[PATCH 2/4] MIPS: pci: Add driver for MT7621 PCIe controller

[Sergio Paracuellos <sergio.paracuellos@gmail.com>]

This patch adds a driver for the PCIe controller of MT7621 SoC.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
---
 arch/mips/pci/Makefile     |   1 +
 arch/mips/pci/pci-mt7621.c | 624 +++++++++++++++++++++++++++++++++++++
 arch/mips/ralink/Kconfig   |   9 +-
 3 files changed, 633 insertions(+), 1 deletion(-)
 create mode 100644 arch/mips/pci/pci-mt7621.c

diff --git a/arch/mips/pci/Makefile b/arch/mips/pci/Makefile
index f3eecc065e5c..178c550739c4 100644
--- a/arch/mips/pci/Makefile
+++ b/arch/mips/pci/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_PCI_AR2315)	+= pci-ar2315.o
 obj-$(CONFIG_SOC_AR71XX)	+= pci-ar71xx.o
 obj-$(CONFIG_PCI_AR724X)	+= pci-ar724x.o
 obj-$(CONFIG_PCI_XTALK_BRIDGE)	+= pci-xtalk-bridge.o
+obj-$(CONFIG_PCI_MT7621)	+= pci-mt7621.o
 #
 # These are still pretty much in the old state, watch, go blind.
 #
diff --git a/arch/mips/pci/pci-mt7621.c b/arch/mips/pci/pci-mt7621.c
new file mode 100644
index 000000000000..fe1945819d25
--- /dev/null
+++ b/arch/mips/pci/pci-mt7621.c
@@ -0,0 +1,624 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * BRIEF MODULE DESCRIPTION
+ *     PCI init for Ralink RT2880 solution
+ *
+ * Copyright 2007 Ralink Inc. (bruce_chang@ralinktech.com.tw)
+ *
+ * May 2007 Bruce Chang
+ * Initial Release
+ *
+ * May 2009 Bruce Chang
+ * support RT2880/RT3883 PCIe
+ *
+ * May 2011 Bruce Chang
+ * support RT6855/MT7620 PCIe
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_pci.h>
+#include <linux/of_platform.h>
+#include <linux/pci.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/sys_soc.h>
+
+/* MediaTek specific configuration registers */
+#define PCIE_FTS_NUM			0x70c
+#define PCIE_FTS_NUM_MASK		GENMASK(15, 8)
+#define PCIE_FTS_NUM_L0(x)		(((x) & 0xff) << 8)
+
+/* Host-PCI bridge registers */
+#define RALINK_PCI_PCICFG_ADDR		0x0000
+#define RALINK_PCI_PCIMSK_ADDR		0x000C
+#define RALINK_PCI_CONFIG_ADDR		0x0020
+#define RALINK_PCI_CONFIG_DATA		0x0024
+#define RALINK_PCI_MEMBASE		0x0028
+#define RALINK_PCI_IOBASE		0x002C
+
+/* PCIe RC control registers */
+#define MT7621_PCIE_OFFSET		0x2000
+#define MT7621_NEXT_PORT		0x1000
+
+#define RALINK_PCI_BAR0SETUP_ADDR	0x0010
+#define RALINK_PCI_ID			0x0030
+#define RALINK_PCI_CLASS		0x0034
+#define RALINK_PCI_SUBID		0x0038
+#define RALINK_PCI_STATUS		0x0050
+
+/* Some definition values */
+#define PCIE_REVISION_ID		BIT(0)
+#define PCIE_CLASS_CODE			(0x60400 << 8)
+#define PCIE_BAR_MAP_MAX		GENMASK(30, 16)
+#define PCIE_BAR_ENABLE			BIT(0)
+#define PCIE_PORT_INT_EN(x)		BIT(20 + (x))
+#define PCIE_PORT_LINKUP		BIT(0)
+
+#define PERST_DELAY_MS			100
+
+/**
+ * struct mt7621_pcie_port - PCIe port information
+ * @base: I/O mapped register base
+ * @list: port list
+ * @pcie: pointer to PCIe host info
+ * @clk: pointer to the port clock gate
+ * @phy: pointer to PHY control block
+ * @pcie_rst: pointer to port reset control
+ * @gpio_rst: gpio reset
+ * @slot: port slot
+ * @enabled: indicates if port is enabled
+ */
+struct mt7621_pcie_port {
+	void __iomem *base;
+	struct list_head list;
+	struct mt7621_pcie *pcie;
+	struct clk *clk;
+	struct phy *phy;
+	struct reset_control *pcie_rst;
+	struct gpio_desc *gpio_rst;
+	u32 slot;
+	bool enabled;
+};
+
+/**
+ * struct mt7621_pcie - PCIe host information
+ * @base: IO Mapped Register Base
+ * @io: IO resource
+ * @mem: pointer to non-prefetchable memory resource
+ * @dev: Pointer to PCIe device
+ * @io_map_base: virtual memory base address for io
+ * @ports: pointer to PCIe port information
+ * @resets_inverted: depends on chip revision
+ * reset lines are inverted.
