drivers/dma/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
  28 struct lpc18xx_dmamux {
  29         u32 value;
  30         bool busy;
  31 };
  32
  33 struct 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
  42 static 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
  53 static 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
  61         if (dma_spec->args_count != 3) {
  62                 dev_err(&pdev->dev, "invalid number of dma mux args\n");
  63                 return ERR_PTR(-EINVAL);
  64         }
  65
  66         mux = dma_spec->args[0];
  67         if (mux >= dmamux->dma_master_requests) {
  68                 dev_err(&pdev->dev, "invalid mux number: %d\n",
  69                         dma_spec->args[0]);
  70                 return ERR_PTR(-EINVAL);
  71         }
  72
  73         if (dma_spec->args[1] > LPC18XX_DMAMUX_MAX_VAL) {
  74                 dev_err(&pdev->dev, "invalid dma mux value: %d\n",
  75                         dma_spec->args[1]);
  76                 return ERR_PTR(-EINVAL);
  77         }
  78
  79         /* The of_node_put() will be done in the core for the node */
  80         dma_spec->np = of_parse_phandle(ofdma->of_node, "dma-masters", 0);
  81         if (!dma_spec->np) {
  82                 dev_err(&pdev->dev, "can't get dma master\n");
  83                 return ERR_PTR(-EINVAL);
  84         }
  85
  86         spin_lock_irqsave(&dmamux->lock, flags);
  87         if (dmamux->muxes[mux].busy) {
  88                 spin_unlock_irqrestore(&dmamux->lock, flags);
  89                 dev_err(&pdev->dev, "dma request %u busy with %u.%u\n",
  90                         mux, mux, dmamux->muxes[mux].value);
  91                 of_node_put(dma_spec->np);
  92                 return ERR_PTR(-EBUSY);
  93         }
  94
  95         dmamux->muxes[mux].busy = true;
  96         dmamux->muxes[mux].value = dma_spec->args[1];
  97
  98         regmap_update_bits(dmamux->reg, LPC18XX_CREG_DMAMUX,
  99                            LPC18XX_DMAMUX_MASK(mux),
 100                            LPC18XX_DMAMUX_VAL(dmamux->muxes[mux].value, mux));
 101         spin_unlock_irqrestore(&dmamux->lock, flags);
 102
 103         dma_spec->args[1] = dma_spec->args[2];
 104         dma_spec->args_count = 2;
 105
 106         dev_dbg(&pdev->dev, "mapping dmamux %u.%u to dma request %u\n", mux,
 107                 dmamux->muxes[mux].value, mux);
 108
 109         return &dmamux->muxes[mux];
 110 }
 111
 112 static int lpc18xx_dmamux_probe(struct platform_device *pdev)
 113 {
 114         struct device_node *dma_np, *np = pdev->dev.of_node;
 115         struct lpc18xx_dmamux_data *dmamux;
 116         int ret;
 117
 118         dmamux = devm_kzalloc(&pdev->dev, sizeof(*dmamux), GFP_KERNEL);
 119         if (!dmamux)
 120                 return -ENOMEM;
 121
 122         dmamux->reg = syscon_regmap_lookup_by_compatible("nxp,lpc1850-creg");
 123         if (IS_ERR(dmamux->reg)) {
 124                 dev_err(&pdev->dev, "syscon lookup failed\n");
 125                 return PTR_ERR(dmamux->reg);
 126         }
 127
 128         ret = of_property_read_u32(np, "dma-requests",
 129                                    &dmamux->dma_mux_requests);
 130         if (ret) {
 131                 dev_err(&pdev->dev, "missing dma-requests property\n");
 132                 return ret;
 133         }
 134
 135         dma_np = of_parse_phandle(np, "dma-masters", 0);
 136         if (!dma_np) {
 137                 dev_err(&pdev->dev, "can't get dma master\n");
 138                 return -ENODEV;
 139         }
 140
 141         ret = of_property_read_u32(dma_np, "dma-requests",
 142                                    &dmamux->dma_master_requests);
 143         of_node_put(dma_np);
 144         if (ret) {
 145                 dev_err(&pdev->dev, "missing master dma-requests property\n");
 146                 return ret;
 147         }
 148
 149         dmamux->muxes = devm_kcalloc(&pdev->dev, dmamux->dma_master_requests,
 150                                      sizeof(struct lpc18xx_dmamux),
 151                                      GFP_KERNEL);
 152         if (!dmamux->muxes)
 153                 return -ENOMEM;
 154
 155         spin_lock_init(&dmamux->lock);
 156         platform_set_drvdata(pdev, dmamux);
 157         dmamux->dmarouter.dev = &pdev->dev;
 158         dmamux->dmarouter.route_free = lpc18xx_dmamux_free;
 159
 160         return of_dma_router_register(np, lpc18xx_dmamux_reserve,
 161                                       &dmamux->dmarouter);
 162 }
 163
 164 static const struct of_device_id lpc18xx_dmamux_match[] = {
 165         { .compatible = "nxp,lpc1850-dmamux" },
 166         {},
 167 };
 168
 169 static struct platform_driver lpc18xx_dmamux_driver = {
 170         .probe  = lpc18xx_dmamux_probe,
 171         .driver = {
 172                 .name = "lpc18xx-dmamux",
 173                 .of_match_table = lpc18xx_dmamux_match,
 174         },
 175 };
 176
 177 static int __init lpc18xx_dmamux_init(void)
 178 {
 179         return platform_driver_register(&lpc18xx_dmamux_driver);
 180 }
 181 arch_initcall(lpc18xx_dmamux_init);