lpc18xx-dmamux.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * DMA Router driver for LPC18xx/43xx DMA MUX
  4 *
  5 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
  6 *
  7 * Based on TI DMA Crossbar driver by:
  8 *   Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
  9 *   Author: Peter Ujfalusi <peter.ujfalusi@ti.com>
 10 */
 11
 12#include <linux/err.h>
 13#include <linux/init.h>
 14#include <linux/mfd/syscon.h>
 15#include <linux/of.h>
 16#include <linux/of_dma.h>
 17#include <linux/of_platform.h>
 18#include <linux/platform_device.h>
 19#include <linux/regmap.h>
 20#include <linux/spinlock.h>
 21
 22/* CREG register offset and macros for mux manipulation */
 23#define LPC18XX_CREG_DMAMUX		0x11c
 24#define LPC18XX_DMAMUX_VAL(v, n)	((v) << (n * 2))
 25#define LPC18XX_DMAMUX_MASK(n)		(0x3 << (n * 2))
 26#define LPC18XX_DMAMUX_MAX_VAL		0x3
 27
 28struct lpc18xx_dmamux {
 29	u32 value;
 30	bool busy;
 31};
 32
 33struct lpc18xx_dmamux_data {
 34	struct dma_router dmarouter;
 35	struct lpc18xx_dmamux *muxes;
 36	u32 dma_master_requests;
 37	u32 dma_mux_requests;
 38	struct regmap *reg;
 39	spinlock_t lock;
 40};
 41
 42static void lpc18xx_dmamux_free(struct device *dev, void *route_data)
 43{
 44	struct lpc18xx_dmamux_data *dmamux = dev_get_drvdata(dev);
 45	struct lpc18xx_dmamux *mux = route_data;
 46	unsigned long flags;
 47
 48	spin_lock_irqsave(&dmamux->lock, flags);
 49	mux->busy = false;
 50	spin_unlock_irqrestore(&dmamux->lock, flags);
 51}
 52
 53static void *lpc18xx_dmamux_reserve(struct of_phandle_args *dma_spec,
 54				    struct of_dma *ofdma)
 55{
 56	struct platform_device *pdev = of_find_device_by_node(ofdma->of_node);
 57	struct lpc18xx_dmamux_data *dmamux = platform_get_drvdata(pdev);
 58	unsigned long flags;
 59	unsigned mux;
 60	int ret = -EINVAL;
 61
 62	if (dma_spec->args_count != 3) {
 63		dev_err(&pdev->dev, "invalid number of dma mux args\n");
 64		goto err_put_pdev;
 65	}
 66
 67	mux = dma_spec->args[0];
 68	if (mux >= dmamux->dma_master_requests) {
 69		dev_err(&pdev->dev, "invalid mux number: %d\n",
 70			dma_spec->args[0]);
 71		goto err_put_pdev;
 72	}
 73
 74	if (dma_spec->args[1] > LPC18XX_DMAMUX_MAX_VAL) {
 75		dev_err(&pdev->dev, "invalid dma mux value: %d\n",
 76			dma_spec->args[1]);
 77		goto err_put_pdev;
 78	}
 79
 80	/* The of_node_put() will be done in the core for the node */
 81	dma_spec->np = of_parse_phandle(ofdma->of_node, "dma-masters", 0);
 82	if (!dma_spec->np) {
 83		dev_err(&pdev->dev, "can't get dma master\n");
 84		goto err_put_pdev;
 85	}
 86
 87	spin_lock_irqsave(&dmamux->lock, flags);
 88	if (dmamux->muxes[mux].busy) {
 89		spin_unlock_irqrestore(&dmamux->lock, flags);
 90		dev_err(&pdev->dev, "dma request %u busy with %u.%u\n",
 91			mux, mux, dmamux->muxes[mux].value);
 92		of_node_put(dma_spec->np);
 93		ret = -EBUSY;
 94		goto err_put_pdev;
 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	put_device(&pdev->dev);
112
113	return &dmamux->muxes[mux];
114
115err_put_pdev:
116	put_device(&pdev->dev);
117
118	return ERR_PTR(ret);
119}
120
121static int lpc18xx_dmamux_probe(struct platform_device *pdev)
122{
123	struct device_node *dma_np, *np = pdev->dev.of_node;
124	struct lpc18xx_dmamux_data *dmamux;
125	int ret;
126
127	dmamux = devm_kzalloc(&pdev->dev, sizeof(*dmamux), GFP_KERNEL);
128	if (!dmamux)
129		return -ENOMEM;
130
131	dmamux->reg = syscon_regmap_lookup_by_compatible("nxp,lpc1850-creg");
132	if (IS_ERR(dmamux->reg)) {
133		dev_err(&pdev->dev, "syscon lookup failed\n");
134		return PTR_ERR(dmamux->reg);
135	}
136
137	ret = of_property_read_u32(np, "dma-requests",
138				   &dmamux->dma_mux_requests);
139	if (ret) {
140		dev_err(&pdev->dev, "missing dma-requests property\n");
141		return ret;
142	}
143
144	dma_np = of_parse_phandle(np, "dma-masters", 0);
145	if (!dma_np) {
146		dev_err(&pdev->dev, "can't get dma master\n");
147		return -ENODEV;
148	}
149
150	ret = of_property_read_u32(dma_np, "dma-requests",
151				   &dmamux->dma_master_requests);
152	of_node_put(dma_np);
153	if (ret) {
154		dev_err(&pdev->dev, "missing master dma-requests property\n");
155		return ret;
156	}
157
158	dmamux->muxes = devm_kcalloc(&pdev->dev, dmamux->dma_master_requests,
159				     sizeof(struct lpc18xx_dmamux),
160				     GFP_KERNEL);
161	if (!dmamux->muxes)
162		return -ENOMEM;
163
164	spin_lock_init(&dmamux->lock);
165	platform_set_drvdata(pdev, dmamux);
166	dmamux->dmarouter.dev = &pdev->dev;
167	dmamux->dmarouter.route_free = lpc18xx_dmamux_free;
168
169	return of_dma_router_register(np, lpc18xx_dmamux_reserve,
170				      &dmamux->dmarouter);
171}
172
173static const struct of_device_id lpc18xx_dmamux_match[] = {
174	{ .compatible = "nxp,lpc1850-dmamux" },
175	{},
176};
177
178static struct platform_driver lpc18xx_dmamux_driver = {
179	.probe	= lpc18xx_dmamux_probe,
180	.driver = {
181		.name = "lpc18xx-dmamux",
182		.of_match_table = lpc18xx_dmamux_match,
183	},
184};
185
186static int __init lpc18xx_dmamux_init(void)
187{
188	return platform_driver_register(&lpc18xx_dmamux_driver);
189}
190arch_initcall(lpc18xx_dmamux_init);