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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /drivers/pci/of.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'drivers/pci/of.c')
-rw-r--r--drivers/pci/of.c788
1 files changed, 788 insertions, 0 deletions
diff --git a/drivers/pci/of.c b/drivers/pci/of.c
new file mode 100644
index 0000000000..51e3dd0ea5
--- /dev/null
+++ b/drivers/pci/of.c
@@ -0,0 +1,788 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * PCI <-> OF mapping helpers
+ *
+ * Copyright 2011 IBM Corp.
+ */
+#define pr_fmt(fmt) "PCI: OF: " fmt
+
+#include <linux/irqdomain.h>
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/of_pci.h>
+#include "pci.h"
+
+#ifdef CONFIG_PCI
+/**
+ * pci_set_of_node - Find and set device's DT device_node
+ * @dev: the PCI device structure to fill
+ *
+ * Returns 0 on success with of_node set or when no device is described in the
+ * DT. Returns -ENODEV if the device is present, but disabled in the DT.
+ */
+int pci_set_of_node(struct pci_dev *dev)
+{
+ struct device_node *node;
+
+ if (!dev->bus->dev.of_node)
+ return 0;
+
+ node = of_pci_find_child_device(dev->bus->dev.of_node, dev->devfn);
+ if (!node)
+ return 0;
+
+ device_set_node(&dev->dev, of_fwnode_handle(node));
+ return 0;
+}
+
+void pci_release_of_node(struct pci_dev *dev)
+{
+ of_node_put(dev->dev.of_node);
+ device_set_node(&dev->dev, NULL);
+}
+
+void pci_set_bus_of_node(struct pci_bus *bus)
+{
+ struct device_node *node;
+
+ if (bus->self == NULL) {
+ node = pcibios_get_phb_of_node(bus);
+ } else {
+ node = of_node_get(bus->self->dev.of_node);
+ if (node && of_property_read_bool(node, "external-facing"))
+ bus->self->external_facing = true;
+ }
+
+ device_set_node(&bus->dev, of_fwnode_handle(node));
+}
+
+void pci_release_bus_of_node(struct pci_bus *bus)
+{
+ of_node_put(bus->dev.of_node);
+ device_set_node(&bus->dev, NULL);
+}
+
+struct device_node * __weak pcibios_get_phb_of_node(struct pci_bus *bus)
+{
+ /* This should only be called for PHBs */
+ if (WARN_ON(bus->self || bus->parent))
+ return NULL;
+
+ /*
+ * Look for a node pointer in either the intermediary device we
+ * create above the root bus or its own parent. Normally only
+ * the later is populated.
+ */
+ if (bus->bridge->of_node)
+ return of_node_get(bus->bridge->of_node);
+ if (bus->bridge->parent && bus->bridge->parent->of_node)
+ return of_node_get(bus->bridge->parent->of_node);
+ return NULL;
+}
+
+struct irq_domain *pci_host_bridge_of_msi_domain(struct pci_bus *bus)
+{
+#ifdef CONFIG_IRQ_DOMAIN
+ struct irq_domain *d;
+
+ if (!bus->dev.of_node)
+ return NULL;
+
+ /* Start looking for a phandle to an MSI controller. */
+ d = of_msi_get_domain(&bus->dev, bus->dev.of_node, DOMAIN_BUS_PCI_MSI);
+ if (d)
+ return d;
+
+ /*
+ * If we don't have an msi-parent property, look for a domain
+ * directly attached to the host bridge.
+ */
+ d = irq_find_matching_host(bus->dev.of_node, DOMAIN_BUS_PCI_MSI);
+ if (d)
+ return d;
+
+ return irq_find_host(bus->dev.of_node);
+#else
+ return NULL;
+#endif
+}
+
+bool pci_host_of_has_msi_map(struct device *dev)
+{
+ if (dev && dev->of_node)
+ return of_get_property(dev->of_node, "msi-map", NULL);
+ return false;
+}
+
+static inline int __of_pci_pci_compare(struct device_node *node,
+ unsigned int data)
+{
+ int devfn;
+
+ devfn = of_pci_get_devfn(node);
+ if (devfn < 0)
+ return 0;
+
+ return devfn == data;
+}
+
+struct device_node *of_pci_find_child_device(struct device_node *parent,
+ unsigned int devfn)
+{
+ struct device_node *node, *node2;
+
+ for_each_child_of_node(parent, node) {
+ if (__of_pci_pci_compare(node, devfn))
+ return node;
+ /*
+ * Some OFs create a parent node "multifunc-device" as
+ * a fake root for all functions of a multi-function
+ * device we go down them as well.
