// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright 2017 IBM Corporation
 */

#include <linux/clk.h>
#include <linux/log2.h>
#include <linux/mfd/syscon.h>
#include <linux/miscdevice.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/poll.h>
#include <linux/regmap.h>

#include <linux/aspeed-lpc-ctrl.h>

#define DEVICE_NAME     "aspeed-lpc-ctrl"

#define HICR5 0x80
#define HICR5_ENL2H     BIT(8)
#define HICR5_ENFWH     BIT(10)

#define HICR6 0x84
#define SW_FWH2AHB      BIT(17)

#define HICR7 0x88
#define HICR8 0x8c

struct aspeed_lpc_ctrl {
        struct miscdevice       miscdev;
        struct regmap           *regmap;
        struct clk              *clk;
        phys_addr_t             mem_base;
        resource_size_t         mem_size;
        u32                     pnor_size;
        u32                     pnor_base;
        bool                    fwh2ahb;
        struct regmap           *scu;
};

static struct aspeed_lpc_ctrl *file_aspeed_lpc_ctrl(struct file *file)
{
        return container_of(file->private_data, struct aspeed_lpc_ctrl,
                        miscdev);
}

static int aspeed_lpc_ctrl_mmap(struct file *file, struct vm_area_struct *vma)
{
        struct aspeed_lpc_ctrl *lpc_ctrl = file_aspeed_lpc_ctrl(file);
        unsigned long vsize = vma->vm_end - vma->vm_start;
        pgprot_t prot = vma->vm_page_prot;

        if (vma->vm_pgoff + vma_pages(vma) > lpc_ctrl->mem_size >> PAGE_SHIFT)
                return -EINVAL;

        /* ast2400/2500 AHB accesses are not cache coherent */
        prot = pgprot_noncached(prot);

        if (remap_pfn_range(vma, vma->vm_start,
                (lpc_ctrl->mem_base >> PAGE_SHIFT) + vma->vm_pgoff,
                vsize, prot))
                return -EAGAIN;

        return 0;
}

static long aspeed_lpc_ctrl_ioctl(struct file *file, unsigned int cmd,
                unsigned long param)
{
        struct aspeed_lpc_ctrl *lpc_ctrl = file_aspeed_lpc_ctrl(file);
        struct device *dev = file->private_data;
        void __user *p = (void __user *)param;
        struct aspeed_lpc_ctrl_mapping map;
        u32 addr;
        u32 size;
        long rc;

        if (copy_from_user(&map, p, sizeof(map)))
                return -EFAULT;

        if (map.flags != 0)
                return -EINVAL;

        switch (cmd) {
        case ASPEED_LPC_CTRL_IOCTL_GET_SIZE:
                /* The flash windows don't report their size */
                if (map.window_type != ASPEED_LPC_CTRL_WINDOW_MEMORY)
                        return -EINVAL;

                /* Support more than one window id in the future */
                if (map.window_id != 0)
                        return -EINVAL;

                /* If memory-region is not described in device tree */
                if (!lpc_ctrl->mem_size) {
                        dev_dbg(dev, "Didn't find reserved memory\n");
                        return -ENXIO;
                }

                map.size = lpc_ctrl->mem_size;

                return copy_to_user(p, &map, sizeof(map)) ? -EFAULT : 0;
        case ASPEED_LPC_CTRL_IOCTL_MAP:

                /*
                 * The top half of HICR7 is the MSB of the BMC address of the
                 * mapping.
                 * The bottom half of HICR7 is the MSB of the HOST LPC
                 * firmware space address of the mapping.
                 *
                 * The 1 bits in the top of half of HICR8 represent the bits
                 * (in the requested address) that should be ignored and
                 * replaced with those from the top half of HICR7.
                 * The 1 bits in the bottom half of HICR8 represent the bits
                 * (in the requested address) that should be kept and pass
                 * into the BMC address space.
                 */

                /*
                 * It doesn't make sense to talk about a size or offset with
                 * low 16 bits set. Both HICR7 and HICR8 talk about the top 16
                 * bits of addresses and sizes.
                 */

                if ((map.size & 0x0000ffff) || (map.offset & 0x0000ffff))
                        return -EINVAL;

