From 75b6f6487cedd0e4c8e07d68b68b8f85cd352bfe Mon Sep 17 00:00:00 2001
From: Dave Jiang <dave.jiang@intel.com>
Date: Mon, 23 Nov 2020 08:36:12 -0700
Subject: [PATCH] ntb: intel: add Intel NTB LTR vendor support for gen4 NTB
Git-commit: 75b6f6487cedd0e4c8e07d68b68b8f85cd352bfe
Patch-mainline: v5.11-rc1
References: jsc#SLE-12710

Intel NTB device has custom LTR management that is not compliant with the
PCIe standard. Add support to set LTR status triggered by link status
change.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/ntb/hw/intel/ntb_hw_gen1.h |  1 +
 drivers/ntb/hw/intel/ntb_hw_gen4.c | 27 ++++++++++++++++++++++++++-
 drivers/ntb/hw/intel/ntb_hw_gen4.h | 15 +++++++++++++++
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/drivers/ntb/hw/intel/ntb_hw_gen1.h b/drivers/ntb/hw/intel/ntb_hw_gen1.h
index 1b759942d8af..344249fc18d1 100644
--- a/drivers/ntb/hw/intel/ntb_hw_gen1.h
+++ b/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;
diff --git a/drivers/ntb/hw/intel/ntb_hw_gen4.c b/drivers/ntb/hw/intel/ntb_hw_gen4.c
index bc4541cbf8c6..fede05151f69 100644
--- a/drivers/ntb/hw/intel/ntb_hw_gen4.c
+++ b/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;
diff --git a/drivers/ntb/hw/intel/ntb_hw_gen4.h b/drivers/ntb/hw/intel/ntb_hw_gen4.h
index a868c788de02..3fcd3fdce9ed 100644
--- a/drivers/ntb/hw/intel/ntb_hw_gen4.h
+++ b/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);
-- 
2.26.2