+ */
+ if (of_node_name_eq(node, "multifunc-device")) {
+ for_each_child_of_node(node, node2) {
+ if (__of_pci_pci_compare(node2, devfn)) {
+ of_node_put(node);
+ return node2;
+ }
+ }
+ }
+ }
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(of_pci_find_child_device);
+
+/**
+ * of_pci_get_devfn() - Get device and function numbers for a device node
+ * @np: device node
+ *
+ * Parses a standard 5-cell PCI resource and returns an 8-bit value that can
+ * be passed to the PCI_SLOT() and PCI_FUNC() macros to extract the device
+ * and function numbers respectively. On error a negative error code is
+ * returned.
+ */
+int of_pci_get_devfn(struct device_node *np)
+{
+ u32 reg[5];
+ int error;
+
+ error = of_property_read_u32_array(np, "reg", reg, ARRAY_SIZE(reg));
+ if (error)
+ return error;
+
+ return (reg[0] >> 8) & 0xff;
+}
+EXPORT_SYMBOL_GPL(of_pci_get_devfn);
+
+/**
+ * of_pci_parse_bus_range() - parse the bus-range property of a PCI device
+ * @node: device node
+ * @res: address to a struct resource to return the bus-range
+ *
+ * Returns 0 on success or a negative error-code on failure.
+ */
+int of_pci_parse_bus_range(struct device_node *node, struct resource *res)
+{
+ u32 bus_range[2];
+ int error;
+
+ error = of_property_read_u32_array(node, "bus-range", bus_range,
+ ARRAY_SIZE(bus_range));
+ if (error)
+ return error;
+
+ res->name = node->name;
+ res->start = bus_range[0];
+ res->end = bus_range[1];
+ res->flags = IORESOURCE_BUS;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(of_pci_parse_bus_range);
+
+/**
+ * of_get_pci_domain_nr - Find the host bridge domain number
+ * of the given device node.
+ * @node: Device tree node with the domain information.
+ *
+ * This function will try to obtain the host bridge domain number by finding
+ * a property called "linux,pci-domain" of the given device node.
+ *
+ * Return:
+ * * > 0 - On success, an associated domain number.
+ * * -EINVAL - The property "linux,pci-domain" does not exist.
+ * * -ENODATA - The linux,pci-domain" property does not have value.
+ * * -EOVERFLOW - Invalid "linux,pci-domain" property value.
+ *
+ * Returns the associated domain number from DT in the range [0-0xffff], or
+ * a negative value if the required property is not found.
+ */
+int of_get_pci_domain_nr(struct device_node *node)
+{
+ u32 domain;
+ int error;
+
+ error = of_property_read_u32(node, "linux,pci-domain", &domain);
+ if (error)
+ return error;
+
+ return (u16)domain;
+}
+EXPORT_SYMBOL_GPL(of_get_pci_domain_nr);
+
+/**
+ * of_pci_check_probe_only - Setup probe only mode if linux,pci-probe-only
+ * is present and valid
+ */
+void of_pci_check_probe_only(void)
+{
+ u32 val;
+ int ret;
+
+ ret = of_property_read_u32(of_chosen, "linux,pci-probe-only", &val);
+ if (ret) {
+ if (ret == -ENODATA || ret == -EOVERFLOW)
+ pr_warn("linux,pci-probe-only without valid value, ignoring\n");
+ return;
+ }
+
+ if (val)
+ pci_add_flags(PCI_PROBE_ONLY);
+ else
+ pci_clear_flags(PCI_PROBE_ONLY);
+
+ pr_info("PROBE_ONLY %s\n", val ? "enabled" : "disabled");
+}
+EXPORT_SYMBOL_GPL(of_pci_check_probe_only);
+
+/**
+ * devm_of_pci_get_host_bridge_resources() - Resource-managed parsing of PCI
+ * host bridge resources from DT
+ * @dev: host bridge device
+ * @busno: bus number associated with the bridge root bus
+ * @bus_max: maximum number of buses for this bridge
+ * @resources: list where the range of resources will be added after DT parsing
+ * @ib_resources: list where the range of inbound resources (with addresses
+ * from 'dma-ranges') will be added after DT parsing
+ * @io_base: pointer to a variable that will contain on return the physical
+ * address for the start of the I/O range. Can be NULL if the caller doesn't
+ * expect I/O ranges to be present in the device tree.