+ */
+struct mt7621_pcie {
+	void __iomem *base;
+	struct device *dev;
+	struct resource io;
+	struct resource *mem;
+	unsigned long io_map_base;
+	struct list_head ports;
+	bool resets_inverted;
+};
+
+static inline u32 pcie_read(struct mt7621_pcie *pcie, u32 reg)
+{
+	return readl(pcie->base + reg);
+}
+
+static inline void pcie_write(struct mt7621_pcie *pcie, u32 val, u32 reg)
+{
+	writel(val, pcie->base + reg);
+}
+
+static inline void pcie_rmw(struct mt7621_pcie *pcie, u32 reg, u32 clr, u32 set)
+{
+	u32 val = readl(pcie->base + reg);
+
+	val &= ~clr;
+	val |= set;
+	writel(val, pcie->base + reg);
+}
+
+static inline u32 pcie_port_read(struct mt7621_pcie_port *port, u32 reg)
+{
+	return readl(port->base + reg);
+}
+
+static inline void pcie_port_write(struct mt7621_pcie_port *port,
+				   u32 val, u32 reg)
+{
+	writel(val, port->base + reg);
+}
+
+static inline u32 mt7621_pci_get_cfgaddr(unsigned int bus, unsigned int slot,
+					 unsigned int func, unsigned int where)
+{
+	return (((where & 0xF00) >> 8) << 24) | (bus << 16) | (slot << 11) |
+		(func << 8) | (where & 0xfc) | 0x80000000;
+}
+
+static void __iomem *mt7621_pcie_map_bus(struct pci_bus *bus,
+					 unsigned int devfn, int where)
+{
+	struct mt7621_pcie *pcie = bus->sysdata;
+	u32 address = mt7621_pci_get_cfgaddr(bus->number, PCI_SLOT(devfn),
+					     PCI_FUNC(devfn), where);
+
+	writel(address, pcie->base + RALINK_PCI_CONFIG_ADDR);
+
+	return pcie->base + RALINK_PCI_CONFIG_DATA + (where & 3);
+}
+
+struct pci_ops mt7621_pci_ops = {
+	.map_bus	= mt7621_pcie_map_bus,
+	.read		= pci_generic_config_read,
+	.write		= pci_generic_config_write,
+};
+
+static u32 read_config(struct mt7621_pcie *pcie, unsigned int dev, u32 reg)
+{
+	u32 address = mt7621_pci_get_cfgaddr(0, dev, 0, reg);
+
+	pcie_write(pcie, address, RALINK_PCI_CONFIG_ADDR);
+	return pcie_read(pcie, RALINK_PCI_CONFIG_DATA);
+}
+
+static void write_config(struct mt7621_pcie *pcie, unsigned int dev,
+			 u32 reg, u32 val)
+{
+	u32 address = mt7621_pci_get_cfgaddr(0, dev, 0, reg);
+
+	pcie_write(pcie, address, RALINK_PCI_CONFIG_ADDR);
+	pcie_write(pcie, val, RALINK_PCI_CONFIG_DATA);
+}
+
+static inline void mt7621_rst_gpio_pcie_assert(struct mt7621_pcie_port *port)
+{
+	if (port->gpio_rst)
