// SPDX-License-Identifier: GPL-2.0-only
//
// Copyright 2024 Timesys Corporation <piotr.wojtaszczyk@timesys.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>

#define LPC32XX_SSP_CLK_CTRL 0x78
#define LPC32XX_I2S_CLK_CTRL 0x7c

struct lpc32xx_dmamux {
        int signal;
        char *name_sel0;
        char *name_sel1;
        int muxval;
        int muxreg;
        int bit;
        bool busy;
};

struct lpc32xx_dmamux_data {
        struct dma_router dmarouter;
        struct regmap *reg;
        spinlock_t lock; /* protects busy status flag */
};

/* From LPC32x0 User manual "3.2.1 DMA request signals" */
static struct lpc32xx_dmamux lpc32xx_muxes[] = {
        {
                .signal = 3,
                .name_sel0 = "spi2-rx-tx",
                .name_sel1 = "ssp1-rx",
                .muxreg = LPC32XX_SSP_CLK_CTRL,
                .bit = 5,
        },
        {
                .signal = 10,
                .name_sel0 = "uart7-rx",
                .name_sel1 = "i2s1-dma1",
                .muxreg = LPC32XX_I2S_CLK_CTRL,
                .bit = 4,
        },
        {
                .signal = 11,
                .name_sel0 = "spi1-rx-tx",
                .name_sel1 = "ssp1-tx",
                .muxreg = LPC32XX_SSP_CLK_CTRL,
                .bit = 4,
        },
        {
                .signal = 14,
                .name_sel0 = "none",
                .name_sel1 = "ssp0-rx",
                .muxreg = LPC32XX_SSP_CLK_CTRL,
                .bit = 3,
        },
        {
                .signal = 15,
                .name_sel0 = "none",
                .name_sel1 = "ssp0-tx",
                .muxreg = LPC32XX_SSP_CLK_CTRL,
                .bit = 2,
        },
};

static void lpc32xx_dmamux_release(struct device *dev, void *route_data)
{
        struct lpc32xx_dmamux_data *dmamux = dev_get_drvdata(dev);
        struct lpc32xx_dmamux *mux = route_data;

        dev_dbg(dev, "releasing dma request signal %d routed to %s\n",
                mux->signal, mux->muxval ? mux->name_sel1 : mux->name_sel1);

        guard(spinlock)(&dmamux->lock);

        mux->busy = false;
}

static void *lpc32xx_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 device *dev = &pdev->dev;
        struct lpc32xx_dmamux_data *dmamux = platform_get_drvdata(pdev);
        unsigned long flags;
        struct lpc32xx_dmamux *mux = NULL;
        int ret = -EINVAL;
        int i;

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

        for (i = 0; i < ARRAY_SIZE(lpc32xx_muxes); i++) {
                if (lpc32xx_muxes[i].signal == dma_spec->args[0]) {
                        mux = &lpc32xx_muxes[i];
                        break;
                }
        }
        if (!mux) {
                dev_err(&pdev->dev, "invalid mux request number: %d\n",
                        dma_spec->args[0]);
                goto err_put_pdev;
        }

        if (dma_spec->args[2] > 1) {
                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 (mux->busy) {
                spin_unlock_irqrestore(&dmamux->lock, flags);
                dev_err(dev, "dma request signal %d busy, routed to %s\n",
                        mux->signal, mux->muxval ? mux->name_sel1 : mux->name_sel1);
                of_node_put(dma_spec->np);
                ret = -EBUSY;
                goto err_put_pdev;
        }

        mux->busy = true;
        mux->muxval = dma_spec->args[2] ? BIT(mux->bit) : 0;

        regmap_update_bits(dmamux->reg, mux->muxreg, BIT(mux->bit), mux->muxval);
        spin_unlock_irqrestore(&dmamux->lock, flags);

        dma_spec->args[2] = 0;
        dma_spec->args_count = 2;

        dev_dbg(dev, "dma request signal %d routed to %s\n",
                mux->signal, mux->muxval ? mux->name_sel1 : mux->name_sel1);

        put_device(&pdev->dev);

        return mux;

err_put_pdev:
        put_device(&pdev->dev);

        return ERR_PTR(ret);
}

static int lpc32xx_dmamux_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct lpc32xx_dmamux_data *dmamux;

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

        dmamux->reg = syscon_node_to_regmap(np->parent);
        if (IS_ERR(dmamux->reg)) {
                dev_err(&pdev->dev, "syscon lookup failed\n");
                return PTR_ERR(dmamux->reg);
        }

        spin_lock_init(&dmamux->lock);
        platform_set_drvdata(pdev, dmamux);
        dmamux->dmarouter.dev = &pdev->dev;
        dmamux->dmarouter.route_free = lpc32xx_dmamux_release;

        return of_dma_router_register(np, lpc32xx_dmamux_reserve,
                                      &dmamux->dmarouter);
}

static const struct of_device_id lpc32xx_dmamux_match[] = {
        { .compatible = "nxp,lpc3220-dmamux" },
        {},
};

static struct platform_driver lpc32xx_dmamux_driver = {
        .probe  = lpc32xx_dmamux_probe,
        .driver = {
                .name = "lpc32xx-dmamux",
                .of_match_table = lpc32xx_dmamux_match,
        },
};

static int __init lpc32xx_dmamux_init(void)
{
        return platform_driver_register(&lpc32xx_dmamux_driver);
}
arch_initcall(lpc32xx_dmamux_init);