drivers/dma/lpc18xx-dmamux.c

   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
  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
  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
 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
 179 static int __init lpc18xx_dmamux_init(void)
 180 {
 181         return platform_driver_register(&lpc18xx_dmamux_driver);
 182 }
 183 arch_initcall(lpc18xx_dmamux_init);