[PATCH V2 2/2] powerpc/85xx: workaround for chips with MSI hardware errata

[Jia Hongtao]

The MPIC version 2.0 has a MSI errata (errata PIC1 of mpc8544), It causes
that neither MSI nor MSI-X can work fine. This is a workaround to allow
MSI-X to function properly.

Signed-off-by: Liu Shuo <soniccat.liu at gmail.com>
Signed-off-by: Li Yang <leoli at freescale.com>
Signed-off-by: Jia Hongtao <hongtao.jia at freescale.com>
---
Changes for V2:
* change the name of function mpic_has_errata() to mpic_has_erratum_pic1().
* move MSI_HW_ERRATA_ENDIAN define to fsl_msi.h with all other defines.

 arch/powerpc/sysdev/fsl_msi.c | 40 +++++++++++++++++++++++++++++++++++++---
 arch/powerpc/sysdev/fsl_msi.h |  2 ++
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/sysdev/fsl_msi.c b/arch/powerpc/sysdev/fsl_msi.c
index 178c994..ca1157a 100644
--- a/arch/powerpc/sysdev/fsl_msi.c
+++ b/arch/powerpc/sysdev/fsl_msi.c
@@ -98,8 +98,18 @@ static int fsl_msi_init_allocator(struct fsl_msi *msi_data)
 
 static int fsl_msi_check_device(struct pci_dev *pdev, int nvec, int type)
 {
-	if (type == PCI_CAP_ID_MSIX)
-		pr_debug("fslmsi: MSI-X untested, trying anyway.\n");
+	struct fsl_msi *msi;
+
+	if (type == PCI_CAP_ID_MSI) {
+		/*
+		 * MPIC version 2.0 has erratum PIC1. For now MSI
+		 * could not work. So check to prevent MSI from
+		 * being used on the board with this erratum.
+		 */
+		list_for_each_entry(msi, &msi_head, list)
+			if (msi->feature & MSI_HW_ERRATA_ENDIAN)
+				return -EINVAL;
+	}
 
 	return 0;
 }
@@ -142,7 +152,17 @@ static void fsl_compose_msi_msg(struct pci_dev *pdev, int hwirq,
 	msg->address_lo = lower_32_bits(address);
 	msg->address_hi = upper_32_bits(address);
 
-	msg->data = hwirq;
+	/*
+	 * MPIC version 2.0 has erratum PIC1. It causes
+	 * that neither MSI nor MSI-X can work fine.
+	 * This is a workaround to allow MSI-X to function
+	 * properly. It only works for MSI-X, we prevent
+	 * MSI on buggy chips in fsl_msi_check_device().
+	 */
+	if (msi_data->feature & MSI_HW_ERRATA_ENDIAN)
+		msg->data = __swab32(hwirq);
+	else
+		msg->data = hwirq;
 
 	pr_debug("%s: allocated srs: %d, ibs: %d\n",
 		__func__, hwirq / IRQS_PER_MSI_REG, hwirq % IRQS_PER_MSI_REG);
@@ -361,6 +381,15 @@ static int fsl_msi_setup_hwirq(struct fsl_msi *msi, struct platform_device *dev,
 	return 0;
 }
 
+/* MPIC version 2.0 has erratum PIC1 */
+static int mpic_has_erratum_pic1(void)
+{
+	if (fsl_mpic_primary_get_version() == 0x0200)
+		return 1;
+
+	return 0;
+}
+
 static const struct of_device_id fsl_of_msi_ids[];
 static int fsl_of_msi_probe(struct platform_device *dev)
 {
@@ -423,6 +452,11 @@ static int fsl_of_msi_probe(struct platform_device *dev)
 
 	msi->feature = features->fsl_pic_ip;
 
+	if ((features->fsl_pic_ip & FSL_PIC_IP_MASK) == FSL_PIC_IP_MPIC) {
+		if (mpic_has_erratum_pic1())
+			msi->feature |= MSI_HW_ERRATA_ENDIAN;
+	}
+
 	/*
 	 * Remember the phandle, so that we can match with any PCI nodes
 	 * that have an "fsl,msi" property.
diff --git a/arch/powerpc/sysdev/fsl_msi.h b/arch/powerpc/sysdev/fsl_msi.h
index 8225f86..7389e8e 100644
--- a/arch/powerpc/sysdev/fsl_msi.h
+++ b/arch/powerpc/sysdev/fsl_msi.h
@@ -25,6 +25,8 @@
 #define FSL_PIC_IP_IPIC   0x00000002
 #define FSL_PIC_IP_VMPIC  0x00000003
 
+#define MSI_HW_ERRATA_ENDIAN 0x00000010
+
 struct fsl_msi {
 	struct irq_domain *irqhost;
 
-- 
1.8.0