[Skiboot] [PATCH 2/2] PHB3: Emulate root complex pref 64-bits window

[Gavin Shan]

On Naples, the prefetchable 64-bits window on root complex can't
be altered. However, Linux kernel depends on that to detect the
window properly. Otherwise, the PCI device BARs that should be
covered by PHB's M64 window are allocated from M32. It leads to
unworkable CAPI card on Linux side.

This checks if the root complex's prefechable 64-bits window
can be changed or not. If not, a PCI config register filter for
it is registered to emulate the behaviour.

Reported-by: Vaibhav Jain <vaibhav at linux.vnet.ibm.com>
Suggested-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
Tested-by: Vaibhav Jain <vaibhav at linux.vnet.ibm.com>
---
 hw/phb3.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 70 insertions(+), 18 deletions(-)

diff --git a/hw/phb3.c b/hw/phb3.c
index 939e610..8ac9a1a 100644
--- a/hw/phb3.c
+++ b/hw/phb3.c
@@ -116,6 +116,36 @@ static bool phb3_fenced(struct phb3 *p)
 	return false;
 }
 
+static void phb3_pcicfg_filter_rc_pref_window(struct pci_device *pd __unused,
+					      struct pci_cfg_reg_filter *pcrf,
+					      uint32_t offset, uint32_t len,
+					      uint32_t *data,  bool write)
+{
+	uint8_t *pdata;
+	uint32_t i;
+
+	/* Cache whatever we received */
+	if (write) {
+		pdata = &pcrf->data[offset - pcrf->start];
+		for (i = 0; i < len; i++, pdata++)
+			*pdata = (uint8_t)(*data >> (8 * i));
+		return;
+	}
+
+	/* Return whatever we cached */
+	*data = 0;
+	pdata = &pcrf->data[offset - pcrf->start + len - 1];
+	for (i = len; i > 0; i--, pdata--) {
+		*data = (*data) << 8;
+		if (offset + i == PCI_CFG_PREF_MEM_BASE) {
+			*data |= ((*pdata & 0xf0) | 0x1);
+			continue;
+		}
+
+		*data |= *pdata;
+	}
+}
+
 /*
  * Configuration space access
  *
@@ -457,30 +487,53 @@ static void phb3_endpoint_init(struct phb *phb,
 static void phb3_check_device_quirks(struct phb *phb, struct pci_device *dev)
 {
 	struct phb3 *p = phb_to_phb3(phb);
-	u64 modectl;
 	u32 vdid;
 	u16 vendor, device;
 
-	/* For these adapters, if they are directly under the PHB, we
-	 * adjust some settings for performances
-	 */
-	xscom_read(p->chip_id, p->pe_xscom + 0x0b, &modectl);
+	if (dev->primary_bus != 0 &&
+	    dev->primary_bus != 1)
+		return;
 
 	pci_cfg_read32(phb, dev->bdfn, 0, &vdid);
 	vendor = vdid & 0xffff;
 	device = vdid >> 16;
-	if (vendor == 0x15b3 &&
-	    (device == 0x1003 ||	/* Travis3-EN (CX3) */
-	     device == 0x1011 ||	/* HydePark (ConnectIB) */
-	     device == 0x1013))	{	/* GlacierPark (CX4) */
-		/* Set disable_wr_scope_group bit */
-		modectl |= PPC_BIT(14);
-	} else {
-		/* Clear disable_wr_scope_group bit */
-		modectl &= ~PPC_BIT(14);
-	}
 
-	xscom_write(p->chip_id, p->pe_xscom + 0x0b, modectl);
+	if (dev->primary_bus == 1) {
+		u64 modectl;
+
+		/* For these adapters, if they are directly under the PHB, we
+		 * adjust some settings for performances
+		 */
+		xscom_read(p->chip_id, p->pe_xscom + 0x0b, &modectl);
+		if (vendor == 0x15b3 &&
+		    (device == 0x1003 ||	/* Travis3-EN (CX3) */
+		     device == 0x1011 ||	/* HydePark (ConnectIB) */
+		     device == 0x1013))	{	/* GlacierPark (CX4) */
+			/* Set disable_wr_scope_group bit */
+			modectl |= PPC_BIT(14);
+		} else {
+			/* Clear disable_wr_scope_group bit */
+			modectl &= ~PPC_BIT(14);
+		}
+
+		xscom_write(p->chip_id, p->pe_xscom + 0x0b, modectl);
+	} else if (dev->primary_bus == 0) {
+		if (vendor == 0x1014 && device == 0x03dc) {
+			uint32_t pref_hi, tmp;
+
+			pci_cfg_read32(phb, dev->bdfn,
+				PCI_CFG_PREF_MEM_BASE_U32, &pref_hi);
+			pci_cfg_write32(phb, dev->bdfn,
+				PCI_CFG_PREF_MEM_BASE_U32, ~pref_hi);
+			pci_cfg_read32(phb, dev->bdfn,
+				PCI_CFG_PREF_MEM_BASE_U32, &tmp);
+			if (tmp == pref_hi)
+				pci_add_cfg_reg_filter(dev,
+					PCI_CFG_PREF_MEM_BASE_U32, 12,
+					PCI_REG_FLAG_READ | PCI_REG_FLAG_WRITE,
+					phb3_pcicfg_filter_rc_pref_window);
+		}
+	}
 }
 
 static void phb3_device_init(struct phb *phb, struct pci_device *dev)
@@ -489,8 +542,7 @@ static void phb3_device_init(struct phb *phb, struct pci_device *dev)
 	int aercap = 0;
 
 	/* Some special adapter tweaks for devices directly under the PHB */
-	if (dev->primary_bus == 1)
-		phb3_check_device_quirks(phb, dev);
+	phb3_check_device_quirks(phb, dev);
 
 	/* Figure out PCIe & AER capability */
 	if (pci_has_cap(dev, PCI_CFG_CAP_ID_EXP, false)) {
-- 
2.1.0