// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2017 Broadcom
 */

/*
 * This driver provides reset support for Broadcom FlexRM ring manager
 * to VFIO platform.
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>

#include "../vfio_platform_private.h"

/* FlexRM configuration */
#define RING_REGS_SIZE                                  0x10000
#define RING_VER_MAGIC                                  0x76303031

/* Per-Ring register offsets */
#define RING_VER                                        0x000
#define RING_CONTROL                                    0x034
#define RING_FLUSH_DONE                                 0x038

/* Register RING_CONTROL fields */
#define CONTROL_FLUSH_SHIFT                             5

/* Register RING_FLUSH_DONE fields */
#define FLUSH_DONE_MASK                                 0x1

static int vfio_platform_bcmflexrm_shutdown(void __iomem *ring)
{
        unsigned int timeout;

        /* Disable/inactivate ring */
        writel_relaxed(0x0, ring + RING_CONTROL);

        /* Set ring flush state */
        timeout = 1000; /* timeout of 1s */
        writel_relaxed(BIT(CONTROL_FLUSH_SHIFT), ring + RING_CONTROL);
        do {
                if (readl_relaxed(ring + RING_FLUSH_DONE) &
                    FLUSH_DONE_MASK)
                        break;
                mdelay(1);
        } while (--timeout);
        if (!timeout)
                return -ETIMEDOUT;

        /* Clear ring flush state */
        timeout = 1000; /* timeout of 1s */
        writel_relaxed(0x0, ring + RING_CONTROL);
        do {
                if (!(readl_relaxed(ring + RING_FLUSH_DONE) &
                      FLUSH_DONE_MASK))
                        break;
                mdelay(1);
        } while (--timeout);
        if (!timeout)
                return -ETIMEDOUT;

        return 0;
}

static int vfio_platform_bcmflexrm_reset(struct vfio_platform_device *vdev)
{
        void __iomem *ring;
        int rc = 0, ret = 0, ring_num = 0;
        struct vfio_platform_region *reg = &vdev->regions[0];

        dev_err_once(vdev->device, "DEPRECATION: VFIO Broadcom FlexRM platform reset is deprecated and will be removed in a future kernel release\n");

        /* Map FlexRM ring registers if not mapped */
        if (!reg->ioaddr) {
                reg->ioaddr = ioremap(reg->addr, reg->size);
                if (!reg->ioaddr)
                        return -ENOMEM;
        }

        /* Discover and shutdown each FlexRM ring */
        for (ring = reg->ioaddr;
             ring < (reg->ioaddr + reg->size); ring += RING_REGS_SIZE) {
                if (readl_relaxed(ring + RING_VER) == RING_VER_MAGIC) {
                        rc = vfio_platform_bcmflexrm_shutdown(ring);
                        if (rc) {
                                dev_warn(vdev->device,
                                         "FlexRM ring%d shutdown error %d\n",
                                         ring_num, rc);
                                ret |= rc;
                        }
                        ring_num++;
                }
        }

        return ret;
}

module_vfio_reset_handler("brcm,iproc-flexrm-mbox",
                          vfio_platform_bcmflexrm_reset);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Anup Patel <anup.patel@broadcom.com>");
MODULE_DESCRIPTION("Reset support for Broadcom FlexRM VFIO platform device");