/*
 * Copyright (C) 2016 Imagination Technologies
 * Author: Paul Burton <paul.burton@mips.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */

#define pr_fmt(fmt) "sead3: " fmt

#include <linux/errno.h>
#include <linux/libfdt.h>
#include <linux/printk.h>
#include <linux/sizes.h>

#include <asm/fw/fw.h>
#include <asm/io.h>
#include <asm/machine.h>
#include <asm/yamon-dt.h>

#define SEAD_CONFIG                     CKSEG1ADDR(0x1b100110)
#define SEAD_CONFIG_GIC_PRESENT         BIT(1)

#define MIPS_REVISION                   CKSEG1ADDR(0x1fc00010)
#define MIPS_REVISION_MACHINE           (0xf << 4)
#define MIPS_REVISION_MACHINE_SEAD3     (0x4 << 4)

/*
 * Maximum 384MB RAM at physical address 0, preceding any I/O.
 */
static struct yamon_mem_region mem_regions[] __initdata = {
        /* start        size */
        { 0,            SZ_256M + SZ_128M },
        {}
};

static __init bool sead3_detect(void)
{
        uint32_t rev;

        rev = __raw_readl((void *)MIPS_REVISION);
        return (rev & MIPS_REVISION_MACHINE) == MIPS_REVISION_MACHINE_SEAD3;
}

static __init int append_memory(void *fdt)
{
        return yamon_dt_append_memory(fdt, mem_regions);
}

static __init int remove_gic(void *fdt)
{
        const unsigned int cpu_ehci_int = 2;
        const unsigned int cpu_uart_int = 4;
        const unsigned int cpu_eth_int = 6;
        int gic_off, cpu_off, uart_off, eth_off, ehci_off, err;
        uint32_t cfg, cpu_phandle;

        /* leave the GIC node intact if a GIC is present */
        cfg = __raw_readl((uint32_t *)SEAD_CONFIG);
        if (cfg & SEAD_CONFIG_GIC_PRESENT)
                return 0;

        gic_off = fdt_node_offset_by_compatible(fdt, -1, "mti,gic");
        if (gic_off < 0) {
                pr_err("unable to find DT GIC node: %d\n", gic_off);
                return gic_off;
        }

        err = fdt_nop_node(fdt, gic_off);
        if (err) {
                pr_err("unable to nop GIC node\n");
                return err;
        }

        cpu_off = fdt_node_offset_by_compatible(fdt, -1,
                        "mti,cpu-interrupt-controller");
        if (cpu_off < 0) {
                pr_err("unable to find CPU intc node: %d\n", cpu_off);
                return cpu_off;
        }

        cpu_phandle = fdt_get_phandle(fdt, cpu_off);
        if (!cpu_phandle) {
                pr_err("unable to get CPU intc phandle\n");
                return -EINVAL;
        }

        uart_off = fdt_node_offset_by_compatible(fdt, -1, "ns16550a");
        while (uart_off >= 0) {
                err = fdt_setprop_u32(fdt, uart_off, "interrupt-parent",
                                      cpu_phandle);
                if (err) {
                        pr_warn("unable to set UART interrupt-parent: %d\n",
                                err);
                        return err;
                }

                err = fdt_setprop_u32(fdt, uart_off, "interrupts",
                                      cpu_uart_int);
                if (err) {
                        pr_err("unable to set UART interrupts property: %d\n",
                               err);
                        return err;
                }

                uart_off = fdt_node_offset_by_compatible(fdt, uart_off,
                                                         "ns16550a");
        }
        if (uart_off != -FDT_ERR_NOTFOUND) {
                pr_err("error searching for UART DT node: %d\n", uart_off);
                return uart_off;
        }

        eth_off = fdt_node_offset_by_compatible(fdt, -1, "smsc,lan9115");
        if (eth_off < 0) {
                pr_err("unable to find ethernet DT node: %d\n", eth_off);
                return eth_off;
        }

        err = fdt_setprop_u32(fdt, eth_off, "interrupt-parent", cpu_phandle);
        if (err) {
                pr_err("unable to set ethernet interrupt-parent: %d\n", err);
                return err;
        }

        err = fdt_setprop_u32(fdt, eth_off, "interrupts", cpu_eth_int);
        if (err) {
                pr_err("unable to set ethernet interrupts property: %d\n", err);
                return err;
        }

        ehci_off = fdt_node_offset_by_compatible(fdt, -1, "generic-ehci");
        if (ehci_off < 0) {
                pr_err("unable to find EHCI DT node: %d\n", ehci_off);
                return ehci_off;
        }

        err = fdt_setprop_u32(fdt, ehci_off, "interrupt-parent", cpu_phandle);
        if (err) {
                pr_err("unable to set EHCI interrupt-parent: %d\n", err);
                return err;
        }

        err = fdt_setprop_u32(fdt, ehci_off, "interrupts", cpu_ehci_int);
        if (err) {
                pr_err("unable to set EHCI interrupts property: %d\n", err);
                return err;
        }

        return 0;
}

static const struct mips_fdt_fixup sead3_fdt_fixups[] __initconst = {
        { yamon_dt_append_cmdline, "append command line" },
        { append_memory, "append memory" },
        { remove_gic, "remove GIC when not present" },
        { yamon_dt_serial_config, "append serial configuration" },
        { },
};

static __init const void *sead3_fixup_fdt(const void *fdt,
                                          const void *match_data)
{
        static unsigned char fdt_buf[16 << 10] __initdata;
        int err;

        if (fdt_check_header(fdt))
                panic("Corrupt DT");

        /* if this isn't SEAD3, something went wrong */
        BUG_ON(fdt_node_check_compatible(fdt, 0, "mti,sead-3"));

        fw_init_cmdline();

        err = apply_mips_fdt_fixups(fdt_buf, sizeof(fdt_buf),
                                    fdt, sead3_fdt_fixups);
        if (err)
                panic("Unable to fixup FDT: %d", err);

        return fdt_buf;
}

static __init unsigned int sead3_measure_hpt_freq(void)
{
        void __iomem *status_reg = (void __iomem *)0xbf000410;
        unsigned int freq, orig, tick = 0;
        unsigned long flags;

        local_irq_save(flags);

        orig = readl(status_reg) & 0x2;               /* get original sample */
        /* wait for transition */
        while ((readl(status_reg) & 0x2) == orig)
                ;
        orig = orig ^ 0x2;                            /* flip the bit */

        write_c0_count(0);

        /* wait 1 second (the sampling clock transitions every 10ms) */
        while (tick < 100) {
                /* wait for transition */
                while ((readl(status_reg) & 0x2) == orig)
                        ;
                orig = orig ^ 0x2;                            /* flip the bit */
                tick++;
        }

        freq = read_c0_count();

        local_irq_restore(flags);

        return freq;
}

extern char __dtb_sead3_begin[];

MIPS_MACHINE(sead3) = {
        .fdt = __dtb_sead3_begin,
        .detect = sead3_detect,
        .fixup_fdt = sead3_fixup_fdt,
        .measure_hpt_freq = sead3_measure_hpt_freq,
};