+		gpiod_set_value(port->gpio_rst, 1);
+}
+
+static inline void mt7621_rst_gpio_pcie_deassert(struct mt7621_pcie_port *port)
+{
+	if (port->gpio_rst)
+		gpiod_set_value(port->gpio_rst, 0);
+}
+
+static inline bool mt7621_pcie_port_is_linkup(struct mt7621_pcie_port *port)
+{
+	return (pcie_port_read(port, RALINK_PCI_STATUS) & PCIE_PORT_LINKUP) != 0;
+}
+
+static inline void mt7621_control_assert(struct mt7621_pcie_port *port)
+{
+	struct mt7621_pcie *pcie = port->pcie;
+
+	if (pcie->resets_inverted)
+		reset_control_assert(port->pcie_rst);
+	else
+		reset_control_deassert(port->pcie_rst);
+}
+
+static inline void mt7621_control_deassert(struct mt7621_pcie_port *port)
+{
+	struct mt7621_pcie *pcie = port->pcie;
+
+	if (pcie->resets_inverted)
+		reset_control_deassert(port->pcie_rst);
+	else
+		reset_control_assert(port->pcie_rst);
+}
+
+static void setup_cm_memory_region(struct mt7621_pcie *pcie)
+{
+	struct resource *mem_resource = pcie->mem;
+	struct device *dev = pcie->dev;
+	resource_size_t mask;
+
+	if (mips_cps_numiocu(0)) {
+		/*
+		 * FIXME: hardware doesn't accept mask values with 1s after
+		 * 0s (e.g. 0xffef), so it would be great to warn if that's
+		 * about to happen
+		 */
+		mask = ~(mem_resource->end - mem_resource->start);
+
+		write_gcr_reg1_base(mem_resource->start);
+		write_gcr_reg1_mask(mask | CM_GCR_REGn_MASK_CMTGT_IOCU0);
+		dev_info(dev, "PCI coherence region base: 0x%08llx, mask/settings: 0x%08llx\n",
+			 (unsigned long long)read_gcr_reg1_base(),
+			 (unsigned long long)read_gcr_reg1_mask());
+	}
+}
+
+static int mt7621_pci_parse_request_of_pci_ranges(struct pci_host_bridge *host)
+{
+	struct mt7621_pcie *pcie = pci_host_bridge_priv(host);
+	struct device *dev = pcie->dev;
+	struct device_node *node = dev->of_node;
+	struct of_pci_range_parser parser;
+	struct resource_entry *entry;
+	struct of_pci_range range;
+	LIST_HEAD(res);
+
+	if (of_pci_range_parser_init(&parser, node)) {
+		dev_err(dev, "missing \"ranges\" property\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * IO_SPACE_LIMIT for MIPS is 0xffff but this platform uses IO at
+	 * upper address 0x001e160000. of_pci_range_to_resource does not work
+	 * well for MIPS platforms that don't define PCI_IOBASE, so set the IO
+	 * resource manually instead.
