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
30 struct lpc18xx_dmamux {
31 u32 value;
32 bool busy;
33 };
34
35 struct 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
lpc18xx_dmamux_free(struct device * dev,void * route_data)44 static 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
lpc18xx_dmamux_reserve(struct of_phandle_args * dma_spec,struct of_dma * ofdma)55 static 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
lpc18xx_dmamux_probe(struct platform_device * pdev)114 static 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
166 static const struct of_device_id lpc18xx_dmamux_match[] = {
167 { .compatible = "nxp,lpc1850-dmamux" },
168 {},
169 };
170
171 static 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
lpc18xx_dmamux_init(void)179 static int __init lpc18xx_dmamux_init(void)
180 {
181 return platform_driver_register(&lpc18xx_dmamux_driver);
182 }
183 arch_initcall(lpc18xx_dmamux_init);
184