[PATCH v2 2/2] pci: host: new driver for Axis ARTPEC-6 PCIe controller

[Niklas Cassel <niklas.cassel@axis.com>]

From: Niklas Cassel <niklas.cassel@axis.com>

The Axis ARTPEC-6 SoC integrates a PCIe controller from Synopsys.
This commit adds a new driver that provides the small glue
needed to use the existing Designware driver to make it work on
the Axis ARTPEC-6 SoC.

Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
---
Changes since v1:
 - Rename syscon DT node to be more descriptive
 - Use module_platform_driver macro

 MAINTAINERS                     |   9 ++
 drivers/pci/host/Kconfig        |   6 +
 drivers/pci/host/Makefile       |   1 +
 drivers/pci/host/pcie-artpec6.c | 293 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 309 insertions(+)
 create mode 100644 drivers/pci/host/pcie-artpec6.c

diff --git a/MAINTAINERS b/MAINTAINERS
index c18feb5..88d5443 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8772,6 +8772,15 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/pci/xgene-pci-msi.txt
 F:	drivers/pci/host/pci-xgene-msi.c
 
+PCIE DRIVER FOR AXIS ARTPEC
+M:	Niklas Cassel <niklas.cassel@axis.com>
+M:	Jesper Nilsson <jesper.nilsson@axis.com>
+L:	linux-arm-kernel@axis.com
+L:	linux-pci@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/pci/axis,artpec*
+F:	drivers/pci/host/*artpec*
+
 PCIE DRIVER FOR HISILICON
 M:	Zhou Wang <wangzhou1@hisilicon.com>
 M:	Gabriele Paoloni <gabriele.paoloni@huawei.com>
diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
index 5855f85..29e159a 100644
--- a/drivers/pci/host/Kconfig
+++ b/drivers/pci/host/Kconfig
@@ -244,4 +244,10 @@ config PCIE_ARMADA_8K
 	  Designware hardware and therefore the driver re-uses the
 	  Designware core functions to implement the driver.
 
