MIPS: pci: Add MT7620a PCIE driver

The "a" version of the MT7620 has single port PCIE bus. The driver is
straightforward without any special magic required. The driver works on
MT7620 and MT7628. There are a few magic values that get written to the
pcie phy and a register of which we only know the name. I marked these
places as vodoo in the comments above the code.

Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11996/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 427 insertions, 0 deletions

diff --git a/arch/mips/pci/Makefile b/arch/mips/pci/Makefile
index 2eda01e..139ad1d 100644
--- a/arch/mips/pci/Makefile
+++ b/arch/mips/pci/Makefile
@@ -43,6 +43,7 @@ obj-$(CONFIG_SIBYTE_BCM1x80)	+= pci-bcm1480.o pci-bcm1480ht.o
 obj-$(CONFIG_SNI_RM)		+= fixup-sni.o ops-sni.o
 obj-$(CONFIG_LANTIQ)		+= fixup-lantiq.o
 obj-$(CONFIG_PCI_LANTIQ)	+= pci-lantiq.o ops-lantiq.o
+obj-$(CONFIG_SOC_MT7620)	+= pci-mt7620.o
 obj-$(CONFIG_SOC_RT288X)	+= pci-rt2880.o
 obj-$(CONFIG_SOC_RT3883)	+= pci-rt3883.o
 obj-$(CONFIG_TANBAC_TB0219)	+= fixup-tb0219.o
diff --git a/arch/mips/pci/pci-mt7620.c b/arch/mips/pci/pci-mt7620.c
new file mode 100644
index 0000000..a009ee4
--- /dev/null
+++ b/arch/mips/pci/pci-mt7620.c
@@ -0,0 +1,426 @@
+/*
+ *  Ralink MT7620A SoC PCI support
+ *
+ *  Copyright (C) 2007-2013 Bruce Chang (Mediatek)
+ *  Copyright (C) 2013-2016 John Crispin <blogic@openwrt.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License version 2 as published
+ *  by the Free Software Foundation.
+ */
+
+#include <linux/types.h>
+#include <linux/pci.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_pci.h>
+#include <linux/reset.h>
+#include <linux/platform_device.h>
+
+#include <asm/mach-ralink/ralink_regs.h>
+#include <asm/mach-ralink/mt7620.h>
+
+#define RALINK_PCI_IO_MAP_BASE		0x10160000
+#define RALINK_PCI_MEMORY_BASE		0x0
+
+#define RALINK_INT_PCIE0		4
+
+#define RALINK_CLKCFG1			0x30
+#define RALINK_GPIOMODE			0x60
+
+#define PPLL_CFG1			0x9c
+#define PDRV_SW_SET			BIT(23)
+
+#define PPLL_DRV			0xa0
+#define PDRV_SW_SET			(1<<31)
+#define LC_CKDRVPD			(1<<19)
+#define LC_CKDRVOHZ			(1<<18)
+#define LC_CKDRVHZ			(1<<17)
+#define LC_CKTEST			(1<<16)
+
+/* PCI Bridge registers */
+#define RALINK_PCI_PCICFG_ADDR		0x00
+#define PCIRST				BIT(1)
+
+#define RALINK_PCI_PCIENA		0x0C
+#define PCIINT2				BIT(20)
+
+#define RALINK_PCI_CONFIG_ADDR		0x20
+#define RALINK_PCI_CONFIG_DATA_VIRT_REG	0x24
+#define RALINK_PCI_MEMBASE		0x28
+#define RALINK_PCI_IOBASE		0x2C
+
+/* PCI RC registers */
+#define RALINK_PCI0_BAR0SETUP_ADDR	0x10
+#define RALINK_PCI0_IMBASEBAR0_ADDR	0x18
+#define RALINK_PCI0_ID			0x30
+#define RALINK_PCI0_CLASS		0x34
+#define RALINK_PCI0_SUBID		0x38
+#define RALINK_PCI0_STATUS		0x50
+#define PCIE_LINK_UP_ST			BIT(0)
+
+#define PCIEPHY0_CFG			0x90
+
+#define RALINK_PCIEPHY_P0_CTL_OFFSET	0x7498
+#define RALINK_PCIE0_CLK_EN		(1 << 26)
+
