On Mon, Dec 16, 2019 at 12:01:09PM +0100, Nicolas Saenz Julienne wrote:

From: Jim Quinlan <redacted>

This adds a basic driver for Broadcom's STB PCIe controller, for now
aimed at Raspberry Pi 4's SoC, bcm2711.

Signed-off-by: Jim Quinlan <redacted>
Co-developed-by: Nicolas Saenz Julienne <redacted>
Signed-off-by: Nicolas Saenz Julienne <redacted>
Reviewed-by: Andrew Murray <redacted>
Reviewed-by: Jeremy Linton <redacted>

---

Changes since v3:
  - Update commit message
  - rollback roundup_pow_two usage, it'll be updated later down the line
  - Remove comment in register definition

Changes since v2:
  - Correct rc_bar2_offset sign

In relation to this change.

[...]

+static inline int brcm_pcie_get_rc_bar2_size_and_offset(struct brcm_pcie *pcie,
+							u64 *rc_bar2_size,
+							u64 *rc_bar2_offset)
+{
+	struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie);
+	struct device *dev = pcie->dev;
+	struct resource_entry *entry;
+
+	entry = resource_list_first_type(&bridge->dma_ranges, IORESOURCE_MEM);
+	if (!entry)
+		return -ENODEV;
+
+	*rc_bar2_offset = -entry->offset;

I think this deserves a comment - I guess it has to do with how the
controller expects CPU<->PCI offsets to be expressed compared to how it
is computed in dma_ranges entries.

I will try to complete the review shortly and try to apply it given
that it has already been reviewed by others.

