PCI: iproc: Convert link check to raw PCI config accessors

The current iproc driver host bridge controller driver requires struct
pci_bus to be created in order to carry out PCI link checks with standard
PCI config space accessors.

This struct pci_bus dependency is fictitious and burdens the driver with
unneeded constraints (eg to use separate APIs to create and scan the root
bus).

Add PCI raw config space accessors to the iproc driver and remove the
fictitious struct pci_bus dependency.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Jon Mason <jonmason@broadcom.com>

drivers/pci/host/pcie-iproc.c

@@ -452,14 +452,13 @@ static inline void iproc_pcie_apb_err_disable(struct pci_bus *bus,
  * Note access to the configuration registers are protected at the higher layer
  * by 'pci_lock' in drivers/pci/access.c
  */
-static void __iomem *iproc_pcie_map_cfg_bus(struct pci_bus *bus,
+static void __iomem *iproc_pcie_map_cfg_bus(struct iproc_pcie *pcie,
+					    int busno,
 					    unsigned int devfn,
 					    int where)
 {
-	struct iproc_pcie *pcie = iproc_data(bus);
 	unsigned slot = PCI_SLOT(devfn);
 	unsigned fn = PCI_FUNC(devfn);
-	unsigned busno = bus->number;
 	u32 val;
 	u16 offset;
 
@@ -499,6 +498,58 @@ static void __iomem *iproc_pcie_map_cfg_bus(struct pci_bus *bus,
 		return (pcie->base + offset);
 }
 
+static void __iomem *iproc_pcie_bus_map_cfg_bus(struct pci_bus *bus,
+						unsigned int devfn,
+						int where)
+{
+	return iproc_pcie_map_cfg_bus(iproc_data(bus), bus->number, devfn,
+				      where);
+}
+
+static int iproc_pci_raw_config_read32(struct iproc_pcie *pcie,
+				       unsigned int devfn, int where,
+				       int size, u32 *val)
+{
+	void __iomem *addr;
+
+	addr = iproc_pcie_map_cfg_bus(pcie, 0, devfn, where & ~0x3);
+	if (!addr) {
+		*val = ~0;
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	}
+
+	*val = readl(addr);
+
+	if (size <= 2)
+		*val = (*val >> (8 * (where & 3))) & ((1 << (size * 8)) - 1);
+
+	return PCIBIOS_SUCCESSFUL;
+}
+
+static int iproc_pci_raw_config_write32(struct iproc_pcie *pcie,
+					unsigned int devfn, int where,
+					int size, u32 val)
+{
+	void __iomem *addr;
+	u32 mask, tmp;
+
+	addr = iproc_pcie_map_cfg_bus(pcie, 0, devfn, where & ~0x3);
+	if (!addr)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+
+	if (size == 4) {
+		writel(val, addr);
+		return PCIBIOS_SUCCESSFUL;
+	}
+
+	mask = ~(((1 << (size * 8)) - 1) << ((where & 0x3) * 8));
+	tmp = readl(addr) & mask;
+	tmp |= val << ((where & 0x3) * 8);
+	writel(tmp, addr);
+
+	return PCIBIOS_SUCCESSFUL;
+}
+
 static int iproc_pcie_config_read32(struct pci_bus *bus, unsigned int devfn,
 				    int where, int size, u32 *val)
 {
@@ -524,7 +575,7 @@ static int iproc_pcie_config_write32(struct pci_bus *bus, unsigned int devfn,
 }
 
 static struct pci_ops iproc_pcie_ops = {
-	.map_bus = iproc_pcie_map_cfg_bus,
+	.map_bus = iproc_pcie_bus_map_cfg_bus,
 	.read = iproc_pcie_config_read32,
 	.write = iproc_pcie_config_write32,
 };
@@ -556,12 +607,11 @@ static void iproc_pcie_reset(struct iproc_pcie *pcie)
 	msleep(100);
 }
 
-static int iproc_pcie_check_link(struct iproc_pcie *pcie, struct pci_bus *bus)
+static int iproc_pcie_check_link(struct iproc_pcie *pcie)
 {
 	struct device *dev = pcie->dev;
-	u8 hdr_type;
-	u32 link_ctrl, class, val;
-	u16 pos = PCI_EXP_CAP, link_status;
+	u32 hdr_type, link_ctrl, link_status, class, val;
+	u16 pos = PCI_EXP_CAP;
 	bool link_is_active = false;
 
