drivers/reset/sti/reset-syscfg.c

   1 /*
   2  * Copyright (C) 2013 STMicroelectronics Limited
   3  * Author: Stephen Gallimore <stephen.gallimore@st.com>
   4  *
   5  * Inspired by mach-imx/src.c
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  */
  12 #include <linux/kernel.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/module.h>
  15 #include <linux/err.h>
  16 #include <linux/types.h>
  17 #include <linux/of_device.h>
  18 #include <linux/regmap.h>
  19 #include <linux/mfd/syscon.h>
  20
  21 #include "reset-syscfg.h"
  22
  23 /**
  24  * Reset channel regmap configuration
  25  *
  26  * @reset: regmap field for the channel's reset bit.
  27  * @ack: regmap field for the channel's ack bit (optional).
  28  */
  29 struct syscfg_reset_channel {
  30         struct regmap_field *reset;
  31         struct regmap_field *ack;
  32 };
  33
  34 /**
  35  * A reset controller which groups together a set of related reset bits, which
  36  * may be located in different system configuration registers.
  37  *
  38  * @rst: base reset controller structure.
  39  * @active_low: are the resets in this controller active low, i.e. clearing
  40  *              the reset bit puts the hardware into reset.
  41  * @channels: An array of reset channels for this controller.
  42  */
  43 struct syscfg_reset_controller {
  44         struct reset_controller_dev rst;
  45         bool active_low;
  46         struct syscfg_reset_channel *channels;
  47 };
  48
  49 #define to_syscfg_reset_controller(_rst) \
  50         container_of(_rst, struct syscfg_reset_controller, rst)
  51
  52 static int syscfg_reset_program_hw(struct reset_controller_dev *rcdev,
  53                                    unsigned long idx, int assert)
  54 {
  55         struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
  56         const struct syscfg_reset_channel *ch;
  57         u32 ctrl_val = rst->active_low ? !assert : !!assert;
  58         int err;
  59
  60         if (idx >= rcdev->nr_resets)
  61                 return -EINVAL;
  62
  63         ch = &rst->channels[idx];
  64
  65         err = regmap_field_write(ch->reset, ctrl_val);
  66         if (err)
  67                 return err;
  68
  69         if (ch->ack) {
  70                 unsigned long timeout = jiffies + msecs_to_jiffies(1000);
  71                 u32 ack_val;
  72
  73                 while (true) {
  74                         err = regmap_field_read(ch->ack, &ack_val);
  75                         if (err)
  76                                 return err;
  77
  78                         if (ack_val == ctrl_val)
  79                                 break;
  80
  81                         if (time_after(jiffies, timeout))
  82                                 return -ETIME;
  83
  84                         cpu_relax();
  85                 }
  86         }
  87
  88         return 0;
  89 }
  90
  91 static int syscfg_reset_assert(struct reset_controller_dev *rcdev,
  92                                unsigned long idx)
  93 {
  94         return syscfg_reset_program_hw(rcdev, idx, true);
  95 }
  96
  97 static int syscfg_reset_deassert(struct reset_controller_dev *rcdev,
  98                                  unsigned long idx)
  99 {
 100         return syscfg_reset_program_hw(rcdev, idx, false);
 101 }
 102
 103 static int syscfg_reset_dev(struct reset_controller_dev *rcdev,
 104                             unsigned long idx)
 105 {
 106         int err;
 107
 108         err = syscfg_reset_assert(rcdev, idx);
 109         if (err)
 110                 return err;
 111
 112         return syscfg_reset_deassert(rcdev, idx);
 113 }
 114
 115 static int syscfg_reset_status(struct reset_controller_dev *rcdev,
 116                                unsigned long idx)
 117 {
 118         struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
 119         const struct syscfg_reset_channel *ch;
 120         u32 ret_val = 0;
 121         int err;
 122
 123         if (idx >= rcdev->nr_resets)
 124                 return -EINVAL;
 125
 126         ch = &rst->channels[idx];
 127         if (ch->ack)
 128                 err = regmap_field_read(ch->ack, &ret_val);
 129         else
 130                 err = regmap_field_read(ch->reset, &ret_val);
 131         if (err)
 132                 return err;
 133
 134         return rst->active_low ? !ret_val : !!ret_val;
 135 }
 136
 137 static const struct reset_control_ops syscfg_reset_ops = {
 138         .reset    = syscfg_reset_dev,
 139         .assert   = syscfg_reset_assert,
 140         .deassert = syscfg_reset_deassert,
 141         .status   = syscfg_reset_status,
 142 };
 143
 144 static int syscfg_reset_controller_register(struct device *dev,
 145                                 const struct syscfg_reset_controller_data *data)
 146 {
 147         struct syscfg_reset_controller *rc;
 148         int i, err;
 149
 150         rc = devm_kzalloc(dev, sizeof(*rc), GFP_KERNEL);
 151         if (!rc)
 152                 return -ENOMEM;
 153
 154         rc->channels = devm_kcalloc(dev, data->nr_channels,
 155                                     sizeof(*rc->channels), GFP_KERNEL);
 156         if (!rc->channels)
 157                 return -ENOMEM;
 158
 159         rc->rst.ops = &syscfg_reset_ops,
 160         rc->rst.of_node = dev->of_node;
 161         rc->rst.nr_resets = data->nr_channels;
 162         rc->active_low = data->active_low;
 163
 164         for (i = 0; i < data->nr_channels; i++) {
 165                 struct regmap *map;
 166                 struct regmap_field *f;
 167                 const char *compatible = data->channels[i].compatible;
 168
 169                 map = syscon_regmap_lookup_by_compatible(compatible);
 170                 if (IS_ERR(map))
 171                         return PTR_ERR(map);
 172
 173                 f = devm_regmap_field_alloc(dev, map, data->channels[i].reset);
 174                 if (IS_ERR(f))
 175                         return PTR_ERR(f);
 176
 177                 rc->channels[i].reset = f;
 178
 179                 if (!data->wait_for_ack)
 180                         continue;
 181
 182                 f = devm_regmap_field_alloc(dev, map, data->channels[i].ack);
 183                 if (IS_ERR(f))
 184                         return PTR_ERR(f);
 185
 186                 rc->channels[i].ack = f;
 187         }
 188
 189         err = reset_controller_register(&rc->rst);
 190         if (!err)
 191                 dev_info(dev, "registered\n");
 192
 193         return err;
 194 }
 195
 196 int syscfg_reset_probe(struct platform_device *pdev)
 197 {
 198         struct device *dev = pdev ? &pdev->dev : NULL;
 199         const struct of_device_id *match;
 200
 201         if (!dev || !dev->driver)
 202                 return -ENODEV;
 203
 204         match = of_match_device(dev->driver->of_match_table, dev);
 205         if (!match || !match->data)
 206                 return -EINVAL;
 207
 208         return syscfg_reset_controller_register(dev, match->data);
 209 }