Lorenzo

+	*rc_bar2_size = 1ULL << fls64(entry->res->end - entry->res->start);
+
+	/*
+	 * We validate the inbound memory view even though we should trust
+	 * whatever the device-tree provides. This is because of an HW issue on
+	 * early Raspberry Pi 4's revisions (bcm2711). It turns out its
+	 * firmware has to dynamically edit dma-ranges due to a bug on the
+	 * PCIe controller integration, which prohibits any access above the
+	 * lower 3GB of memory. Given this, we decided to keep the dma-ranges
+	 * in check, avoiding hard to debug device-tree related issues in the
+	 * future:
+	 *
+	 * The PCIe host controller by design must set the inbound viewport to
+	 * be a contiguous arrangement of all of the system's memory.  In
+	 * addition, its size mut be a power of two.  To further complicate
+	 * matters, the viewport must start on a pcie-address that is aligned
+	 * on a multiple of its size.  If a portion of the viewport does not
+	 * represent system memory -- e.g. 3GB of memory requires a 4GB
+	 * viewport -- we can map the outbound memory in or after 3GB and even
+	 * though the viewport will overlap the outbound memory the controller
+	 * will know to send outbound memory downstream and everything else
+	 * upstream.
+	 *
+	 * For example:
+	 *
+	 * - The best-case scenario, memory up to 3GB, is to place the inbound
+	 *   region in the first 4GB of pcie-space, as some legacy devices can
+	 *   only address 32bits. We would also like to put the MSI under 4GB
+	 *   as well, since some devices require a 32bit MSI target address.
+	 *
+	 * - If the system memory is 4GB or larger we cannot start the inbound
+	 *   region at location 0 (since we have to allow some space for
+	 *   outbound memory @ 3GB). So instead it will  start at the 1x
+	 *   multiple of its size
+	 */
+	if (!*rc_bar2_size || *rc_bar2_offset % *rc_bar2_size ||
+	    (*rc_bar2_offset < SZ_4G && *rc_bar2_offset > SZ_2G)) {
+		dev_err(dev, "Invalid rc_bar2_offset/size: size 0x%llx, off 0x%llx\n",
+			*rc_bar2_size, *rc_bar2_offset);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int brcm_pcie_setup(struct brcm_pcie *pcie)
+{
+	struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie);
+	u64 rc_bar2_offset, rc_bar2_size;
+	void __iomem *base = pcie->base;
+	struct device *dev = pcie->dev;
+	struct resource_entry *entry;
+	unsigned int scb_size_val;
+	bool ssc_good = false;
+	struct resource *res;
+	int num_out_wins = 0;
+	u16 nlw, cls, lnksta;
+	int i, ret;
+	u32 tmp;
+
+	/* Reset the bridge */
+	brcm_pcie_bridge_sw_init_set(pcie, 1);
+
+	usleep_range(100, 200);
+
+	/* Take the bridge out of reset */
+	brcm_pcie_bridge_sw_init_set(pcie, 0);
+
+	tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
+	tmp &= ~PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK;
+	writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
+	/* Wait for SerDes to be stable */
+	usleep_range(100, 200);
+
+	/* Set SCB_MAX_BURST_SIZE, CFG_READ_UR_MODE, SCB_ACCESS_EN */
+	u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_SCB_ACCESS_EN_MASK);
+	u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_CFG_READ_UR_MODE_MASK);
+	u32p_replace_bits(&tmp, PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_128,
+			  PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_MASK);
+	writel(tmp, base + PCIE_MISC_MISC_CTRL);
+
+	ret = brcm_pcie_get_rc_bar2_size_and_offset(pcie, &rc_bar2_size,
+						    &rc_bar2_offset);
+	if (ret)
+		return ret;
+
+	tmp = lower_32_bits(rc_bar2_offset);
+	u32p_replace_bits(&tmp, brcm_pcie_encode_ibar_size(rc_bar2_size),
+			  PCIE_MISC_RC_BAR2_CONFIG_LO_SIZE_MASK);
+	writel(tmp, base + PCIE_MISC_RC_BAR2_CONFIG_LO);
+	writel(upper_32_bits(rc_bar2_offset),
+	       base + PCIE_MISC_RC_BAR2_CONFIG_HI);
+
+	scb_size_val = rc_bar2_size ?