+#define BUSY				0x80000000
+#define WAITRETRY_MAX			10
+#define WRITE_MODE			(1UL << 23)
+#define DATA_SHIFT			0
+#define ADDR_SHIFT			8
+
+
+static void __iomem *bridge_base;
+static void __iomem *pcie_base;
+
+static struct reset_control *rstpcie0;
+
+static inline void bridge_w32(u32 val, unsigned reg)
+{
+	iowrite32(val, bridge_base + reg);
+}
+
+static inline u32 bridge_r32(unsigned reg)
+{
+	return ioread32(bridge_base + reg);
+}
+
+static inline void pcie_w32(u32 val, unsigned reg)
+{
+	iowrite32(val, pcie_base + reg);
+}
+
+static inline u32 pcie_r32(unsigned reg)
+{
+	return ioread32(pcie_base + reg);
+}
+
+static inline void pcie_m32(u32 clr, u32 set, unsigned reg)
+{
+	u32 val = pcie_r32(reg);
+
+	val &= ~clr;
+	val |= set;
+	pcie_w32(val, reg);
+}
+
+static int wait_pciephy_busy(void)
+{
+	unsigned long reg_value = 0x0, retry = 0;
+
+	while (1) {
+		reg_value = pcie_r32(PCIEPHY0_CFG);
+
+		if (reg_value & BUSY)
+			mdelay(100);
+		else
+			break;
+		if (retry++ > WAITRETRY_MAX) {
+			printk(KERN_WARN "PCIE-PHY retry failed.\n");
+			return -1;
+		}
+	}
+	return 0;
+}
+
+static void pcie_phy(unsigned long addr, unsigned long val)
+{
+	wait_pciephy_busy();
+	pcie_w32(WRITE_MODE | (val << DATA_SHIFT) | (addr << ADDR_SHIFT),
+		 PCIEPHY0_CFG);
+	mdelay(1);
+	wait_pciephy_busy();
+}
+
+static int pci_config_read(struct pci_bus *bus, unsigned int devfn, int where,
+			   int size, u32 *val)
+{
+	unsigned int slot = PCI_SLOT(devfn);
+	u8 func = PCI_FUNC(devfn);
+	u32 address;
+	u32 data;
+	u32 num = 0;
+
+	if (bus)
+		num = bus->number;
+
+	address = (((where & 0xF00) >> 8) << 24) | (num << 16) | (slot << 11) |
+		  (func << 8) | (where & 0xfc) | 0x80000000;
+	bridge_w32(address, RALINK_PCI_CONFIG_ADDR);
+	data = bridge_r32(RALINK_PCI_CONFIG_DATA_VIRT_REG);
+
+	switch (size) {
+	case 1:
+		*val = (data >> ((where & 3) << 3)) & 0xff;
+		break;
+	case 2:
+		*val = (data >> ((where & 3) << 3)) & 0xffff;
+		break;
+	case 4:
+		*val = data;
+		break;
+	}
+
+	return PCIBIOS_SUCCESSFUL;
+}
+
+static int pci_config_write(struct pci_bus *bus, unsigned int devfn, int where,
+			    int size, u32 val)
+{
+	unsigned int slot = PCI_SLOT(devfn);
+	u8 func = PCI_FUNC(devfn);
+	u32 address;
+	u32 data;
+	u32 num = 0;
+
+	if (bus)
+		num = bus->number;
+
+	address = (((where & 0xF00) >> 8) << 24) | (num << 16) | (slot << 11) |
+		  (func << 8) | (where & 0xfc) | 0x80000000;
+	bridge_w32(address, RALINK_PCI_CONFIG_ADDR);
+	data = bridge_r32(RALINK_PCI_CONFIG_DATA_VIRT_REG);
+
+	switch (size) {
+	case 1:
+		data = (data & ~(0xff << ((where & 3) << 3))) |
+			(val << ((where & 3) << 3));
+		break;
+	case 2:
+		data = (data & ~(0xffff << ((where & 3) << 3))) |
+			(val << ((where & 3) << 3));
+		break;
+	case 4:
+		data = val;
+		break;
+	}
+
+	bridge_w32(data, RALINK_PCI_CONFIG_DATA_VIRT_REG);
+
+	return PCIBIOS_SUCCESSFUL;
+}
+
+struct pci_ops mt7620_pci_ops = {
