// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2017, NVIDIA CORPORATION.  All rights reserved.
 */
#include <linux/debugfs.h>
#include <linux/dma-mapping.h>
#include <linux/slab.h>
#include <linux/uaccess.h>

#include <soc/tegra/bpmp.h>
#include <soc/tegra/bpmp-abi.h>

static DEFINE_MUTEX(bpmp_debug_lock);

struct seqbuf {
	char *buf;
	size_t pos;
	size_t size;
};

static void seqbuf_init(struct seqbuf *seqbuf, void *buf, size_t size)
{
	seqbuf->buf = buf;
	seqbuf->size = size;
	seqbuf->pos = 0;
}

static size_t seqbuf_avail(struct seqbuf *seqbuf)
{
	return seqbuf->pos < seqbuf->size ? seqbuf->size - seqbuf->pos : 0;
}

static size_t seqbuf_status(struct seqbuf *seqbuf)
{
	return seqbuf->pos <= seqbuf->size ? 0 : -EOVERFLOW;
}

static int seqbuf_eof(struct seqbuf *seqbuf)
{
	return seqbuf->pos >= seqbuf->size;
}

static int seqbuf_read(struct seqbuf *seqbuf, void *buf, size_t nbyte)
{
	nbyte = min(nbyte, seqbuf_avail(seqbuf));
	memcpy(buf, seqbuf->buf + seqbuf->pos, nbyte);
	seqbuf->pos += nbyte;
	return seqbuf_status(seqbuf);
}

static int seqbuf_read_u32(struct seqbuf *seqbuf, uint32_t *v)
{
	int err;

	err = seqbuf_read(seqbuf, v, 4);
	*v = le32_to_cpu(*v);
	return err;
}

static int seqbuf_read_str(struct seqbuf *seqbuf, const char **str)
{
	*str = seqbuf->buf + seqbuf->pos;
	seqbuf->pos += strnlen(*str, seqbuf_avail(seqbuf));
	seqbuf->pos++;
	return seqbuf_status(seqbuf);
}

static void seqbuf_seek(struct seqbuf *seqbuf, ssize_t offset)
{
	seqbuf->pos += offset;
}

/* map filename in Linux debugfs to corresponding entry in BPMP */
static const char *get_filename(struct tegra_bpmp *bpmp,
				const struct file *file, char *buf, int size)
{
	const char *root_path, *filename = NULL;
	char *root_path_buf;
	size_t root_len;
	size_t root_path_buf_len = 512;

	root_path_buf = kzalloc(root_path_buf_len, GFP_KERNEL);
	if (!root_path_buf)
		goto out;

	root_path = dentry_path(bpmp->debugfs_mirror, root_path_buf,
				root_path_buf_len);
	if (IS_ERR(root_path))
		goto out;

	root_len = strlen(root_path);

	filename = dentry_path(file->f_path.dentry, buf, size);
	if (IS_ERR(filename)) {
		filename = NULL;
		goto out;
	}

	if (strlen(filename) < root_len || strncmp(filename, root_path, root_len)) {
		filename = NULL;
		goto out;
	}

	filename += root_len;

out:
	kfree(root_path_buf);
	return filename;
}

static int mrq_debug_open(struct tegra_bpmp *bpmp, const char *name,
			  uint32_t *fd, uint32_t *len, bool write)
{
	struct mrq_debug_request req = {
		.cmd = cpu_to_le32(write ? CMD_DEBUG_OPEN_WO : CMD_DEBUG_OPEN_RO),
	};
	struct mrq_debug_response resp;
	struct tegra_bpmp_message msg = {
		.mrq = MRQ_DEBUG,
		.tx = {
			.data = &req,
			.size = sizeof(req),
		},
		.rx = {
			.data = &resp,
			.size = sizeof(resp),
		},
	};
	ssize_t sz_name;
	int err = 0;

	sz_name = strscpy(req.fop.name, name, sizeof(req.fop.name));
	if (sz_name < 0) {
		pr_err("File name too large: %s\n", name);
		return -EINVAL;
	}

	err = tegra_bpmp_transfer(bpmp, &msg);
	if (err < 0)
		return err;
	else if (msg.rx.ret < 0)
		return -EINVAL;

