1/*
  2 * DMA Router driver for LPC18xx/43xx DMA MUX
  3 *
  4 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
  5 *
  6 * Based on TI DMA Crossbar driver by:
  7 *   Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
  8 *   Author: Peter Ujfalusi <peter.ujfalusi@ti.com>
  9 *
 10 * This program is free software; you can redistribute it and/or modify
 11 * it under the terms of the GNU General Public License version 2 as
 12 * published by the Free Software Foundation.
 13 *
 14 */
 15
 16#include <linux/err.h>
 17#include <linux/init.h>
 18#include <linux/mfd/syscon.h>
 19#include <linux/of_device.h>
 20#include <linux/of_dma.h>
 21#include <linux/regmap.h>
 22#include <linux/spinlock.h>
 23
 24/* CREG register offset and macros for mux manipulation */
 25#define LPC18XX_CREG_DMAMUX		0x11c
 26#define LPC18XX_DMAMUX_VAL(v, n)	((v) << (n * 2))
 27#define LPC18XX_DMAMUX_MASK(n)		(0x3 << (n * 2))
 28#define LPC18XX_DMAMUX_MAX_VAL		0x3
 29
 30struct lpc18xx_dmamux {
 31	u32 value;
 32	bool busy;
 33};
 34
 35struct lpc18xx_dmamux_data {
 36	struct dma_router dmarouter;
 37	struct lpc18xx_dmamux *muxes;
 38	u32 dma_master_requests;
 39	u32 dma_mux_requests;
 40	struct regmap *reg;
 41	spinlock_t lock;
 42};
 43
 44static void lpc18xx_dmamux_free(struct device *dev, void *route_data)
 45{
 46	struct lpc18xx_dmamux_data *dmamux = dev_get_drvdata(dev);
 47	struct lpc18xx_dmamux *mux = route_data;
 48	unsigned long flags;
 49
 50	spin_lock_irqsave(&dmamux->lock, flags);
 51	mux->busy = false;
 52	spin_unlock_irqrestore(&dmamux->lock, flags);
 53}
 54
 55static void *lpc18xx_dmamux_reserve(struct of_phandle_args *dma_spec,
 56				    struct of_dma *ofdma)
 57{
 58	struct platform_device *pdev = of_find_device_by_node(ofdma->of_node);
 59	struct lpc18xx_dmamux_data *dmamux = platform_get_drvdata(pdev);
 60	unsigned long flags;
 61	unsigned mux;
 62
 63	if (dma_spec->args_count != 3) {
 64		dev_err(&pdev->dev, "invalid number of dma mux args\n");
 65		return ERR_PTR(-EINVAL);
 66	}
 67
 68	mux = dma_spec->args[0];
 69	if (mux >= dmamux->dma_master_requests) {
 70		dev_err(&pdev->dev, "invalid mux number: %d\n",
 71			dma_spec->args[0]);
 72		return ERR_PTR(-EINVAL);
 73	}
 74
 75	if (dma_spec->args[1] > LPC18XX_DMAMUX_MAX_VAL) {
 76		dev_err(&pdev->dev, "invalid dma mux value: %d\n",
 77			dma_spec->args[1]);
 78		return ERR_PTR(-EINVAL);
 79	}
 80
 81	/* The of_node_put() will be done in the core for the node */
 82	dma_spec->np = of_parse_phandle(ofdma->of_node, "dma-masters", 0);
 83	if (!dma_spec->np) {
 84		dev_err(&pdev->dev, "can't get dma master\n");
 85		return ERR_PTR(-EINVAL);
 86	}
 87
 88	spin_lock_irqsave(&dmamux->lock, flags);
 89	if (dmamux->muxes[mux].busy) {
 90		spin_unlock_irqrestore(&dmamux->lock, flags);
 91		dev_err(&pdev->dev, "dma request %u busy with %u.%u\n",
 92			mux, mux, dmamux->muxes[mux].value);
 93		of_node_put(dma_spec->np);
 94		return ERR_PTR(-EBUSY);
 95	}
 96
 97	dmamux->muxes[mux].busy = true;
 98	dmamux->muxes[mux].value = dma_spec->args[1];
 99
100	regmap_update_bits(dmamux->reg, LPC18XX_CREG_DMAMUX,
101			   LPC18XX_DMAMUX_MASK(mux),
102			   LPC18XX_DMAMUX_VAL(dmamux->muxes[mux].value, mux));
103	spin_unlock_irqrestore(&dmamux->lock, flags);
104
105	dma_spec->args[1] = dma_spec->args[2];
106	dma_spec->args_count = 2;
107
108	dev_dbg(&pdev->dev, "mapping dmamux %u.%u to dma request %u\n", mux,
109		dmamux->muxes[mux].value, mux);
110
111	return &dmamux->muxes[mux];
112}
113
114static int lpc18xx_dmamux_probe(struct platform_device *pdev)
115{
116	struct device_node *dma_np, *np = pdev->dev.of_node;
117	struct lpc18xx_dmamux_data *dmamux;
118	int ret;
119
120	dmamux = devm_kzalloc(&pdev->dev, sizeof(*dmamux), GFP_KERNEL);
121	if (!dmamux)
122		return -ENOMEM;
123
124	dmamux->reg = syscon_regmap_lookup_by_compatible("nxp,lpc1850-creg");
125	if (IS_ERR(dmamux->reg)) {
126		dev_err(&pdev->dev, "syscon lookup failed\n");
127		return PTR_ERR(dmamux->reg);
128	}
129
130	ret = of_property_read_u32(np, "dma-requests",
131				   &dmamux->dma_mux_requests);
132	if (ret) {
133		dev_err(&pdev->dev, "missing dma-requests property\n");
134		return ret;
135	}
136
137	dma_np = of_parse_phandle(np, "dma-masters", 0);
138	if (!dma_np) {
139		dev_err(&pdev->dev, "can't get dma master\n");
140		return -ENODEV;
141	}
142
143	ret = of_property_read_u32(dma_np, "dma-requests",
144				   &dmamux->dma_master_requests);
145	of_node_put(dma_np);
146	if (ret) {
147		dev_err(&pdev->dev, "missing master dma-requests property\n");
148		return ret;
149	}
150
151	dmamux->muxes = devm_kcalloc(&pdev->dev, dmamux->dma_master_requests,
152				     sizeof(struct lpc18xx_dmamux),
153				     GFP_KERNEL);
154	if (!dmamux->muxes)
155		return -ENOMEM;
156
157	spin_lock_init(&dmamux->lock);
158	platform_set_drvdata(pdev, dmamux);
159	dmamux->dmarouter.dev = &pdev->dev;
160	dmamux->dmarouter.route_free = lpc18xx_dmamux_free;
161
162	return of_dma_router_register(np, lpc18xx_dmamux_reserve,
163				      &dmamux->dmarouter);
164}
165
166static const struct of_device_id lpc18xx_dmamux_match[] = {
167	{ .compatible = "nxp,lpc1850-dmamux" },
168	{},
169};
170
171static struct platform_driver lpc18xx_dmamux_driver = {
172	.probe	= lpc18xx_dmamux_probe,
173	.driver = {
174		.name = "lpc18xx-dmamux",
175		.of_match_table = lpc18xx_dmamux_match,
176	},
177};
178
179static int __init lpc18xx_dmamux_init(void)
180{
181	return platform_driver_register(&lpc18xx_dmamux_driver);
182}
183arch_initcall(lpc18xx_dmamux_init);