1. 根目录:
2. drivers
3. dma
4. lpc18xx-dmamux.c

/*
 * 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>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/err.h>
#include <linux/init.h>
#include <linux/mfd/syscon.h>
#include <linux/of_device.h>
#include <linux/of_dma.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;

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

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

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

	/* 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");
		return ERR_PTR(-EINVAL);
	}

	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);
		return ERR_PTR(-EBUSY);
	}

	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);

	return &dmamux->muxes[mux];
}

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);