	*len = resp.fop.datalen;
	*fd = resp.fop.fd;

	return 0;
}

static int mrq_debug_close(struct tegra_bpmp *bpmp, uint32_t fd)
{
	struct mrq_debug_request req = {
		.cmd = cpu_to_le32(CMD_DEBUG_CLOSE),
		.frd = {
			.fd = fd,
		},
	};
	struct mrq_debug_response resp;
	struct tegra_bpmp_message msg = {
		.mrq = MRQ_DEBUG,
		.tx = {
			.data = &req,
			.size = sizeof(req),
		},
		.rx = {
			.data = &resp,
			.size = sizeof(resp),
		},
	};
	int err = 0;

	err = tegra_bpmp_transfer(bpmp, &msg);
	if (err < 0)
		return err;
	else if (msg.rx.ret < 0)
		return -EINVAL;

	return 0;
}

static int mrq_debug_read(struct tegra_bpmp *bpmp, const char *name,
			  char *data, size_t sz_data, uint32_t *nbytes)
{
	struct mrq_debug_request req = {
		.cmd = cpu_to_le32(CMD_DEBUG_READ),
	};
	struct mrq_debug_response resp;
	struct tegra_bpmp_message msg = {
		.mrq = MRQ_DEBUG,
		.tx = {
			.data = &req,
			.size = sizeof(req),
		},
		.rx = {
			.data = &resp,
			.size = sizeof(resp),
		},
	};
	uint32_t fd = 0, len = 0;
	int remaining, err;

	mutex_lock(&bpmp_debug_lock);
	err = mrq_debug_open(bpmp, name, &fd, &len, 0);
	if (err)
		goto out;

	if (len > sz_data) {
		err = -EFBIG;
		goto close;
	}

	req.frd.fd = fd;
	remaining = len;

	while (remaining > 0) {
		err = tegra_bpmp_transfer(bpmp, &msg);
		if (err < 0) {
			goto close;
		} else if (msg.rx.ret < 0) {
			err = -EINVAL;
			goto close;
		}

		if (resp.frd.readlen > remaining) {
			pr_err("%s: read data length invalid\n", __func__);
			err = -EINVAL;
			goto close;
		}

		memcpy(data, resp.frd.data, resp.frd.readlen);
		data += resp.frd.readlen;
		remaining -= resp.frd.readlen;
	}

	*nbytes = len;

close:
	err = mrq_debug_close(bpmp, fd);
out:
	mutex_unlock(&bpmp_debug_lock);
	return err;
}

static int mrq_debug_write(struct tegra_bpmp *bpmp, const char *name,
			   uint8_t *data, size_t sz_data)
{
	struct mrq_debug_request req = {
		.cmd = cpu_to_le32(CMD_DEBUG_WRITE)
	};
	struct mrq_debug_response resp;
	struct tegra_bpmp_message msg = {
		.mrq = MRQ_DEBUG,
		.tx = {
			.data = &req,
			.size = sizeof(req),
		},
		.rx = {
			.data = &resp,
			.size = sizeof(resp),
		},
	};
	uint32_t fd = 0, len = 0;
	size_t remaining;
	int err;

	mutex_lock(&bpmp_debug_lock);
	err = mrq_debug_open(bpmp, name, &fd, &len, 1);
	if (err)
		goto out;

	if (sz_data > len) {
		err = -EINVAL;
		goto close;
	}

	req.fwr.fd = fd;
	remaining = sz_data;

	while (remaining > 0) {
		len = min(remaining, sizeof(req.fwr.data));
		memcpy(req.fwr.data, data, len);
		req.fwr.datalen = len;

		err = tegra_bpmp_transfer(bpmp, &msg);
		if (err < 0) {
			goto close;
		} else if (msg.rx.ret < 0) {
			err = -EINVAL;
			goto close;
		}

		data += req.fwr.datalen;
		remaining -= req.fwr.datalen;
	}

close:
	err = mrq_debug_close(bpmp, fd);
out:
	mutex_unlock(&bpmp_debug_lock);
	return err;
}

static int bpmp_debug_show(struct seq_file *m, void *p)
{
	struct file *file = m->private;
	struct inode *inode = file_inode(file);
	struct tegra_bpmp *bpmp = inode->i_private;
	char fnamebuf[256];
	const char *filename;
	struct mrq_debug_request req = {
		.cmd = cpu_to_le32(CMD_DEBUG_READ),
	};
	struct mrq_debug_response resp;
	struct tegra_bpmp_message msg = {
		.mrq = MRQ_DEBUG,
		.tx = {
			.data = &req,
			.size = sizeof(req),
		},
		.rx = {
			.data = &resp,
			.size = sizeof(resp),
		},
	};
	uint32_t fd = 0, len = 0;
	int remaining, err;

	filename = get_filename(bpmp, file, fnamebuf, sizeof(fnamebuf));
	if (!filename)
		return -ENOENT;

	mutex_lock(&bpmp_debug_lock);
	err = mrq_debug_open(bpmp, filename, &fd, &len, 0);
	if (err)
		goto out;

