// SPDX-License-Identifier: GPL-2.0-only
/*
 * DMA Router driver for LPC18xx/43xx DMA MUX
 *
 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
 *
 * Based on TI DMA Crossbar driver by:
 *   Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
 *   Author: Peter Ujfalusi <peter.ujfalusi@ti.com>
 */

#include <linux/err.h>
#include <linux/init.h>
#include <linux/mfd/syscon.h>
#include <linux/of.h>
#include <linux/of_dma.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/spinlock.h>

/* CREG register offset and macros for mux manipulation */
#define LPC18XX_CREG_DMAMUX             0x11c
#define LPC18XX_DMAMUX_VAL(v, n)        ((v) << (n * 2))
#define LPC18XX_DMAMUX_MASK(n)          (0x3 << (n * 2))
#define LPC18XX_DMAMUX_MAX_VAL          0x3

struct lpc18xx_dmamux {
        u32 value;
        bool busy;
};

struct lpc18xx_dmamux_data {
        struct dma_router dmarouter;
        struct lpc18xx_dmamux *muxes;
        u32 dma_master_requests;
        u32 dma_mux_requests;
        struct regmap *reg;
        spinlock_t lock;
};

static void lpc18xx_dmamux_free(struct device *dev, void *route_data)
{
        struct lpc18xx_dmamux_data *dmamux = dev_get_drvdata(dev);
        struct lpc18xx_dmamux *mux = route_data;
        unsigned long flags;

        spin_lock_irqsave(&dmamux->lock, flags);
        mux->busy = false;
        spin_unlock_irqrestore(&dmamux->lock, flags);
}

static void *lpc18xx_dmamux_reserve(struct of_phandle_args *dma_spec,
                                    struct of_dma *ofdma)
{
        struct platform_device *pdev = of_find_device_by_node(ofdma->of_node);
        struct lpc18xx_dmamux_data *dmamux = platform_get_drvdata(pdev);
        unsigned long flags;
        unsigned mux;
        int ret = -EINVAL;

        if (dma_spec->args_count != 3) {
                dev_err(&pdev->dev, "invalid number of dma mux args\n");
                goto err_put_pdev;
        }

        mux = dma_spec->args[0];
        if (mux >= dmamux->dma_master_requests) {
                dev_err(&pdev->dev, "invalid mux number: %d\n",
                        dma_spec->args[0]);
                goto err_put_pdev;
        }

        if (dma_spec->args[1] > LPC18XX_DMAMUX_MAX_VAL) {
                dev_err(&pdev->dev, "invalid dma mux value: %d\n",
                        dma_spec->args[1]);
                goto err_put_pdev;
        }

        /* The of_node_put() will be done in the core for the node */
        dma_spec->np = of_parse_phandle(ofdma->of_node, "dma-masters", 0);
        if (!dma_spec->np) {
                dev_err(&pdev->dev, "can't get dma master\n");
                goto err_put_pdev;
        }

        spin_lock_irqsave(&dmamux->lock, flags);
        if (dmamux->muxes[mux].busy) {
                spin_unlock_irqrestore(&dmamux->lock, flags);
                dev_err(&pdev->dev, "dma request %u busy with %u.%u\n",
                        mux, mux, dmamux->muxes[mux].value);
                of_node_put(dma_spec->np);
                ret = -EBUSY;
                goto err_put_pdev;
        }

        dmamux->muxes[mux].busy = true;
        dmamux->muxes[mux].value = dma_spec->args[1];

        regmap_update_bits(dmamux->reg, LPC18XX_CREG_DMAMUX,
                           LPC18XX_DMAMUX_MASK(mux),
                           LPC18XX_DMAMUX_VAL(dmamux->muxes[mux].value, mux));
        spin_unlock_irqrestore(&dmamux->lock, flags);

        dma_spec->args[1] = dma_spec->args[2];
        dma_spec->args_count = 2;

        dev_dbg(&pdev->dev, "mapping dmamux %u.%u to dma request %u\n", mux,
                dmamux->muxes[mux].value, mux);

        put_device(&pdev->dev);

        return &dmamux->muxes[mux];

err_put_pdev:
        put_device(&pdev->dev);

        return ERR_PTR(ret);
}

static int lpc18xx_dmamux_probe(struct platform_device *pdev)
{
        struct device_node *dma_np, *np = pdev->dev.of_node;
        struct lpc18xx_dmamux_data *dmamux;
        int ret;

        dmamux = devm_kzalloc(&pdev->dev, sizeof(*dmamux), GFP_KERNEL);
        if (!dmamux)
                return -ENOMEM;

        dmamux->reg = syscon_regmap_lookup_by_compatible("nxp,lpc1850-creg");
        if (IS_ERR(dmamux->reg)) {
                dev_err(&pdev->dev, "syscon lookup failed\n");
                return PTR_ERR(dmamux->reg);
        }

        ret = of_property_read_u32(np, "dma-requests",
                                   &dmamux->dma_mux_requests);
        if (ret) {
                dev_err(&pdev->dev, "missing dma-requests property\n");
                return ret;
        }

        dma_np = of_parse_phandle(np, "dma-masters", 0);
        if (!dma_np) {
                dev_err(&pdev->dev, "can't get dma master\n");
                return -ENODEV;
        }

        ret = of_property_read_u32(dma_np, "dma-requests",
                                   &dmamux->dma_master_requests);
        of_node_put(dma_np);
        if (ret) {
                dev_err(&pdev->dev, "missing master dma-requests property\n");
                return ret;
        }

        dmamux->muxes = devm_kcalloc(&pdev->dev, dmamux->dma_master_requests,
                                     sizeof(struct lpc18xx_dmamux),
                                     GFP_KERNEL);
        if (!dmamux->muxes)
                return -ENOMEM;

        spin_lock_init(&dmamux->lock);
        platform_set_drvdata(pdev, dmamux);
        dmamux->dmarouter.dev = &pdev->dev;
        dmamux->dmarouter.route_free = lpc18xx_dmamux_free;

        return of_dma_router_register(np, lpc18xx_dmamux_reserve,
                                      &dmamux->dmarouter);
}

static const struct of_device_id lpc18xx_dmamux_match[] = {
        { .compatible = "nxp,lpc1850-dmamux" },
        {},
};

static struct platform_driver lpc18xx_dmamux_driver = {
        .probe  = lpc18xx_dmamux_probe,
        .driver = {
                .name = "lpc18xx-dmamux",
                .of_match_table = lpc18xx_dmamux_match,
        },
};

static int __init lpc18xx_dmamux_init(void)
{
        return platform_driver_register(&lpc18xx_dmamux_driver);
}
arch_initcall(lpc18xx_dmamux_init);