)
378	395	{
379	396	struct pci_dn *pdn;
...	...	@@ -381,6 +398,7 @@
381	398	struct msi_desc *entry;
382	399	struct msi_msg msg;
383	400	int nvec = nvec_in;
	401	+ int use_32bit_msi_hack = 0;
384	402
385	403	pdn = pci_get_pdn(pdev);
386	404	if (!pdn)
387	405
388	406
389	407
...	...	@@ -408,15 +426,31 @@
408	426	*/
409	427	again:
410	428	if (type == PCI_CAP_ID_MSI) {
411		- if (pdn->force_32bit_msi)
	429	+ if (pdn->force_32bit_msi) {
412	430	rc = rtas_change_msi(pdn, RTAS_CHANGE_32MSI_FN, nvec);
413		- else
	431	+ if (rc < 0) {
	432	+ /*
	433	+ * We only want to run the 32 bit MSI hack below if
	434	+ * the max bus speed is Gen2 speed
	435	+ */
	436	+ if (pdev->bus->max_bus_speed != PCIE_SPEED_5_0GT)
	437	+ return rc;
	438	+
	439	+ use_32bit_msi_hack = 1;
	440	+ }
	441	+ } else
	442	+ rc = -1;
	443	+
	444	+ if (rc < 0)
414	445	rc = rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, nvec);
415	446
416		- if (rc < 0 && !pdn->force_32bit_msi) {
	447	+ if (rc < 0) {
417	448	pr_debug("rtas_msi: trying the old firmware call.\n");
418	449	rc = rtas_change_msi(pdn, RTAS_CHANGE_FN, nvec);
419	450	}
	451	+
	452	+ if (use_32bit_msi_hack && rc > 0)
	453	+ rtas_hack_32bit_msi_gen2(pdev);
420	454	} else
421	455	rc = rtas_change_msi(pdn, RTAS_CHANGE_MSIX_FN, nvec);
422	456