/*
 * Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 2000 MIPS Technologies, Inc.  All rights reserved.
 * Portions copyright (C) 2009 Cisco Systems, Inc.
 *
 *  This program is free software; you can distribute it and/or modify it
 *  under the terms of the GNU General Public License (Version 2) as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope it will be useful, but WITHOUT
 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
 */
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/pci.h>
#include <linux/screen_info.h>
#include <linux/notifier.h>
#include <linux/etherdevice.h>
#include <linux/if_ether.h>
#include <linux/ctype.h>
#include <linux/cpu.h>
#include <linux/time.h>

#include <asm/bootinfo.h>
#include <asm/irq.h>
#include <asm/mips-boards/generic.h>
#include <asm/dma.h>
#include <asm/asm.h>
#include <asm/traps.h>
#include <asm/asm-offsets.h>
#include "reset.h"

#define VAL(n)          STR(n)

/*
 * Macros for loading addresses and storing registers:
 * LONG_L_      Stringified version of LONG_L for use in asm() statement
 * LONG_S_      Stringified version of LONG_S for use in asm() statement
 * PTR_LA_      Stringified version of PTR_LA for use in asm() statement
 * REG_SIZE     Number of 8-bit bytes in a full width register
 */
#define LONG_L_         VAL(LONG_L) " "
#define LONG_S_         VAL(LONG_S) " "
#define PTR_LA_         VAL(PTR_LA) " "

#ifdef CONFIG_64BIT
#warning TODO: 64-bit code needs to be verified
#define REG_SIZE        "8"             /* In bytes */
#endif

#ifdef CONFIG_32BIT
#define REG_SIZE        "4"             /* In bytes */
#endif

static void register_panic_notifier(void);
static int panic_handler(struct notifier_block *notifier_block,
        unsigned long event, void *cause_string);

const char *get_system_type(void)
{
        return "PowerTV";
}

void __init plat_mem_setup(void)
{
        panic_on_oops = 1;
        register_panic_notifier();

#if 0
        mips_pcibios_init();
#endif
        mips_reboot_setup();
}

/*
 * Install a panic notifier for platform-specific diagnostics
 */
static void register_panic_notifier()
{
        static struct notifier_block panic_notifier = {
                .notifier_call = panic_handler,
                .next = NULL,
                .priority       = INT_MAX
        };
        atomic_notifier_chain_register(&panic_notifier_list, &panic_notifier);
}

static int panic_handler(struct notifier_block *notifier_block,
        unsigned long event, void *cause_string)
{
        struct pt_regs  my_regs;

        /* Save all of the registers */
        {
                unsigned long   at, v0, v1; /* Must be on the stack */

                /* Start by saving $at and v0 on the stack. We use $at
                 * ourselves, but it looks like the compiler may use v0 or v1
                 * to load the address of the pt_regs structure. We'll come
                 * back later to store the registers in the pt_regs
                 * structure. */
                __asm__ __volatile__ (
                        ".set   noat\n"
                        LONG_S_         "$at, %[at]\n"
                        LONG_S_         "$2, %[v0]\n"
                        LONG_S_         "$3, %[v1]\n"
                :
                        [at] "=m" (at),
                        [v0] "=m" (v0),
                        [v1] "=m" (v1)
                :
                :       "at"
                );

                __asm__ __volatile__ (
                        ".set   noat\n"
                        "move           $at, %[pt_regs]\n"

                        /* Argument registers */
                        LONG_S_         "$4, " VAL(PT_R4) "($at)\n"
                        LONG_S_         "$5, " VAL(PT_R5) "($at)\n"
                        LONG_S_         "$6, " VAL(PT_R6) "($at)\n"
                        LONG_S_         "$7, " VAL(PT_R7) "($at)\n"

                        /* Temporary regs */
                        LONG_S_         "$8, " VAL(PT_R8) "($at)\n"
                        LONG_S_         "$9, " VAL(PT_R9) "($at)\n"
                        LONG_S_         "$10, " VAL(PT_R10) "($at)\n"
                        LONG_S_         "$11, " VAL(PT_R11) "($at)\n"
                        LONG_S_         "$12, " VAL(PT_R12) "($at)\n"
                        LONG_S_         "$13, " VAL(PT_R13) "($at)\n"
                        LONG_S_         "$14, " VAL(PT_R14) "($at)\n"
                        LONG_S_         "$15, " VAL(PT_R15) "($at)\n"

                        /* "Saved" registers */
                        LONG_S_         "$16, " VAL(PT_R16) "($at)\n"
                        LONG_S_         "$17, " VAL(PT_R17) "($at)\n"
                        LONG_S_         "$18, " VAL(PT_R18) "($at)\n"
                        LONG_S_         "$19, " VAL(PT_R19) "($at)\n"
                        LONG_S_         "$20, " VAL(PT_R20) "($at)\n"
                        LONG_S_         "$21, " VAL(PT_R21) "($at)\n"
                        LONG_S_         "$22, " VAL(PT_R22) "($at)\n"
                        LONG_S_         "$23, " VAL(PT_R23) "($at)\n"

                        /* Add'l temp regs */
                        LONG_S_         "$24, " VAL(PT_R24) "($at)\n"
                        LONG_S_         "$25, " VAL(PT_R25) "($at)\n"

                        /* Kernel temp regs */
                        LONG_S_         "$26, " VAL(PT_R26) "($at)\n"
                        LONG_S_         "$27, " VAL(PT_R27) "($at)\n"

                        /* Global pointer, stack pointer, frame pointer and
                         * return address */
                        LONG_S_         "$gp, " VAL(PT_R28) "($at)\n"
                        LONG_S_         "$sp, " VAL(PT_R29) "($at)\n"
                        LONG_S_         "$fp, " VAL(PT_R30) "($at)\n"
                        LONG_S_         "$ra, " VAL(PT_R31) "($at)\n"

