Big fix for IDT NTB and Intel NTB LTR management support

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Merge tag 'ntb-5.11' of git://github.com/jonmason/ntb

Pull NTB fixes from Jon Mason:
 "Bug fix for IDT NTB and Intel NTB LTR management support"

* tag 'ntb-5.11' of git://github.com/jonmason/ntb:
  ntb: intel: add Intel NTB LTR vendor support for gen4 NTB
  ntb: idt: fix error check in ntb_hw_idt.c

drivers/ntb/hw/idt/ntb_hw_idt.c

@@ -2511,7 +2511,7 @@ static int idt_init_dbgfs(struct idt_ntb_dev *ndev)
 	/* If the top directory is not created then do nothing */
 	if (IS_ERR_OR_NULL(dbgfs_topdir)) {
 		dev_info(&ndev->ntb.pdev->dev, "Top DebugFS directory absent");
-		return PTR_ERR(dbgfs_topdir);
+		return PTR_ERR_OR_ZERO(dbgfs_topdir);
 	}
 
 	/* Create the info file node */
@@ -2756,7 +2756,7 @@ static int idt_pci_probe(struct pci_dev *pdev,
 
 	/* Allocate the memory for IDT NTB device data */
 	ndev = idt_create_dev(pdev, id);
-	if (IS_ERR_OR_NULL(ndev))
+	if (IS_ERR(ndev))
 		return PTR_ERR(ndev);
 
 	/* Initialize the basic PCI subsystem of the device */

drivers/ntb/hw/intel/ntb_hw_gen1.h

@@ -141,6 +141,7 @@
 #define NTB_HWERR_B2BDOORBELL_BIT14	BIT_ULL(2)
 #define NTB_HWERR_MSIX_VECTOR32_BAD	BIT_ULL(3)
 #define NTB_HWERR_BAR_ALIGN		BIT_ULL(4)
+#define NTB_HWERR_LTR_BAD		BIT_ULL(5)
 
 extern struct intel_b2b_addr xeon_b2b_usd_addr;
 extern struct intel_b2b_addr xeon_b2b_dsd_addr;

drivers/ntb/hw/intel/ntb_hw_gen4.c

@@ -177,8 +177,10 @@ int gen4_init_dev(struct intel_ntb_dev *ndev)
 
 	ndev->reg = &gen4_reg;
 
-	if (pdev_is_ICX(pdev))
+	if (pdev_is_ICX(pdev)) {
 		ndev->hwerr_flags |= NTB_HWERR_BAR_ALIGN;
+		ndev->hwerr_flags |= NTB_HWERR_LTR_BAD;
+	}
 
 	ppd1 = ioread32(ndev->self_mmio + GEN4_PPD1_OFFSET);
 	ndev->ntb.topo = gen4_ppd_topo(ndev, ppd1);
@@ -431,6 +433,25 @@ static int intel_ntb4_link_enable(struct ntb_dev *ntb,
 		dev_dbg(&ntb->pdev->dev,
 				"ignoring max_width %d\n", max_width);
 
+	if (!(ndev->hwerr_flags & NTB_HWERR_LTR_BAD)) {
+		u32 ltr;
+
+		/* Setup active snoop LTR values */
+		ltr = NTB_LTR_ACTIVE_REQMNT | NTB_LTR_ACTIVE_VAL | NTB_LTR_ACTIVE_LATSCALE;
+		/* Setup active non-snoop values */
+		ltr = (ltr << NTB_LTR_NS_SHIFT) | ltr;
+		iowrite32(ltr, ndev->self_mmio + GEN4_LTR_ACTIVE_OFFSET);
+
+		/* Setup idle snoop LTR values */
+		ltr = NTB_LTR_IDLE_VAL | NTB_LTR_IDLE_LATSCALE | NTB_LTR_IDLE_REQMNT;
+		/* Setup idle non-snoop values */
+		ltr = (ltr << NTB_LTR_NS_SHIFT) | ltr;
+		iowrite32(ltr, ndev->self_mmio + GEN4_LTR_IDLE_OFFSET);
+
+		/* setup PCIe LTR to active */
+		iowrite8(NTB_LTR_SWSEL_ACTIVE, ndev->self_mmio + GEN4_LTR_SWSEL_OFFSET);
+	}
+
 	ntb_ctl = NTB_CTL_E2I_BAR23_SNOOP | NTB_CTL_I2E_BAR23_SNOOP;
 	ntb_ctl |= NTB_CTL_E2I_BAR45_SNOOP | NTB_CTL_I2E_BAR45_SNOOP;
 	iowrite32(ntb_ctl, ndev->self_mmio + ndev->reg->ntb_ctl);
@@ -476,6 +497,10 @@ static int intel_ntb4_link_disable(struct ntb_dev *ntb)
 	lnkctl |= GEN4_LINK_CTRL_LINK_DISABLE;
 	iowrite16(lnkctl, ndev->self_mmio + GEN4_LINK_CTRL_OFFSET);
 
+	/* set LTR to idle */
+	if (!(ndev->hwerr_flags & NTB_HWERR_LTR_BAD))
+		iowrite8(NTB_LTR_SWSEL_IDLE, ndev->self_mmio + GEN4_LTR_SWSEL_OFFSET);
+
 	ndev->dev_up = 0;
 
 	return 0;

drivers/ntb/hw/intel/ntb_hw_gen4.h

@@ -35,6 +35,9 @@
 #define GEN4_IM_SPAD_SEM_OFFSET		0x00c0	/* SPAD hw semaphore */
 #define GEN4_IM_SPAD_STICKY_OFFSET	0x00c4  /* sticky SPAD */
 #define GEN4_IM_DOORBELL_OFFSET		0x0100  /* 0-31 doorbells */
+#define GEN4_LTR_SWSEL_OFFSET		0x30ec
+#define GEN4_LTR_ACTIVE_OFFSET		0x30f0
+#define GEN4_LTR_IDLE_OFFSET		0x30f4
 #define GEN4_EM_SPAD_OFFSET		0x8080
 /* note, link status is now in MMIO and not config space for NTB */
 #define GEN4_LINK_CTRL_OFFSET		0xb050
@@ -80,6 +83,18 @@
 
 #define NTB_SJC_FORCEDETECT		0x000004
 
+#define NTB_LTR_SWSEL_ACTIVE		0x0
+#define NTB_LTR_SWSEL_IDLE		0x1
+
+#define NTB_LTR_NS_SHIFT		16
+#define NTB_LTR_ACTIVE_VAL		0x0000  /* 0 us */
+#define NTB_LTR_ACTIVE_LATSCALE		0x0800  /* 1us scale */
+#define NTB_LTR_ACTIVE_REQMNT		0x8000  /* snoop req enable */
+
+#define NTB_LTR_IDLE_VAL		0x0258  /* 600 us */
+#define NTB_LTR_IDLE_LATSCALE		0x0800  /* 1us scale */
+#define NTB_LTR_IDLE_REQMNT		0x8000  /* snoop req enable */
+
 ssize_t ndev_ntb4_debugfs_read(struct file *filp, char __user *ubuf,
 				      size_t count, loff_t *offp);
 int gen4_init_dev(struct intel_ntb_dev *ndev);