drivers/mfd/vexpress-config.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License version 2 as
   4  * published by the Free Software Foundation.
   5  *
   6  * This program is distributed in the hope that it will be useful,
   7  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   8  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9  * GNU General Public License for more details.
  10  *
  11  * Copyright (C) 2012 ARM Limited
  12  */
  13
  14 #define pr_fmt(fmt) "vexpress-config: " fmt
  15
  16 #include <linux/bitops.h>
  17 #include <linux/completion.h>
  18 #include <linux/export.h>
  19 #include <linux/init.h>
  20 #include <linux/list.h>
  21 #include <linux/of.h>
  22 #include <linux/of_device.h>
  23 #include <linux/slab.h>
  24 #include <linux/string.h>
  25 #include <linux/vexpress.h>
  26
  27
  28 #define VEXPRESS_CONFIG_MAX_BRIDGES 2
  29
  30 struct vexpress_config_bridge {
  31         struct device_node *node;
  32         struct vexpress_config_bridge_info *info;
  33         struct list_head transactions;
  34         spinlock_t transactions_lock;
  35 } vexpress_config_bridges[VEXPRESS_CONFIG_MAX_BRIDGES];
  36
  37 static DECLARE_BITMAP(vexpress_config_bridges_map,
  38                 ARRAY_SIZE(vexpress_config_bridges));
  39 static DEFINE_MUTEX(vexpress_config_bridges_mutex);
  40
  41 struct vexpress_config_bridge *vexpress_config_bridge_register(
  42                 struct device_node *node,
  43                 struct vexpress_config_bridge_info *info)
  44 {
  45         struct vexpress_config_bridge *bridge;
  46         int i;
  47
  48         pr_debug("Registering bridge '%s'\n", info->name);
  49
  50         mutex_lock(&vexpress_config_bridges_mutex);
  51         i = find_first_zero_bit(vexpress_config_bridges_map,
  52                         ARRAY_SIZE(vexpress_config_bridges));
  53         if (i >= ARRAY_SIZE(vexpress_config_bridges)) {
  54                 pr_err("Can't register more bridges!\n");
  55                 mutex_unlock(&vexpress_config_bridges_mutex);
  56                 return NULL;
  57         }
  58         __set_bit(i, vexpress_config_bridges_map);
  59         bridge = &vexpress_config_bridges[i];
  60
  61         bridge->node = node;
  62         bridge->info = info;
  63         INIT_LIST_HEAD(&bridge->transactions);
  64         spin_lock_init(&bridge->transactions_lock);
  65
  66         mutex_unlock(&vexpress_config_bridges_mutex);
  67
  68         return bridge;
  69 }
  70 EXPORT_SYMBOL(vexpress_config_bridge_register);
  71
  72 void vexpress_config_bridge_unregister(struct vexpress_config_bridge *bridge)
  73 {
  74         struct vexpress_config_bridge __bridge = *bridge;
  75         int i;
  76
  77         mutex_lock(&vexpress_config_bridges_mutex);
  78         for (i = 0; i < ARRAY_SIZE(vexpress_config_bridges); i++)
  79                 if (&vexpress_config_bridges[i] == bridge)
  80                         __clear_bit(i, vexpress_config_bridges_map);
  81         mutex_unlock(&vexpress_config_bridges_mutex);
  82
  83         WARN_ON(!list_empty(&__bridge.transactions));
  84         while (!list_empty(&__bridge.transactions))
  85                 cpu_relax();
  86 }
  87 EXPORT_SYMBOL(vexpress_config_bridge_unregister);
  88
  89
  90 struct vexpress_config_func {
  91         struct vexpress_config_bridge *bridge;
  92         void *func;
  93 };
  94
  95 struct vexpress_config_func *__vexpress_config_func_get(struct device *dev,
  96                 struct device_node *node)
  97 {
  98         struct device_node *bridge_node;
  99         struct vexpress_config_func *func;
 100         int i;
 101
 102         if (WARN_ON(dev && node && dev->of_node != node))
 103                 return NULL;
 104         if (dev && !node)
 105                 node = dev->of_node;
 106
 107         func = kzalloc(sizeof(*func), GFP_KERNEL);
 108         if (!func)
 109                 return NULL;
 110
 111         bridge_node = of_node_get(node);
 112         while (bridge_node) {
 113                 const __be32 *prop = of_get_property(bridge_node,
 114                                 "arm,vexpress,config-bridge", NULL);
 115
 116                 if (prop) {
 117                         bridge_node = of_find_node_by_phandle(
 118                                         be32_to_cpup(prop));
 119                         break;
 120                 }
 121
 122                 bridge_node = of_get_next_parent(bridge_node);
 123         }
 124
 125         mutex_lock(&vexpress_config_bridges_mutex);
 126         for (i = 0; i < ARRAY_SIZE(vexpress_config_bridges); i++) {
 127                 struct vexpress_config_bridge *bridge =
 128                                 &vexpress_config_bridges[i];
 129
 130                 if (test_bit(i, vexpress_config_bridges_map) &&
 131                                 bridge->node == bridge_node) {
 132                         func->bridge = bridge;
 133                         func->func = bridge->info->func_get(dev, node);
 134                         break;
 135                 }
 136         }
 137         mutex_unlock(&vexpress_config_bridges_mutex);
 138
 139         if (!func->func) {
 140                 of_node_put(node);
 141                 kfree(func);
 142                 return NULL;