 	/*
@@ -578,7 +628,7 @@ static int iproc_pcie_check_link(struct iproc_pcie *pcie, struct pci_bus *bus)
 	}
 
 	/* make sure we are not in EP mode */
-	pci_bus_read_config_byte(bus, 0, PCI_HEADER_TYPE, &hdr_type);
+	iproc_pci_raw_config_read32(pcie,  0, PCI_HEADER_TYPE, 1, &hdr_type);
 	if ((hdr_type & 0x7f) != PCI_HEADER_TYPE_BRIDGE) {
 		dev_err(dev, "in EP mode, hdr=%#02x\n", hdr_type);
 		return -EFAULT;
@@ -588,13 +638,16 @@ static int iproc_pcie_check_link(struct iproc_pcie *pcie, struct pci_bus *bus)
 #define PCI_BRIDGE_CTRL_REG_OFFSET 0x43c
 #define PCI_CLASS_BRIDGE_MASK      0xffff00
 #define PCI_CLASS_BRIDGE_SHIFT     8
-	pci_bus_read_config_dword(bus, 0, PCI_BRIDGE_CTRL_REG_OFFSET, &class);
+	iproc_pci_raw_config_read32(pcie, 0, PCI_BRIDGE_CTRL_REG_OFFSET,
+				    4, &class);
 	class &= ~PCI_CLASS_BRIDGE_MASK;
 	class |= (PCI_CLASS_BRIDGE_PCI << PCI_CLASS_BRIDGE_SHIFT);
-	pci_bus_write_config_dword(bus, 0, PCI_BRIDGE_CTRL_REG_OFFSET, class);
+	iproc_pci_raw_config_write32(pcie, 0, PCI_BRIDGE_CTRL_REG_OFFSET,
+				     4, class);
 
 	/* check link status to see if link is active */
-	pci_bus_read_config_word(bus, 0, pos + PCI_EXP_LNKSTA, &link_status);
+	iproc_pci_raw_config_read32(pcie, 0, pos + PCI_EXP_LNKSTA,
+				    2, &link_status);
 	if (link_status & PCI_EXP_LNKSTA_NLW)
 		link_is_active = true;
 
@@ -603,20 +656,21 @@ static int iproc_pcie_check_link(struct iproc_pcie *pcie, struct pci_bus *bus)
 #define PCI_TARGET_LINK_SPEED_MASK    0xf
 #define PCI_TARGET_LINK_SPEED_GEN2    0x2
 #define PCI_TARGET_LINK_SPEED_GEN1    0x1
-		pci_bus_read_config_dword(bus, 0,
-					  pos + PCI_EXP_LNKCTL2,
+		iproc_pci_raw_config_read32(pcie, 0,
+					  pos + PCI_EXP_LNKCTL2, 4,
 					  &link_ctrl);
 		if ((link_ctrl & PCI_TARGET_LINK_SPEED_MASK) ==
 		    PCI_TARGET_LINK_SPEED_GEN2) {
 			link_ctrl &= ~PCI_TARGET_LINK_SPEED_MASK;
 			link_ctrl |= PCI_TARGET_LINK_SPEED_GEN1;
-			pci_bus_write_config_dword(bus, 0,
-					   pos + PCI_EXP_LNKCTL2,
-					   link_ctrl);
+			iproc_pci_raw_config_write32(pcie, 0,
+						pos + PCI_EXP_LNKCTL2,
+						4, link_ctrl);
 			msleep(100);
 
-			pci_bus_read_config_word(bus, 0, pos + PCI_EXP_LNKSTA,
-						 &link_status);
+			iproc_pci_raw_config_read32(pcie, 0,
+						pos + PCI_EXP_LNKSTA,
+						2, &link_status);
 			if (link_status & PCI_EXP_LNKSTA_NLW)
 				link_is_active = true;
 		}
@@ -1260,7 +1314,7 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res)
 	}
 	pcie->root_bus = bus;
 
-	ret = iproc_pcie_check_link(pcie, bus);
+	ret = iproc_pcie_check_link(pcie);
 	if (ret) {
 		dev_err(dev, "no PCIe EP device detected\n");
 		goto err_rm_root_bus;