// SPDX-License-Identifier: GPL-2.0+
/*
 * A hack to create a platform device from a DMI entry.  This will
 * allow autoloading of the IPMI drive based on SMBIOS entries.
 */

#define pr_fmt(fmt) "%s" fmt, "ipmi:dmi: "
#define dev_fmt pr_fmt

#include <linux/ipmi.h>
#include <linux/init.h>
#include <linux/dmi.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include "ipmi_dmi.h"
#include "ipmi_plat_data.h"

#define IPMI_DMI_TYPE_KCS       0x01
#define IPMI_DMI_TYPE_SMIC      0x02
#define IPMI_DMI_TYPE_BT        0x03
#define IPMI_DMI_TYPE_SSIF      0x04

struct ipmi_dmi_info {
        enum si_type si_type;
        unsigned int space; /* addr space for si, intf# for ssif */
        unsigned long addr;
        u8 slave_addr;
        struct ipmi_dmi_info *next;
};

static struct ipmi_dmi_info *ipmi_dmi_infos;

static int ipmi_dmi_nr __initdata;

static void __init dmi_add_platform_ipmi(unsigned long base_addr,
                                         unsigned int space,
                                         u8 slave_addr,
                                         int irq,
                                         int offset,
                                         int type)
{
        const char *name;
        struct ipmi_dmi_info *info;
        struct ipmi_plat_data p;

        memset(&p, 0, sizeof(p));

        name = "dmi-ipmi-si";
        p.iftype = IPMI_PLAT_IF_SI;
        switch (type) {
        case IPMI_DMI_TYPE_SSIF:
                name = "dmi-ipmi-ssif";
                p.iftype = IPMI_PLAT_IF_SSIF;
                p.type = SI_TYPE_INVALID;
                break;
        case IPMI_DMI_TYPE_BT:
                p.type = SI_BT;
                break;
        case IPMI_DMI_TYPE_KCS:
                p.type = SI_KCS;
                break;
        case IPMI_DMI_TYPE_SMIC:
                p.type = SI_SMIC;
                break;
        default:
                pr_err("Invalid IPMI type: %d\n", type);
                return;
        }

        p.addr = base_addr;
        p.space = space;
        p.regspacing = offset;
        p.irq = irq;
        p.slave_addr = slave_addr;
        p.addr_source = SI_SMBIOS;

        info = kmalloc(sizeof(*info), GFP_KERNEL);
        if (!info) {
                pr_warn("Could not allocate dmi info\n");
        } else {
                info->si_type = p.type;
                info->space = space;
                info->addr = base_addr;
                info->slave_addr = slave_addr;
                info->next = ipmi_dmi_infos;
                ipmi_dmi_infos = info;
        }

        if (ipmi_platform_add(name, ipmi_dmi_nr, &p))
                ipmi_dmi_nr++;
}

/*
 * Look up the slave address for a given interface.  This is here
 * because ACPI doesn't have a slave address while SMBIOS does, but we
 * prefer using ACPI so the ACPI code can use the IPMI namespace.
 * This function allows an ACPI-specified IPMI device to look up the
 * slave address from the DMI table.
 */
int ipmi_dmi_get_slave_addr(enum si_type si_type, unsigned int space,
                            unsigned long base_addr)
{
        struct ipmi_dmi_info *info = ipmi_dmi_infos;

        while (info) {
                if (info->si_type == si_type &&
                    info->space == space &&
                    info->addr == base_addr)
                        return info->slave_addr;
                info = info->next;
        }

        return 0;
}
EXPORT_SYMBOL(ipmi_dmi_get_slave_addr);

#define DMI_IPMI_MIN_LENGTH     0x10
#define DMI_IPMI_VER2_LENGTH    0x12
#define DMI_IPMI_TYPE           4
#define DMI_IPMI_SLAVEADDR      6
#define DMI_IPMI_ADDR           8
#define DMI_IPMI_ACCESS         0x10
#define DMI_IPMI_IRQ            0x11
#define DMI_IPMI_IO_MASK        0xfffe

static void __init dmi_decode_ipmi(const struct dmi_header *dm)
{
        const u8 *data = (const u8 *) dm;
        int space = IPMI_IO_ADDR_SPACE;
        unsigned long base_addr;
        u8 len = dm->length;
        u8 slave_addr;
        int irq = 0, offset = 0;
        int type;

        if (len < DMI_IPMI_MIN_LENGTH)
                return;

        type = data[DMI_IPMI_TYPE];
        slave_addr = data[DMI_IPMI_SLAVEADDR];

        memcpy(&base_addr, data + DMI_IPMI_ADDR, sizeof(unsigned long));
        if (!base_addr) {
                pr_err("Base address is zero, assuming no IPMI interface\n");
                return;
        }
        if (len >= DMI_IPMI_VER2_LENGTH) {
                if (type == IPMI_DMI_TYPE_SSIF) {
                        space = 0; /* Match I2C interface 0. */
                        base_addr = data[DMI_IPMI_ADDR] >> 1;
                        if (base_addr == 0) {
                                /*
                                 * Some broken systems put the I2C address in
                                 * the slave address field.  We try to
                                 * accommodate them here.
                                 */
                                base_addr = data[DMI_IPMI_SLAVEADDR] >> 1;
                                slave_addr = 0;
                        }
                } else {
                        if (base_addr & 1) {
                                /* I/O */
                                base_addr &= DMI_IPMI_IO_MASK;
                        } else {
                                /* Memory */
                                space = IPMI_MEM_ADDR_SPACE;
                        }

                        /*
                         * If bit 4 of byte 0x10 is set, then the lsb
                         * for the address is odd.
                         */
                        base_addr |= (data[DMI_IPMI_ACCESS] >> 4) & 1;

                        irq = data[DMI_IPMI_IRQ];

                        /*
                         * The top two bits of byte 0x10 hold the
                         * register spacing.
                         */
                        switch ((data[DMI_IPMI_ACCESS] >> 6) & 3) {
                        case 0: /* Byte boundaries */
                                offset = 1;
                                break;
                        case 1: /* 32-bit boundaries */
                                offset = 4;
                                break;
                        case 2: /* 16-byte boundaries */
                                offset = 16;
                                break;
                        default:
                                pr_err("Invalid offset: 0\n");
                                return;
                        }
                }
        } else {
                /* Old DMI spec. */
                /*
                 * Note that technically, the lower bit of the base
                 * address should be 1 if the address is I/O and 0 if
                 * the address is in memory.  So many systems get that
                 * wrong (and all that I have seen are I/O) so we just
                 * ignore that bit and assume I/O.  Systems that use
                 * memory should use the newer spec, anyway.
                 */
                base_addr = base_addr & DMI_IPMI_IO_MASK;
                offset = 1;
        }

        dmi_add_platform_ipmi(base_addr, space, slave_addr, irq,
                              offset, type);
}

static int __init scan_for_dmi_ipmi(void)
{
        const struct dmi_device *dev = NULL;

        while ((dev = dmi_find_device(DMI_DEV_TYPE_IPMI, NULL, dev)))
                dmi_decode_ipmi((const struct dmi_header *) dev->device_data);

        return 0;
}
subsys_initcall(scan_for_dmi_ipmi);