                /*
                 * Because of the way the masks work in HICR8 offset has to
                 * be a multiple of size.
                 */
                if (map.offset & (map.size - 1))
                        return -EINVAL;

                if (map.window_type == ASPEED_LPC_CTRL_WINDOW_FLASH) {
                        if (!lpc_ctrl->pnor_size) {
                                dev_dbg(dev, "Didn't find host pnor flash\n");
                                return -ENXIO;
                        }
                        addr = lpc_ctrl->pnor_base;
                        size = lpc_ctrl->pnor_size;
                } else if (map.window_type == ASPEED_LPC_CTRL_WINDOW_MEMORY) {
                        /* If memory-region is not described in device tree */
                        if (!lpc_ctrl->mem_size) {
                                dev_dbg(dev, "Didn't find reserved memory\n");
                                return -ENXIO;
                        }
                        addr = lpc_ctrl->mem_base;
                        size = lpc_ctrl->mem_size;
                } else {
                        return -EINVAL;
                }

                /* Check overflow first! */
                if (map.offset + map.size < map.offset ||
                        map.offset + map.size > size)
                        return -EINVAL;

                if (map.size == 0 || map.size > size)
                        return -EINVAL;

                addr += map.offset;

                /*
                 * addr (host lpc address) is safe regardless of values. This
                 * simply changes the address the host has to request on its
                 * side of the LPC bus. This cannot impact the hosts own
                 * memory space by surprise as LPC specific accessors are
                 * required. The only strange thing that could be done is
                 * setting the lower 16 bits but the shift takes care of that.
                 */

                rc = regmap_write(lpc_ctrl->regmap, HICR7,
                                (addr | (map.addr >> 16)));
                if (rc)
                        return rc;

                rc = regmap_write(lpc_ctrl->regmap, HICR8,
                                (~(map.size - 1)) | ((map.size >> 16) - 1));
                if (rc)
                        return rc;

                /*
                 * Switch to FWH2AHB mode, AST2600 only.
                 */
                if (lpc_ctrl->fwh2ahb) {
                        /*
                         * Enable FWH2AHB in SCU debug control register 2. This
                         * does not turn it on, but makes it available for it
                         * to be configured in HICR6.
                         */
                        regmap_update_bits(lpc_ctrl->scu, 0x0D8, BIT(2), 0);

                        /*
                         * The other bits in this register are interrupt status bits
                         * that are cleared by writing 1. As we don't want to clear
                         * them, set only the bit of interest.
                         */
                        regmap_write(lpc_ctrl->regmap, HICR6, SW_FWH2AHB);
                }

                /*
                 * Enable LPC FHW cycles. This is required for the host to
                 * access the regions specified.
                 */
                return regmap_update_bits(lpc_ctrl->regmap, HICR5,
                                HICR5_ENFWH | HICR5_ENL2H,
                                HICR5_ENFWH | HICR5_ENL2H);
        }

        return -EINVAL;
}

static const struct file_operations aspeed_lpc_ctrl_fops = {
        .owner          = THIS_MODULE,
        .mmap           = aspeed_lpc_ctrl_mmap,
        .unlocked_ioctl = aspeed_lpc_ctrl_ioctl,
};

static int aspeed_lpc_ctrl_probe(struct platform_device *pdev)
{
        struct aspeed_lpc_ctrl *lpc_ctrl;
        struct device_node *node;
        struct resource resm;
        struct device *dev;
        struct device_node *np;
        int rc;

        dev = &pdev->dev;

        lpc_ctrl = devm_kzalloc(dev, sizeof(*lpc_ctrl), GFP_KERNEL);
        if (!lpc_ctrl)
                return -ENOMEM;

        /* If flash is described in device tree then store */
        node = of_parse_phandle(dev->of_node, "flash", 0);
        if (!node) {
                dev_dbg(dev, "Didn't find host pnor flash node\n");
        } else {
                rc = of_address_to_resource(node, 1, &resm);
                of_node_put(node);
                if (rc) {
                        dev_err(dev, "Couldn't address to resource for flash\n");
                        return rc;
                }

                lpc_ctrl->pnor_size = resource_size(&resm);
                lpc_ctrl->pnor_base = resm.start;
        }


        dev_set_drvdata(&pdev->dev, lpc_ctrl);

