[PATCH v6 2/5] PCI: Add Loongson PCI Controller support

Jiaxun Yang
2020-04-27T06:06:30Z

This controller can be found on Loongson-2K SoC, Loongson-3
systems with RS780E/LS7A PCH.

The RS780E part of code was previously located at
arch/mips/pci/ops-loongson3.c and now it can use generic PCI
driver implementation.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>

--
v2:
- Clean up according to rob's suggestions
- Claim that it can't work as a module
v3:
- Fix a typo
v4:
- More clean-ups: Drop flag check, use devfn
---
drivers/pci/controller/Kconfig | 10 +
drivers/pci/controller/Makefile | 1 +
drivers/pci/controller/pci-loongson.c | 251 ++++++++++++++++++++++++++
3 files changed, 262 insertions(+)
create mode 100644 drivers/pci/controller/pci-loongson.c

diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
index 91bfdb784829..ae36edb1d7db 100644
--- a/drivers/pci/controller/Kconfig
+++ b/drivers/pci/controller/Kconfig
@@ -258,6 +258,16 @@ config PCI_HYPERV_INTERFACE
The Hyper-V PCI Interface is a helper driver allows other drivers to
have a common interface with the Hyper-V PCI frontend driver.

+config PCI_LOONGSON
+ bool "LOONGSON PCI Controller"
+ depends on MACH_LOONGSON64 || COMPILE_TEST
+ depends on OF
+ depends on PCI_QUIRKS
+ default MACH_LOONGSON64
+ help
+ Say Y here if you want to enable PCI controller support on
+ Loongson systems.
+
source "drivers/pci/controller/dwc/Kconfig"
source "drivers/pci/controller/mobiveil/Kconfig"
source "drivers/pci/controller/cadence/Kconfig"
diff --git a/drivers/pci/controller/Makefile b/drivers/pci/controller/Makefile
index 158c59771824..fbac4b0190a0 100644
--- a/drivers/pci/controller/Makefile
+++ b/drivers/pci/controller/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_PCIE_MEDIATEK) += pcie-mediatek.o
obj-$(CONFIG_PCIE_TANGO_SMP8759) += pcie-tango.o
obj-$(CONFIG_VMD) += vmd.o
obj-$(CONFIG_PCIE_BRCMSTB) += pcie-brcmstb.o
+obj-$(CONFIG_PCI_LOONGSON) += pci-loongson.o
# pcie-hisi.o quirks are needed even without CONFIG_PCIE_DW
obj-y += dwc/
obj-y += mobiveil/
diff --git a/drivers/pci/controller/pci-loongson.c b/drivers/pci/controller/pci-loongson.c
new file mode 100644
index 000000000000..6cb8de384d36
--- /dev/null
+++ b/drivers/pci/controller/pci-loongson.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Loongson PCI Host Controller Driver
+ *
+ * Copyright (C) 2020 Jiaxun Yang <jiaxun.yang@flygoat.com>
+ */
+
+#include <linux/of_device.h>
+#include <linux/of_pci.h>
+#include <linux/pci.h>
+#include <linux/pci_ids.h>
+
+#include "../pci.h"
+
+/* Device IDs */
+#define DEV_PCIE_PORT_0 0x7a09
+#define DEV_PCIE_PORT_1 0x7a19
+#define DEV_PCIE_PORT_2 0x7a29
+
+#define DEV_LS2K_APB 0x7a02
+#define DEV_LS7A_CONF 0x7a10
+#define DEV_LS7A_LPC 0x7a0c
+
+#define FLAG_CFG0 BIT(0)
+#define FLAG_CFG1 BIT(1)
+#define FLAG_DEV_FIX BIT(2)
+
+struct loongson_pci {
+ void __iomem *cfg0_base;
+ void __iomem *cfg1_base;
+ struct platform_device *pdev;
+ u32 flags;
+};
+