+		       ilog2(rc_bar2_size) - 15 : 0xf; /* 0xf is 1GB */
+	tmp = readl(base + PCIE_MISC_MISC_CTRL);
+	u32p_replace_bits(&tmp, scb_size_val,
+			  PCIE_MISC_MISC_CTRL_SCB0_SIZE_MASK);
+	writel(tmp, base + PCIE_MISC_MISC_CTRL);
+
+	/* disable the PCIe->GISB memory window (RC_BAR1) */
+	tmp = readl(base + PCIE_MISC_RC_BAR1_CONFIG_LO);
+	tmp &= ~PCIE_MISC_RC_BAR1_CONFIG_LO_SIZE_MASK;
+	writel(tmp, base + PCIE_MISC_RC_BAR1_CONFIG_LO);
+
+	/* disable the PCIe->SCB memory window (RC_BAR3) */
+	tmp = readl(base + PCIE_MISC_RC_BAR3_CONFIG_LO);
+	tmp &= ~PCIE_MISC_RC_BAR3_CONFIG_LO_SIZE_MASK;
+	writel(tmp, base + PCIE_MISC_RC_BAR3_CONFIG_LO);
+
+	/* Mask all interrupts since we are not handling any yet */
+	writel(0xffffffff, pcie->base + PCIE_MSI_INTR2_MASK_SET);
+
+	/* clear any interrupts we find on boot */
+	writel(0xffffffff, pcie->base + PCIE_MSI_INTR2_CLR);
+
+	if (pcie->gen)
+		brcm_pcie_set_gen(pcie, pcie->gen);
+
+	/* Unassert the fundamental reset */
+	brcm_pcie_perst_set(pcie, 0);
+
+	/*
+	 * Give the RC/EP time to wake up, before trying to configure RC.
+	 * Intermittently check status for link-up, up to a total of 100ms.
+	 */
+	for (i = 0; i < 100 && !brcm_pcie_link_up(pcie); i += 5)
+		msleep(5);
+
+	if (!brcm_pcie_link_up(pcie)) {
+		dev_err(dev, "link down\n");
+		return -ENODEV;
+	}
+
+	if (!brcm_pcie_rc_mode(pcie)) {
+		dev_err(dev, "PCIe misconfigured; is in EP mode\n");
+		return -EINVAL;
+	}
+
+	resource_list_for_each_entry(entry, &bridge->windows) {
+		res = entry->res;
+
+		if (resource_type(res) != IORESOURCE_MEM)
+			continue;
+
+		if (num_out_wins >= BRCM_NUM_PCIE_OUT_WINS) {
+			dev_err(pcie->dev, "too many outbound wins\n");
+			return -EINVAL;
+		}
+
+		brcm_pcie_set_outbound_win(pcie, num_out_wins, res->start,
+					   res->start - entry->offset,
+					   res->end - res->start + 1);
+		num_out_wins++;
+	}
+
+	/*
+	 * For config space accesses on the RC, show the right class for
+	 * a PCIe-PCIe bridge (the default setting is to be EP mode).
+	 */
+	tmp = readl(base + PCIE_RC_CFG_PRIV1_ID_VAL3);
+	u32p_replace_bits(&tmp, 0x060400,
+			  PCIE_RC_CFG_PRIV1_ID_VAL3_CLASS_CODE_MASK);
+	writel(tmp, base + PCIE_RC_CFG_PRIV1_ID_VAL3);
+
+	if (pcie->ssc) {
+		ret = brcm_pcie_set_ssc(pcie);
+		if (ret == 0)
+			ssc_good = true;
+		else
+			dev_err(dev, "failed attempt to enter ssc mode\n");
+	}
+
+	lnksta = readw(base + BRCM_PCIE_CAP_REGS + PCI_EXP_LNKSTA);
+	cls = FIELD_GET(PCI_EXP_LNKSTA_CLS, lnksta);
+	nlw = FIELD_GET(PCI_EXP_LNKSTA_NLW, lnksta);
+	dev_info(dev, "link up, %s x%u %s\n",
+		 PCIE_SPEED2STR(cls + PCI_SPEED_133MHz_PCIX_533),
+		 nlw, ssc_good ? "(SSC)" : "(!SSC)");
+
+	/* PCIe->SCB endian mode for BAR */
+	tmp = readl(base + PCIE_RC_CFG_VENDOR_VENDOR_SPECIFIC_REG1);
+	u32p_replace_bits(&tmp, PCIE_RC_CFG_VENDOR_SPCIFIC_REG1_LITTLE_ENDIAN,
+		PCIE_RC_CFG_VENDOR_VENDOR_SPECIFIC_REG1_ENDIAN_MODE_BAR2_MASK);
+	writel(tmp, base + PCIE_RC_CFG_VENDOR_VENDOR_SPECIFIC_REG1);
+
+	/*
+	 * Refclk from RC should be gated with CLKREQ# input when ASPM L0s,L1
+	 * is enabled => setting the CLKREQ_DEBUG_ENABLE field to 1.
+	 */
+	tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
+	tmp |= PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_DEBUG_ENABLE_MASK;
+	writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
+
+	return 0;
+}
+
+/* L23 is a low-power PCIe link state */
+static void brcm_pcie_enter_l23(struct brcm_pcie *pcie)
+{
+	void __iomem *base = pcie->base;
+	int l23, i;
+	u32 tmp;
+
+	/* Assert request for L23 */
+	tmp = readl(base + PCIE_MISC_PCIE_CTRL);
+	u32p_replace_bits(&tmp, 1, PCIE_MISC_PCIE_CTRL_PCIE_L23_REQUEST_MASK);
+	writel(tmp, base + PCIE_MISC_PCIE_CTRL);
+
+	/* Wait up to 36 msec for L23 */
+	tmp = readl(base + PCIE_MISC_PCIE_STATUS);
+	l23 = FIELD_GET(PCIE_MISC_PCIE_STATUS_PCIE_LINK_IN_L23_MASK, tmp);
