Revert "unicode: Don't special case ignorable code points"

[linux.git] / drivers / pci / of.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * PCI <-> OF mapping helpers
 *
 * Copyright 2011 IBM Corp.
 */
#define pr_fmt(fmt)     "PCI: OF: " fmt

#include <linux/cleanup.h>
#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 <linux/platform_device.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)
{
        if (!dev->bus->dev.of_node)
                return 0;

        struct device_node *node __free(device_node) =
                of_pci_find_child_device(dev->bus->dev.of_node, dev->devfn);
        if (!node)
                return 0;

        struct device *pdev __free(put_device) =
                bus_find_device_by_of_node(&platform_bus_type, node);
        if (pdev)
                dev->bus->dev.of_node_reused = true;

        device_set_node(&dev->dev, of_fwnode_handle(no_free_ptr(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_preserve_config - Return true if the boot configuration needs to
 *                          be preserved
 * @node: Device tree node.
 *
 * Look for "linux,pci-probe-only" property for a given PCI controller's
 * node and return true if found. Also look in the chosen node if the
 * property is not found in the given controller's node.  Having this
 * property ensures that the kernel doesn't reconfigure the BARs and bridge
 * windows that are already done by the platform firmware.
 *
 * Return: true if the property exists; false otherwise.
 */
bool of_pci_preserve_config(struct device_node *node)
{
        u32 val = 0;
        int ret;

        if (!node) {
                pr_warn("device node is NULL, trying with of_chosen\n");
                node = of_chosen;
        }

retry:
        ret = of_property_read_u32(node, "linux,pci-probe-only", &val);
        if (ret) {
                if (ret == -ENODATA || ret == -EOVERFLOW) {
                        pr_warn("Incorrect value for linux,pci-probe-only in %pOF, ignoring\n",
                                node);
                        return false;
                }
                if (ret == -EINVAL) {
                        if (node == of_chosen)
                                return false;

                        node = of_chosen;
                        goto retry;
                }
        }

        if (val)
                return true;
        else
                return false;
}

/**
 * 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)
{
        if (of_pci_preserve_config(of_chosen))
                pci_add_flags(PCI_PROBE_ONLY);
        else
                pci_clear_flags(PCI_PROBE_ONLY);
}
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

/**
 * of_pci_supply_present() - Check if the power supply is present for the PCI
 *                              device
 * @np: Device tree node
 *
 * Check if the power supply for the PCI device is present in the device tree
 * node or not.
 *
 * Return: true if at least one power supply exists; false otherwise.
 */
bool of_pci_supply_present(struct device_node *np)
{
        struct property *prop;
        char *supply;

        if (!np)
                return false;

        for_each_property_of_node(np, prop) {
                supply = strrchr(prop->name, '-');
                if (supply && !strcmp(supply, "-supply"))
                        return true;
        }

        return false;
}

#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);