+/* Fixup wrong class code in PCIe bridges */
+static void bridge_class_quirk(struct pci_dev *dev)
+{
+ dev->class = PCI_CLASS_BRIDGE_PCI << 8;
+}
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LOONGSON,
+ DEV_PCIE_PORT_0, bridge_class_quirk);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LOONGSON,
+ DEV_PCIE_PORT_1, bridge_class_quirk);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LOONGSON,
+ DEV_PCIE_PORT_2, bridge_class_quirk);
+
+static void system_bus_quirk(struct pci_dev *pdev)
+{
+ u16 tmp;
+
+ pdev->mmio_always_on = 1;
+ pdev->non_compliant_bars = 1;
+ /* Enable MEM & IO Decoding */
+ pci_read_config_word(pdev, PCI_STATUS, &tmp);
+ tmp |= PCI_COMMAND_IO | PCI_COMMAND_MEMORY;
+ pci_write_config_word(pdev, PCI_STATUS, tmp);
+}
+
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON,
+ DEV_LS2K_APB, system_bus_quirk);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON,
+ DEV_LS7A_CONF, system_bus_quirk);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON,
+ DEV_LS7A_LPC, system_bus_quirk);
+
+static void loongson_mrrs_quirk(struct pci_dev *dev)
+{
+ struct pci_bus *bus = dev->bus;
+ struct pci_dev *bridge;
+ static const struct pci_device_id bridge_devids[] = {
+ { PCI_VDEVICE(LOONGSON, DEV_PCIE_PORT_0) },
+ { PCI_VDEVICE(LOONGSON, DEV_PCIE_PORT_1) },
+ { PCI_VDEVICE(LOONGSON, DEV_PCIE_PORT_2) },
+ { 0, },
+ };
+
+
+ /* look for the matching bridge */
+ while (!pci_is_root_bus(bus)) {
+ bridge = bus->self;
+ bus = bus->parent;
+ /*
+ * Some Loongson PCIE ports has a h/w limitation of
+ * 256 bytes maximum read request size. It can't handle
+ * anything higher than this. So force this limit on
+ * any devices attached under these ports.
+ */
+ if (pci_match_id(bridge_devids, bridge)) {
+ if (pcie_get_readrq(dev) > 256) {
+ dev_info(&dev->dev, "limiting MRRS to 256\n");
+ pcie_set_readrq(dev, 256);
+ }
+ break;
+ }
+ }
+}
+DECLARE_PCI_FIXUP_ENABLE(PCI_ANY_ID, PCI_ANY_ID, loongson_mrrs_quirk);
+
+static void __iomem *cfg1_map(struct loongson_pci *priv, int bus,
+ unsigned int devfn, int where)
+{
+ unsigned long addroff = 0x0;
+
+ if (bus != 0)
+ addroff |= BIT(28); /* Type 1 Access */
+ addroff |= (where & 0xff) | ((where & 0xf00) << 16);
+ addroff |= (bus << 16) | (devfn << 8);
+ return priv->cfg1_base + addroff;
+}
+
+static void __iomem *cfg0_map(struct loongson_pci *priv, int bus,
+ unsigned int devfn, int where)
+{
+ unsigned long addroff = 0x0;
+
+ if (bus != 0)
+ addroff |= BIT(24); /* Type 1 Access */
+ addroff |= (bus << 16) | (devfn << 8) | where;
+ return priv->cfg0_base + addroff;
+}
+
+void __iomem *pci_loongson_map_bus(struct pci_bus *bus, unsigned int devfn,
+ int where)
+{
+ unsigned char busnum = bus->number;
+ struct pci_host_bridge *bridge = pci_find_host_bridge(bus);
+ struct loongson_pci *priv = pci_host_bridge_priv(bridge);
+
+ /*
+ * Do not read more than one device on the bus other than
+ * the host bridge.
+ */
+ if (bus->primary != 0 && PCI_SLOT(devfn) > 0 &&
