drivers/soc/qcom/smem_state.c

   1 /*
   2  * Copyright (c) 2015, Sony Mobile Communications Inc.
   3  * Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 and
   7  * only version 2 as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14 #include <linux/device.h>
  15 #include <linux/list.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/slab.h>
  19 #include <linux/soc/qcom/smem_state.h>
  20
  21 static LIST_HEAD(smem_states);
  22 static DEFINE_MUTEX(list_lock);
  23
  24 /**
  25  * struct qcom_smem_state - state context
  26  * @refcount:   refcount for the state
  27  * @orphan:     boolean indicator that this state has been unregistered
  28  * @list:       entry in smem_states list
  29  * @of_node:    of_node to use for matching the state in DT
  30  * @priv:       implementation private data
  31  * @ops:        ops for the state
  32  */
  33 struct qcom_smem_state {
  34         struct kref refcount;
  35         bool orphan;
  36
  37         struct list_head list;
  38         struct device_node *of_node;
  39
  40         void *priv;
  41
  42         struct qcom_smem_state_ops ops;
  43 };
  44
  45 /**
  46  * qcom_smem_state_update_bits() - update the masked bits in state with value
  47  * @state:      state handle acquired by calling qcom_smem_state_get()
  48  * @mask:       bit mask for the change
  49  * @value:      new value for the masked bits
  50  *
  51  * Returns 0 on success, otherwise negative errno.
  52  */
  53 int qcom_smem_state_update_bits(struct qcom_smem_state *state,
  54                                 u32 mask,
  55                                 u32 value)
  56 {
  57         if (state->orphan)
  58                 return -ENXIO;
  59
  60         if (!state->ops.update_bits)
  61                 return -ENOTSUPP;
  62
  63         return state->ops.update_bits(state->priv, mask, value);
  64 }
  65 EXPORT_SYMBOL_GPL(qcom_smem_state_update_bits);
  66
  67 static struct qcom_smem_state *of_node_to_state(struct device_node *np)
  68 {
  69         struct qcom_smem_state *state;
  70
  71         mutex_lock(&list_lock);
  72
  73         list_for_each_entry(state, &smem_states, list) {
  74                 if (state->of_node == np) {
  75                         kref_get(&state->refcount);
  76                         goto unlock;
  77                 }
  78         }
  79         state = ERR_PTR(-EPROBE_DEFER);
  80
  81 unlock:
  82         mutex_unlock(&list_lock);
  83
  84         return state;
  85 }
  86
  87 /**
  88  * qcom_smem_state_get() - acquire handle to a state
  89  * @dev:        client device pointer
  90  * @con_id:     name of the state to lookup
  91  * @bit:        flags from the state reference, indicating which bit's affected
  92  *
  93  * Returns handle to the state, or ERR_PTR(). qcom_smem_state_put() must be
  94  * called to release the returned state handle.
  95  */
  96 struct qcom_smem_state *qcom_smem_state_get(struct device *dev,
  97                                             const char *con_id,
  98                                             unsigned *bit)
  99 {
 100         struct qcom_smem_state *state;
 101         struct of_phandle_args args;
 102         int index = 0;
 103         int ret;
 104
 105         if (con_id) {
 106                 index = of_property_match_string(dev->of_node,
 107                                                  "qcom,smem-state-names",
 108                                                  con_id);
 109                 if (index < 0) {
 110                         dev_err(dev, "missing qcom,smem-state-names\n");
 111                         return ERR_PTR(index);
 112                 }
 113         }
 114
 115         ret = of_parse_phandle_with_args(dev->of_node,
 116                                          "qcom,smem-states",
 117                                          "#qcom,smem-state-cells",
 118                                          index,
 119                                          &args);
 120         if (ret) {
 121                 dev_err(dev, "failed to parse qcom,smem-states property\n");
 122                 return ERR_PTR(ret);
 123         }
 124
 125         if (args.args_count != 1) {
 126                 dev_err(dev, "invalid #qcom,smem-state-cells\n");
 127                 return ERR_PTR(-EINVAL);
 128         }
 129
 130         state = of_node_to_state(args.np);
 131         if (IS_ERR(state))
 132                 goto put;
 133
 134         *bit = args.args[0];
 135
 136 put:
 137         of_node_put(args.np);
 138         return state;
 139 }
 140 EXPORT_SYMBOL_GPL(qcom_smem_state_get);
 141
 142 static void qcom_smem_state_release(struct kref *ref)
 143 {
 144         struct qcom_smem_state *state = container_of(ref, struct qcom_smem_state, refcount);
 145
 146         list_del(&state->list);
 147         kfree(state);
 148 }
 149
 150 /**
 151  * qcom_smem_state_put() - release state handle
 152  * @state:      state handle to be released
 153  */
 154 void qcom_smem_state_put(struct qcom_smem_state *state)
 155 {
 156         mutex_lock(&list_lock);
 157         kref_put(&state->refcount, qcom_smem_state_release);
 158         mutex_unlock(&list_lock);
 159 }
 160 EXPORT_SYMBOL_GPL(qcom_smem_state_put);
 161
 162 /**
 163  * qcom_smem_state_register() - register a new state
 164  * @of_node:    of_node used for matching client lookups
 165  * @ops:        implementation ops
 166  * @priv:       implementation specific private data
 167  */
 168 struct qcom_smem_state *qcom_smem_state_register(struct device_node *of_node,
 169                                                  const struct qcom_smem_state_ops *ops,
 170                                                  void *priv)
 171 {
 172         struct qcom_smem_state *state;
 173
 174         state = kzalloc(sizeof(*state), GFP_KERNEL);
 175         if (!state)
 176                 return ERR_PTR(-ENOMEM);
 177
 178         kref_init(&state->refcount);
 179
 180         state->of_node = of_node;
 181         state->ops = *ops;
 182         state->priv = priv;
 183
 184         mutex_lock(&list_lock);
 185         list_add(&state->list, &smem_states);
 186         mutex_unlock(&list_lock);
 187
 188         return state;
 189 }
 190 EXPORT_SYMBOL_GPL(qcom_smem_state_register);
 191
 192 /**
 193  * qcom_smem_state_unregister() - unregister a registered state
 194  * @state:      state handle to be unregistered
 195  */
 196 void qcom_smem_state_unregister(struct qcom_smem_state *state)
 197 {
 198         state->orphan = true;
 199         qcom_smem_state_put(state);
 200 }
 201 EXPORT_SYMBOL_GPL(qcom_smem_state_unregister);