+config PCIE_ARTPEC6
+	bool "Axis ARTPEC-6 PCIe controller"
+	depends on MACH_ARTPEC6
+	select PCIE_DW
+	select PCIEPORTBUS
+
 endmenu
diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile
index 9c8698e..5bc0af2 100644
--- a/drivers/pci/host/Makefile
+++ b/drivers/pci/host/Makefile
@@ -29,3 +29,4 @@ obj-$(CONFIG_PCIE_QCOM) += pcie-qcom.o
 obj-$(CONFIG_PCI_HOST_THUNDER_ECAM) += pci-thunder-ecam.o
 obj-$(CONFIG_PCI_HOST_THUNDER_PEM) += pci-thunder-pem.o
 obj-$(CONFIG_PCIE_ARMADA_8K) += pcie-armada8k.o
+obj-$(CONFIG_PCIE_ARTPEC6) += pcie-artpec6.o
diff --git a/drivers/pci/host/pcie-artpec6.c b/drivers/pci/host/pcie-artpec6.c
new file mode 100644
index 0000000..d53dbaf
--- /dev/null
+++ b/drivers/pci/host/pcie-artpec6.c
@@ -0,0 +1,293 @@
+/*
+ * PCIe host controller driver for Axis ARTPEC-6 SoC
+ *
+ * Based on work done by Phil Edworthy <phil@edworthys.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/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/resource.h>
+#include <linux/signal.h>
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+
+#include "pcie-designware.h"
+
+#define to_artpec6_pcie(x)	container_of(x, struct artpec6_pcie, pp)
+
+struct artpec6_pcie {
+	struct pcie_port	pp;
+	struct regmap		*regmap;
+	void __iomem		*phy_base;
+};
+
+/* PCIe Port Logic registers (memory-mapped) */
+#define PL_OFFSET			0x700
+#define PCIE_PHY_DEBUG_R0		(PL_OFFSET + 0x28)
+#define PCIE_PHY_DEBUG_R1		(PL_OFFSET + 0x2c)
+
+#define MISC_CONTROL_1_OFF		(PL_OFFSET + 0x1bc)
+#define  DBI_RO_WR_EN			1
+
+/* ARTPEC-6 specific registers */
+#define PCIECFG				0x18
+#define  PCIECFG_DBG_OEN		(1 << 24)
+#define  PCIECFG_CORE_RESET_REQ		(1 << 21)
+#define  PCIECFG_LTSSM_ENABLE		(1 << 20)
+#define  PCIECFG_CLKREQ_B		(1 << 11)
+#define  PCIECFG_REFCLK_ENABLE		(1 << 10)
+#define  PCIECFG_PLL_ENABLE		(1 << 9)
+#define  PCIECFG_PCLK_ENABLE		(1 << 8)
+#define  PCIECFG_RISRCREN		(1 << 4)
+#define  PCIECFG_MODE_TX_DRV_EN		(1 << 3)
+#define  PCIECFG_CISRREN		(1 << 2)
+#define  PCIECFG_MACRO_ENABLE		(1 << 0)
+
+#define NOCCFG				0x40
+#define NOCCFG_ENABLE_CLK_PCIE		(1 << 4)
+#define NOCCFG_POWER_PCIE_IDLEACK	(1 << 3)
+#define NOCCFG_POWER_PCIE_IDLE		(1 << 2)
+#define NOCCFG_POWER_PCIE_IDLEREQ	(1 << 1)
+
+#define PHY_STATUS			0x118
+#define PHY_COSPLLLOCK			(1 << 0)
+
+#define ARTPEC6_CPU_TO_BUS_ADDR		0x0FFFFFFF
+
+static int artpec6_pcie_establish_link(struct pcie_port *pp)
+{
+	struct artpec6_pcie *artpec6_pcie = to_artpec6_pcie(pp);
+	u32 val;
+	unsigned int retries;
+
+	/* Hold DW core in reset */
+	regmap_read(artpec6_pcie->regmap, PCIECFG, &val);
+	val |= PCIECFG_CORE_RESET_REQ;
+	regmap_write(artpec6_pcie->regmap, PCIECFG, val);
+
+	regmap_read(artpec6_pcie->regmap, PCIECFG, &val);
+	val |=  PCIECFG_RISRCREN |	/* Receiver term. 50 Ohm */
+		PCIECFG_MODE_TX_DRV_EN |
+		PCIECFG_CISRREN |	/* Reference clock term. 100 Ohm */
+		PCIECFG_MACRO_ENABLE;
+	val |= PCIECFG_REFCLK_ENABLE;
+	val &= ~PCIECFG_DBG_OEN;
+	val &= ~PCIECFG_CLKREQ_B;
+	regmap_write(artpec6_pcie->regmap, PCIECFG, val);
+	usleep_range(5000, 6000);
+
+	regmap_read(artpec6_pcie->regmap, NOCCFG, &val);
+	val |= NOCCFG_ENABLE_CLK_PCIE;
+	regmap_write(artpec6_pcie->regmap, NOCCFG, val);
+	usleep_range(20, 30);
+
+	regmap_read(artpec6_pcie->regmap, PCIECFG, &val);
+	val |= PCIECFG_PCLK_ENABLE | PCIECFG_PLL_ENABLE;
+	regmap_write(artpec6_pcie->regmap, PCIECFG, val);
+	usleep_range(6000, 7000);
+
+	regmap_read(artpec6_pcie->regmap, NOCCFG, &val);
+	val &= ~NOCCFG_POWER_PCIE_IDLEREQ;
+	regmap_write(artpec6_pcie->regmap, NOCCFG, val);
+
+	retries = 50;
+	do {
+		usleep_range(1000, 2000);
+		regmap_read(artpec6_pcie->regmap, NOCCFG, &val);
+		retries--;
+	} while (retries &&
+		(val & (NOCCFG_POWER_PCIE_IDLEACK | NOCCFG_POWER_PCIE_IDLE)));
+
+	retries = 50;
+	do {
+		usleep_range(1000, 2000);
+		val = readl(artpec6_pcie->phy_base + PHY_STATUS);
+		retries--;
+	} while (retries && !(val & PHY_COSPLLLOCK));
+
+	/* Take DW core out of reset */
+	regmap_read(artpec6_pcie->regmap, PCIECFG, &val);
+	val &= ~PCIECFG_CORE_RESET_REQ;
+	regmap_write(artpec6_pcie->regmap, PCIECFG, val);
+	usleep_range(100, 200);
+
+	/*
+	 * Enable writing to config regs. This is required as the Synopsys
