// SPDX-License-Identifier: GPL-2.0+
/*
 * DAWR infrastructure
 *
 * Copyright 2019, Michael Neuling, IBM Corporation.
 */

#include <linux/types.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <asm/machdep.h>
#include <asm/hvcall.h>
#include <asm/firmware.h>

bool dawr_force_enable;
EXPORT_SYMBOL_GPL(dawr_force_enable);

int set_dawr(int nr, struct arch_hw_breakpoint *brk)
{
        unsigned long dawr, dawrx, mrd;

        dawr = brk->address;

        dawrx  = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE))
                << (63 - 58);
        dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) << (63 - 59);
        dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) >> 3;
        /*
         * DAWR length is stored in field MDR bits 48:53.  Matches range in
         * doublewords (64 bits) biased by -1 eg. 0b000000=1DW and
         * 0b111111=64DW.
         * brk->hw_len is in bytes.
         * This aligns up to double word size, shifts and does the bias.
         */
        mrd = ((brk->hw_len + 7) >> 3) - 1;
        dawrx |= (mrd & 0x3f) << (63 - 53);

        if (ppc_md.set_dawr)
                return ppc_md.set_dawr(nr, dawr, dawrx);

        if (nr == 0) {
                mtspr(SPRN_DAWR0, dawr);
                mtspr(SPRN_DAWRX0, dawrx);
        } else {
                mtspr(SPRN_DAWR1, dawr);
                mtspr(SPRN_DAWRX1, dawrx);
        }

        return 0;
}

static void disable_dawrs_cb(void *info)
{
        struct arch_hw_breakpoint null_brk = {0};
        int i;

        for (i = 0; i < nr_wp_slots(); i++)
                set_dawr(i, &null_brk);
}

static ssize_t dawr_write_file_bool(struct file *file,
                                    const char __user *user_buf,
                                    size_t count, loff_t *ppos)
{
        struct arch_hw_breakpoint null_brk = {0};
        size_t rc;

        /* Send error to user if they hypervisor won't allow us to write DAWR */
        if (!dawr_force_enable &&
            firmware_has_feature(FW_FEATURE_LPAR) &&
            set_dawr(0, &null_brk) != H_SUCCESS)
                return -ENODEV;

        rc = debugfs_write_file_bool(file, user_buf, count, ppos);
        if (rc)
                return rc;

        /* If we are clearing, make sure all CPUs have the DAWR cleared */
        if (!dawr_force_enable)
                smp_call_function(disable_dawrs_cb, NULL, 0);

        return rc;
}

static const struct file_operations dawr_enable_fops = {
        .read =         debugfs_read_file_bool,
        .write =        dawr_write_file_bool,
        .open =         simple_open,
        .llseek =       default_llseek,
};

static int __init dawr_force_setup(void)
{
        if (cpu_has_feature(CPU_FTR_DAWR)) {
                /* Don't setup sysfs file for user control on P8 */
                dawr_force_enable = true;
                return 0;
        }

        if (PVR_VER(mfspr(SPRN_PVR)) == PVR_POWER9) {
                /* Turn DAWR off by default, but allow admin to turn it on */
                debugfs_create_file_unsafe("dawr_enable_dangerous", 0600,
                                           arch_debugfs_dir,
                                           &dawr_force_enable,
                                           &dawr_enable_fops);
        }
        return 0;
}
arch_initcall(dawr_force_setup);