drivers/reset/reset-meson-audio-arb.c

   1 // SPDX-License-Identifier: (GPL-2.0 OR MIT)
   2 // Copyright (c) 2018 BayLibre, SAS.
   3 // Author: Jerome Brunet <jbrunet@baylibre.com>
   4
   5 #include <linux/clk.h>
   6 #include <linux/io.h>
   7 #include <linux/module.h>
   8 #include <linux/of_platform.h>
   9 #include <linux/reset-controller.h>
  10 #include <linux/spinlock.h>
  11
  12 #include <dt-bindings/reset/amlogic,meson-axg-audio-arb.h>
  13
  14 struct meson_audio_arb_data {
  15         struct reset_controller_dev rstc;
  16         void __iomem *regs;
  17         struct clk *clk;
  18         const unsigned int *reset_bits;
  19         spinlock_t lock;
  20 };
  21
  22 #define ARB_GENERAL_BIT 31
  23
  24 static const unsigned int axg_audio_arb_reset_bits[] = {
  25         [AXG_ARB_TODDR_A]       = 0,
  26         [AXG_ARB_TODDR_B]       = 1,
  27         [AXG_ARB_TODDR_C]       = 2,
  28         [AXG_ARB_FRDDR_A]       = 4,
  29         [AXG_ARB_FRDDR_B]       = 5,
  30         [AXG_ARB_FRDDR_C]       = 6,
  31 };
  32
  33 static int meson_audio_arb_update(struct reset_controller_dev *rcdev,
  34                                   unsigned long id, bool assert)
  35 {
  36         u32 val;
  37         struct meson_audio_arb_data *arb =
  38                 container_of(rcdev, struct meson_audio_arb_data, rstc);
  39
  40         spin_lock(&arb->lock);
  41         val = readl(arb->regs);
  42
  43         if (assert)
  44                 val &= ~BIT(arb->reset_bits[id]);
  45         else
  46                 val |= BIT(arb->reset_bits[id]);
  47
  48         writel(val, arb->regs);
  49         spin_unlock(&arb->lock);
  50
  51         return 0;
  52 }
  53
  54 static int meson_audio_arb_status(struct reset_controller_dev *rcdev,
  55                                   unsigned long id)
  56 {
  57         u32 val;
  58         struct meson_audio_arb_data *arb =
  59                 container_of(rcdev, struct meson_audio_arb_data, rstc);
  60
  61         val = readl(arb->regs);
  62
  63         return !(val & BIT(arb->reset_bits[id]));
  64 }
  65
  66 static int meson_audio_arb_assert(struct reset_controller_dev *rcdev,
  67                                   unsigned long id)
  68 {
  69         return meson_audio_arb_update(rcdev, id, true);
  70 }
  71
  72 static int meson_audio_arb_deassert(struct reset_controller_dev *rcdev,
  73                                     unsigned long id)
  74 {
  75         return meson_audio_arb_update(rcdev, id, false);
  76 }
  77
  78 static const struct reset_control_ops meson_audio_arb_rstc_ops = {
  79         .assert = meson_audio_arb_assert,
  80         .deassert = meson_audio_arb_deassert,
  81         .status = meson_audio_arb_status,
  82 };
  83
  84 static const struct of_device_id meson_audio_arb_of_match[] = {
  85         { .compatible = "amlogic,meson-axg-audio-arb", },
  86         {}
  87 };
  88 MODULE_DEVICE_TABLE(of, meson_audio_arb_of_match);
  89
  90 static int meson_audio_arb_remove(struct platform_device *pdev)
  91 {
  92         struct meson_audio_arb_data *arb = platform_get_drvdata(pdev);
  93
  94         /* Disable all access */
  95         spin_lock(&arb->lock);
  96         writel(0, arb->regs);
  97         spin_unlock(&arb->lock);
  98
  99         clk_disable_unprepare(arb->clk);
 100
 101         return 0;
 102 }
 103
 104 static int meson_audio_arb_probe(struct platform_device *pdev)
 105 {
 106         struct device *dev = &pdev->dev;
 107         struct meson_audio_arb_data *arb;
 108         struct resource *res;
 109         int ret;
 110
 111         arb = devm_kzalloc(dev, sizeof(*arb), GFP_KERNEL);
 112         if (!arb)
 113                 return -ENOMEM;
 114         platform_set_drvdata(pdev, arb);
 115
 116         arb->clk = devm_clk_get(dev, NULL);
 117         if (IS_ERR(arb->clk)) {
 118                 if (PTR_ERR(arb->clk) != -EPROBE_DEFER)
 119                         dev_err(dev, "failed to get clock\n");
 120                 return PTR_ERR(arb->clk);
 121         }
 122
 123         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 124         arb->regs = devm_ioremap_resource(dev, res);
 125         if (IS_ERR(arb->regs))
 126                 return PTR_ERR(arb->regs);
 127
 128         spin_lock_init(&arb->lock);
 129         arb->reset_bits = axg_audio_arb_reset_bits;
 130         arb->rstc.nr_resets = ARRAY_SIZE(axg_audio_arb_reset_bits);
 131         arb->rstc.ops = &meson_audio_arb_rstc_ops;
 132         arb->rstc.of_node = dev->of_node;
 133         arb->rstc.owner = THIS_MODULE;
 134
 135         /*
 136          * Enable general :
 137          * In the initial state, all memory interfaces are disabled
 138          * and the general bit is on
 139          */
 140         ret = clk_prepare_enable(arb->clk);
 141         if (ret) {
 142                 dev_err(dev, "failed to enable arb clock\n");
 143                 return ret;
 144         }
 145         writel(BIT(ARB_GENERAL_BIT), arb->regs);
 146
 147         /* Register reset controller */
 148         ret = devm_reset_controller_register(dev, &arb->rstc);
 149         if (ret) {
 150                 dev_err(dev, "failed to register arb reset controller\n");
 151                 meson_audio_arb_remove(pdev);
 152         }
 153
 154         return ret;
 155 }
 156
 157 static struct platform_driver meson_audio_arb_pdrv = {
 158         .probe = meson_audio_arb_probe,
 159         .remove = meson_audio_arb_remove,
 160         .driver = {
 161                 .name = "meson-audio-arb-reset",
 162                 .of_match_table = meson_audio_arb_of_match,
 163         },
 164 };
 165 module_platform_driver(meson_audio_arb_pdrv);
 166
 167 MODULE_DESCRIPTION("Amlogic A113 Audio Memory Arbiter");
 168 MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>");
 169 MODULE_LICENSE("GPL v2");