drivers/reset/reset-zynq.c

   1 /*
   2  * Copyright (c) 2015, National Instruments Corp.
   3  *
   4  * Xilinx Zynq Reset controller driver
   5  *
   6  * Author: Moritz Fischer <moritz.fischer@ettus.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; version 2 of the License.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15  * GNU General Public License for more details.
  16  */
  17
  18 #include <linux/err.h>
  19 #include <linux/io.h>
  20 #include <linux/init.h>
  21 #include <linux/mfd/syscon.h>
  22 #include <linux/of.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/reset-controller.h>
  25 #include <linux/regmap.h>
  26 #include <linux/types.h>
  27
  28 struct zynq_reset_data {
  29         struct regmap *slcr;
  30         struct reset_controller_dev rcdev;
  31         u32 offset;
  32 };
  33
  34 #define to_zynq_reset_data(p)           \
  35         container_of((p), struct zynq_reset_data, rcdev)
  36
  37 static int zynq_reset_assert(struct reset_controller_dev *rcdev,
  38                              unsigned long id)
  39 {
  40         struct zynq_reset_data *priv = to_zynq_reset_data(rcdev);
  41
  42         int bank = id / BITS_PER_LONG;
  43         int offset = id % BITS_PER_LONG;
  44
  45         pr_debug("%s: %s reset bank %u offset %u\n", KBUILD_MODNAME, __func__,
  46                  bank, offset);
  47
  48         return regmap_update_bits(priv->slcr,
  49                                   priv->offset + (bank * 4),
  50                                   BIT(offset),
  51                                   BIT(offset));
  52 }
  53
  54 static int zynq_reset_deassert(struct reset_controller_dev *rcdev,
  55                                unsigned long id)
  56 {
  57         struct zynq_reset_data *priv = to_zynq_reset_data(rcdev);
  58
  59         int bank = id / BITS_PER_LONG;
  60         int offset = id % BITS_PER_LONG;
  61
  62         pr_debug("%s: %s reset bank %u offset %u\n", KBUILD_MODNAME, __func__,
  63                  bank, offset);
  64
  65         return regmap_update_bits(priv->slcr,
  66                                   priv->offset + (bank * 4),
  67                                   BIT(offset),
  68                                   ~BIT(offset));
  69 }
  70
  71 static int zynq_reset_status(struct reset_controller_dev *rcdev,
  72                              unsigned long id)
  73 {
  74         struct zynq_reset_data *priv = to_zynq_reset_data(rcdev);
  75
  76         int bank = id / BITS_PER_LONG;
  77         int offset = id % BITS_PER_LONG;
  78         int ret;
  79         u32 reg;
  80
  81         pr_debug("%s: %s reset bank %u offset %u\n", KBUILD_MODNAME, __func__,
  82                  bank, offset);
  83
  84         ret = regmap_read(priv->slcr, priv->offset + (bank * 4), &reg);
  85         if (ret)
  86                 return ret;
  87
  88         return !!(reg & BIT(offset));
  89 }
  90
  91 static const struct reset_control_ops zynq_reset_ops = {
  92         .assert         = zynq_reset_assert,
  93         .deassert       = zynq_reset_deassert,
  94         .status         = zynq_reset_status,
  95 };
  96
  97 static int zynq_reset_probe(struct platform_device *pdev)
  98 {
  99         struct resource *res;
 100         struct zynq_reset_data *priv;
 101
 102         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 103         if (!priv)
 104                 return -ENOMEM;
 105         platform_set_drvdata(pdev, priv);
 106
 107         priv->slcr = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
 108                                                      "syscon");
 109         if (IS_ERR(priv->slcr)) {
 110                 dev_err(&pdev->dev, "unable to get zynq-slcr regmap");
 111                 return PTR_ERR(priv->slcr);
 112         }
 113
 114         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 115         if (!res) {
 116                 dev_err(&pdev->dev, "missing IO resource\n");
 117                 return -ENODEV;
 118         }
 119
 120         priv->offset = res->start;
 121
 122         priv->rcdev.owner = THIS_MODULE;
 123         priv->rcdev.nr_resets = resource_size(res) / 4 * BITS_PER_LONG;
 124         priv->rcdev.ops = &zynq_reset_ops;
 125         priv->rcdev.of_node = pdev->dev.of_node;
 126
 127         return devm_reset_controller_register(&pdev->dev, &priv->rcdev);
 128 }
 129
 130 static const struct of_device_id zynq_reset_dt_ids[] = {
 131         { .compatible = "xlnx,zynq-reset", },
 132         { /* sentinel */ },
 133 };
 134
 135 static struct platform_driver zynq_reset_driver = {
 136         .probe  = zynq_reset_probe,
 137         .driver = {
 138                 .name           = KBUILD_MODNAME,
 139                 .of_match_table = zynq_reset_dt_ids,
 140         },
 141 };
 142 builtin_platform_driver(zynq_reset_driver);