[PATCH v2 2/6] PCI: apple: Add initial hardware bring-up

[Alyssa Rosenzweig <alyssa@rosenzweig.io>]

Add a minimal driver to bring up the PCIe bus on Apple system-on-chips,
particularly the Apple M1. This driver exposes the internal bus used for
the USB type-A ports, Ethernet, Wi-Fi, and Bluetooth. Bringing up the
radios requires additional drivers beyond what's necessary for PCIe
itself.

In this patch, a minimal driver is added that brings up the PCIe bus on
probe. This logic is derived from Corellium's driver via Mark Kettenis's
U-Boot patches.

Co-developed-by: Stan Skowronek <stan@corellium.com>
Signed-off-by: Stan Skowronek <stan@corellium.com>
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
---
 MAINTAINERS                         |   6 +
 drivers/pci/controller/Kconfig      |  12 ++
 drivers/pci/controller/Makefile     |   1 +
 drivers/pci/controller/pcie-apple.c | 251 ++++++++++++++++++++++++++++
 4 files changed, 270 insertions(+)
 create mode 100644 drivers/pci/controller/pcie-apple.c

diff --git a/MAINTAINERS b/MAINTAINERS
index a5687cf6f925..47cb3d320c56 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1269,6 +1269,12 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/iommu/apple,dart.yaml
 F:	drivers/iommu/apple-dart.c
 
+APPLE PCIE CONTROLLER DRIVER
+M:	Alyssa Rosenzweig <alyssa@rosenzweig.io>
+L:	linux-pci@vger.kernel.org
+S:	Maintained
+F:	drivers/pci/controller/pcie-apple.c
+
 APPLE SMC DRIVER
 M:	Henrik Rydberg <rydberg@bitmath.org>
 L:	linux-hwmon@vger.kernel.org
diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
index 326f7d13024f..814833a8120d 100644
--- a/drivers/pci/controller/Kconfig
+++ b/drivers/pci/controller/Kconfig
@@ -312,6 +312,18 @@ config PCIE_HISI_ERR
 	  Say Y here if you want error handling support
 	  for the PCIe controller's errors on HiSilicon HIP SoCs
 