        /* If memory-region is described in device tree then store */
        node = of_parse_phandle(dev->of_node, "memory-region", 0);
        if (!node) {
                dev_dbg(dev, "Didn't find reserved memory\n");
        } else {
                rc = of_address_to_resource(node, 0, &resm);
                of_node_put(node);
                if (rc) {
                        dev_err(dev, "Couldn't address to resource for reserved memory\n");
                        return -ENXIO;
                }

                lpc_ctrl->mem_size = resource_size(&resm);
                lpc_ctrl->mem_base = resm.start;

                if (!is_power_of_2(lpc_ctrl->mem_size)) {
                        dev_err(dev, "Reserved memory size must be a power of 2, got %u\n",
                               (unsigned int)lpc_ctrl->mem_size);
                        return -EINVAL;
                }

                if (!IS_ALIGNED(lpc_ctrl->mem_base, lpc_ctrl->mem_size)) {
                        dev_err(dev, "Reserved memory must be naturally aligned for size %u\n",
                               (unsigned int)lpc_ctrl->mem_size);
                        return -EINVAL;
                }
        }

        np = pdev->dev.parent->of_node;
        if (!of_device_is_compatible(np, "aspeed,ast2400-lpc-v2") &&
            !of_device_is_compatible(np, "aspeed,ast2500-lpc-v2") &&
            !of_device_is_compatible(np, "aspeed,ast2600-lpc-v2")) {
                dev_err(dev, "unsupported LPC device binding\n");
                return -ENODEV;
        }

        lpc_ctrl->regmap = syscon_node_to_regmap(np);
        if (IS_ERR(lpc_ctrl->regmap)) {
                dev_err(dev, "Couldn't get regmap\n");
                return -ENODEV;
        }

        if (of_device_is_compatible(dev->of_node, "aspeed,ast2600-lpc-ctrl")) {
                lpc_ctrl->fwh2ahb = true;

                lpc_ctrl->scu = syscon_regmap_lookup_by_compatible("aspeed,ast2600-scu");
                if (IS_ERR(lpc_ctrl->scu)) {
                        dev_err(dev, "couldn't find scu\n");
                        return PTR_ERR(lpc_ctrl->scu);
                }
        }

        lpc_ctrl->clk = devm_clk_get(dev, NULL);
        if (IS_ERR(lpc_ctrl->clk)) {
                dev_err(dev, "couldn't get clock\n");
                return PTR_ERR(lpc_ctrl->clk);
        }
        rc = clk_prepare_enable(lpc_ctrl->clk);
        if (rc) {
                dev_err(dev, "couldn't enable clock\n");
                return rc;
        }

        lpc_ctrl->miscdev.minor = MISC_DYNAMIC_MINOR;
        lpc_ctrl->miscdev.name = DEVICE_NAME;
        lpc_ctrl->miscdev.fops = &aspeed_lpc_ctrl_fops;
        lpc_ctrl->miscdev.parent = dev;
        rc = misc_register(&lpc_ctrl->miscdev);
        if (rc) {
                dev_err(dev, "Unable to register device\n");
                goto err;
        }

        return 0;

err:
        clk_disable_unprepare(lpc_ctrl->clk);
        return rc;
}

static int aspeed_lpc_ctrl_remove(struct platform_device *pdev)
{
        struct aspeed_lpc_ctrl *lpc_ctrl = dev_get_drvdata(&pdev->dev);

        misc_deregister(&lpc_ctrl->miscdev);
        clk_disable_unprepare(lpc_ctrl->clk);

        return 0;
}

static const struct of_device_id aspeed_lpc_ctrl_match[] = {
        { .compatible = "aspeed,ast2400-lpc-ctrl" },
        { .compatible = "aspeed,ast2500-lpc-ctrl" },
        { .compatible = "aspeed,ast2600-lpc-ctrl" },
        { },
};

static struct platform_driver aspeed_lpc_ctrl_driver = {
        .driver = {
                .name           = DEVICE_NAME,
                .of_match_table = aspeed_lpc_ctrl_match,
        },
        .probe = aspeed_lpc_ctrl_probe,
        .remove = aspeed_lpc_ctrl_remove,
};

module_platform_driver(aspeed_lpc_ctrl_driver);

MODULE_DEVICE_TABLE(of, aspeed_lpc_ctrl_match);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Cyril Bur <cyrilbur@gmail.com>");
MODULE_DESCRIPTION("Control for ASPEED LPC HOST to BMC mappings");