+ *
+ * This function will parse the "ranges" property of a PCI host bridge device
+ * node and setup the resource mapping based on its content. It is expected
+ * that the property conforms with the Power ePAPR document.
+ *
+ * It returns zero if the range parsing has been successful or a standard error
+ * value if it failed.
+ */
+static int devm_of_pci_get_host_bridge_resources(struct device *dev,
+ unsigned char busno, unsigned char bus_max,
+ struct list_head *resources,
+ struct list_head *ib_resources,
+ resource_size_t *io_base)
+{
+ struct device_node *dev_node = dev->of_node;
+ struct resource *res, tmp_res;
+ struct resource *bus_range;
+ struct of_pci_range range;
+ struct of_pci_range_parser parser;
+ const char *range_type;
+ int err;
+
+ if (io_base)
+ *io_base = (resource_size_t)OF_BAD_ADDR;
+
+ bus_range = devm_kzalloc(dev, sizeof(*bus_range), GFP_KERNEL);
+ if (!bus_range)
+ return -ENOMEM;
+
+ dev_info(dev, "host bridge %pOF ranges:\n", dev_node);
+
+ err = of_pci_parse_bus_range(dev_node, bus_range);
+ if (err) {
+ bus_range->start = busno;
+ bus_range->end = bus_max;
+ bus_range->flags = IORESOURCE_BUS;
+ dev_info(dev, " No bus range found for %pOF, using %pR\n",
+ dev_node, bus_range);
+ } else {
+ if (bus_range->end > bus_range->start + bus_max)
+ bus_range->end = bus_range->start + bus_max;
+ }
+ pci_add_resource(resources, bus_range);
+
+ /* Check for ranges property */
+ err = of_pci_range_parser_init(&parser, dev_node);
+ if (err)
+ return 0;
+
+ dev_dbg(dev, "Parsing ranges property...\n");
+ for_each_of_pci_range(&parser, &range) {
+ /* Read next ranges element */
+ if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_IO)
+ range_type = "IO";
+ else if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_MEM)
+ range_type = "MEM";
+ else
+ range_type = "err";
+ dev_info(dev, " %6s %#012llx..%#012llx -> %#012llx\n",
+ range_type, range.cpu_addr,
+ range.cpu_addr + range.size - 1, range.pci_addr);
+
+ /*
+ * If we failed translation or got a zero-sized region
+ * then skip this range
+ */
+ if (range.cpu_addr == OF_BAD_ADDR || range.size == 0)
+ continue;
+
+ err = of_pci_range_to_resource(&range, dev_node, &tmp_res);
+ if (err)
+ continue;
+
+ res = devm_kmemdup(dev, &tmp_res, sizeof(tmp_res), GFP_KERNEL);
+ if (!res) {
+ err = -ENOMEM;
+ goto failed;
+ }
+
+ if (resource_type(res) == IORESOURCE_IO) {
+ if (!io_base) {
+ dev_err(dev, "I/O range found for %pOF. Please provide an io_base pointer to save CPU base address\n",
+ dev_node);
+ err = -EINVAL;
+ goto failed;
+ }
+ if (*io_base != (resource_size_t)OF_BAD_ADDR)
+ dev_warn(dev, "More than one I/O resource converted for %pOF. CPU base address for old range lost!\n",
+ dev_node);
+ *io_base = range.cpu_addr;
+ } else if (resource_type(res) == IORESOURCE_MEM) {
+ res->flags &= ~IORESOURCE_MEM_64;
+ }
+
+ pci_add_resource_offset(resources, res, res->start - range.pci_addr);
+ }
+
+ /* Check for dma-ranges property */
+ if (!ib_resources)
+ return 0;
+ err = of_pci_dma_range_parser_init(&parser, dev_node);
+ if (err)
+ return 0;
+
+ dev_dbg(dev, "Parsing dma-ranges property...\n");
+ for_each_of_pci_range(&parser, &range) {
+ /*
+ * If we failed translation or got a zero-sized region
+ * then skip this range
+ */
+ if (((range.flags & IORESOURCE_TYPE_BITS) != IORESOURCE_MEM) ||
+ range.cpu_addr == OF_BAD_ADDR || range.size == 0)
+ continue;
+
+ dev_info(dev, " %6s %#012llx..%#012llx -> %#012llx\n",
+ "IB MEM", range.cpu_addr,
+ range.cpu_addr + range.size - 1, range.pci_addr);
+
+
+ err = of_pci_range_to_resource(&range, dev_node, &tmp_res);
+ if (err)
+ continue;
+
+ res = devm_kmemdup(dev, &tmp_res, sizeof(tmp_res), GFP_KERNEL);
+ if (!res) {
+ err = -ENOMEM;
+ goto failed;
+ }
+
+ pci_add_resource_offset(ib_resources, res,
+ res->start - range.pci_addr);
+ }
+
+ return 0;
+
+failed:
+ pci_free_resource_list(resources);
+ return err;
+}
+
+#if IS_ENABLED(CONFIG_OF_IRQ)
+/**
+ * of_irq_parse_pci - Resolve the interrupt for a PCI device
+ * @pdev: the device whose interrupt is to be resolved
+ * @out_irq: structure of_phandle_args filled by this function
+ *
+ * This function resolves the PCI interrupt for a given PCI device. If a
+ * device-node exists for a given pci_dev, it will use normal OF tree
+ * walking. If not, it will implement standard swizzling and walk up the
+ * PCI tree until an device-node is found, at which point it will finish
+ * resolving using the OF tree walking.
