hte.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2021-2022 NVIDIA Corporation
 *
 * Author: Dipen Patel <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>
#include <linux/hte.h>
#include <linux/delay.h>
#include <linux/debugfs.h>
#include <linux/device.h>

/* Global list of the HTE devices */
static DEFINE_SPINLOCK(hte_lock);
static LIST_HEAD(hte_devices);

enum {
	HTE_TS_REGISTERED,
	HTE_TS_REQ,
	HTE_TS_DISABLE,
	HTE_TS_QUEUE_WK,
};

/**
 * struct hte_ts_info - Information related to requested timestamp.
 *
 * @xlated_id: Timestamp ID as understood between HTE subsys and HTE provider,
 * See xlate callback API.
 * @flags: Flags holding state information.
 * @hte_cb_flags: Callback related flags.
 * @seq: Timestamp sequence counter.
 * @line_name: HTE allocated line name.
 * @free_attr_name: If set, free the attr name.
 * @cb: A nonsleeping callback function provided by clients.
 * @tcb: A secondary sleeping callback function provided by clients.
 * @dropped_ts: Dropped timestamps.
 * @slock: Spin lock to synchronize between disable/enable,
 * request/release APIs.
 * @cb_work: callback workqueue, used when tcb is specified.
 * @req_mlock: Lock during timestamp request/release APIs.
 * @ts_dbg_root: Root for the debug fs.
 * @gdev: HTE abstract device that this timestamp information belongs to.
 * @cl_data: Client specific data.
 */
struct hte_ts_info {
	u32 xlated_id;
	unsigned long flags;
	unsigned long hte_cb_flags;
	u64 seq;
	char *line_name;
	bool free_attr_name;
	hte_ts_cb_t cb;
	hte_ts_sec_cb_t tcb;
	atomic_t dropped_ts;
	spinlock_t slock;
	struct work_struct cb_work;
	struct mutex req_mlock;
	struct dentry *ts_dbg_root;
	struct hte_device *gdev;
	void *cl_data;
};

/**
 * struct hte_device - HTE abstract device
 * @nlines: Number of entities this device supports.
 * @ts_req: Total number of entities requested.
 * @sdev: Device used at various debug prints.
 * @dbg_root: Root directory for debug fs.
 * @list: List node to store hte_device for each provider.
 * @chip: HTE chip providing this HTE device.
 * @owner: helps prevent removal of modules when in use.
 * @ei: Timestamp information.
 */
struct hte_device {
	u32 nlines;
	atomic_t ts_req;
	struct device *sdev;
	struct dentry *dbg_root;
	struct list_head list;
	struct hte_chip *chip;
	struct module *owner;
	struct hte_ts_info ei[] __counted_by(nlines);
};

#ifdef CONFIG_DEBUG_FS

static struct dentry *hte_root;

static int __init hte_subsys_dbgfs_init(void)
{
	/* creates /sys/kernel/debug/hte/ */
	hte_root = debugfs_create_dir("hte", NULL);

	return 0;
}
subsys_initcall(hte_subsys_dbgfs_init);

static void hte_chip_dbgfs_init(struct hte_device *gdev)
{
	const struct hte_chip *chip = gdev->chip;
	const char *name = chip->name ? chip->name : dev_name(chip->dev);

	gdev->dbg_root = debugfs_create_dir(name, hte_root);

	debugfs_create_atomic_t("ts_requested", 0444, gdev->dbg_root,
				&gdev->ts_req);
	debugfs_create_u32("total_ts", 0444, gdev->dbg_root,
			   &gdev->nlines);
}

static void hte_ts_dbgfs_init(const char *name, struct hte_ts_info *ei)
{
	if (!ei->gdev->dbg_root || !name)
		return;

	ei->ts_dbg_root = debugfs_create_dir(name, ei->gdev->dbg_root);

	debugfs_create_atomic_t("dropped_timestamps", 0444, ei->ts_dbg_root,
				&ei->dropped_ts);
}

#else

static void hte_chip_dbgfs_init(struct hte_device *gdev)
{
}

static void hte_ts_dbgfs_init(const char *name, struct hte_ts_info *ei)
{
}

#endif

/**
 * hte_ts_put() - Release and disable timestamp for the given desc.
 *
 * @desc: timestamp descriptor.
 *
 * Context: debugfs_remove_recursive() function call may use sleeping locks,
 *	    not suitable from atomic context.
 * Returns: 0 on success or a negative error code on failure.
 */
int hte_ts_put(struct hte_ts_desc *desc)
{
	int ret = 0;
	unsigned long flag;
	struct hte_device *gdev;
	struct hte_ts_info *ei;

	if (!desc)
		return -EINVAL;

	ei = desc->hte_data;

	if (!ei || !ei->gdev)
		return -EINVAL;

	gdev = ei->gdev;

	mutex_lock(&ei->req_mlock);

	if (unlikely(!test_bit(HTE_TS_REQ, &ei->flags) &&
	    !test_bit(HTE_TS_REGISTERED, &ei->flags))) {
		dev_info(gdev->sdev, "id:%d is not requested\n",
			 desc->attr.line_id);
		ret = -EINVAL;
		goto unlock;
	}

	if (unlikely(!test_bit(HTE_TS_REQ, &ei->flags) &&
	    test_bit(HTE_TS_REGISTERED, &ei->flags))) {
		dev_info(gdev->sdev, "id:%d is registered but not requested\n",
			 desc->attr.line_id);
		ret = -EINVAL;
		goto unlock;
	}

	if (test_bit(HTE_TS_REQ, &ei->flags) &&
	    !test_bit(HTE_TS_REGISTERED, &ei->flags)) {
		clear_bit(HTE_TS_REQ, &ei->flags);
		desc->hte_data = NULL;
		ret = 0;
		goto mod_put;
	}

	ret = gdev->chip->ops->release(gdev->chip, desc, ei->xlated_id);
	if (ret) {
		dev_err(gdev->sdev, "id: %d free failed\n",
			desc->attr.line_id);
		goto unlock;
	}

	kfree(ei->line_name);
	if (ei->free_attr_name)
		kfree_const(desc->attr.name);

	debugfs_remove_recursive(ei->ts_dbg_root);

	spin_lock_irqsave(&ei->slock, flag);

	if (test_bit(HTE_TS_QUEUE_WK, &ei->flags)) {
		spin_unlock_irqrestore(&ei->slock, flag);
		flush_work(&ei->cb_work);
		spin_lock_irqsave(&ei->slock, flag);
	}

	atomic_dec(&gdev->ts_req);
	atomic_set(&ei->dropped_ts, 0);

	ei->seq = 1;
	ei->flags = 0;
	desc->hte_data = NULL;

	spin_unlock_irqrestore(&ei->slock, flag);

	ei->cb = NULL;
	ei->tcb = NULL;
	ei->cl_data = NULL;

mod_put:
	module_put(gdev->owner);
unlock:
	mutex_unlock(&ei->req_mlock);
	dev_dbg(gdev->sdev, "release id: %d\n", desc->attr.line_id);

	return ret;
}
EXPORT_SYMBOL_GPL(hte_ts_put);

static int hte_ts_dis_en_common(struct hte_ts_desc *desc, bool en)
{
	u32 ts_id;
	struct hte_device *gdev;
	struct hte_ts_info *ei;
	int ret;
	unsigned long flag;

	if (!desc)
		return -EINVAL;

	ei = desc->hte_data;

	if (!ei || !ei->gdev)
		return -EINVAL;

	gdev = ei->gdev;
	ts_id = desc->attr.line_id;

	mutex_lock(&ei->req_mlock);

	if (!test_bit(HTE_TS_REGISTERED, &ei->flags)) {
		dev_dbg(gdev->sdev, "id:%d is not registered", ts_id);
		ret = -EUSERS;
		goto out;
	}

	spin_lock_irqsave(&ei->slock, flag);

	if (en) {
		if (!test_bit(HTE_TS_DISABLE, &ei->flags)) {
			ret = 0;
			goto out_unlock;
		}

		spin_unlock_irqrestore(&ei->slock, flag);
		ret = gdev->chip->ops->enable(gdev->chip, ei->xlated_id);
		if (ret) {
			dev_warn(gdev->sdev, "id: %d enable failed\n",
				 ts_id);
			goto out;
		}

		spin_lock_irqsave(&ei->slock, flag);
		clear_bit(HTE_TS_DISABLE, &ei->flags);
	} else {
		if (test_bit(HTE_TS_DISABLE, &ei->flags)) {
			ret = 0;
			goto out_unlock;
		}

		spin_unlock_irqrestore(&ei->slock, flag);
		ret = gdev->chip->ops->disable(gdev->chip, ei->xlated_id);
		if (ret) {
			dev_warn(gdev->sdev, "id: %d disable failed\n",
				 ts_id);
			goto out;
		}

		spin_lock_irqsave(&ei->slock, flag);
		set_bit(HTE_TS_DISABLE, &ei->flags);
	}

out_unlock:
	spin_unlock_irqrestore(&ei->slock, flag);
out:
	mutex_unlock(&ei->req_mlock);
	return ret;
}

/**
 * hte_disable_ts() - Disable timestamp on given descriptor.
 *
 * The API does not release any resources associated with desc.
 *
 * @desc: ts descriptor, this is the same as returned by the request API.
 *
 * Context: Holds mutex lock, not suitable from atomic context.
 * Returns: 0 on success or a negative error code on failure.
 */
int hte_disable_ts(struct hte_ts_desc *desc)
{
	return hte_ts_dis_en_common(desc, false);
}
EXPORT_SYMBOL_GPL(hte_disable_ts);

/**
 * hte_enable_ts() - Enable timestamp on given descriptor.
 *
 * @desc: ts descriptor, this is the same as returned by the request API.
 *
 * Context: Holds mutex lock, not suitable from atomic context.
 * Returns: 0 on success or a negative error code on failure.
 */
int hte_enable_ts(struct hte_ts_desc *desc)
{
	return hte_ts_dis_en_common(desc, true);
}
EXPORT_SYMBOL_GPL(hte_enable_ts);

static void hte_do_cb_work(struct work_struct *w)
{
	unsigned long flag;
	struct hte_ts_info *ei = container_of(w, struct hte_ts_info, cb_work);

	if (unlikely(!ei->tcb))
		return;

	ei->tcb(ei->cl_data);

	spin_lock_irqsave(&ei->slock, flag);
	clear_bit(HTE_TS_QUEUE_WK, &ei->flags);
	spin_unlock_irqrestore(&ei->slock, flag);
}

static int __hte_req_ts(struct hte_ts_desc *desc, hte_ts_cb_t cb,
			hte_ts_sec_cb_t tcb, void *data)
{
	int ret;
	struct hte_device *gdev;
	struct hte_ts_info *ei = desc->hte_data;

	gdev = ei->gdev;
	/*
	 * There is a chance that multiple consumers requesting same entity,
	 * lock here.
	 */
	mutex_lock(&ei->req_mlock);

	if (test_bit(HTE_TS_REGISTERED, &ei->flags) ||
	    !test_bit(HTE_TS_REQ, &ei->flags)) {
		dev_dbg(gdev->chip->dev, "id:%u req failed\n",
			desc->attr.line_id);
		ret = -EUSERS;
		goto unlock;
	}

	ei->cb = cb;
	ei->tcb = tcb;
	if (tcb)
		INIT_WORK(&ei->cb_work, hte_do_cb_work);

	ret = gdev->chip->ops->request(gdev->chip, desc, ei->xlated_id);
	if (ret < 0) {
		dev_err(gdev->chip->dev, "ts request failed\n");
		goto unlock;
	}

	ei->cl_data = data;
	ei->seq = 1;

	atomic_inc(&gdev->ts_req);

	if (desc->attr.name)
		ei->line_name = NULL;
	else
		ei->line_name = kasprintf(GFP_KERNEL, "ts_%u", desc->attr.line_id);

	hte_ts_dbgfs_init(desc->attr.name == NULL ?
			  ei->line_name : desc->attr.name, ei);
	set_bit(HTE_TS_REGISTERED, &ei->flags);

	dev_dbg(gdev->chip->dev, "id: %u, xlated id:%u",
		desc->attr.line_id, ei->xlated_id);

	ret = 0;

unlock:
	mutex_unlock(&ei->req_mlock);

	return ret;
}

static int hte_bind_ts_info_locked(struct hte_ts_info *ei,
				   struct hte_ts_desc *desc, u32 x_id)
{
	int ret = 0;

	mutex_lock(&ei->req_mlock);

	if (test_bit(HTE_TS_REQ, &ei->flags)) {
		dev_dbg(ei->gdev->chip->dev, "id:%u is already requested\n",
			desc->attr.line_id);
		ret = -EUSERS;
		goto out;
	}

	set_bit(HTE_TS_REQ, &ei->flags);
	desc->hte_data = ei;
	ei->xlated_id = x_id;

out:
	mutex_unlock(&ei->req_mlock);

	return ret;
}

static struct hte_device *of_node_to_htedevice(struct device_node *np)
{
	struct hte_device *gdev;

	spin_lock(&hte_lock);

	list_for_each_entry(gdev, &hte_devices, list)
		if (gdev->chip && gdev->chip->dev &&
		    device_match_of_node(gdev->chip->dev, np)) {
			spin_unlock(&hte_lock);
			return gdev;
		}

	spin_unlock(&hte_lock);

	return ERR_PTR(-ENODEV);
}

static struct hte_device *hte_find_dev_from_linedata(struct hte_ts_desc *desc)
{
	struct hte_device *gdev;

	spin_lock(&hte_lock);

	list_for_each_entry(gdev, &hte_devices, list)
		if (gdev->chip && gdev->chip->match_from_linedata) {
			if (!gdev->chip->match_from_linedata(gdev->chip, desc))
				continue;
			spin_unlock(&hte_lock);
			return gdev;
		}

	spin_unlock(&hte_lock);

	return ERR_PTR(-ENODEV);
}

/**
 * of_hte_req_count - Return the number of entities to timestamp.
 *
 * The function returns the total count of the requested entities to timestamp
 * by parsing device tree.
 *
 * @dev: The HTE consumer.
 *
 * Returns: Positive number on success, -ENOENT if no entries,
 * -EINVAL for other errors.
 */
int of_hte_req_count(struct device *dev)
{
	int count;

	if (!dev || !dev->of_node)
		return -EINVAL;

	count = of_count_phandle_with_args(dev->of_node, "timestamps",
					   "#timestamp-cells");

	return count ? count : -ENOENT;
}
EXPORT_SYMBOL_GPL(of_hte_req_count);

static inline struct hte_device *hte_get_dev(struct hte_ts_desc *desc)
{
	return hte_find_dev_from_linedata(desc);
}

static struct hte_device *hte_of_get_dev(struct device *dev,
					 struct hte_ts_desc *desc,
					 int index,
					 struct of_phandle_args *args,
					 bool *free_name)
{
	int ret;
	struct device_node *np;
	char *temp;

	if (!dev->of_node)
		return ERR_PTR(-EINVAL);

	np = dev->of_node;

	if (!of_property_present(np, "timestamp-names")) {
		/* Let hte core construct it during request time */
		desc->attr.name = NULL;
	} else {
		ret = of_property_read_string_index(np, "timestamp-names",
						    index, &desc->attr.name);
		if (ret) {
			pr_err("can't parse \"timestamp-names\" property\n");
			return ERR_PTR(ret);
		}
		*free_name = false;
		if (desc->attr.name) {
			temp = skip_spaces(desc->attr.name);
			if (!*temp)
				desc->attr.name = NULL;
		}
	}

	ret = of_parse_phandle_with_args(np, "timestamps", "#timestamp-cells",
					 index, args);
	if (ret) {
		pr_err("%s(): can't parse \"timestamps\" property\n",
		       __func__);
		return ERR_PTR(ret);
	}

	of_node_put(args->np);

	return of_node_to_htedevice(args->np);
}

/**
 * hte_ts_get() - The function to initialize and obtain HTE desc.
 *
 * The function initializes the consumer provided HTE descriptor. If consumer
 * has device tree node, index is used to parse the line id and other details.
 * The function needs to be called before using any request APIs.
 *
 * @dev: HTE consumer/client device, used in case of parsing device tree node.
 * @desc: Pre-allocated timestamp descriptor.
 * @index: The index will be used as an index to parse line_id from the
 * device tree node if node is present.
 *
 * Context: Holds mutex lock.
 * Returns: Returns 0 on success or negative error code on failure.
 */
int hte_ts_get(struct device *dev, struct hte_ts_desc *desc, int index)
{
	struct hte_device *gdev;
	struct hte_ts_info *ei;
	const struct fwnode_handle *fwnode;
	struct of_phandle_args args;
	u32 xlated_id;
	int ret;
	bool free_name = false;

	if (!desc)
		return -EINVAL;

	fwnode = dev ? dev_fwnode(dev) : NULL;

	if (is_of_node(fwnode))
		gdev = hte_of_get_dev(dev, desc, index, &args, &free_name);
	else
		gdev = hte_get_dev(desc);

	if (IS_ERR(gdev)) {
		pr_err("%s() no hte dev found\n", __func__);
		return PTR_ERR(gdev);
	}

	if (!try_module_get(gdev->owner))
		return -ENODEV;

	if (!gdev->chip) {
		pr_err("%s(): requested id does not have provider\n",
		       __func__);
		ret = -ENODEV;
		goto put;
	}

	if (is_of_node(fwnode)) {
		if (!gdev->chip->xlate_of)
			ret = -EINVAL;
		else
			ret = gdev->chip->xlate_of(gdev->chip, &args,
						   desc, &xlated_id);
	} else {
		if (!gdev->chip->xlate_plat)
			ret = -EINVAL;
		else
			ret = gdev->chip->xlate_plat(gdev->chip, desc,
						     &xlated_id);
	}

	if (ret < 0)
		goto put;

	ei = &gdev->ei[xlated_id];

	ret = hte_bind_ts_info_locked(ei, desc, xlated_id);
	if (ret)
		goto put;

	ei->free_attr_name = free_name;

	return 0;

put:
	module_put(gdev->owner);
	return ret;
}
EXPORT_SYMBOL_GPL(hte_ts_get);

static void __devm_hte_release_ts(void *res)
{
	hte_ts_put(res);
}

/**
 * hte_request_ts_ns() - The API to request and enable hardware timestamp in
 * nanoseconds.
 *
 * The entity is provider specific for example, GPIO lines, signals, buses
 * etc...The API allocates necessary resources and enables the timestamp.
 *
 * @desc: Pre-allocated and initialized timestamp descriptor.
 * @cb: Callback to push the timestamp data to consumer.
 * @tcb: Optional callback. If its provided, subsystem initializes
 * workqueue. It is called when cb returns HTE_RUN_SECOND_CB.
 * @data: Client data, used during cb and tcb callbacks.
 *
 * Context: Holds mutex lock.
 * Returns: Returns 0 on success or negative error code on failure.
 */
int hte_request_ts_ns(struct hte_ts_desc *desc, hte_ts_cb_t cb,
		      hte_ts_sec_cb_t tcb, void *data)
{
	int ret;
	struct hte_ts_info *ei;

	if (!desc || !desc->hte_data || !cb)
		return -EINVAL;

	ei = desc->hte_data;
	if (!ei || !ei->gdev)
		return -EINVAL;

	ret = __hte_req_ts(desc, cb, tcb, data);
	if (ret < 0) {
		dev_err(ei->gdev->chip->dev,
			"failed to request id: %d\n", desc->attr.line_id);
		return ret;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(hte_request_ts_ns);

/**
 * devm_hte_request_ts_ns() - Resource managed API to request and enable
 * hardware timestamp in nanoseconds.
 *
 * The entity is provider specific for example, GPIO lines, signals, buses
 * etc...The API allocates necessary resources and enables the timestamp. It
 * deallocates and disables automatically when the consumer exits.
 *
 * @dev: HTE consumer/client device.
 * @desc: Pre-allocated and initialized timestamp descriptor.
 * @cb: Callback to push the timestamp data to consumer.
 * @tcb: Optional callback. If its provided, subsystem initializes
 * workqueue. It is called when cb returns HTE_RUN_SECOND_CB.
 * @data: Client data, used during cb and tcb callbacks.
 *
 * Context: Holds mutex lock.
 * Returns: Returns 0 on success or negative error code on failure.
 */
int devm_hte_request_ts_ns(struct device *dev, struct hte_ts_desc *desc,
			   hte_ts_cb_t cb, hte_ts_sec_cb_t tcb,
			   void *data)
{
	int err;

	if (!dev)
		return -EINVAL;

	err = hte_request_ts_ns(desc, cb, tcb, data);
	if (err)
		return err;

	err = devm_add_action_or_reset(dev, __devm_hte_release_ts, desc);
	if (err)
		return err;

	return 0;
}
EXPORT_SYMBOL_GPL(devm_hte_request_ts_ns);

/**
 * hte_init_line_attr() - Initialize line attributes.
 *
 * Zeroes out line attributes and initializes with provided arguments.
 * The function needs to be called before calling any consumer facing
 * functions.
 *
 * @desc: Pre-allocated timestamp descriptor.
 * @line_id: line id.
 * @edge_flags: edge flags related to line_id.
 * @name: name of the line.
 * @data: line data related to line_id.
 *
 * Context: Any.
 * Returns: 0 on success or negative error code for the failure.
 */
int hte_init_line_attr(struct hte_ts_desc *desc, u32 line_id,
		       unsigned long edge_flags, const char *name, void *data)
{
	if (!desc)
		return -EINVAL;

	memset(&desc->attr, 0, sizeof(desc->attr));

	desc->attr.edge_flags = edge_flags;
	desc->attr.line_id = line_id;
	desc->attr.line_data = data;
	if (name) {
		name =  kstrdup_const(name, GFP_KERNEL);
		if (!name)
			return -ENOMEM;
	}

	desc->attr.name = name;

	return 0;
}
EXPORT_SYMBOL_GPL(hte_init_line_attr);

/**
 * hte_get_clk_src_info() - Get the clock source information for a ts
 * descriptor.
 *
 * @desc: ts descriptor, same as returned from request API.
 * @ci: The API fills this structure with the clock information data.
 *
 * Context: Any context.
 * Returns: 0 on success else negative error code on failure.
 */
int hte_get_clk_src_info(const struct hte_ts_desc *desc,
			 struct hte_clk_info *ci)
{
	struct hte_chip *chip;
	struct hte_ts_info *ei;

	if (!desc || !desc->hte_data || !ci) {
		pr_debug("%s:%d\n", __func__, __LINE__);
		return -EINVAL;
	}

	ei = desc->hte_data;
	if (!ei->gdev || !ei->gdev->chip)
		return -EINVAL;

	chip = ei->gdev->chip;
	if (!chip->ops->get_clk_src_info)
		return -EOPNOTSUPP;

	return chip->ops->get_clk_src_info(chip, ci);
}
EXPORT_SYMBOL_GPL(hte_get_clk_src_info);

/**
 * hte_push_ts_ns() - Push timestamp data in nanoseconds.
 *
 * It is used by the provider to push timestamp data.
 *
 * @chip: The HTE chip, used during the registration.
 * @xlated_id: entity id understood by both subsystem and provider, this is
 * obtained from xlate callback during request API.
 * @data: timestamp data.
 *
 * Returns: 0 on success or a negative error code on failure.
 */
int hte_push_ts_ns(const struct hte_chip *chip, u32 xlated_id,
		   struct hte_ts_data *data)
{
	enum hte_return ret;
	int st = 0;
	struct hte_ts_info *ei;
	unsigned long flag;

	if (!chip || !data || !chip->gdev)
		return -EINVAL;

	if (xlated_id >= chip->nlines)
		return -EINVAL;

	ei = &chip->gdev->ei[xlated_id];

	spin_lock_irqsave(&ei->slock, flag);

	/* timestamp sequence counter */
	data->seq = ei->seq++;

	if (!test_bit(HTE_TS_REGISTERED, &ei->flags) ||
	    test_bit(HTE_TS_DISABLE, &ei->flags)) {
		dev_dbg(chip->dev, "Unknown timestamp push\n");
		atomic_inc(&ei->dropped_ts);
		st = -EINVAL;
		goto unlock;
	}

	ret = ei->cb(data, ei->cl_data);
	if (ret == HTE_RUN_SECOND_CB && ei->tcb) {
		queue_work(system_unbound_wq, &ei->cb_work);
		set_bit(HTE_TS_QUEUE_WK, &ei->flags);
	}

unlock:
	spin_unlock_irqrestore(&ei->slock, flag);

	return st;
}
EXPORT_SYMBOL_GPL(hte_push_ts_ns);

static int hte_register_chip(struct hte_chip *chip)
{
	struct hte_device *gdev;
	u32 i;

	if (!chip || !chip->dev || !chip->dev->of_node)
		return -EINVAL;

	if (!chip->ops || !chip->ops->request || !chip->ops->release) {
		dev_err(chip->dev, "Driver needs to provide ops\n");
		return -EINVAL;
	}

	gdev = kzalloc(struct_size(gdev, ei, chip->nlines), GFP_KERNEL);
	if (!gdev)
		return -ENOMEM;

	gdev->chip = chip;
	chip->gdev = gdev;
	gdev->nlines = chip->nlines;
	gdev->sdev = chip->dev;

	for (i = 0; i < chip->nlines; i++) {
		gdev->ei[i].gdev = gdev;
		mutex_init(&gdev->ei[i].req_mlock);
		spin_lock_init(&gdev->ei[i].slock);
	}

	if (chip->dev->driver)
		gdev->owner = chip->dev->driver->owner;
	else
		gdev->owner = THIS_MODULE;

	of_node_get(chip->dev->of_node);

	INIT_LIST_HEAD(&gdev->list);

	spin_lock(&hte_lock);
	list_add_tail(&gdev->list, &hte_devices);
	spin_unlock(&hte_lock);

	hte_chip_dbgfs_init(gdev);

	dev_dbg(chip->dev, "Added hte chip\n");

	return 0;
}

static int hte_unregister_chip(struct hte_chip *chip)
{
	struct hte_device *gdev;

	if (!chip)
		return -EINVAL;

	gdev = chip->gdev;

	spin_lock(&hte_lock);
	list_del(&gdev->list);
	spin_unlock(&hte_lock);

	gdev->chip = NULL;

	of_node_put(chip->dev->of_node);
	debugfs_remove_recursive(gdev->dbg_root);
	kfree(gdev);

	dev_dbg(chip->dev, "Removed hte chip\n");

	return 0;
}

static void _hte_devm_unregister_chip(void *chip)
{
	hte_unregister_chip(chip);
}

/**
 * devm_hte_register_chip() - Resource managed API to register HTE chip.
 *
 * It is used by the provider to register itself with the HTE subsystem.
 * The unregistration is done automatically when the provider exits.
 *
 * @chip: the HTE chip to add to subsystem.
 *
 * Returns: 0 on success or a negative error code on failure.
 */
int devm_hte_register_chip(struct hte_chip *chip)
{
	int err;

	err = hte_register_chip(chip);
	if (err)
		return err;

	err = devm_add_action_or_reset(chip->dev, _hte_devm_unregister_chip,
				       chip);
	if (err)
		return err;

	return 0;
}
EXPORT_SYMBOL_GPL(devm_hte_register_chip);