drivers/reset/reset-lantiq.c

   1 /*
   2  *  This program is free software; you can redistribute it and/or modify it
   3  *  under the terms of the GNU General Public License version 2 as published
   4  *  by the Free Software Foundation.
   5  *
   6  *  Copyright (C) 2010 John Crispin <blogic@phrozen.org>
   7  *  Copyright (C) 2013-2015 Lantiq Beteiligungs-GmbH & Co.KG
   8  *  Copyright (C) 2016 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
   9  *  Copyright (C) 2017 Hauke Mehrtens <hauke@hauke-m.de>
  10  */
  11
  12 #include <linux/mfd/syscon.h>
  13 #include <linux/module.h>
  14 #include <linux/regmap.h>
  15 #include <linux/reset-controller.h>
  16 #include <linux/of_address.h>
  17 #include <linux/of_platform.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/property.h>
  20
  21 #define LANTIQ_RCU_RESET_TIMEOUT        10000
  22
  23 struct lantiq_rcu_reset_priv {
  24         struct reset_controller_dev rcdev;
  25         struct device *dev;
  26         struct regmap *regmap;
  27         u32 reset_offset;
  28         u32 status_offset;
  29 };
  30
  31 static struct lantiq_rcu_reset_priv *to_lantiq_rcu_reset_priv(
  32         struct reset_controller_dev *rcdev)
  33 {
  34         return container_of(rcdev, struct lantiq_rcu_reset_priv, rcdev);
  35 }
  36
  37 static int lantiq_rcu_reset_status(struct reset_controller_dev *rcdev,
  38                                    unsigned long id)
  39 {
  40         struct lantiq_rcu_reset_priv *priv = to_lantiq_rcu_reset_priv(rcdev);
  41         unsigned int status = (id >> 8) & 0x1f;
  42         u32 val;
  43         int ret;
  44
  45         ret = regmap_read(priv->regmap, priv->status_offset, &val);
  46         if (ret)
  47                 return ret;
  48
  49         return !!(val & BIT(status));
  50 }
  51
  52 static int lantiq_rcu_reset_status_timeout(struct reset_controller_dev *rcdev,
  53                                            unsigned long id, bool assert)
  54 {
  55         int ret;
  56         int retry = LANTIQ_RCU_RESET_TIMEOUT;
  57
  58         do {
  59                 ret = lantiq_rcu_reset_status(rcdev, id);
  60                 if (ret < 0)
  61                         return ret;
  62                 if (ret == assert)
  63                         return 0;
  64                 usleep_range(20, 40);
  65         } while (--retry);
  66
  67         return -ETIMEDOUT;
  68 }
  69
  70 static int lantiq_rcu_reset_update(struct reset_controller_dev *rcdev,
  71                                    unsigned long id, bool assert)
  72 {
  73         struct lantiq_rcu_reset_priv *priv = to_lantiq_rcu_reset_priv(rcdev);
  74         unsigned int set = id & 0x1f;
  75         u32 val = assert ? BIT(set) : 0;
  76         int ret;
  77
  78         ret = regmap_update_bits(priv->regmap, priv->reset_offset, BIT(set),
  79                                  val);
  80         if (ret) {
  81                 dev_err(priv->dev, "Failed to set reset bit %u\n", set);
  82                 return ret;
  83         }
  84
  85
  86         ret = lantiq_rcu_reset_status_timeout(rcdev, id, assert);
  87         if (ret)
  88                 dev_err(priv->dev, "Failed to %s bit %u\n",
  89                         assert ? "assert" : "deassert", set);
  90
  91         return ret;
  92 }
  93
  94 static int lantiq_rcu_reset_assert(struct reset_controller_dev *rcdev,
  95                              unsigned long id)
  96 {
  97         return lantiq_rcu_reset_update(rcdev, id, true);
  98 }
  99
 100 static int lantiq_rcu_reset_deassert(struct reset_controller_dev *rcdev,
 101                                unsigned long id)
 102 {
 103         return lantiq_rcu_reset_update(rcdev, id, false);
 104 }
 105
 106 static int lantiq_rcu_reset_reset(struct reset_controller_dev *rcdev,
