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
  71 void vexpress_config_bridge_unregister(struct vexpress_config_bridge *bridge)
  72 {
  73         struct vexpress_config_bridge __bridge = *bridge;
  74         int i;
  75
  76         mutex_lock(&vexpress_config_bridges_mutex);
  77         for (i = 0; i < ARRAY_SIZE(vexpress_config_bridges); i++)
  78                 if (&vexpress_config_bridges[i] == bridge)
  79                         __clear_bit(i, vexpress_config_bridges_map);
  80         mutex_unlock(&vexpress_config_bridges_mutex);
  81
  82         WARN_ON(!list_empty(&__bridge.transactions));
  83         while (!list_empty(&__bridge.transactions))
  84                 cpu_relax();
  85 }
  86
  87
  88 struct vexpress_config_func {
  89         struct vexpress_config_bridge *bridge;
  90         void *func;
  91 };
  92
  93 struct vexpress_config_func *__vexpress_config_func_get(struct device *dev,
  94                 struct device_node *node)
  95 {
  96         struct device_node *bridge_node;
  97         struct vexpress_config_func *func;
  98         int i;
  99
 100         if (WARN_ON(dev && node && dev->of_node != node))
 101                 return NULL;
 102         if (dev && !node)
 103                 node = dev->of_node;
 104
 105         func = kzalloc(sizeof(*func), GFP_KERNEL);
 106         if (!func)
 107                 return NULL;
 108
 109         bridge_node = of_node_get(node);
 110         while (bridge_node) {
 111                 const __be32 *prop = of_get_property(bridge_node,
 112                                 "arm,vexpress,config-bridge", NULL);
 113
 114                 if (prop) {
 115                         bridge_node = of_find_node_by_phandle(
 116                                         be32_to_cpup(prop));
 117                         break;
 118                 }
 119
 120                 bridge_node = of_get_next_parent(bridge_node);
 121         }
 122
 123         mutex_lock(&vexpress_config_bridges_mutex);
 124         for (i = 0; i < ARRAY_SIZE(vexpress_config_bridges); i++) {
 125                 struct vexpress_config_bridge *bridge =
 126                                 &vexpress_config_bridges[i];
 127
 128                 if (test_bit(i, vexpress_config_bridges_map) &&
 129                                 bridge->node == bridge_node) {
 130                         func->bridge = bridge;
 131                         func->func = bridge->info->func_get(dev, node);
 132                         break;
 133                 }
 134         }
 135         mutex_unlock(&vexpress_config_bridges_mutex);
 136
 137         if (!func->func) {
 138                 of_node_put(node);
 139                 kfree(func);
 140                 return NULL;
 141         }
 142
 143         return func;
 144 }
 145
 146 void vexpress_config_func_put(struct vexpress_config_func *func)
 147 {
 148         func->bridge->info->func_put(func->func);
 149         of_node_put(func->bridge->node);
 150         kfree(func);
 151 }
 152
 153
 154 struct vexpress_config_trans {
 155         struct vexpress_config_func *func;
 156         int offset;
 157         bool write;
 158         u32 *data;
 159         int status;
 160         struct completion completion;
 161         struct list_head list;
 162 };
 163
 164 static void vexpress_config_dump_trans(const char *what,
 165                 struct vexpress_config_trans *trans)
 166 {
 167         pr_debug("%s %s trans %p func 0x%p offset %d data 0x%x status %d\n",
 168                         what, trans->write ? "write" : "read", trans,
 169                         trans->func->func, trans->offset,
 170                         trans->data ? *trans->data : 0, trans->status);
 171 }
 172
 173 static int vexpress_config_schedule(struct vexpress_config_trans *trans)
 174 {
 175         int status;
 176         struct vexpress_config_bridge *bridge = trans->func->bridge;
 177         unsigned long flags;
 178
 179         init_completion(&trans->completion);
 180         trans->status = -EFAULT;
 181
 182         spin_lock_irqsave(&bridge->transactions_lock, flags);
 183
 184         vexpress_config_dump_trans("Executing", trans);
 185
 186         if (list_empty(&bridge->transactions))
 187                 status = bridge->info->func_exec(trans->func->func,
 188                                 trans->offset, trans->write, trans->data);
 189         else
 190                 status = VEXPRESS_CONFIG_STATUS_WAIT;
 191
 192         switch (status) {
 193         case VEXPRESS_CONFIG_STATUS_DONE:
 194                 vexpress_config_dump_trans("Finished", trans);
 195                 trans->status = status;
 196                 break;
 197         case VEXPRESS_CONFIG_STATUS_WAIT:
 198                 list_add_tail(&trans->list, &bridge->transactions);
 199                 break;
 200         }
 201
 202         spin_unlock_irqrestore(&bridge->transactions_lock, flags);
 203
 204         return status;
 205 }
 206
 207 void vexpress_config_complete(struct vexpress_config_bridge *bridge,
 208                 int status)
 209 {
 210         struct vexpress_config_trans *trans;
 211         unsigned long flags;
 212
 213         spin_lock_irqsave(&bridge->transactions_lock, flags);
 214
 215         trans = list_first_entry(&bridge->transactions,
 216                         struct vexpress_config_trans, list);
 217         vexpress_config_dump_trans("Completed", trans);
 218
 219         trans->status = status;
 220         list_del(&trans->list);
 221
 222         if (!list_empty(&bridge->transactions)) {
 223                 vexpress_config_dump_trans("Pending", trans);
 224
 225                 bridge->info->func_exec(trans->func->func, trans->offset,
 226                                 trans->write, trans->data);
 227         }
 228         spin_unlock_irqrestore(&bridge->transactions_lock, flags);
 229
 230         complete(&trans->completion);
 231 }
 232
 233 int vexpress_config_wait(struct vexpress_config_trans *trans)
 234 {
 235         wait_for_completion(&trans->completion);
 236
 237         return trans->status;
 238 }
 239
 240
 241 int vexpress_config_read(struct vexpress_config_func *func, int offset,
 242                 u32 *data)
 243 {
 244         struct vexpress_config_trans trans = {
 245                 .func = func,
 246                 .offset = offset,
 247                 .write = false,
 248                 .data = data,
 249                 .status = 0,
 250         };
 251         int status = vexpress_config_schedule(&trans);
 252
 253         if (status == VEXPRESS_CONFIG_STATUS_WAIT)
 254                 status = vexpress_config_wait(&trans);
 255
 256         return status;
 257 }
 258 EXPORT_SYMBOL(vexpress_config_read);
 259
 260 int vexpress_config_write(struct vexpress_config_func *func, int offset,
 261                 u32 data)
 262 {
 263         struct vexpress_config_trans trans = {
 264                 .func = func,
 265                 .offset = offset,
 266                 .write = true,
 267                 .data = &data,
 268                 .status = 0,
 269         };
 270         int status = vexpress_config_schedule(&trans);
 271
 272         if (status == VEXPRESS_CONFIG_STATUS_WAIT)
 273                 status = vexpress_config_wait(&trans);
 274
 275         return status;
 276 }
 277 EXPORT_SYMBOL(vexpress_config_write);