drivers/firmware/tegra/bpmp-debugfs.c - linux - Git at Google

 /*
  * Copyright (c) 2017, 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/debugfs.h>
 #include <linux/dma-mapping.h>
 #include <linux/uaccess.h>

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

 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)
 {
 	char root_path_buf[512];
 	const char *root_path;
 	const char *filename;
 	size_t root_len;

 	root_path = dentry_path(bpmp->debugfs_mirror, root_path_buf,
 				sizeof(root_path_buf));
 	if (IS_ERR(root_path))
 		return NULL;

 	root_len = strlen(root_path);

 	filename = dentry_path(file->f_path.dentry, buf, size);
 	if (IS_ERR(filename))
 		return NULL;

 	if (strlen(filename) < root_len ||
 			strncmp(filename, root_path, root_len))
 		return NULL;

 	filename += root_len;

 	return filename;
 }

 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;

 	*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;

 	*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 ret;

 	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) {
 		ret = -ENOMEM;
 		goto free_namebuf;
 	}

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

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

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

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

 	return ret;
 }

 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 ret;

 	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) {
 		ret = -ENOMEM;
 		goto free_namebuf;
 	}

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

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

 	ret = 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 ret ?: 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 create_debugfs_mirror(struct tegra_bpmp *bpmp, void *buf,
 				 size_t bufsize, struct dentry *root)
 {
 	struct seqbuf seqbuf;
 	int err;

 	bpmp->debugfs_mirror = debugfs_create_dir("debug", root);
 	if (!bpmp->debugfs_mirror)
 		return -ENOMEM;

 	seqbuf_init(&seqbuf, buf, bufsize);
 	err = bpmp_populate_dir(bpmp, &seqbuf, bpmp->debugfs_mirror, 0);
 	if (err < 0) {
 		debugfs_remove_recursive(bpmp->debugfs_mirror);
 		bpmp->debugfs_mirror = NULL;
 	}

 	return err;
 }

 static int mrq_is_supported(struct tegra_bpmp *bpmp, unsigned int mrq)
 {
 	struct mrq_query_abi_request req = { .mrq = cpu_to_le32(mrq) };
 	struct mrq_query_abi_response resp;
 	struct tegra_bpmp_message msg = {
 		.mrq = MRQ_QUERY_ABI,
 		.tx = {
 			.data = &req,
 			.size = sizeof(req),
 		},
 		.rx = {
 			.data = &resp,
 			.size = sizeof(resp),
 		},
 	};
 	int ret;

 	ret = tegra_bpmp_transfer(bpmp, &msg);
 	if (ret < 0) {
 		/* something went wrong; assume not supported */
 		dev_warn(bpmp->dev, "tegra_bpmp_transfer failed (%d)\n", ret);
 		return 0;
 	}

 	return resp.status ? 0 : 1;
 }

 int tegra_bpmp_init_debugfs(struct tegra_bpmp *bpmp)
 {
 	dma_addr_t phys;
 	void *virt;
 	const size_t sz = SZ_256K;
 	size_t nbytes;
 	int ret;
 	struct dentry *root;

 	if (!mrq_is_supported(bpmp, MRQ_DEBUGFS))
 		return 0;

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

 	virt = dma_alloc_coherent(bpmp->dev, sz, &phys,
 				  GFP_KERNEL | GFP_DMA32);
 	if (!virt) {
 		ret = -ENOMEM;
 		goto out;
 	}

 	ret = mrq_debugfs_dumpdir(bpmp, phys, sz, &nbytes);
 	if (ret < 0)
 		goto free;

 	ret = create_debugfs_mirror(bpmp, virt, nbytes, root);
 free:
 	dma_free_coherent(bpmp->dev, sz, virt, phys);
 out:
 	if (ret < 0)
 		debugfs_remove(root);

 	return ret;
 }
	/*
	* Copyright (c) 2017, 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/debugfs.h>
	#include <linux/dma-mapping.h>
	#include <linux/uaccess.h>

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

	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)
	{
	char root_path_buf[512];
	const char *root_path;
	const char *filename;
	size_t root_len;

	root_path = dentry_path(bpmp->debugfs_mirror, root_path_buf,
	sizeof(root_path_buf));
	if (IS_ERR(root_path))
	return NULL;

	root_len = strlen(root_path);

	filename = dentry_path(file->f_path.dentry, buf, size);
	if (IS_ERR(filename))
	return NULL;

	if (strlen(filename) < root_len \|\|
	strncmp(filename, root_path, root_len))
	return NULL;

	filename += root_len;

	return filename;
	}

	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;

	*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;

	*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 ret;

	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) {
	ret = -ENOMEM;
	goto free_namebuf;
	}

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

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

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

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

	return ret;
	}

	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 ret;

	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) {
	ret = -ENOMEM;
	goto free_namebuf;
	}

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

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

	ret = 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 ret ?: 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 create_debugfs_mirror(struct tegra_bpmp bpmp, void buf,
	size_t bufsize, struct dentry *root)
	{
	struct seqbuf seqbuf;
	int err;

	bpmp->debugfs_mirror = debugfs_create_dir("debug", root);
	if (!bpmp->debugfs_mirror)
	return -ENOMEM;

	seqbuf_init(&seqbuf, buf, bufsize);
	err = bpmp_populate_dir(bpmp, &seqbuf, bpmp->debugfs_mirror, 0);
	if (err < 0) {
	debugfs_remove_recursive(bpmp->debugfs_mirror);
	bpmp->debugfs_mirror = NULL;
	}

	return err;
	}

	static int mrq_is_supported(struct tegra_bpmp *bpmp, unsigned int mrq)
	{
	struct mrq_query_abi_request req = { .mrq = cpu_to_le32(mrq) };
	struct mrq_query_abi_response resp;
	struct tegra_bpmp_message msg = {
	.mrq = MRQ_QUERY_ABI,
	.tx = {
	.data = &req,
	.size = sizeof(req),
	},
	.rx = {
	.data = &resp,
	.size = sizeof(resp),
	},
	};
	int ret;

	ret = tegra_bpmp_transfer(bpmp, &msg);
	if (ret < 0) {
	/* something went wrong; assume not supported */
	dev_warn(bpmp->dev, "tegra_bpmp_transfer failed (%d)\n", ret);
	return 0;
	}

	return resp.status ? 0 : 1;
	}

	int tegra_bpmp_init_debugfs(struct tegra_bpmp *bpmp)
	{
	dma_addr_t phys;
	void *virt;
	const size_t sz = SZ_256K;
	size_t nbytes;
	int ret;
	struct dentry *root;

	if (!mrq_is_supported(bpmp, MRQ_DEBUGFS))
	return 0;

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

	virt = dma_alloc_coherent(bpmp->dev, sz, &phys,
	GFP_KERNEL \| GFP_DMA32);
	if (!virt) {
	ret = -ENOMEM;
	goto out;
	}

	ret = mrq_debugfs_dumpdir(bpmp, phys, sz, &nbytes);
	if (ret < 0)
	goto free;

	ret = create_debugfs_mirror(bpmp, virt, nbytes, root);
	free:
	dma_free_coherent(bpmp->dev, sz, virt, phys);
	out:
	if (ret < 0)
	debugfs_remove(root);

	return ret;
	}