linux-kernel - [PATCH] firmware: tegra: stop using seq_get

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Message-Id: <20210810155439.1813109-1-hch@lst.de>
Date:   Tue, 10 Aug 2021 17:54:39 +0200
From:   Christoph Hellwig <hch@....de>
To:     thierry.reding@...il.com, jonathanh@...dia.com
Cc:     linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] firmware: tegra: stop using seq_get_buf

Opencode a copy of mrq_debug_read in bpmp_debug_show so that it
can use seq_write directly instead of poking holes into the seq_file
abstractions using seq_get_buf.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 drivers/firmware/tegra/bpmp-debugfs.c | 58 ++++++++++++++++++++++-----
 1 file changed, 47 insertions(+), 11 deletions(-)

diff --git a/drivers/firmware/tegra/bpmp-debugfs.c b/drivers/firmware/tegra/bpmp-debugfs.c
index 440d99c63638..3e9fa4b54358 100644
--- a/drivers/firmware/tegra/bpmp-debugfs.c
+++ b/drivers/firmware/tegra/bpmp-debugfs.c
@@ -296,25 +296,61 @@ 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 *databuf = NULL;
 	char fnamebuf[256];
 	const char *filename;
-	uint32_t nbytes = 0;
-	size_t len;
-	int err;
-
-	len = seq_get_buf(m, &databuf);
-	if (!databuf)
-		return -ENOMEM;
+	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;
 
-	err = mrq_debug_read(bpmp, filename, databuf, len, &nbytes);
-	if (!err)
-		seq_commit(m, nbytes);
+	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;
 }
 
-- 
2.30.2