	req.frd.fd = fd;
	remaining = len;

	while (remaining > 0) {
		err = tegra_bpmp_transfer(bpmp, &msg);
		if (err < 0) {
			goto close;
		} else if (msg.rx.ret < 0) {
			err = -EINVAL;
			goto close;
		}

		if (resp.frd.readlen > remaining) {
			pr_err("%s: read data length invalid\n", __func__);
			err = -EINVAL;
			goto close;
		}

		seq_write(m, resp.frd.data, resp.frd.readlen);
		remaining -= resp.frd.readlen;
	}

close:
	err = mrq_debug_close(bpmp, fd);
out:
	mutex_unlock(&bpmp_debug_lock);
	return err;
}

static ssize_t bpmp_debug_store(struct file *file, const char __user *buf,
		size_t count, loff_t *f_pos)
{
	struct inode *inode = file_inode(file);
	struct tegra_bpmp *bpmp = inode->i_private;
	char *databuf = NULL;
	char fnamebuf[256];
	const char *filename;
	ssize_t err;

	filename = get_filename(bpmp, file, fnamebuf, sizeof(fnamebuf));
	if (!filename)
		return -ENOENT;

	databuf = kmalloc(count, GFP_KERNEL);
	if (!databuf)
		return -ENOMEM;

	if (copy_from_user(databuf, buf, count)) {
		err = -EFAULT;
		goto free_ret;
	}

	err = mrq_debug_write(bpmp, filename, databuf, count);

free_ret:
	kfree(databuf);

	return err ?: count;
}

static int bpmp_debug_open(struct inode *inode, struct file *file)
{
	return single_open_size(file, bpmp_debug_show, file, SZ_256K);
}

static const struct file_operations bpmp_debug_fops = {
	.open		= bpmp_debug_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.write		= bpmp_debug_store,
	.release	= single_release,
};

static int bpmp_populate_debugfs_inband(struct tegra_bpmp *bpmp,
					struct dentry *parent,
					char *ppath)
{
	const size_t pathlen = SZ_256;
	const size_t bufsize = SZ_16K;
	uint32_t dsize, attrs = 0;
	struct dentry *dentry;
	struct seqbuf seqbuf;
	char *buf, *pathbuf;
	const char *name;
	int err = 0;

	if (!bpmp || !parent || !ppath)
		return -EINVAL;

	buf = kmalloc(bufsize, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	pathbuf = kzalloc(pathlen, GFP_KERNEL);
	if (!pathbuf) {
		kfree(buf);
		return -ENOMEM;
	}

	err = mrq_debug_read(bpmp, ppath, buf, bufsize, &dsize);
	if (err)
		goto out;

	seqbuf_init(&seqbuf, buf, dsize);

	while (!seqbuf_eof(&seqbuf)) {
		err = seqbuf_read_u32(&seqbuf, &attrs);
		if (err)
			goto out;

		err = seqbuf_read_str(&seqbuf, &name);
		if (err < 0)
			goto out;

		if (attrs & DEBUGFS_S_ISDIR) {
			size_t len;

			dentry = debugfs_create_dir(name, parent);
			if (IS_ERR(dentry)) {
				err = PTR_ERR(dentry);
				goto out;
			}

			len = snprintf(pathbuf, pathlen, "%s%s/", ppath, name);
			if (len >= pathlen) {
				err = -EINVAL;
				goto out;
			}

			err = bpmp_populate_debugfs_inband(bpmp, dentry,
							   pathbuf);
			if (err < 0)
				goto out;
		} else {
			umode_t mode;

			mode = attrs & DEBUGFS_S_IRUSR ? 0400 : 0;
			mode |= attrs & DEBUGFS_S_IWUSR ? 0200 : 0;
			dentry = debugfs_create_file(name, mode, parent, bpmp,
						     &bpmp_debug_fops);
			if (!dentry) {
				err = -ENOMEM;
				goto out;
			}
		}
	}

out:
	kfree(pathbuf);
	kfree(buf);

	return err;
}

static int mrq_debugfs_read(struct tegra_bpmp *bpmp,
			    dma_addr_t name, size_t sz_name,
			    dma_addr_t data, size_t sz_data,
			    size_t *nbytes)
{
	struct mrq_debugfs_request req = {
		.cmd = cpu_to_le32(CMD_DEBUGFS_READ),
		.fop = {
			.fnameaddr = cpu_to_le32((uint32_t)name),
			.fnamelen = cpu_to_le32((uint32_t)sz_name),
			.dataaddr = cpu_to_le32((uint32_t)data),
			.datalen = cpu_to_le32((uint32_t)sz_data),
		},
	};
	struct mrq_debugfs_response resp;
	struct tegra_bpmp_message msg = {
		.mrq = MRQ_DEBUGFS,
		.tx = {
			.data = &req,
			.size = sizeof(req),
		},
		.rx = {
			.data = &resp,
			.size = sizeof(resp),
		},
	};
	int err;

	err = tegra_bpmp_transfer(bpmp, &msg);
	if (err < 0)
		return err;
	else if (msg.rx.ret < 0)
		return -EINVAL;