+	 */
+	for_each_of_pci_range(&parser, &range) {
+		switch (range.flags & IORESOURCE_TYPE_BITS) {
+		case IORESOURCE_IO:
+			pcie->io_map_base =
+				(unsigned long)ioremap(range.cpu_addr,
+						       range.size);
+			pcie->io.name = node->full_name;
+			pcie->io.flags = range.flags;
+			pcie->io.start = range.cpu_addr;
+			pcie->io.end = range.cpu_addr + range.size - 1;
+			pcie->io.parent = pcie->io.child = pcie->io.sibling = NULL;
+			set_io_port_base(pcie->io_map_base);
+			break;
+		}
+	}
+
+	entry = resource_list_first_type(&host->windows, IORESOURCE_MEM);
+	if (!entry) {
+		dev_err(dev, "Cannot get memory resource");
+		return -EINVAL;
+	}
+
+	pcie->mem = entry->res;
+	pci_add_resource(&res, &pcie->io);
+	pci_add_resource(&res, entry->res);
+	list_splice_init(&res, &host->windows);
+
+	return 0;
+}
+
+static int mt7621_pcie_parse_port(struct mt7621_pcie *pcie,
+				  int slot)
+{
+	struct mt7621_pcie_port *port;
+	struct device *dev = pcie->dev;
+	struct platform_device *pdev = to_platform_device(dev);
+	char name[10];
+
+	port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
+	if (!port)
+		return -ENOMEM;
+
+	port->base = devm_platform_ioremap_resource(pdev, slot + 1);
+	if (IS_ERR(port->base))
+		return PTR_ERR(port->base);
+
+	snprintf(name, sizeof(name), "pcie%d", slot);
+	port->clk = devm_clk_get(dev, name);
+	if (IS_ERR(port->clk)) {
+		dev_err(dev, "failed to get pcie%d clock\n", slot);
+		return PTR_ERR(port->clk);
+	}
+
+	snprintf(name, sizeof(name), "pcie%d", slot);
+	port->pcie_rst = devm_reset_control_get_exclusive(dev, name);
+	if (PTR_ERR(port->pcie_rst) == -EPROBE_DEFER) {
+		dev_err(dev, "failed to get pcie%d reset control\n", slot);
+		return PTR_ERR(port->pcie_rst);
+	}
+
+	snprintf(name, sizeof(name), "pcie-phy%d", slot);
+	port->phy = devm_phy_get(dev, name);
+	if (IS_ERR(port->phy) && slot != 1)
+		return PTR_ERR(port->phy);
+
+	port->gpio_rst = devm_gpiod_get_index_optional(dev, "reset", slot,
+						       GPIOD_OUT_LOW);
+	if (IS_ERR(port->gpio_rst)) {
+		dev_err(dev, "Failed to get GPIO for PCIe%d\n", slot);
+		return PTR_ERR(port->gpio_rst);
+	}
+
+	port->slot = slot;
+	port->pcie = pcie;
+
+	INIT_LIST_HEAD(&port->list);
+	list_add_tail(&port->list, &pcie->ports);
+
+	return 0;
+}
+
+static int mt7621_pcie_parse_dt(struct mt7621_pcie *pcie)
+{
+	struct device *dev = pcie->dev;
+	struct platform_device *pdev = to_platform_device(dev);
+	struct device_node *node = dev->of_node, *child;
+	int err;
+
+	pcie->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(pcie->base))
+		return PTR_ERR(pcie->base);
+
+	for_each_available_child_of_node(node, child) {
+		int slot;
+
+		err = of_pci_get_devfn(child);
+		if (err < 0) {
+			of_node_put(child);
+			dev_err(dev, "failed to parse devfn: %d\n", err);
+			return err;
+		}
+
+		slot = PCI_SLOT(err);
+
+		err = mt7621_pcie_parse_port(pcie, slot);
+		if (err) {
+			of_node_put(child);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static int mt7621_pcie_init_port(struct mt7621_pcie_port *port)
+{
+	struct mt7621_pcie *pcie = port->pcie;
+	struct device *dev = pcie->dev;
+	u32 slot = port->slot;
+	int err;
+