+ */
+static int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
+{
+ struct device_node *dn, *ppnode = NULL;
+ struct pci_dev *ppdev;
+ __be32 laddr[3];
+ u8 pin;
+ int rc;
+
+ /*
+ * Check if we have a device node, if yes, fallback to standard
+ * device tree parsing
+ */
+ dn = pci_device_to_OF_node(pdev);
+ if (dn) {
+ rc = of_irq_parse_one(dn, 0, out_irq);
+ if (!rc)
+ return rc;
+ }
+
+ /*
+ * Ok, we don't, time to have fun. Let's start by building up an
+ * interrupt spec. we assume #interrupt-cells is 1, which is standard
+ * for PCI. If you do different, then don't use that routine.
+ */
+ rc = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
+ if (rc != 0)
+ goto err;
+ /* No pin, exit with no error message. */
+ if (pin == 0)
+ return -ENODEV;
+
+ /* Local interrupt-map in the device node? Use it! */
+ if (of_property_present(dn, "interrupt-map")) {
+ pin = pci_swizzle_interrupt_pin(pdev, pin);
+ ppnode = dn;
+ }
+
+ /* Now we walk up the PCI tree */
+ while (!ppnode) {
+ /* Get the pci_dev of our parent */
+ ppdev = pdev->bus->self;
+
+ /* Ouch, it's a host bridge... */
+ if (ppdev == NULL) {
+ ppnode = pci_bus_to_OF_node(pdev->bus);
+
+ /* No node for host bridge ? give up */
+ if (ppnode == NULL) {
+ rc = -EINVAL;
+ goto err;
+ }
+ } else {
+ /* We found a P2P bridge, check if it has a node */
+ ppnode = pci_device_to_OF_node(ppdev);
+ }
+
+ /*
+ * Ok, we have found a parent with a device-node, hand over to
+ * the OF parsing code.
+ * We build a unit address from the linux device to be used for
+ * resolution. Note that we use the linux bus number which may
+ * not match your firmware bus numbering.
+ * Fortunately, in most cases, interrupt-map-mask doesn't
+ * include the bus number as part of the matching.
+ * You should still be careful about that though if you intend
+ * to rely on this function (you ship a firmware that doesn't
+ * create device nodes for all PCI devices).