+	 * driver changes the class code. That register needs DBI write enable.
+	 */
+	writel(DBI_RO_WR_EN, pp->dbi_base + MISC_CONTROL_1_OFF);
+
+	pp->io_base &= ARTPEC6_CPU_TO_BUS_ADDR;
+	pp->mem_base &= ARTPEC6_CPU_TO_BUS_ADDR;
+	pp->cfg0_base &= ARTPEC6_CPU_TO_BUS_ADDR;
+	pp->cfg1_base &= ARTPEC6_CPU_TO_BUS_ADDR;
+
+	/* setup root complex */
+	dw_pcie_setup_rc(pp);
+
+	/* assert LTSSM enable */
+	regmap_read(artpec6_pcie->regmap, PCIECFG, &val);
+	val |= PCIECFG_LTSSM_ENABLE;
+	regmap_write(artpec6_pcie->regmap, PCIECFG, val);
+
+	/* check if the link is up or not */
+	if (!dw_pcie_wait_for_link(pp))
+		return 0;
+
+	dev_dbg(pp->dev, "DEBUG_R0: 0x%08x, DEBUG_R1: 0x%08x\n",
+		readl(pp->dbi_base + PCIE_PHY_DEBUG_R0),
+		readl(pp->dbi_base + PCIE_PHY_DEBUG_R1));
+
+	return -ETIMEDOUT;
+}
+
+static void artpec6_pcie_enable_interrupts(struct pcie_port *pp)
+{
+	if (IS_ENABLED(CONFIG_PCI_MSI))
+		dw_pcie_msi_init(pp);
+}
+
+static void artpec6_pcie_host_init(struct pcie_port *pp)
+{
+	artpec6_pcie_establish_link(pp);
+	artpec6_pcie_enable_interrupts(pp);
+}
+
+static int artpec6_pcie_link_up(struct pcie_port *pp)
+{
+	u32 rc;
+
+	/*
+	 * Get status from Synopsys IP
+	 * link is debug bit 36, debug register 1 starts at bit 32
+	 */
+	rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1) & (0x1 << (36 - 32));
+	if (rc)
+		return 1;
+
+	return 0;
+}
+
+static struct pcie_host_ops artpec6_pcie_host_ops = {
+	.link_up = artpec6_pcie_link_up,
+	.host_init = artpec6_pcie_host_init,
+};
+
+static irqreturn_t artpec6_pcie_msi_handler(int irq, void *arg)
+{
+	struct pcie_port *pp = arg;
+
+	return dw_handle_msi_irq(pp);
+}
+
+static int __init artpec6_add_pcie_port(struct pcie_port *pp,
+					struct platform_device *pdev)
+{
+	int ret;
+
+	if (IS_ENABLED(CONFIG_PCI_MSI)) {
+		pp->msi_irq = platform_get_irq_byname(pdev, "msi");
+		if (pp->msi_irq <= 0) {
+			dev_err(&pdev->dev, "failed to get MSI irq\n");
+			return -ENODEV;
+		}
+
+		ret = devm_request_irq(&pdev->dev, pp->msi_irq,
+				       artpec6_pcie_msi_handler,
+				       IRQF_SHARED | IRQF_NO_THREAD,
+				       "artpec6-pcie-msi", pp);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to request MSI irq\n");
+			return ret;
+		}
+	}
+
+	pp->root_bus_nr = -1;
+	pp->ops = &artpec6_pcie_host_ops;
+
+	ret = dw_pcie_host_init(pp);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to initialize host\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int __init artpec6_pcie_probe(struct platform_device *pdev)
+{
+	struct artpec6_pcie *artpec6_pcie;
+	struct pcie_port *pp;
+	struct resource *dbi_base;
+	struct resource *phy_base;
+	int ret;
+
+	artpec6_pcie = devm_kzalloc(&pdev->dev, sizeof(*artpec6_pcie),
+				    GFP_KERNEL);
+	if (!artpec6_pcie)
+		return -ENOMEM;
+
+	pp = &artpec6_pcie->pp;
+	pp->dev = &pdev->dev;
+
+	dbi_base = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dbi");
+	pp->dbi_base = devm_ioremap_resource(&pdev->dev, dbi_base);
+	if (IS_ERR(pp->dbi_base)) {
+		ret = PTR_ERR(pp->dbi_base);
+		goto fail;
+	}
+
+	phy_base = platform_get_resource_byname(pdev, IORESOURCE_MEM, "phy");
+	artpec6_pcie->phy_base = devm_ioremap_resource(&pdev->dev, phy_base);
+	if (IS_ERR(artpec6_pcie->phy_base)) {
+		ret = PTR_ERR(artpec6_pcie->phy_base);
+		goto fail;
+	}
+
+	artpec6_pcie->regmap =
+		syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
+						"axis,syscon-pcie");
+	if (IS_ERR(artpec6_pcie->regmap)) {
+		ret = PTR_ERR(artpec6_pcie->regmap);
+		goto fail;
+	}
+
+	ret = artpec6_add_pcie_port(pp, pdev);
+	if (ret < 0)
+		goto fail;
+
+	platform_set_drvdata(pdev, artpec6_pcie);
+	return 0;
+
+fail:
+	return ret;
+}
+
+static const struct of_device_id artpec6_pcie_of_match[] = {
+	{ .compatible = "axis,artpec6-pcie", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, artpec6_pcie_of_match);
+
+static struct platform_driver artpec6_pcie_driver = {
+	.probe = artpec6_pcie_probe,
+	.driver = {
+		.name	= "artpec6-pcie",
+		.of_match_table = artpec6_pcie_of_match,
+	},
+};
+
+module_platform_driver(artpec6_pcie_driver);
+
+MODULE_AUTHOR("Niklas Cassel <niklas.cassel@axis.com>");
+MODULE_DESCRIPTION("Axis ARTPEC-6 PCIe host controller driver");
+MODULE_LICENSE("GPL v2");
-- 
2.1.4