+config PCIE_APPLE
+	tristate "Apple PCIe controller"
+	depends on ARCH_APPLE || COMPILE_TEST
+	depends on OF
+	depends on PCI_MSI_IRQ_DOMAIN
+	help
+	  Say Y here if you want to enable PCIe controller support on Apple
+	  system-on-chips, like the Apple M1. This is required for the USB
+	  type-A ports, Ethernet, Wi-Fi, and Bluetooth.
+
+	  If unsure, say Y if you have an Apple Silicon system.
+
 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 aaf30b3dcc14..f9d40bad932c 100644
--- a/drivers/pci/controller/Makefile
+++ b/drivers/pci/controller/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_VMD) += vmd.o
 obj-$(CONFIG_PCIE_BRCMSTB) += pcie-brcmstb.o
 obj-$(CONFIG_PCI_LOONGSON) += pci-loongson.o
 obj-$(CONFIG_PCIE_HISI_ERR) += pcie-hisi-error.o
+obj-$(CONFIG_PCIE_APPLE) += pcie-apple.o
 # pcie-hisi.o quirks are needed even without CONFIG_PCIE_DW
 obj-y				+= dwc/
 obj-y				+= mobiveil/
diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
new file mode 100644
index 000000000000..a1efcc3373ea
--- /dev/null
+++ b/drivers/pci/controller/pcie-apple.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PCIe host bridge driver for Apple system-on-chips.
+ *
+ * The HW is ECAM compliant, so once the controller is initialized, the driver
+ * mostly only needs MSI handling. Initialization requires enabling power and
+ * clocks, along with a number of register pokes.
+ *
+ * Copyright (C) 2021 Alyssa Rosenzweig <alyssa@rosenzweig.io>
+ * Copyright (C) 2021 Google LLC
+ * Copyright (C) 2021 Corellium LLC
+ * Copyright (C) 2021 Mark Kettenis <kettenis@openbsd.org>
+ *
+ * Author: Alyssa Rosenzweig <alyssa@rosenzweig.io>
+ * Author: Marc Zyngier <maz@kernel.org>
+ */
+
+#include <linux/kernel.h>
+#include <linux/irqdomain.h>
+#include <linux/module.h>
+#include <linux/msi.h>
+#include <linux/of_irq.h>
+#include <linux/pci-ecam.h>
+#include <linux/iopoll.h>
+#include <linux/gpio/consumer.h>
+
+#define CORE_RC_PHYIF_CTL		0x00024
+#define   CORE_RC_PHYIF_CTL_RUN		BIT(0)
+#define CORE_RC_PHYIF_STAT		0x00028
+#define   CORE_RC_PHYIF_STAT_REFCLK	BIT(4)
+#define CORE_RC_CTL			0x00050
+#define   CORE_RC_CTL_RUN		BIT(0)
+#define CORE_RC_STAT			0x00058
+#define   CORE_RC_STAT_READY		BIT(0)
+#define CORE_FABRIC_STAT		0x04000
+#define   CORE_FABRIC_STAT_MASK		0x001F001F
+#define CORE_LANE_CFG(port)		(0x84000 + 0x4000 * (port))
+#define   CORE_LANE_CFG_REFCLK0REQ	BIT(0)
+#define   CORE_LANE_CFG_REFCLK1		BIT(1)
+#define   CORE_LANE_CFG_REFCLK0ACK	BIT(2)
+#define   CORE_LANE_CFG_REFCLKEN	(BIT(9) | BIT(10))
+#define CORE_LANE_CTL(port)		(0x84004 + 0x4000 * (port))
+#define   CORE_LANE_CTL_CFGACC		BIT(15)
+
+#define PORT_LTSSMCTL			0x00080
+#define   PORT_LTSSMCTL_START		BIT(0)
+#define PORT_INTSTAT			0x00100
+#define   PORT_INT_TUNNEL_ERR		BIT(31)
+#define   PORT_INT_CPL_TIMEOUT		BIT(23)
+#define   PORT_INT_RID2SID_MAPERR	BIT(22)
+#define   PORT_INT_CPL_ABORT		BIT(21)
+#define   PORT_INT_MSI_BAD_DATA		BIT(19)
+#define   PORT_INT_MSI_ERR		BIT(18)
+#define   PORT_INT_REQADDR_GT32		BIT(17)
+#define   PORT_INT_AF_TIMEOUT		BIT(15)
+#define   PORT_INT_LINK_DOWN		BIT(14)
+#define   PORT_INT_LINK_UP		BIT(12)
+#define   PORT_INT_LINK_BWMGMT		BIT(11)
+#define   PORT_INT_AER_MASK		(15 << 4)
+#define   PORT_INT_PORT_ERR		BIT(4)
+#define   PORT_INT_INTx(i)		BIT(i)
+#define   PORT_INT_INTxALL		15
+#define PORT_INTMSK			0x00104
+#define PORT_INTMSKSET			0x00108
+#define PORT_INTMSKCLR			0x0010c
+#define PORT_MSICFG			0x00124
+#define   PORT_MSICFG_EN		BIT(0)
+#define   PORT_MSICFG_L2MSINUM_SHIFT	4
+#define PORT_MSIBASE			0x00128
+#define   PORT_MSIBASE_1_SHIFT		16
+#define PORT_MSIADDR			0x00168
+#define PORT_LINKSTS			0x00208
+#define   PORT_LINKSTS_UP		BIT(0)
+#define   PORT_LINKSTS_BUSY		BIT(2)
+#define PORT_LINKCMDSTS			0x00210
+#define PORT_OUTS_NPREQS		0x00284
+#define   PORT_OUTS_NPREQS_REQ		BIT(24)
+#define   PORT_OUTS_NPREQS_CPL		BIT(16)
+#define PORT_RXWR_FIFO			0x00288
+#define   PORT_RXWR_FIFO_HDR		GENMASK(15, 10)
+#define   PORT_RXWR_FIFO_DATA		GENMASK(9, 0)
+#define PORT_RXRD_FIFO			0x0028C
+#define   PORT_RXRD_FIFO_REQ		GENMASK(6, 0)
+#define PORT_OUTS_CPLS			0x00290
+#define   PORT_OUTS_CPLS_SHRD		GENMASK(14, 8)
+#define   PORT_OUTS_CPLS_WAIT		GENMASK(6, 0)
+#define PORT_APPCLK			0x00800
+#define   PORT_APPCLK_EN		BIT(0)
+#define   PORT_APPCLK_CGDIS		BIT(8)
+#define PORT_STATUS			0x00804