+ */
+ if (ppnode)
+ break;
+
+ /*
+ * We can only get here if we hit a P2P bridge with no node;
+ * let's do standard swizzling and try again
+ */
+ pin = pci_swizzle_interrupt_pin(pdev, pin);
+ pdev = ppdev;
+ }
+
+ out_irq->np = ppnode;
+ out_irq->args_count = 1;
+ out_irq->args[0] = pin;
+ laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
+ laddr[1] = laddr[2] = cpu_to_be32(0);
+ rc = of_irq_parse_raw(laddr, out_irq);
+ if (rc)
+ goto err;
+ return 0;
+err:
+ if (rc == -ENOENT) {
+ dev_warn(&pdev->dev,
+ "%s: no interrupt-map found, INTx interrupts not available\n",
+ __func__);
+ pr_warn_once("%s: possibly some PCI slots don't have level triggered interrupts capability\n",
+ __func__);
+ } else {
+ dev_err(&pdev->dev, "%s: failed with rc=%d\n", __func__, rc);
+ }
+ return rc;
+}
+
+/**
+ * of_irq_parse_and_map_pci() - Decode a PCI IRQ from the device tree and map to a VIRQ
+ * @dev: The PCI device needing an IRQ
+ * @slot: PCI slot number; passed when used as map_irq callback. Unused
+ * @pin: PCI IRQ pin number; passed when used as map_irq callback. Unused
+ *
+ * @slot and @pin are unused, but included in the function so that this
+ * function can be used directly as the map_irq callback to
+ * pci_assign_irq() and struct pci_host_bridge.map_irq pointer
+ */
+int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
+{
+ struct of_phandle_args oirq;
+ int ret;
+
+ ret = of_irq_parse_pci(dev, &oirq);
+ if (ret)
+ return 0; /* Proper return code 0 == NO_IRQ */
+
+ return irq_create_of_mapping(&oirq);
+}
+EXPORT_SYMBOL_GPL(of_irq_parse_and_map_pci);
+#endif /* CONFIG_OF_IRQ */
+
+static int pci_parse_request_of_pci_ranges(struct device *dev,
+ struct pci_host_bridge *bridge)
+{
+ int err, res_valid = 0;
+ resource_size_t iobase;
+ struct resource_entry *win, *tmp;
+
+ INIT_LIST_HEAD(&bridge->windows);
+ INIT_LIST_HEAD(&bridge->dma_ranges);
+
+ err = devm_of_pci_get_host_bridge_resources(dev, 0, 0xff, &bridge->windows,
+ &bridge->dma_ranges, &iobase);
+ if (err)
+ return err;
+
+ err = devm_request_pci_bus_resources(dev, &bridge->windows);
+ if (err)
+ return err;
+
+ resource_list_for_each_entry_safe(win, tmp, &bridge->windows) {
+ struct resource *res = win->res;
+
+ switch (resource_type(res)) {
+ case IORESOURCE_IO:
+ err = devm_pci_remap_iospace(dev, res, iobase);
+ if (err) {
+ dev_warn(dev, "error %d: failed to map resource %pR\n",
+ err, res);
+ resource_list_destroy_entry(win);
+ }
+ break;
+ case IORESOURCE_MEM:
+ res_valid |= !(res->flags & IORESOURCE_PREFETCH);
+
+ if (!(res->flags & IORESOURCE_PREFETCH))
+ if (upper_32_bits(resource_size(res)))
+ dev_warn(dev, "Memory resource size exceeds max for 32 bits\n");
+
+ break;
+ }
+ }
+
+ if (!res_valid)
+ dev_warn(dev, "non-prefetchable memory resource required\n");
+
+ return 0;
+}
+
+int devm_of_pci_bridge_init(struct device *dev, struct pci_host_bridge *bridge)
+{
+ if (!dev->of_node)
+ return 0;
+
+ bridge->swizzle_irq = pci_common_swizzle;
+ bridge->map_irq = of_irq_parse_and_map_pci;
+
+ return pci_parse_request_of_pci_ranges(dev, bridge);
+}
+
+#ifdef CONFIG_PCI_DYNAMIC_OF_NODES
+
+void of_pci_remove_node(struct pci_dev *pdev)
+{
+ struct device_node *np;
+
+ np = pci_device_to_OF_node(pdev);
+ if (!np || !of_node_check_flag(np, OF_DYNAMIC))
+ return;
+ pdev->dev.of_node = NULL;
+
+ of_changeset_revert(np->data);
+ of_changeset_destroy(np->data);
+ of_node_put(np);
+}
+
+void of_pci_make_dev_node(struct pci_dev *pdev)
+{
+ struct device_node *ppnode, *np = NULL;
+ const char *pci_type;
+ struct of_changeset *cset;
+ const char *name;
+ int ret;
+
+ /*
+ * If there is already a device tree node linked to this device,
+ * return immediately.
+ */
+ if (pci_device_to_OF_node(pdev))
+ return;
+
+ /* Check if there is device tree node for parent device */
+ if (!pdev->bus->self)
+ ppnode = pdev->bus->dev.of_node;
+ else
+ ppnode = pdev->bus->self->dev.of_node;
+ if (!ppnode)
+ return;
+
+ if (pci_is_bridge(pdev))
+ pci_type = "pci";
+ else
+ pci_type = "dev";
+
+ name = kasprintf(GFP_KERNEL, "%s@%x,%x", pci_type,
+ PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
+ if (!name)
+ return;
+
+ cset = kmalloc(sizeof(*cset), GFP_KERNEL);
+ if (!cset)
+ goto out_free_name;
+ of_changeset_init(cset);
+
+ np = of_changeset_create_node(cset, ppnode, name);
+ if (!np)
+ goto out_destroy_cset;
+
+ ret = of_pci_add_properties(pdev, cset, np);
+ if (ret)
+ goto out_free_node;
+
+ ret = of_changeset_apply(cset);
+ if (ret)
+ goto out_free_node;
+
+ np->data = cset;
+ pdev->dev.of_node = np;
+ kfree(name);
+
+ return;
+
+out_free_node:
+ of_node_put(np);
+out_destroy_cset:
+ of_changeset_destroy(cset);
+ kfree(cset);
+out_free_name:
+ kfree(name);
+}
+#endif
+
+#endif /* CONFIG_PCI */
+
+/**
+ * of_pci_get_max_link_speed - Find the maximum link speed of the given device node.