+	.read	= pci_config_read,
+	.write	= pci_config_write,
+};
+
+static struct resource mt7620_res_pci_mem1;
+static struct resource mt7620_res_pci_io1;
+struct pci_controller mt7620_controller = {
+	.pci_ops	= &mt7620_pci_ops,
+	.mem_resource	= &mt7620_res_pci_mem1,
+	.mem_offset	= 0x00000000UL,
+	.io_resource	= &mt7620_res_pci_io1,
+	.io_offset	= 0x00000000UL,
+	.io_map_base	= 0xa0000000,
+};
+
+static int mt7620_pci_hw_init(struct platform_device *pdev)
+{
+	/* bypass PCIe DLL */
+	pcie_phy(0x0, 0x80);
+	pcie_phy(0x1, 0x04);
+
+	/* Elastic buffer control */
+	pcie_phy(0x68, 0xB4);
+
+	/* put core into reset */
+	pcie_m32(0, PCIRST, RALINK_PCI_PCICFG_ADDR);
+	reset_control_assert(rstpcie0);
+
+	/* disable power and all clocks */
+	rt_sysc_m32(RALINK_PCIE0_CLK_EN, 0, RALINK_CLKCFG1);
+	rt_sysc_m32(LC_CKDRVPD, PDRV_SW_SET, PPLL_DRV);
+
+	/* bring core out of reset */
+	reset_control_deassert(rstpcie0);
+	rt_sysc_m32(0, RALINK_PCIE0_CLK_EN, RALINK_CLKCFG1);
+	mdelay(100);
+
+	if (!(rt_sysc_r32(PPLL_CFG1) & PDRV_SW_SET)) {
+		dev_err(&pdev->dev, "MT7620 PPLL unlock\n");
+		reset_control_assert(rstpcie0);
+		rt_sysc_m32(RALINK_PCIE0_CLK_EN, 0, RALINK_CLKCFG1);
+		return -1;
+	}
+
+	/* power up the bus */
+	rt_sysc_m32(LC_CKDRVHZ | LC_CKDRVOHZ, LC_CKDRVPD | PDRV_SW_SET,
+		    PPLL_DRV);
+
+	return 0;
+}
+
+static int mt7628_pci_hw_init(struct platform_device *pdev)
+{
+	u32 val = 0;
+
+	/* bring the core out of reset */
+	rt_sysc_m32(BIT(16), 0, RALINK_GPIOMODE);
+	reset_control_deassert(rstpcie0);
+
+	/* enable the pci clk */
+	rt_sysc_m32(0, RALINK_PCIE0_CLK_EN, RALINK_CLKCFG1);
+	mdelay(100);
+
+	/* voodoo from the SDK driver */
+	pcie_m32(~0xff, 0x5, RALINK_PCIEPHY_P0_CTL_OFFSET);
+
+	pci_config_read(NULL, 0, 0x70c, 4, &val);
+	val &= ~(0xff) << 8;
+	val |= 0x50 << 8;
+	pci_config_write(NULL, 0, 0x70c, 4, val);
+
+	pci_config_read(NULL, 0, 0x70c, 4, &val);
+	dev_err(&pdev->dev, "Port 0 N_FTS = %x\n", (unsigned int) val);
+
+	return 0;
+}
+
+static int mt7620_pci_probe(struct platform_device *pdev)
+{
+	struct resource *bridge_res = platform_get_resource(pdev,
+							    IORESOURCE_MEM, 0);
+	struct resource *pcie_res = platform_get_resource(pdev,
+							  IORESOURCE_MEM, 1);
+	u32 val = 0;
+
+	rstpcie0 = devm_reset_control_get(&pdev->dev, "pcie0");
+	if (IS_ERR(rstpcie0))
+		return PTR_ERR(rstpcie0);
+
+	bridge_base = devm_ioremap_resource(&pdev->dev, bridge_res);
+	if (!bridge_base)
+		return -ENOMEM;
+
+	pcie_base = devm_ioremap_resource(&pdev->dev, pcie_res);
+	if (!pcie_base)
+		return -ENOMEM;
+
+	iomem_resource.start = 0;
+	iomem_resource.end = ~0;
+	ioport_resource.start = 0;
+	ioport_resource.end = ~0;
+
+	/* bring up the pci core */
+	switch (ralink_soc) {
+	case MT762X_SOC_MT7620A:
+		if (mt7620_pci_hw_init(pdev))
+			return -1;
+		break;
+
+	case MT762X_SOC_MT7628AN:
+		if (mt7628_pci_hw_init(pdev))
+			return -1;
+		break;
+