+	err = phy_init(port->phy);
+	if (err) {
+		dev_err(dev, "failed to initialize port%d phy\n", slot);
+		return err;
+	}
+
+	err = phy_power_on(port->phy);
+	if (err) {
+		dev_err(dev, "failed to power on port%d phy\n", slot);
+		phy_exit(port->phy);
+		return err;
+	}
+
+	port->enabled = true;
+
+	return 0;
+}
+
+static void mt7621_pcie_reset_assert(struct mt7621_pcie *pcie)
+{
+	struct mt7621_pcie_port *port;
+
+	list_for_each_entry(port, &pcie->ports, list) {
+		/* PCIe RC reset assert */
+		mt7621_control_assert(port);
+
+		/* PCIe EP reset assert */
+		mt7621_rst_gpio_pcie_assert(port);
+	}
+
+	msleep(PERST_DELAY_MS);
+}
+
+static void mt7621_pcie_reset_rc_deassert(struct mt7621_pcie *pcie)
+{
+	struct mt7621_pcie_port *port;
+
+	list_for_each_entry(port, &pcie->ports, list)
+		mt7621_control_deassert(port);
+}
+
+static void mt7621_pcie_reset_ep_deassert(struct mt7621_pcie *pcie)
+{
+	struct mt7621_pcie_port *port;
+
+	list_for_each_entry(port, &pcie->ports, list)
+		mt7621_rst_gpio_pcie_deassert(port);
+
+	msleep(PERST_DELAY_MS);
+}
+
+static void mt7621_pcie_init_ports(struct mt7621_pcie *pcie)
+{
+	struct device *dev = pcie->dev;
+	struct mt7621_pcie_port *port, *tmp;
+	int err;
+
+	mt7621_pcie_reset_assert(pcie);
+	mt7621_pcie_reset_rc_deassert(pcie);
+
+	list_for_each_entry_safe(port, tmp, &pcie->ports, list) {
+		u32 slot = port->slot;
+
+		if (slot == 1) {
+			port->enabled = true;
+			continue;
+		}
+
+		err = mt7621_pcie_init_port(port);
+		if (err) {
+			dev_err(dev, "Initiating port %d failed\n", slot);
+			list_del(&port->list);
+		}
+	}
+
+	mt7621_pcie_reset_ep_deassert(pcie);
+
+	tmp = NULL;
+	list_for_each_entry(port, &pcie->ports, list) {
+		u32 slot = port->slot;
+
+		if (!mt7621_pcie_port_is_linkup(port)) {
+			dev_err(dev, "pcie%d no card, disable it (RST & CLK)\n",
+				slot);
+			mt7621_control_assert(port);
+			clk_disable_unprepare(port->clk);
+			port->enabled = false;
+
+			if (slot == 0) {
+				tmp = port;
+				continue;
+			}
+
+			if (slot == 1 && tmp && !tmp->enabled)
+				phy_power_off(tmp->phy);
+		}
+	}
+}
+
+static void mt7621_pcie_enable_port(struct mt7621_pcie_port *port)
+{
+	struct mt7621_pcie *pcie = port->pcie;
+	u32 slot = port->slot;
+	u32 offset = MT7621_PCIE_OFFSET + (slot * MT7621_NEXT_PORT);
+	u32 val;
+
+	/* enable pcie interrupt */
+	val = pcie_read(pcie, RALINK_PCI_PCIMSK_ADDR);
+	val |= PCIE_PORT_INT_EN(slot);
+	pcie_write(pcie, val, RALINK_PCI_PCIMSK_ADDR);
+
+	/* map 2G DDR region */
+	pcie_write(pcie, PCIE_BAR_MAP_MAX | PCIE_BAR_ENABLE,
+		   offset + RALINK_PCI_BAR0SETUP_ADDR);
+
+	/* configure class code and revision ID */
+	pcie_write(pcie, PCIE_CLASS_CODE | PCIE_REVISION_ID,
+		   offset + RALINK_PCI_CLASS);
+}
+
+static int mt7621_pcie_enable_ports(struct mt7621_pcie *pcie)
+{
+	struct device *dev = pcie->dev;
+	struct mt7621_pcie_port *port;
+	u8 num_slots_enabled = 0;
+	u32 slot;
+	u32 val;
+	int err;
+
+	/* Setup MEMWIN and IOWIN */
+	pcie_write(pcie, 0xffffffff, RALINK_PCI_MEMBASE);
+	pcie_write(pcie, pcie->io.start, RALINK_PCI_IOBASE);
+
+	list_for_each_entry(port, &pcie->ports, list) {
+		if (port->enabled) {