                        /* Now we can get the $at and v0 registers back and
                         * store them */
                        LONG_L_         "$8, %[at]\n"
                        LONG_S_         "$8, " VAL(PT_R1) "($at)\n"
                        LONG_L_         "$8, %[v0]\n"
                        LONG_S_         "$8, " VAL(PT_R2) "($at)\n"
                        LONG_L_         "$8, %[v1]\n"
                        LONG_S_         "$8, " VAL(PT_R3) "($at)\n"
                :
                :
                        [at] "m" (at),
                        [v0] "m" (v0),
                        [v1] "m" (v1),
                        [pt_regs] "r" (&my_regs)
                :       "at", "t0"
                );

                /* Set the current EPC value to be the current location in this
                 * function */
                __asm__ __volatile__ (
                        ".set   noat\n"
                "1:\n"
                        PTR_LA_         "$at, 1b\n"
                        LONG_S_         "$at, %[cp0_epc]\n"
                :
                        [cp0_epc] "=m" (my_regs.cp0_epc)
                :
                :       "at"
                );

                my_regs.cp0_cause = read_c0_cause();
                my_regs.cp0_status = read_c0_status();
        }

        pr_crit("I'm feeling a bit sleepy. hmmmmm... perhaps a nap would... "
                "zzzz... \n");

        return NOTIFY_DONE;
}

/* Information about the RF MAC address, if one was supplied on the
 * command line. */
static bool have_rfmac;
static u8 rfmac[ETH_ALEN];

static int rfmac_param(char *p)
{
        u8      *q;
        bool    is_high_nibble;
        int     c;

        /* Skip a leading "0x", if present */
        if (*p == '0' && *(p+1) == 'x')
                p += 2;

        q = rfmac;
        is_high_nibble = true;

        for (c = (unsigned char) *p++;
                isxdigit(c) && q - rfmac < ETH_ALEN;
                c = (unsigned char) *p++) {
                int     nibble;

                nibble = (isdigit(c) ? (c - '0') :
                        (isupper(c) ? c - 'A' + 10 : c - 'a' + 10));

                if (is_high_nibble)
                        *q = nibble << 4;
                else
                        *q++ |= nibble;

                is_high_nibble = !is_high_nibble;
        }

        /* If we parsed all the way to the end of the parameter value and
         * parsed all ETH_ALEN bytes, we have a usable RF MAC address */
        have_rfmac = (c == '\0' && q - rfmac == ETH_ALEN);

        return 0;
}

early_param("rfmac", rfmac_param);

/*
 * Generate an Ethernet MAC address that has a good chance of being unique.
 * @addr:       Pointer to six-byte array containing the Ethernet address
 * Generates an Ethernet MAC address that is highly likely to be unique for
 * this particular system on a network with other systems of the same type.
 *
 * The problem we are solving is that, when eth_random_addr() is used to
 * generate MAC addresses at startup, there isn't much entropy for the random
 * number generator to use and the addresses it produces are fairly likely to
 * be the same as those of other identical systems on the same local network.
 * This is true even for relatively small numbers of systems (for the reason
 * why, see the Wikipedia entry for "Birthday problem" at:
 *      http://en.wikipedia.org/wiki/Birthday_problem
 *
 * The good news is that we already have a MAC address known to be unique, the
 * RF MAC address. The bad news is that this address is already in use on the
 * RF interface. Worse, the obvious trick, taking the RF MAC address and
 * turning on the locally managed bit, has already been used for other devices.
 * Still, this does give us something to work with.
 *
 * The approach we take is:
 * 1.   If we can't get the RF MAC Address, just call eth_random_addr.
 * 2.   Use the 24-bit NIC-specific bits of the RF MAC address as the last 24
 *      bits of the new address. This is very likely to be unique, except for
 *      the current box.
 * 3.   To avoid using addresses already on the current box, we set the top
 *      six bits of the address with a value different from any currently
 *      registered Scientific Atlanta organizationally unique identifyer
 *      (OUI). This avoids duplication with any addresses on the system that
 *      were generated from valid Scientific Atlanta-registered address by
 *      simply flipping the locally managed bit.
 * 4.   We aren't generating a multicast address, so we leave the multicast
 *      bit off. Since we aren't using a registered address, we have to set
 *      the locally managed bit.
 * 5.   We then randomly generate the remaining 16-bits. This does two
 *      things:
 *      a.      It allows us to call this function for more than one device
 *              in this system
 *      b.      It ensures that things will probably still work even if
 *              some device on the device network has a locally managed
 *              address that matches the top six bits from step 2.
 */
void platform_random_ether_addr(u8 addr[ETH_ALEN])
{
        const int num_random_bytes = 2;
        const unsigned char non_sciatl_oui_bits = 0xc0u;
        const unsigned char mac_addr_locally_managed = (1 << 1);

        if (!have_rfmac) {
                pr_warning("rfmac not available on command line; "
                        "generating random MAC address\n");
                eth_random_addr(addr);
        }

        else {
                int     i;

                /* Set the first byte to something that won't match a Scientific
                 * Atlanta OUI, is locally managed, and isn't a multicast
                 * address */
                addr[0] = non_sciatl_oui_bits | mac_addr_locally_managed;

                /* Get some bytes of random address information */
                get_random_bytes(&addr[1], num_random_bytes);

                /* Copy over the NIC-specific bits of the RF MAC address */
                for (i = 1 + num_random_bytes; i < ETH_ALEN; i++)
                        addr[i] = rfmac[i];
        }
}