drivers/soc/qcom/smem_state.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2015, Sony Mobile Communications Inc.
   4  * Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
   5  */
   6 #include <linux/device.h>
   7 #include <linux/list.h>
   8 #include <linux/module.h>
   9 #include <linux/of.h>
  10 #include <linux/slab.h>
  11 #include <linux/soc/qcom/smem_state.h>
  12
  13 static LIST_HEAD(smem_states);
  14 static DEFINE_MUTEX(list_lock);
  15
  16 /**
  17  * struct qcom_smem_state - state context
  18  * @refcount:   refcount for the state
  19  * @orphan:     boolean indicator that this state has been unregistered
  20  * @list:       entry in smem_states list
  21  * @of_node:    of_node to use for matching the state in DT
  22  * @priv:       implementation private data
  23  * @ops:        ops for the state
  24  */
  25 struct qcom_smem_state {
  26         struct kref refcount;
  27         bool orphan;
  28
  29         struct list_head list;
  30         struct device_node *of_node;
  31
  32         void *priv;
  33
  34         struct qcom_smem_state_ops ops;
  35 };
  36
  37 /**
  38  * qcom_smem_state_update_bits() - update the masked bits in state with value
  39  * @state:      state handle acquired by calling qcom_smem_state_get()
  40  * @mask:       bit mask for the change
  41  * @value:      new value for the masked bits
  42  *
  43  * Returns 0 on success, otherwise negative errno.
  44  */
  45 int qcom_smem_state_update_bits(struct qcom_smem_state *state,
  46                                 u32 mask,
  47                                 u32 value)
  48 {
  49         if (state->orphan)
  50                 return -ENXIO;
  51
  52         if (!state->ops.update_bits)
  53                 return -ENOTSUPP;
  54
  55         return state->ops.update_bits(state->priv, mask, value);
  56 }
  57 EXPORT_SYMBOL_GPL(qcom_smem_state_update_bits);
  58
  59 static struct qcom_smem_state *of_node_to_state(struct device_node *np)
  60 {
  61         struct qcom_smem_state *state;
  62
  63         mutex_lock(&list_lock);
  64
  65         list_for_each_entry(state, &smem_states, list) {
  66                 if (state->of_node == np) {
  67                         kref_get(&state->refcount);
  68                         goto unlock;
  69                 }
  70         }
  71         state = ERR_PTR(-EPROBE_DEFER);
  72
  73 unlock:
  74         mutex_unlock(&list_lock);
  75
  76         return state;
  77 }
  78
  79 /**
  80  * qcom_smem_state_get() - acquire handle to a state
  81  * @dev:        client device pointer
  82  * @con_id:     name of the state to lookup
  83  * @bit:        flags from the state reference, indicating which bit's affected
  84  *
  85  * Returns handle to the state, or ERR_PTR(). qcom_smem_state_put() must be
  86  * called to release the returned state handle.
  87  */
  88 struct qcom_smem_state *qcom_smem_state_get(struct device *dev,
  89                                             const char *con_id,
  90                                             unsigned *bit)
  91 {
  92         struct qcom_smem_state *state;
  93         struct of_phandle_args args;
  94         int index = 0;
  95         int ret;
  96
  97         if (con_id) {
  98                 index = of_property_match_string(dev->of_node,
  99                                                  "qcom,smem-state-names",
 100                                                  con_id);
 101                 if (index < 0) {
 102                         dev_err(dev, "missing qcom,smem-state-names\n");
 103                         return ERR_PTR(index);
 104                 }
 105         }
 106
 107         ret = of_parse_phandle_with_args(dev->of_node,
 108                                          "qcom,smem-states",
 109                                          "#qcom,smem-state-cells",
 110                                          index,
 111                                          &args);
 112         if (ret) {
 113                 dev_err(dev, "failed to parse qcom,smem-states property\n");
 114                 return ERR_PTR(ret);
 115         }
 116
 117         if (args.args_count != 1) {
 118                 dev_err(dev, "invalid #qcom,smem-state-cells\n");
 119                 return ERR_PTR(-EINVAL);
 120         }
 121
 122         state = of_node_to_state(args.np);
 123         if (IS_ERR(state))
 124                 goto put;
 125
 126         *bit = args.args[0];
 127
 128 put:
 129         of_node_put(args.np);
 130         return state;
 131 }
 132 EXPORT_SYMBOL_GPL(qcom_smem_state_get);
 133
 134 static void qcom_smem_state_release(struct kref *ref)
 135 {
 136         struct qcom_smem_state *state = container_of(ref, struct qcom_smem_state, refcount);
 137
 138         list_del(&state->list);
 139         kfree(state);
 140 }
 141
 142 /**
 143  * qcom_smem_state_put() - release state handle
 144  * @state:      state handle to be released
 145  */
 146 void qcom_smem_state_put(struct qcom_smem_state *state)
 147 {
 148         mutex_lock(&list_lock);
 149         kref_put(&state->refcount, qcom_smem_state_release);
 150         mutex_unlock(&list_lock);
 151 }
 152 EXPORT_SYMBOL_GPL(qcom_smem_state_put);
 153
 154 /**
 155  * qcom_smem_state_register() - register a new state
 156  * @of_node:    of_node used for matching client lookups
 157  * @ops:        implementation ops
 158  * @priv:       implementation specific private data
 159  */
 160 struct qcom_smem_state *qcom_smem_state_register(struct device_node *of_node,
 161                                                  const struct qcom_smem_state_ops *ops,
 162                                                  void *priv)
 163 {
 164         struct qcom_smem_state *state;
 165
 166         state = kzalloc(sizeof(*state), GFP_KERNEL);
 167         if (!state)
 168                 return ERR_PTR(-ENOMEM);
 169
 170         kref_init(&state->refcount);
 171
 172         state->of_node = of_node;
 173         state->ops = *ops;
 174         state->priv = priv;
 175
 176         mutex_lock(&list_lock);
 177         list_add(&state->list, &smem_states);
 178         mutex_unlock(&list_lock);
 179
 180         return state;
 181 }
 182 EXPORT_SYMBOL_GPL(qcom_smem_state_register);
 183
 184 /**
 185  * qcom_smem_state_unregister() - unregister a registered state
 186  * @state:      state handle to be unregistered
 187  */
 188 void qcom_smem_state_unregister(struct qcom_smem_state *state)
 189 {
 190         state->orphan = true;
 191         qcom_smem_state_put(state);
 192 }
 193 EXPORT_SYMBOL_GPL(qcom_smem_state_unregister);