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(lock: &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(np: 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(np: ofdma->of_node, phandle_name: "dma-masters", index: 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(lock: &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(node: 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(map: dmamux->reg, LPC18XX_CREG_DMAMUX,
101 LPC18XX_DMAMUX_MASK(mux),
102 LPC18XX_DMAMUX_VAL(dmamux->muxes[mux].value, mux));
103 spin_unlock_irqrestore(lock: &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(dev: &pdev->dev);
112
113 return &dmamux->muxes[mux];
114
115err_put_pdev:
116 put_device(dev: &pdev->dev);
117
118 return ERR_PTR(error: 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(dev: &pdev->dev, size: sizeof(*dmamux), GFP_KERNEL);
128 if (!dmamux)
129 return -ENOMEM;
130
131 dmamux->reg = syscon_regmap_lookup_by_compatible(s: "nxp,lpc1850-creg");
132 if (IS_ERR(ptr: dmamux->reg)) {
133 dev_err(&pdev->dev, "syscon lookup failed\n");
134 return PTR_ERR(ptr: dmamux->reg);
135 }
136
137 ret = of_property_read_u32(np, propname: "dma-requests",
138 out_value: &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, phandle_name: "dma-masters", index: 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(np: dma_np, propname: "dma-requests",
151 out_value: &dmamux->dma_master_requests);
152 of_node_put(node: 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(dev: &pdev->dev, n: dmamux->dma_master_requests,
159 size: 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, data: dmamux);
166 dmamux->dmarouter.dev = &pdev->dev;
167 dmamux->dmarouter.route_free = lpc18xx_dmamux_free;
168
169 return of_dma_router_register(np, of_dma_route_allocate: lpc18xx_dmamux_reserve,
170 dma_router: &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);
191

source code of linux/drivers/dma/lpc18xx-dmamux.c