+ priv->flags & FLAG_DEV_FIX)
+ return NULL;
+
+ /* CFG0 can only access standard space */
+ if (where < PCI_CFG_SPACE_SIZE && priv->cfg0_base)
+ return cfg0_map(priv, busnum, devfn, where);
+
+ /* CFG1 can access extended space */
+ if (where < PCI_CFG_SPACE_EXP_SIZE && priv->cfg1_base)
+ return cfg1_map(priv, busnum, devfn, where);
+
+ return NULL;
+}
+
+static int loongson_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
+{
+ int irq;
+ u8 val;
+
+ irq = of_irq_parse_and_map_pci(dev, slot, pin);
+ if (irq > 0)
+ return irq;
+
+ /* Care i8259 legacy systems */
+ pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &val);
+ /* i8259 only have 15 IRQs */
+ if (val > 15)
+ return 0;
+
+ return val;
+}
+
+/* H/w only accept 32-bit PCI operations */
+static struct pci_ops loongson_pci_ops = {
+ .map_bus = pci_loongson_map_bus,
+ .read = pci_generic_config_read32,
+ .write = pci_generic_config_write32,
+};
+
+static const struct of_device_id loongson_pci_of_match[] = {
+ { .compatible = "loongson,rs780e-pci",
+ .data = (void *)(FLAG_CFG0), },
+ { .compatible = "loongson,ls2k-pci",
+ .data = (void *)(FLAG_CFG0 | FLAG_CFG1 | FLAG_DEV_FIX), },
+ { .compatible = "loongson,ls7a-pci",
+ .data = (void *)(FLAG_CFG0 | FLAG_CFG1 | FLAG_DEV_FIX), },
+ {}
+};
+
+static int loongson_pci_probe(struct platform_device *pdev)
+{
+ struct loongson_pci *priv;
+ struct device *dev = &pdev->dev;
+ struct device_node *node = dev->of_node;
+ struct pci_host_bridge *bridge;
+ struct resource *regs;
+ int err;
+
+ if (!node)
+ return -ENODEV;
+
+ bridge = devm_pci_alloc_host_bridge(dev, sizeof(*priv));
+ if (!bridge)
+ return -ENODEV;
+
+ priv = pci_host_bridge_priv(bridge);
+ priv->pdev = pdev;
+ priv->flags = (unsigned long)of_device_get_match_data(dev);
+
+ regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!regs) {
+ dev_err(dev, "missing mem resources for cfg0\n");
+ return -EINVAL;
+ }
+
+ priv->cfg0_base = devm_pci_remap_cfg_resource(dev, regs);
+ if (IS_ERR(priv->cfg0_base))
+ return PTR_ERR(priv->cfg0_base);
+
+ /* CFG1 is optional */
+ if (priv->flags & FLAG_CFG1) {
+ regs = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+ if (!regs)
+ dev_info(dev, "missing mem resource for cfg1\n");
+ else {
+ priv->cfg1_base = devm_pci_remap_cfg_resource(dev, regs);
+ if (IS_ERR(priv->cfg1_base))
+ priv->cfg1_base = NULL;
+ }
+ }
+
+ err = pci_parse_request_of_pci_ranges(dev, &bridge->windows,
+ &bridge->dma_ranges, NULL);
+ if (err) {
+ dev_err(dev, "Failed to get bridge resources\n");
+ return err;
+ }
+
+ bridge->dev.parent = dev;
+ bridge->sysdata = priv;
+ bridge->ops = &loongson_pci_ops;
+ bridge->map_irq = loongson_map_irq;
+
+ err = pci_host_probe(bridge);
+ if (err)
+ return err;
+
+ return 0;
+}
+
+static struct platform_driver loongson_pci_driver = {
+ .driver = {
+ .name = "loongson-pci",
+ .of_match_table = loongson_pci_of_match,
+ },
+ .probe = loongson_pci_probe,
+};
+builtin_platform_driver(loongson_pci_driver);
--
2.26.0.rc2