+	for (i = 0; i < 15 && !l23; i++) {
+		usleep_range(2000, 2400);
+		tmp = readl(base + PCIE_MISC_PCIE_STATUS);
+		l23 = FIELD_GET(PCIE_MISC_PCIE_STATUS_PCIE_LINK_IN_L23_MASK,
+				tmp);
+	}
+
+	if (!l23)
+		dev_err(pcie->dev, "failed to enter low-power link state\n");
+}
+
+static void brcm_pcie_turn_off(struct brcm_pcie *pcie)
+{
+	void __iomem *base = pcie->base;
+	int tmp;
+
+	if (brcm_pcie_link_up(pcie))
+		brcm_pcie_enter_l23(pcie);
+	/* Assert fundamental reset */
+	brcm_pcie_perst_set(pcie, 1);
+
+	/* Deassert request for L23 in case it was asserted */
+	tmp = readl(base + PCIE_MISC_PCIE_CTRL);
+	u32p_replace_bits(&tmp, 0, PCIE_MISC_PCIE_CTRL_PCIE_L23_REQUEST_MASK);
+	writel(tmp, base + PCIE_MISC_PCIE_CTRL);
+
+	/* Turn off SerDes */
+	tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
+	u32p_replace_bits(&tmp, 1, PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK);
+	writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
+
+	/* Shutdown PCIe bridge */
+	brcm_pcie_bridge_sw_init_set(pcie, 1);
+}
+
+static void __brcm_pcie_remove(struct brcm_pcie *pcie)
+{
+	brcm_pcie_turn_off(pcie);
+	clk_disable_unprepare(pcie->clk);
+	clk_put(pcie->clk);
+}
+
+static int brcm_pcie_remove(struct platform_device *pdev)
+{
+	struct brcm_pcie *pcie = platform_get_drvdata(pdev);
+
+	pci_stop_root_bus(pcie->root_bus);
+	pci_remove_root_bus(pcie->root_bus);
+	__brcm_pcie_remove(pcie);
+
+	return 0;
+}
+
+static int brcm_pcie_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct pci_host_bridge *bridge;
+	struct brcm_pcie *pcie;
+	struct pci_bus *child;
+	struct resource *res;
+	int ret;
+
+	bridge = devm_pci_alloc_host_bridge(&pdev->dev, sizeof(*pcie));
+	if (!bridge)
+		return -ENOMEM;
+
+	pcie = pci_host_bridge_priv(bridge);
+	pcie->dev = &pdev->dev;
+	pcie->np = np;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	pcie->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(pcie->base))
+		return PTR_ERR(pcie->base);
+
+	pcie->clk = devm_clk_get_optional(&pdev->dev, "sw_pcie");
+	if (IS_ERR(pcie->clk))
+		return PTR_ERR(pcie->clk);
+
+	ret = of_pci_get_max_link_speed(np);
+	pcie->gen = (ret < 0) ? 0 : ret;
+
+	pcie->ssc = of_property_read_bool(np, "brcm,enable-ssc");
+
+	ret = pci_parse_request_of_pci_ranges(pcie->dev, &bridge->windows,
+					      &bridge->dma_ranges, NULL);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(pcie->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "could not enable clock\n");
+		return ret;
+	}
+
+	ret = brcm_pcie_setup(pcie);
+	if (ret)
+		goto fail;
+
+	bridge->dev.parent = &pdev->dev;
+	bridge->busnr = 0;
+	bridge->ops = &brcm_pcie_ops;
+	bridge->sysdata = pcie;
+	bridge->map_irq = of_irq_parse_and_map_pci;
+	bridge->swizzle_irq = pci_common_swizzle;
+
+	ret = pci_scan_root_bus_bridge(bridge);
+	if (ret < 0) {
+		dev_err(pcie->dev, "Scanning root bridge failed\n");
+		goto fail;
+	}
+
+	pci_assign_unassigned_bus_resources(bridge->bus);
+	list_for_each_entry(child, &bridge->bus->children, node)
+		pcie_bus_configure_settings(child);
+	pci_bus_add_devices(bridge->bus);
+	platform_set_drvdata(pdev, pcie);
+	pcie->root_bus = bridge->bus;
+
+	return 0;
+fail:
+	__brcm_pcie_remove(pcie);
+	return ret;
+}
+
+static const struct of_device_id brcm_pcie_match[] = {
+	{ .compatible = "brcm,bcm2711-pcie" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, brcm_pcie_match);
+
+static struct platform_driver brcm_pcie_driver = {
+	.probe = brcm_pcie_probe,
+	.remove = brcm_pcie_remove,
+	.driver = {
+		.name = "brcm-pcie",
+		.of_match_table = brcm_pcie_match,
+	},
+};
+module_platform_driver(brcm_pcie_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Broadcom STB PCIe RC driver");
+MODULE_AUTHOR("Broadcom");
-- 
2.24.0

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