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_device.h>
  16 #include <linux/of_dma.h>
  17 #include <linux/regmap.h>
  18 #include <linux/spinlock.h>
  19
  20 /* CREG register offset and macros for mux manipulation */
  21 #define LPC18XX_CREG_DMAMUX             0x11c
  22 #define LPC18XX_DMAMUX_VAL(v, n)        ((v) << (n * 2))
  23 #define LPC18XX_DMAMUX_MASK(n)          (0x3 << (n * 2))
  24 #define LPC18XX_DMAMUX_MAX_VAL          0x3
  25
  26 struct lpc18xx_dmamux {
  27         u32 value;
  28         bool busy;
  29 };
  30
  31 struct lpc18xx_dmamux_data {
  32         struct dma_router dmarouter;
  33         struct lpc18xx_dmamux *muxes;
  34         u32 dma_master_requests;
  35         u32 dma_mux_requests;
  36         struct regmap *reg;
  37         spinlock_t lock;
  38 };
  39
  40 static void lpc18xx_dmamux_free(struct device *dev, void *route_data)
  41 {
  42         struct lpc18xx_dmamux_data *dmamux = dev_get_drvdata(dev);
  43         struct lpc18xx_dmamux *mux = route_data;
  44         unsigned long flags;
  45
  46         spin_lock_irqsave(&dmamux->lock, flags);
  47         mux->busy = false;
  48         spin_unlock_irqrestore(&dmamux->lock, flags);
  49 }
  50
  51 static void *lpc18xx_dmamux_reserve(struct of_phandle_args *dma_spec,
  52                                     struct of_dma *ofdma)
  53 {
  54         struct platform_device *pdev = of_find_device_by_node(ofdma->of_node);
  55         struct lpc18xx_dmamux_data *dmamux = platform_get_drvdata(pdev);
  56         unsigned long flags;
  57         unsigned mux;
  58
  59         if (dma_spec->args_count != 3) {
  60                 dev_err(&pdev->dev, "invalid number of dma mux args\n");
  61                 return ERR_PTR(-EINVAL);
  62         }
  63
  64         mux = dma_spec->args[0];
  65         if (mux >= dmamux->dma_master_requests) {
  66                 dev_err(&pdev->dev, "invalid mux number: %d\n",
  67                         dma_spec->args[0]);
  68                 return ERR_PTR(-EINVAL);
  69         }
  70
  71         if (dma_spec->args[1] > LPC18XX_DMAMUX_MAX_VAL) {
  72                 dev_err(&pdev->dev, "invalid dma mux value: %d\n",
  73                         dma_spec->args[1]);
  74                 return ERR_PTR(-EINVAL);
  75         }
  76
  77         /* The of_node_put() will be done in the core for the node */
  78         dma_spec->np = of_parse_phandle(ofdma->of_node, "dma-masters", 0);
  79         if (!dma_spec->np) {
  80                 dev_err(&pdev->dev, "can't get dma master\n");
  81                 return ERR_PTR(-EINVAL);
  82         }
  83
  84         spin_lock_irqsave(&dmamux->lock, flags);
  85         if (dmamux->muxes[mux].busy) {
  86                 spin_unlock_irqrestore(&dmamux->lock, flags);
  87                 dev_err(&pdev->dev, "dma request %u busy with %u.%u\n",
  88                         mux, mux, dmamux->muxes[mux].value);
  89                 of_node_put(dma_spec->np);
  90                 return ERR_PTR(-EBUSY);
  91         }
  92
  93         dmamux->muxes[mux].busy = true;
  94         dmamux->muxes[mux].value = dma_spec->args[1];
  95
  96         regmap_update_bits(dmamux->reg, LPC18XX_CREG_DMAMUX,
  97                            LPC18XX_DMAMUX_MASK(mux),
  98                            LPC18XX_DMAMUX_VAL(dmamux->muxes[mux].value, mux));
  99         spin_unlock_irqrestore(&dmamux->lock, flags);
 100
 101         dma_spec->args[1] = dma_spec->args[2];
 102         dma_spec->args_count = 2;
 103
 104         dev_dbg(&pdev->dev, "mapping dmamux %u.%u to dma request %u\n", mux,
 105                 dmamux->muxes[mux].value, mux);
 106
 107         return &dmamux->muxes[mux];
 108 }
 109
 110 static int lpc18xx_dmamux_probe(struct platform_device *pdev)
 111 {
 112         struct device_node *dma_np, *np = pdev->dev.of_node;
 113         struct lpc18xx_dmamux_data *dmamux;
 114         int ret;
 115
 116         dmamux = devm_kzalloc(&pdev->dev, sizeof(*dmamux), GFP_KERNEL);
 117         if (!dmamux)
 118                 return -ENOMEM;
 119
 120         dmamux->reg = syscon_regmap_lookup_by_compatible("nxp,lpc1850-creg");
 121         if (IS_ERR(dmamux->reg)) {
 122                 dev_err(&pdev->dev, "syscon lookup failed\n");
 123                 return PTR_ERR(dmamux->reg);
 124         }
 125
 126         ret = of_property_read_u32(np, "dma-requests",
 127                                    &dmamux->dma_mux_requests);
 128         if (ret) {
 129                 dev_err(&pdev->dev, "missing dma-requests property\n");
 130                 return ret;
 131         }
 132
 133         dma_np = of_parse_phandle(np, "dma-masters", 0);
 134         if (!dma_np) {
 135                 dev_err(&pdev->dev, "can't get dma master\n");
 136                 return -ENODEV;
 137         }
 138
 139         ret = of_property_read_u32(dma_np, "dma-requests",
 140                                    &dmamux->dma_master_requests);
 141         of_node_put(dma_np);
 142         if (ret) {
 143                 dev_err(&pdev->dev, "missing master dma-requests property\n");
 144                 return ret;
 145         }
 146
 147         dmamux->muxes = devm_kcalloc(&pdev->dev, dmamux->dma_master_requests,
 148                                      sizeof(struct lpc18xx_dmamux),
 149                                      GFP_KERNEL);
 150         if (!dmamux->muxes)
 151                 return -ENOMEM;
 152
 153         spin_lock_init(&dmamux->lock);
 154         platform_set_drvdata(pdev, dmamux);
 155         dmamux->dmarouter.dev = &pdev->dev;
 156         dmamux->dmarouter.route_free = lpc18xx_dmamux_free;
 157
 158         return of_dma_router_register(np, lpc18xx_dmamux_reserve,
 159                                       &dmamux->dmarouter);
 160 }
 161
 162 static const struct of_device_id lpc18xx_dmamux_match[] = {
 163         { .compatible = "nxp,lpc1850-dmamux" },
 164         {},
 165 };
 166
 167 static struct platform_driver lpc18xx_dmamux_driver = {
 168         .probe  = lpc18xx_dmamux_probe,
 169         .driver = {
 170                 .name = "lpc18xx-dmamux",
 171                 .of_match_table = lpc18xx_dmamux_match,
 172         },
 173 };
 174
 175 static int __init lpc18xx_dmamux_init(void)
 176 {
 177         return platform_driver_register(&lpc18xx_dmamux_driver);
 178 }
 179 arch_initcall(lpc18xx_dmamux_init);