+ * @node: Device tree node with the maximum link speed information.
+ *
+ * This function will try to find the limitation of link speed by finding
+ * a property called "max-link-speed" of the given device node.
+ *
+ * Return:
+ * * > 0 - On success, a maximum link speed.
+ * * -EINVAL - Invalid "max-link-speed" property value, or failure to access
+ * the property of the device tree node.
+ *
+ * Returns the associated max link speed from DT, or a negative value if the
+ * required property is not found or is invalid.
+ */
+int of_pci_get_max_link_speed(struct device_node *node)
+{
+ u32 max_link_speed;
+
+ if (of_property_read_u32(node, "max-link-speed", &max_link_speed) ||
+ max_link_speed == 0 || max_link_speed > 4)
+ return -EINVAL;
+
+ return max_link_speed;
+}
+EXPORT_SYMBOL_GPL(of_pci_get_max_link_speed);
+
+/**
+ * of_pci_get_slot_power_limit - Parses the "slot-power-limit-milliwatt"
+ * property.
+ *
+ * @node: device tree node with the slot power limit information
+ * @slot_power_limit_value: pointer where the value should be stored in PCIe
+ * Slot Capabilities Register format
+ * @slot_power_limit_scale: pointer where the scale should be stored in PCIe
+ * Slot Capabilities Register format
+ *
+ * Returns the slot power limit in milliwatts and if @slot_power_limit_value
+ * and @slot_power_limit_scale pointers are non-NULL, fills in the value and
+ * scale in format used by PCIe Slot Capabilities Register.
+ *
+ * If the property is not found or is invalid, returns 0.
+ */
+u32 of_pci_get_slot_power_limit(struct device_node *node,
+ u8 *slot_power_limit_value,
+ u8 *slot_power_limit_scale)
+{
+ u32 slot_power_limit_mw;
+ u8 value, scale;
+
+ if (of_property_read_u32(node, "slot-power-limit-milliwatt",
+ &slot_power_limit_mw))
+ slot_power_limit_mw = 0;
+
+ /* Calculate Slot Power Limit Value and Slot Power Limit Scale */
+ if (slot_power_limit_mw == 0) {
+ value = 0x00;
+ scale = 0;
+ } else if (slot_power_limit_mw <= 255) {
+ value = slot_power_limit_mw;
+ scale = 3;
+ } else if (slot_power_limit_mw <= 255*10) {
+ value = slot_power_limit_mw / 10;
+ scale = 2;
+ slot_power_limit_mw = slot_power_limit_mw / 10 * 10;
+ } else if (slot_power_limit_mw <= 255*100) {
+ value = slot_power_limit_mw / 100;
+ scale = 1;
+ slot_power_limit_mw = slot_power_limit_mw / 100 * 100;
+ } else if (slot_power_limit_mw <= 239*1000) {
+ value = slot_power_limit_mw / 1000;
+ scale = 0;
+ slot_power_limit_mw = slot_power_limit_mw / 1000 * 1000;
+ } else if (slot_power_limit_mw < 250*1000) {
+ value = 0xEF;
+ scale = 0;
+ slot_power_limit_mw = 239*1000;
+ } else if (slot_power_limit_mw <= 600*1000) {
+ value = 0xF0 + (slot_power_limit_mw / 1000 - 250) / 25;
+ scale = 0;
+ slot_power_limit_mw = slot_power_limit_mw / (1000*25) * (1000*25);
+ } else {
+ value = 0xFE;
+ scale = 0;
+ slot_power_limit_mw = 600*1000;
+ }
+
+ if (slot_power_limit_value)
+ *slot_power_limit_value = value;
+
+ if (slot_power_limit_scale)
+ *slot_power_limit_scale = scale;
+
+ return slot_power_limit_mw;
+}
+EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit);