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/*
 * Copyright (c) 2016, NVIDIA CORPORATION.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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/interrupt.h>
#include <linux/io.h>
#include <linux/mailbox_controller.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include <dt-bindings/mailbox/tegra186-hsp.h>

#define HSP_INT_DIMENSIONING	0x380
#define HSP_nSM_SHIFT		0
#define HSP_nSS_SHIFT		4
#define HSP_nAS_SHIFT		8
#define HSP_nDB_SHIFT		12
#define HSP_nSI_SHIFT		16
#define HSP_nINT_MASK		0xf

#define HSP_DB_TRIGGER	0x0
#define HSP_DB_ENABLE	0x4
#define HSP_DB_RAW	0x8
#define HSP_DB_PENDING	0xc

#define HSP_DB_CCPLEX		1
#define HSP_DB_BPMP		3
#define HSP_DB_MAX		7

struct tegra_hsp_channel;
struct tegra_hsp;

struct tegra_hsp_channel {
	struct tegra_hsp *hsp;
	struct mbox_chan *chan;
	void __iomem *regs;
};

struct tegra_hsp_doorbell {
	struct tegra_hsp_channel channel;
	struct list_head list;
	const char *name;
	unsigned int master;
	unsigned int index;
};

struct tegra_hsp_db_map {
	const char *name;
	unsigned int master;
	unsigned int index;
};

struct tegra_hsp_soc {
	const struct tegra_hsp_db_map *map;
};

struct tegra_hsp {
	const struct tegra_hsp_soc *soc;
	struct mbox_controller mbox;
	void __iomem *regs;
	unsigned int irq;
	unsigned int num_sm;
	unsigned int num_as;
	unsigned int num_ss;
	unsigned int num_db;
	unsigned int num_si;
	spinlock_t lock;

	struct list_head doorbells;
};

static inline struct tegra_hsp *
to_tegra_hsp(struct mbox_controller *mbox)
{
	return container_of(mbox, struct tegra_hsp, mbox);
}

static inline u32 tegra_hsp_readl(struct tegra_hsp *hsp, unsigned int offset)
{
	return readl(hsp->regs + offset);
}

static inline void tegra_hsp_writel(struct tegra_hsp *hsp, u32 value,
				    unsigned int offset)
{
	writel(value, hsp->regs + offset);
}

static inline u32 tegra_hsp_channel_readl(struct tegra_hsp_channel *channel,
					  unsigned int offset)
{
	return readl(channel->regs + offset);
}

static inline void tegra_hsp_channel_writel(struct tegra_hsp_channel *channel,
					    u32 value, unsigned int offset)
{
	writel(value, channel->regs + offset);
}

static bool tegra_hsp_doorbell_can_ring(struct tegra_hsp_doorbell *db)
{
	u32 value;

	value = tegra_hsp_channel_readl(&db->channel, HSP_DB_ENABLE);

	return (value & BIT(TEGRA_HSP_DB_MASTER_CCPLEX)) != 0;
}

static struct tegra_hsp_doorbell *
__tegra_hsp_doorbell_get(struct tegra_hsp *hsp, unsigned int master)
{
	struct tegra_hsp_doorbell *entry;

	list_for_each_entry(entry, &hsp->doorbells, list)
		if (entry->master == master)
			return entry;

	return NULL;
}

static struct tegra_hsp_doorbell *
tegra_hsp_doorbell_get(struct tegra_hsp *hsp, unsigned int master)
{
	struct tegra_hsp_doorbell *db;
	unsigned long flags;

	spin_lock_irqsave(&hsp->lock, flags);
	db = __tegra_hsp_doorbell_get(hsp, master);
	spin_unlock_irqrestore(&hsp->lock, flags);

	return db;
}

static irqreturn_t tegra_hsp_doorbell_irq(int irq, void *data)
{
	struct tegra_hsp *hsp = data;
	struct tegra_hsp_doorbell *db;
	unsigned long master, value;

	db = tegra_hsp_doorbell_get(hsp, TEGRA_HSP_DB_MASTER_CCPLEX);
	if (!db)
		return IRQ_NONE;

	value = tegra_hsp_channel_readl(&db->channel, HSP_DB_PENDING);
	tegra_hsp_channel_writel(&db->channel, value, HSP_DB_PENDING);

	spin_lock(&hsp->lock);

	for_each_set_bit(master, &value, hsp->mbox.num_chans) {
		struct tegra_hsp_doorbell *db;

		db = __tegra_hsp_doorbell_get(hsp, master);
		/*
		 * Depending on the bootloader chain, the CCPLEX doorbell will
		 * have some doorbells enabled, which means that requesting an
		 * interrupt will immediately fire.
		 *
		 * In that case, db->channel.chan will still be NULL here and
		 * cause a crash if not properly guarded.
		 *
		 * It remains to be seen if ignoring the doorbell in that case
		 * is the correct solution.
		 */
		if (db && db->channel.chan)
			mbox_chan_received_data(db->channel.chan, NULL);
	}

	spin_unlock(&hsp->lock);

	return IRQ_HANDLED;
}

static struct tegra_hsp_channel *
tegra_hsp_doorbell_create(struct tegra_hsp *hsp, const char *name,
			  unsigned int master, unsigned int index)
{
	struct tegra_hsp_doorbell *db;
	unsigned int offset;
	unsigned long flags;

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

	offset = (1 + (hsp->num_sm / 2) + hsp->num_ss + hsp->num_as) << 16;
	offset += index * 0x100;

	db->channel.regs = hsp->regs + offset;
	db->channel.hsp = hsp;

	db->name = kstrdup_const(name, GFP_KERNEL);
	db->master = master;
	db->index = index;

	spin_lock_irqsave(&hsp->lock, flags);
	list_add_tail(&db->list, &hsp->doorbells);
	spin_unlock_irqrestore(&hsp->lock, flags);

	return &db->channel;
}

static void __tegra_hsp_doorbell_destroy(struct tegra_hsp_doorbell *db)
{
	list_del(&db->list);
	kfree_const(db->name);
	kfree(db);
}

static int tegra_hsp_doorbell_send_data(struct mbox_chan *chan, void *data)
{
	struct tegra_hsp_doorbell *db = chan->con_priv;

	tegra_hsp_channel_writel(&db->channel, 1, HSP_DB_TRIGGER);

	return 0;
}

static int tegra_hsp_doorbell_startup(struct mbox_chan *chan)
{
	struct tegra_hsp_doorbell *db = chan->con_priv;
	struct tegra_hsp *hsp = db->channel.hsp;
	struct tegra_hsp_doorbell *ccplex;
	unsigned long flags;
	u32 value;

	if (db->master >= hsp->mbox.num_chans) {
		dev_err(hsp->mbox.dev,
			"invalid master ID %u for HSP channel\n",
			db->master);
		return -EINVAL;
	}

	ccplex = tegra_hsp_doorbell_get(hsp, TEGRA_HSP_DB_MASTER_CCPLEX);
	if (!ccplex)
		return -ENODEV;

	if (!tegra_hsp_doorbell_can_ring(db))
		return -ENODEV;

	spin_lock_irqsave(&hsp->lock, flags);

	value = tegra_hsp_channel_readl(&ccplex->channel, HSP_DB_ENABLE);
	value |= BIT(db->master);
	tegra_hsp_channel_writel(&ccplex->channel, value, HSP_DB_ENABLE);

	spin_unlock_irqrestore(&hsp->lock, flags);

	return 0;
}

static void tegra_hsp_doorbell_shutdown(struct mbox_chan *chan)
{
	struct tegra_hsp_doorbell *db = chan->con_priv;
	struct tegra_hsp *hsp = db->channel.hsp;
	struct tegra_hsp_doorbell *ccplex;
	unsigned long flags;
	u32 value;

	ccplex = tegra_hsp_doorbell_get(hsp, TEGRA_HSP_DB_MASTER_CCPLEX);
	if (!ccplex)
		return;

	spin_lock_irqsave(&hsp->lock, flags);

	value = tegra_hsp_channel_readl(&ccplex->channel, HSP_DB_ENABLE);
	value &= ~BIT(db->master);
	tegra_hsp_channel_writel(&ccplex->channel, value, HSP_DB_ENABLE);

	spin_unlock_irqrestore(&hsp->lock, flags);
}

static const struct mbox_chan_ops tegra_hsp_doorbell_ops = {
	.send_data = tegra_hsp_doorbell_send_data,
	.startup = tegra_hsp_doorbell_startup,
	.shutdown = tegra_hsp_doorbell_shutdown,
};

static struct mbox_chan *of_tegra_hsp_xlate(struct mbox_controller *mbox,
					    const struct of_phandle_args *args)
{
	struct tegra_hsp_channel *channel = ERR_PTR(-ENODEV);
	struct tegra_hsp *hsp = to_tegra_hsp(mbox);
	unsigned int type = args->args[0];
	unsigned int master = args->args[1];
	struct tegra_hsp_doorbell *db;
	struct mbox_chan *chan;
	unsigned long flags;
	unsigned int i;

	switch (type) {
	case TEGRA_HSP_MBOX_TYPE_DB:
		db = tegra_hsp_doorbell_get(hsp, master);
		if (db)
			channel = &db->channel;

		break;

	default:
		break;
	}

	if (IS_ERR(channel))
		return ERR_CAST(channel);

	spin_lock_irqsave(&hsp->lock, flags);

	for (i = 0; i < hsp->mbox.num_chans; i++) {
		chan = &hsp->mbox.chans[i];
		if (!chan->con_priv) {
			chan->con_priv = channel;
			channel->chan = chan;
			break;
		}

		chan = NULL;
	}

	spin_unlock_irqrestore(&hsp->lock, flags);

	return chan ?: ERR_PTR(-EBUSY);
}

static void tegra_hsp_remove_doorbells(struct tegra_hsp *hsp)
{
	struct tegra_hsp_doorbell *db, *tmp;
	unsigned long flags;

	spin_lock_irqsave(&hsp->lock, flags);

	list_for_each_entry_safe(db, tmp, &hsp->doorbells, list)
		__tegra_hsp_doorbell_destroy(db);

	spin_unlock_irqrestore(&hsp->lock, flags);
}

static int tegra_hsp_add_doorbells(struct tegra_hsp *hsp)
{
	const struct tegra_hsp_db_map *map = hsp->soc->map;
	struct tegra_hsp_channel *channel;

	while (map->name) {
		channel = tegra_hsp_doorbell_create(hsp, map->name,
						    map->master, map->index);
		if (IS_ERR(channel)) {
			tegra_hsp_remove_doorbells(hsp);
			return PTR_ERR(channel);
		}

		map++;
	}

	return 0;
}

static int tegra_hsp_probe(struct platform_device *pdev)
{
	struct tegra_hsp *hsp;
	struct resource *res;
	u32 value;
	int err;

	hsp = devm_kzalloc(&pdev->dev, sizeof(*hsp), GFP_KERNEL);
	if (!hsp)
		return -ENOMEM;

	hsp->soc = of_device_get_match_data(&pdev->dev);
	INIT_LIST_HEAD(&hsp->doorbells);
	spin_lock_init(&hsp->lock);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	hsp->regs = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(hsp->regs))
		return PTR_ERR(hsp->regs);

	value = tegra_hsp_readl(hsp, HSP_INT_DIMENSIONING);
	hsp->num_sm = (value >> HSP_nSM_SHIFT) & HSP_nINT_MASK;
	hsp->num_ss = (value >> HSP_nSS_SHIFT) & HSP_nINT_MASK;
	hsp->num_as = (value >> HSP_nAS_SHIFT) & HSP_nINT_MASK;
	hsp->num_db = (value >> HSP_nDB_SHIFT) & HSP_nINT_MASK;
	hsp->num_si = (value >> HSP_nSI_SHIFT) & HSP_nINT_MASK;

	err = platform_get_irq_byname(pdev, "doorbell");
	if (err < 0) {
		dev_err(&pdev->dev, "failed to get doorbell IRQ: %d\n", err);
		return err;
	}

	hsp->irq = err;

	hsp->mbox.of_xlate = of_tegra_hsp_xlate;
	hsp->mbox.num_chans = 32;
	hsp->mbox.dev = &pdev->dev;
	hsp->mbox.txdone_irq = false;
	hsp->mbox.txdone_poll = false;
	hsp->mbox.ops = &tegra_hsp_doorbell_ops;

	hsp->mbox.chans = devm_kcalloc(&pdev->dev, hsp->mbox.num_chans,
					sizeof(*hsp->mbox.chans),
					GFP_KERNEL);
	if (!hsp->mbox.chans)
		return -ENOMEM;

	err = tegra_hsp_add_doorbells(hsp);
	if (err < 0) {
		dev_err(&pdev->dev, "failed to add doorbells: %d\n", err);
		return err;
	}

	platform_set_drvdata(pdev, hsp);

	err = mbox_controller_register(&hsp->mbox);
	if (err) {
		dev_err(&pdev->dev, "failed to register mailbox: %d\n", err);
		tegra_hsp_remove_doorbells(hsp);
		return err;
	}

	err = devm_request_irq(&pdev->dev, hsp->irq, tegra_hsp_doorbell_irq,
			       IRQF_NO_SUSPEND, dev_name(&pdev->dev), hsp);
	if (err < 0) {
		dev_err(&pdev->dev, "failed to request IRQ#%u: %d\n",
			hsp->irq, err);
		return err;
	}

	return 0;
}

static int tegra_hsp_remove(struct platform_device *pdev)
{
	struct tegra_hsp *hsp = platform_get_drvdata(pdev);

	mbox_controller_unregister(&hsp->mbox);
	tegra_hsp_remove_doorbells(hsp);

	return 0;
}

static const struct tegra_hsp_db_map tegra186_hsp_db_map[] = {
	{ "ccplex", TEGRA_HSP_DB_MASTER_CCPLEX, HSP_DB_CCPLEX, },
	{ "bpmp",   TEGRA_HSP_DB_MASTER_BPMP,   HSP_DB_BPMP,   },
	{ /* sentinel */ }
};

static const struct tegra_hsp_soc tegra186_hsp_soc = {
	.map = tegra186_hsp_db_map,
};

static const struct of_device_id tegra_hsp_match[] = {
	{ .compatible = "nvidia,tegra186-hsp", .data = &tegra186_hsp_soc },
	{ }
};

static struct platform_driver tegra_hsp_driver = {
	.driver = {
		.name = "tegra-hsp",
		.of_match_table = tegra_hsp_match,
	},
	.probe = tegra_hsp_probe,
	.remove = tegra_hsp_remove,
};

static int __init tegra_hsp_init(void)
{
	return platform_driver_register(&tegra_hsp_driver);
}
core_initcall(tegra_hsp_init);