+			err = clk_prepare_enable(port->clk);
+			if (err) {
+				dev_err(dev, "enabling clk pcie%d\n", slot);
+				return err;
+			}
+
+			mt7621_pcie_enable_port(port);
+			dev_info(dev, "PCIE%d enabled\n", port->slot);
+			num_slots_enabled++;
+		}
+	}
+
+	for (slot = 0; slot < num_slots_enabled; slot++) {
+		val = read_config(pcie, slot, PCI_COMMAND);
+		val |= PCI_COMMAND_MASTER;
+		write_config(pcie, slot, PCI_COMMAND, val);
+		/* configure RC FTS number to 250 when it leaves L0s */
+		val = read_config(pcie, slot, PCIE_FTS_NUM);
+		val &= ~PCIE_FTS_NUM_MASK;
+		val |= PCIE_FTS_NUM_L0(0x50);
+		write_config(pcie, slot, PCIE_FTS_NUM, val);
+	}
+
+	return 0;
+}
+
+static int mt7621_pcie_register_host(struct pci_host_bridge *host)
+{
+	struct mt7621_pcie *pcie = pci_host_bridge_priv(host);
+
+	host->ops = &mt7621_pci_ops;
+	host->sysdata = pcie;
+	return pci_host_probe(host);
+}
+
+static const struct soc_device_attribute mt7621_pci_quirks_match[] = {
+	{ .soc_id = "mt7621", .revision = "E2" }
+};
+
+static int mt7621_pci_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct soc_device_attribute *attr;
+	struct mt7621_pcie *pcie;
+	struct pci_host_bridge *bridge;
+	int err;
+
+	if (!dev->of_node)
+		return -ENODEV;
+
+	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*pcie));
+	if (!bridge)
+		return -ENOMEM;
+
+	pcie = pci_host_bridge_priv(bridge);
+	pcie->dev = dev;
+	platform_set_drvdata(pdev, pcie);
+	INIT_LIST_HEAD(&pcie->ports);
+
+	attr = soc_device_match(mt7621_pci_quirks_match);
+	if (attr)
+		pcie->resets_inverted = true;
+
+	err = mt7621_pcie_parse_dt(pcie);
+	if (err) {
+		dev_err(dev, "Parsing DT failed\n");
+		return err;
+	}
+
+	err = mt7621_pci_parse_request_of_pci_ranges(bridge);
+	if (err) {
+		dev_err(dev, "Error requesting pci resources from ranges");
+		return err;
+	}
+
+	/* set resources limits */
+	ioport_resource.start = pcie->io.start;
+	ioport_resource.end = pcie->io.end;
+
+	mt7621_pcie_init_ports(pcie);
+
+	err = mt7621_pcie_enable_ports(pcie);
+	if (err) {
+		dev_err(dev, "Error enabling pcie ports\n");
+		return err;
+	}
+
+	setup_cm_memory_region(pcie);
+
+	return mt7621_pcie_register_host(bridge);
+}
+
+static const struct of_device_id mt7621_pci_ids[] = {
+	{ .compatible = "mediatek,mt7621-pci" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mt7621_pci_ids);
+
+static struct platform_driver mt7621_pci_driver = {
+	.probe = mt7621_pci_probe,
+	.driver = {
+		.name = "mt7621-pci",
+		.of_match_table = of_match_ptr(mt7621_pci_ids),
+	},
+};
+builtin_platform_driver(mt7621_pci_driver);
diff --git a/arch/mips/ralink/Kconfig b/arch/mips/ralink/Kconfig
index ec4daa63c5e3..50e5a54f7d9e 100644
--- a/arch/mips/ralink/Kconfig
+++ b/arch/mips/ralink/Kconfig
@@ -56,7 +56,7 @@ choice
 		select MIPS_GIC
 		select COMMON_CLK
 		select CLKSRC_MIPS_GIC
-		select HAVE_PCI if PCI_MT7621
+		select HAVE_PCI
 		select SOC_BUS
 endchoice
 
@@ -101,4 +101,11 @@ choice
 
 endchoice
 
+config PCI_MT7621
+	bool "MediaTek MT7621 PCI Controller"
+	depends on RALINK && SOC_MT7621
+	select PCI_DRIVERS_GENERIC
+	help
+	  This selects a driver for the MediaTek MT7621 PCI Controller.
+
 endif
-- 
2.25.1