+#define   PORT_STATUS_READY		BIT(0)
+#define PORT_REFCLK			0x00810
+#define   PORT_REFCLK_EN		BIT(0)
+#define   PORT_REFCLK_CGDIS		BIT(8)
+#define PORT_PERST			0x00814
+#define   PORT_PERST_OFF		BIT(0)
+#define PORT_RID2SID(i16)		(0x00828 + 4 * (i16))
+#define   PORT_RID2SID_VALID		BIT(31)
+#define   PORT_RID2SID_SID_SHIFT	16
+#define   PORT_RID2SID_BUS_SHIFT	8
+#define   PORT_RID2SID_DEV_SHIFT	3
+#define   PORT_RID2SID_FUNC_SHIFT	0
+#define PORT_OUTS_PREQS_HDR		0x00980
+#define   PORT_OUTS_PREQS_HDR_MASK	GENMASK(9, 0)
+#define PORT_OUTS_PREQS_DATA		0x00984
+#define   PORT_OUTS_PREQS_DATA_MASK	GENMASK(15, 0)
+#define PORT_TUNCTRL			0x00988
+#define   PORT_TUNCTRL_PERST_ON		BIT(0)
+#define   PORT_TUNCTRL_PERST_ACK_REQ	BIT(1)
+#define PORT_TUNSTAT			0x0098c
+#define   PORT_TUNSTAT_PERST_ON		BIT(0)
+#define   PORT_TUNSTAT_PERST_ACK_PEND	BIT(1)
+#define PORT_PREFMEM_ENABLE		0x00994
+
+/* The doorbell address is "well known" */
+#define DOORBELL_ADDR			0xfffff000
+
+struct apple_pcie {
+	struct mutex		lock;
+	struct device		*dev;
+	void __iomem            *rc;
+};
+
+static inline void rmwl(u32 clr, u32 set, void __iomem *addr)
+{
+	writel_relaxed((readl_relaxed(addr) & ~clr) | set, addr);
+}
+
+static int apple_pcie_setup_port(struct apple_pcie *pcie,
+				 struct gpio_desc *reset,
+				 unsigned int i)
+{
+	struct platform_device *platform = to_platform_device(pcie->dev);
+	void __iomem *port;
+	uint32_t stat;
+	int ret;
+
+	port = devm_platform_ioremap_resource(platform, i + 2);
+
+	if (IS_ERR(port))
+		return -ENODEV;
+
+	/* Skip setup if the link was already enabled by the bootloader */
+	if (readl_relaxed(port + PORT_LINKSTS) & PORT_LINKSTS_UP)
+		return 0;
+
+	rmwl(0, PORT_PERST_OFF, port + PORT_PERST);
+	gpiod_set_value(reset, 1);
+
+	ret = readl_relaxed_poll_timeout(port + PORT_STATUS, stat,
+					 stat & PORT_STATUS_READY, 100, 250000);
+	if (ret < 0) {
+		dev_err(pcie->dev, "port %u ready wait timeout\n", i);
+		return ret;
+	}
+
+	/* Configure MSIs */
+	writel_relaxed(DOORBELL_ADDR, port + PORT_MSIADDR);
+	writel_relaxed(0, port + PORT_MSIBASE);
+
+	/* Enable 32 MSIs */
+	writel_relaxed((5 << PORT_MSICFG_L2MSINUM_SHIFT) | PORT_MSICFG_EN,
+		       port + PORT_MSICFG);
+
+	/* Enable link interrupts */
+	writel_relaxed(0xfb512fff, port + PORT_INTMSKSET);
+
+	writel_relaxed(PORT_INT_LINK_UP | PORT_INT_LINK_DOWN |
+		       PORT_INT_AF_TIMEOUT | PORT_INT_REQADDR_GT32 |
+		       PORT_INT_MSI_ERR | PORT_INT_MSI_BAD_DATA |
+		       PORT_INT_CPL_ABORT | PORT_INT_CPL_TIMEOUT | (1 << 26),
+		       port + PORT_INTSTAT);
+
+	/* Flush writes and enable the link */
+	dma_wmb();
+	writel_relaxed(PORT_LTSSMCTL_START, port + PORT_LTSSMCTL);
+
+	return 0;
+}
+
+static int apple_m1_pci_init(struct pci_config_window *cfg)
+{
+	struct device *dev = cfg->parent;
+	struct platform_device *platform = to_platform_device(dev);
+
+	struct apple_pcie *pcie;
+	struct device_node *of_port;
+	int ret, i;
+
+	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
+	if (!pcie)
+		return -ENOMEM;
+
+	pcie->dev = dev;
+
+	mutex_init(&pcie->lock);
+
+	pcie->rc = devm_platform_ioremap_resource(platform, 1);
+
+	if (IS_ERR(pcie->rc))
+		return -ENODEV;
+
+	i = 0;
+
+	for_each_child_of_node(dev->of_node, of_port) {
+		struct gpio_desc *reset;
+
+		reset = gpiod_get_from_of_node(of_port, "reset-gpios", 0,
+					       GPIOD_OUT_LOW, "#PERST");
+		if (IS_ERR(reset))
+			return PTR_ERR(reset);
+
+		ret = apple_pcie_setup_port(pcie, reset, i);
+
+		if (ret) {
+			dev_err(pcie->dev, "Port %u setup fail: %d\n", i, ret);
+			return ret;
+		}
+
+		++i;
+	}
+
+	return 0;
+}
+
+static const struct pci_ecam_ops apple_m1_cfg_ecam_ops = {
+	.init		= apple_m1_pci_init,
+	.pci_ops	= {
+		.map_bus	= pci_ecam_map_bus,
+		.read		= pci_generic_config_read,
+		.write		= pci_generic_config_write,
+	}
+};
+
+static const struct of_device_id apple_pci_of_match[] = {
+	{ .compatible = "apple,pcie", .data = &apple_m1_cfg_ecam_ops },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, apple_pci_of_match);
+
+static struct platform_driver apple_pci_driver = {
+	.driver = {
+		.name = "pcie-apple",
+		.of_match_table = apple_pci_of_match,
+	},
+	.probe = pci_host_common_probe,
+	.remove = pci_host_common_remove,
+};
+module_platform_driver(apple_pci_driver);
+
+MODULE_LICENSE("GPL v2");
-- 
2.30.2