/*
 * Copyright (c) 2015, Sony Mobile Communications Inc.
 * Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
#include <linux/device.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/soc/qcom/smem_state.h>

static LIST_HEAD(smem_states);
static DEFINE_MUTEX(list_lock);

/**
 * struct qcom_smem_state - state context
 * @refcount:   refcount for the state
 * @orphan:     boolean indicator that this state has been unregistered
 * @list:       entry in smem_states list
 * @of_node:    of_node to use for matching the state in DT
 * @priv:       implementation private data
 * @ops:        ops for the state
 */
struct qcom_smem_state {
        struct kref refcount;
        bool orphan;

        struct list_head list;
        struct device_node *of_node;

        void *priv;

        struct qcom_smem_state_ops ops;
};

/**
 * qcom_smem_state_update_bits() - update the masked bits in state with value
 * @state:      state handle acquired by calling qcom_smem_state_get()
 * @mask:       bit mask for the change
 * @value:      new value for the masked bits
 *
 * Returns 0 on success, otherwise negative errno.
 */
int qcom_smem_state_update_bits(struct qcom_smem_state *state,
                                u32 mask,
                                u32 value)
{
        if (state->orphan)
                return -ENXIO;

        if (!state->ops.update_bits)
                return -ENOTSUPP;

        return state->ops.update_bits(state->priv, mask, value);
}
EXPORT_SYMBOL_GPL(qcom_smem_state_update_bits);

static struct qcom_smem_state *of_node_to_state(struct device_node *np)
{
        struct qcom_smem_state *state;

        mutex_lock(&list_lock);

        list_for_each_entry(state, &smem_states, list) {
                if (state->of_node == np) {
                        kref_get(&state->refcount);
                        goto unlock;
                }
        }
        state = ERR_PTR(-EPROBE_DEFER);

unlock:
        mutex_unlock(&list_lock);

        return state;
}

/**
 * qcom_smem_state_get() - acquire handle to a state
 * @dev:        client device pointer
 * @con_id:     name of the state to lookup
 * @bit:        flags from the state reference, indicating which bit's affected
 *
 * Returns handle to the state, or ERR_PTR(). qcom_smem_state_put() must be
 * called to release the returned state handle.
 */
struct qcom_smem_state *qcom_smem_state_get(struct device *dev,
                                            const char *con_id,
                                            unsigned *bit)
{
        struct qcom_smem_state *state;
        struct of_phandle_args args;
        int index = 0;
        int ret;

        if (con_id) {
                index = of_property_match_string(dev->of_node,
                                                 "qcom,smem-state-names",
                                                 con_id);
                if (index < 0) {
                        dev_err(dev, "missing qcom,smem-state-names\n");
                        return ERR_PTR(index);
                }
        }

        ret = of_parse_phandle_with_args(dev->of_node,
                                         "qcom,smem-states",
                                         "#qcom,smem-state-cells",
                                         index,
                                         &args);
        if (ret) {
                dev_err(dev, "failed to parse qcom,smem-states property\n");
                return ERR_PTR(ret);
        }

        if (args.args_count != 1) {
                dev_err(dev, "invalid #qcom,smem-state-cells\n");
                return ERR_PTR(-EINVAL);
        }

        state = of_node_to_state(args.np);
        if (IS_ERR(state))
                goto put;

        *bit = args.args[0];

put:
        of_node_put(args.np);
        return state;
}
EXPORT_SYMBOL_GPL(qcom_smem_state_get);

static void qcom_smem_state_release(struct kref *ref)
{
        struct qcom_smem_state *state = container_of(ref, struct qcom_smem_state, refcount);

        list_del(&state->list);
        kfree(state);
}

/**
 * qcom_smem_state_put() - release state handle
 * @state:      state handle to be released
 */
void qcom_smem_state_put(struct qcom_smem_state *state)
{
        mutex_lock(&list_lock);
        kref_put(&state->refcount, qcom_smem_state_release);
        mutex_unlock(&list_lock);
}
EXPORT_SYMBOL_GPL(qcom_smem_state_put);

/**
 * qcom_smem_state_register() - register a new state
 * @of_node:    of_node used for matching client lookups
 * @ops:        implementation ops
 * @priv:       implementation specific private data
 */
struct qcom_smem_state *qcom_smem_state_register(struct device_node *of_node,
                                                 const struct qcom_smem_state_ops *ops,
                                                 void *priv)
{
        struct qcom_smem_state *state;

        state = kzalloc(sizeof(*state), GFP_KERNEL);
        if (!state)
                return ERR_PTR(-ENOMEM);

        kref_init(&state->refcount);

        state->of_node = of_node;
        state->ops = *ops;
        state->priv = priv;

        mutex_lock(&list_lock);
        list_add(&state->list, &smem_states);
        mutex_unlock(&list_lock);

        return state;
}
EXPORT_SYMBOL_GPL(qcom_smem_state_register);

/**
 * qcom_smem_state_unregister() - unregister a registered state
 * @state:      state handle to be unregistered
 */
void qcom_smem_state_unregister(struct qcom_smem_state *state)
{
        state->orphan = true;
        qcom_smem_state_put(state);
}
EXPORT_SYMBOL_GPL(qcom_smem_state_unregister);