 107                             unsigned long id)
 108 {
 109         int ret;
 110
 111         ret = lantiq_rcu_reset_assert(rcdev, id);
 112         if (ret)
 113                 return ret;
 114
 115         return lantiq_rcu_reset_deassert(rcdev, id);
 116 }
 117
 118 static const struct reset_control_ops lantiq_rcu_reset_ops = {
 119         .assert = lantiq_rcu_reset_assert,
 120         .deassert = lantiq_rcu_reset_deassert,
 121         .status = lantiq_rcu_reset_status,
 122         .reset  = lantiq_rcu_reset_reset,
 123 };
 124
 125 static int lantiq_rcu_reset_of_parse(struct platform_device *pdev,
 126                                struct lantiq_rcu_reset_priv *priv)
 127 {
 128         struct device *dev = &pdev->dev;
 129         const __be32 *offset;
 130
 131         priv->regmap = syscon_node_to_regmap(dev->of_node->parent);
 132         if (IS_ERR(priv->regmap)) {
 133                 dev_err(&pdev->dev, "Failed to lookup RCU regmap\n");
 134                 return PTR_ERR(priv->regmap);
 135         }
 136
 137         offset = of_get_address(dev->of_node, 0, NULL, NULL);
 138         if (!offset) {
 139                 dev_err(&pdev->dev, "Failed to get RCU reset offset\n");
 140                 return -ENOENT;
 141         }
 142         priv->reset_offset = __be32_to_cpu(*offset);
 143
 144         offset = of_get_address(dev->of_node, 1, NULL, NULL);
 145         if (!offset) {
 146                 dev_err(&pdev->dev, "Failed to get RCU status offset\n");
 147                 return -ENOENT;
 148         }
 149         priv->status_offset = __be32_to_cpu(*offset);
 150
 151         return 0;
 152 }
 153
 154 static int lantiq_rcu_reset_xlate(struct reset_controller_dev *rcdev,
 155                                   const struct of_phandle_args *reset_spec)
 156 {
 157         unsigned int status, set;
 158
 159         set = reset_spec->args[0];
 160         status = reset_spec->args[1];
 161
 162         if (set >= rcdev->nr_resets || status >= rcdev->nr_resets)
 163                 return -EINVAL;
 164
 165         return (status << 8) | set;
 166 }
 167
 168 static int lantiq_rcu_reset_probe(struct platform_device *pdev)
 169 {
 170         struct lantiq_rcu_reset_priv *priv;
 171         int err;
 172
 173         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 174         if (!priv)
 175                 return -ENOMEM;
 176
 177         priv->dev = &pdev->dev;
 178         platform_set_drvdata(pdev, priv);
 179
 180         err = lantiq_rcu_reset_of_parse(pdev, priv);
 181         if (err)
 182                 return err;
 183
 184         priv->rcdev.ops = &lantiq_rcu_reset_ops;
 185         priv->rcdev.owner = THIS_MODULE;
 186         priv->rcdev.of_node = pdev->dev.of_node;
 187         priv->rcdev.nr_resets = 32;
 188         priv->rcdev.of_xlate = lantiq_rcu_reset_xlate;
 189         priv->rcdev.of_reset_n_cells = 2;
 190
 191         return reset_controller_register(&priv->rcdev);
 192 }
 193
 194 static const struct of_device_id lantiq_rcu_reset_dt_ids[] = {
 195         { .compatible = "lantiq,danube-reset", },
 196         { .compatible = "lantiq,xrx200-reset", },
 197         { },
 198 };
 199 MODULE_DEVICE_TABLE(of, lantiq_rcu_reset_dt_ids);
 200
 201 static struct platform_driver lantiq_rcu_reset_driver = {
 202         .probe  = lantiq_rcu_reset_probe,
 203         .driver = {
 204                 .name           = "lantiq-reset",
 205                 .of_match_table = lantiq_rcu_reset_dt_ids,
 206         },
 207 };
 208 module_platform_driver(lantiq_rcu_reset_driver);
 209
 210 MODULE_AUTHOR("Martin Blumenstingl <martin.blumenstingl@googlemail.com>");
 211 MODULE_DESCRIPTION("Lantiq XWAY RCU Reset Controller Driver");
 212 MODULE_LICENSE("GPL");