	*nbytes = (size_t)resp.fop.nbytes;

	return 0;
}

static int mrq_debugfs_write(struct tegra_bpmp *bpmp,
			     dma_addr_t name, size_t sz_name,
			     dma_addr_t data, size_t sz_data)
{
	const struct mrq_debugfs_request req = {
		.cmd = cpu_to_le32(CMD_DEBUGFS_WRITE),
		.fop = {
			.fnameaddr = cpu_to_le32((uint32_t)name),
			.fnamelen = cpu_to_le32((uint32_t)sz_name),
			.dataaddr = cpu_to_le32((uint32_t)data),
			.datalen = cpu_to_le32((uint32_t)sz_data),
		},
	};
	struct tegra_bpmp_message msg = {
		.mrq = MRQ_DEBUGFS,
		.tx = {
			.data = &req,
			.size = sizeof(req),
		},
	};

	return tegra_bpmp_transfer(bpmp, &msg);
}

static int mrq_debugfs_dumpdir(struct tegra_bpmp *bpmp, dma_addr_t addr,
			       size_t size, size_t *nbytes)
{
	const struct mrq_debugfs_request req = {
		.cmd = cpu_to_le32(CMD_DEBUGFS_DUMPDIR),
		.dumpdir = {
			.dataaddr = cpu_to_le32((uint32_t)addr),
			.datalen = cpu_to_le32((uint32_t)size),
		},
	};
	struct mrq_debugfs_response resp;
	struct tegra_bpmp_message msg = {
		.mrq = MRQ_DEBUGFS,
		.tx = {
			.data = &req,
			.size = sizeof(req),
		},
		.rx = {
			.data = &resp,
			.size = sizeof(resp),
		},
	};
	int err;

	err = tegra_bpmp_transfer(bpmp, &msg);
	if (err < 0)
		return err;
	else if (msg.rx.ret < 0)
		return -EINVAL;

	*nbytes = (size_t)resp.dumpdir.nbytes;

	return 0;
}

static int debugfs_show(struct seq_file *m, void *p)
{
	struct file *file = m->private;
	struct inode *inode = file_inode(file);
	struct tegra_bpmp *bpmp = inode->i_private;
	const size_t datasize = m->size;
	const size_t namesize = SZ_256;
	void *datavirt, *namevirt;
	dma_addr_t dataphys, namephys;
	char buf[256];
	const char *filename;
	size_t len, nbytes;
	int err;

	filename = get_filename(bpmp, file, buf, sizeof(buf));
	if (!filename)
		return -ENOENT;

	namevirt = dma_alloc_coherent(bpmp->dev, namesize, &namephys,
				      GFP_KERNEL | GFP_DMA32);
	if (!namevirt)
		return -ENOMEM;

	datavirt = dma_alloc_coherent(bpmp->dev, datasize, &dataphys,
				      GFP_KERNEL | GFP_DMA32);
	if (!datavirt) {
		err = -ENOMEM;
		goto free_namebuf;
	}

	len = strlen(filename);
	strncpy(namevirt, filename, namesize);

	err = mrq_debugfs_read(bpmp, namephys, len, dataphys, datasize,
			       &nbytes);

	if (!err)
		seq_write(m, datavirt, nbytes);

	dma_free_coherent(bpmp->dev, datasize, datavirt, dataphys);
free_namebuf:
	dma_free_coherent(bpmp->dev, namesize, namevirt, namephys);

	return err;
}

static int debugfs_open(struct inode *inode, struct file *file)
{
	return single_open_size(file, debugfs_show, file, SZ_128K);
}

static ssize_t debugfs_store(struct file *file, const char __user *buf,
		size_t count, loff_t *f_pos)
{
	struct inode *inode = file_inode(file);
	struct tegra_bpmp *bpmp = inode->i_private;
	const size_t datasize = count;
	const size_t namesize = SZ_256;
	void *datavirt, *namevirt;
	dma_addr_t dataphys, namephys;
	char fnamebuf[256];
	const char *filename;
	size_t len;
	int err;