 143         }
 144
 145         return func;
 146 }
 147 EXPORT_SYMBOL(__vexpress_config_func_get);
 148
 149 void vexpress_config_func_put(struct vexpress_config_func *func)
 150 {
 151         func->bridge->info->func_put(func->func);
 152         of_node_put(func->bridge->node);
 153         kfree(func);
 154 }
 155 EXPORT_SYMBOL(vexpress_config_func_put);
 156
 157 struct vexpress_config_trans {
 158         struct vexpress_config_func *func;
 159         int offset;
 160         bool write;
 161         u32 *data;
 162         int status;
 163         struct completion completion;
 164         struct list_head list;
 165 };
 166
 167 static void vexpress_config_dump_trans(const char *what,
 168                 struct vexpress_config_trans *trans)
 169 {
 170         pr_debug("%s %s trans %p func 0x%p offset %d data 0x%x status %d\n",
 171                         what, trans->write ? "write" : "read", trans,
 172                         trans->func->func, trans->offset,
 173                         trans->data ? *trans->data : 0, trans->status);
 174 }
 175
 176 static int vexpress_config_schedule(struct vexpress_config_trans *trans)
 177 {
 178         int status;
 179         struct vexpress_config_bridge *bridge = trans->func->bridge;
 180         unsigned long flags;
 181
 182         init_completion(&trans->completion);
 183         trans->status = -EFAULT;
 184
 185         spin_lock_irqsave(&bridge->transactions_lock, flags);
 186
 187         if (list_empty(&bridge->transactions)) {
 188                 vexpress_config_dump_trans("Executing", trans);
 189                 status = bridge->info->func_exec(trans->func->func,
 190                                 trans->offset, trans->write, trans->data);
 191         } else {
 192                 vexpress_config_dump_trans("Queuing", trans);
 193                 status = VEXPRESS_CONFIG_STATUS_WAIT;
 194         }
 195
 196         switch (status) {
 197         case VEXPRESS_CONFIG_STATUS_DONE:
 198                 vexpress_config_dump_trans("Finished", trans);
 199                 trans->status = status;
 200                 break;
 201         case VEXPRESS_CONFIG_STATUS_WAIT:
 202                 list_add_tail(&trans->list, &bridge->transactions);
 203                 break;
 204         }
 205
 206         spin_unlock_irqrestore(&bridge->transactions_lock, flags);
 207
 208         return status;
 209 }
 210
 211 void vexpress_config_complete(struct vexpress_config_bridge *bridge,
 212                 int status)
 213 {
 214         struct vexpress_config_trans *trans;
 215         unsigned long flags;
 216         const char *message = "Completed";
 217
 218         spin_lock_irqsave(&bridge->transactions_lock, flags);
 219
 220         trans = list_first_entry(&bridge->transactions,
 221                         struct vexpress_config_trans, list);
 222         trans->status = status;
 223
 224         do {
 225                 vexpress_config_dump_trans(message, trans);
 226                 list_del(&trans->list);
 227                 complete(&trans->completion);
 228
 229                 if (list_empty(&bridge->transactions))
 230                         break;
 231
 232                 trans = list_first_entry(&bridge->transactions,
 233                                 struct vexpress_config_trans, list);
 234                 vexpress_config_dump_trans("Executing pending", trans);
 235                 trans->status = bridge->info->func_exec(trans->func->func,
 236                                 trans->offset, trans->write, trans->data);
 237                 message = "Finished pending";
 238         } while (trans->status == VEXPRESS_CONFIG_STATUS_DONE);
 239
 240         spin_unlock_irqrestore(&bridge->transactions_lock, flags);
 241 }
 242 EXPORT_SYMBOL(vexpress_config_complete);
 243
 244 int vexpress_config_wait(struct vexpress_config_trans *trans)
 245 {
 246         wait_for_completion(&trans->completion);
 247
 248         return trans->status;
 249 }
 250 EXPORT_SYMBOL(vexpress_config_wait);
 251
 252 int vexpress_config_read(struct vexpress_config_func *func, int offset,
 253                 u32 *data)
 254 {
 255         struct vexpress_config_trans trans = {
 256                 .func = func,
 257                 .offset = offset,
 258                 .write = false,
 259                 .data = data,
 260                 .status = 0,
 261         };
 262         int status = vexpress_config_schedule(&trans);
 263
 264         if (status == VEXPRESS_CONFIG_STATUS_WAIT)
 265                 status = vexpress_config_wait(&trans);
 266
 267         return status;
 268 }
 269 EXPORT_SYMBOL(vexpress_config_read);
 270
 271 int vexpress_config_write(struct vexpress_config_func *func, int offset,
 272                 u32 data)
 273 {
 274         struct vexpress_config_trans trans = {
 275                 .func = func,
 276                 .offset = offset,
 277                 .write = true,
 278                 .data = &data,
 279                 .status = 0,
 280         };
 281         int status = vexpress_config_schedule(&trans);
 282
 283         if (status == VEXPRESS_CONFIG_STATUS_WAIT)
 284                 status = vexpress_config_wait(&trans);
 285
 286         return status;
 287 }
 288 EXPORT_SYMBOL(vexpress_config_write);