+	default:
+		dev_err(&pdev->dev, "pcie is not supported on this hardware\n");
+		return -1;
+	}
+	mdelay(50);
+
+	/* enable write access */
+	pcie_m32(PCIRST, 0, RALINK_PCI_PCICFG_ADDR);
+	mdelay(100);
+
+	/* check if there is a card present */
+	if ((pcie_r32(RALINK_PCI0_STATUS) & PCIE_LINK_UP_ST) == 0) {
+		reset_control_assert(rstpcie0);
+		rt_sysc_m32(RALINK_PCIE0_CLK_EN, 0, RALINK_CLKCFG1);
+		if (ralink_soc == MT762X_SOC_MT7620A)
+			rt_sysc_m32(LC_CKDRVPD, PDRV_SW_SET, PPLL_DRV);
+		dev_err(&pdev->dev, "PCIE0 no card, disable it(RST&CLK)\n");
+		return -1;
+	}
+
+	/* setup ranges */
+	bridge_w32(0xffffffff, RALINK_PCI_MEMBASE);
+	bridge_w32(RALINK_PCI_IO_MAP_BASE, RALINK_PCI_IOBASE);
+
+	pcie_w32(0x7FFF0001, RALINK_PCI0_BAR0SETUP_ADDR);
+	pcie_w32(RALINK_PCI_MEMORY_BASE, RALINK_PCI0_IMBASEBAR0_ADDR);
+	pcie_w32(0x06040001, RALINK_PCI0_CLASS);
+
+	/* enable interrupts */
+	pcie_m32(0, PCIINT2, RALINK_PCI_PCIENA);
+
+	/* voodoo from the SDK driver */
+	pci_config_read(NULL, 0, 4, 4, &val);
+	pci_config_write(NULL, 0, 4, 4, val | 0x7);
+
+	pci_load_of_ranges(&mt7620_controller, pdev->dev.of_node);
+	register_pci_controller(&mt7620_controller);
+
+	return 0;
+}
+
+int __init pcibios_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
+{
+	u16 cmd;
+	u32 val;
+	int irq = 0;
+
+	if ((dev->bus->number == 0) && (slot == 0)) {
+		pcie_w32(0x7FFF0001, RALINK_PCI0_BAR0SETUP_ADDR);
+		pci_config_write(dev->bus, 0, PCI_BASE_ADDRESS_0, 4,
+				 RALINK_PCI_MEMORY_BASE);
+		pci_config_read(dev->bus, 0, PCI_BASE_ADDRESS_0, 4, &val);
+	} else if ((dev->bus->number == 1) && (slot == 0x0)) {
+		irq = RALINK_INT_PCIE0;
+	} else {
+		dev_err(&dev->dev, "no irq found - bus=0x%x, slot = 0x%x\n",
+			dev->bus->number, slot);
+		return 0;
+	}
+	dev_err(&dev->dev, "card - bus=0x%x, slot = 0x%x irq=%d\n",
+		dev->bus->number, slot, irq);
+
+	/* configure the cache line size to 0x14 */
+	pci_write_config_byte(dev, PCI_CACHE_LINE_SIZE, 0x14);
+
+	/* configure latency timer to 0xff */
+	pci_write_config_byte(dev, PCI_LATENCY_TIMER, 0xff);
+	pci_read_config_word(dev, PCI_COMMAND, &cmd);
+
+	/* setup the slot */
+	cmd = cmd | PCI_COMMAND_MASTER | PCI_COMMAND_IO | PCI_COMMAND_MEMORY;
+	pci_write_config_word(dev, PCI_COMMAND, cmd);
+	pci_write_config_byte(dev, PCI_INTERRUPT_LINE, dev->irq);
+
+	return irq;
+}
+
+int pcibios_plat_dev_init(struct pci_dev *dev)
+{
+	return 0;
+}
+
+static const struct of_device_id mt7620_pci_ids[] = {
+	{ .compatible = "mediatek,mt7620-pci" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mt7620_pci_ids);
+
+static struct platform_driver mt7620_pci_driver = {
+	.probe = mt7620_pci_probe,
+	.driver = {
+		.name = "mt7620-pci",
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(mt7620_pci_ids),
+	},
+};
+
+static int __init mt7620_pci_init(void)
+{
+	return platform_driver_register(&mt7620_pci_driver);
+}
+
+arch_initcall(mt7620_pci_init);