	filename = get_filename(bpmp, file, fnamebuf, sizeof(fnamebuf));
	if (!filename)
		return -ENOENT;

	namevirt = dma_alloc_coherent(bpmp->dev, namesize, &namephys,
				      GFP_KERNEL | GFP_DMA32);
	if (!namevirt)
		return -ENOMEM;

	datavirt = dma_alloc_coherent(bpmp->dev, datasize, &dataphys,
				      GFP_KERNEL | GFP_DMA32);
	if (!datavirt) {
		err = -ENOMEM;
		goto free_namebuf;
	}

	len = strlen(filename);
	strncpy(namevirt, filename, namesize);

	if (copy_from_user(datavirt, buf, count)) {
		err = -EFAULT;
		goto free_databuf;
	}

	err = mrq_debugfs_write(bpmp, namephys, len, dataphys,
				count);

free_databuf:
	dma_free_coherent(bpmp->dev, datasize, datavirt, dataphys);
free_namebuf:
	dma_free_coherent(bpmp->dev, namesize, namevirt, namephys);

	return err ?: count;
}

static const struct file_operations debugfs_fops = {
	.open		= debugfs_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.write		= debugfs_store,
	.release	= single_release,
};

static int bpmp_populate_dir(struct tegra_bpmp *bpmp, struct seqbuf *seqbuf,
			     struct dentry *parent, uint32_t depth)
{
	int err;
	uint32_t d, t;
	const char *name;
	struct dentry *dentry;

	while (!seqbuf_eof(seqbuf)) {
		err = seqbuf_read_u32(seqbuf, &d);
		if (err < 0)
			return err;

		if (d < depth) {
			seqbuf_seek(seqbuf, -4);
			/* go up a level */
			return 0;
		} else if (d != depth) {
			/* malformed data received from BPMP */
			return -EIO;
		}

		err = seqbuf_read_u32(seqbuf, &t);
		if (err < 0)
			return err;
		err = seqbuf_read_str(seqbuf, &name);
		if (err < 0)
			return err;

		if (t & DEBUGFS_S_ISDIR) {
			dentry = debugfs_create_dir(name, parent);
			if (!dentry)
				return -ENOMEM;
			err = bpmp_populate_dir(bpmp, seqbuf, dentry, depth+1);
			if (err < 0)
				return err;
		} else {
			umode_t mode;

			mode = t & DEBUGFS_S_IRUSR ? S_IRUSR : 0;
			mode |= t & DEBUGFS_S_IWUSR ? S_IWUSR : 0;
			dentry = debugfs_create_file(name, mode,
						     parent, bpmp,
						     &debugfs_fops);
			if (!dentry)
				return -ENOMEM;
		}
	}

	return 0;
}

static int bpmp_populate_debugfs_shmem(struct tegra_bpmp *bpmp)
{
	struct seqbuf seqbuf;
	const size_t sz = SZ_512K;
	dma_addr_t phys;
	size_t nbytes;
	void *virt;
	int err;

	virt = dma_alloc_coherent(bpmp->dev, sz, &phys,
				  GFP_KERNEL | GFP_DMA32);
	if (!virt)
		return -ENOMEM;

	err = mrq_debugfs_dumpdir(bpmp, phys, sz, &nbytes);
	if (err < 0) {
		goto free;
	} else if (nbytes > sz) {
		err = -EINVAL;
		goto free;
	}

	seqbuf_init(&seqbuf, virt, nbytes);
	err = bpmp_populate_dir(bpmp, &seqbuf, bpmp->debugfs_mirror, 0);
free:
	dma_free_coherent(bpmp->dev, sz, virt, phys);

	return err;
}

int tegra_bpmp_init_debugfs(struct tegra_bpmp *bpmp)
{
	struct dentry *root;
	bool inband;
	int err;

	inband = tegra_bpmp_mrq_is_supported(bpmp, MRQ_DEBUG);

	if (!inband && !tegra_bpmp_mrq_is_supported(bpmp, MRQ_DEBUGFS))
		return 0;

	root = debugfs_create_dir("bpmp", NULL);
	if (!root)
		return -ENOMEM;

	bpmp->debugfs_mirror = debugfs_create_dir("debug", root);
	if (!bpmp->debugfs_mirror) {
		err = -ENOMEM;
		goto out;
	}

	if (inband)
		err = bpmp_populate_debugfs_inband(bpmp, bpmp->debugfs_mirror,
						   "/");
	else
		err = bpmp_populate_debugfs_shmem(bpmp);

out:
	if (err < 0)
		debugfs_remove_recursive(root);

	return err;
}