linux-kernel - [PATCH 2/2] fsi: sbefifo: implement FSI_SBEFIFO_READ

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Message-Id: <20211215005833.222841-2-amitay@ozlabs.org>
Date:   Wed, 15 Dec 2021 11:58:33 +1100
From:   Amitay Isaacs <amitay@...abs.org>
To:     linux-kernel@...r.kernel.org, linux-fsi@...ts.ozlabs.org,
        jk@...abs.org, joel@....id.au, alistair@...ple.id.au,
        eajames@...ux.ibm.com
Cc:     Amitay Isaacs <amitay@...abs.org>
Subject: [PATCH 2/2] fsi: sbefifo: implement FSI_SBEFIFO_READ_TIMEOUT ioctl

FSI_SBEFIFO_READ_TIMEOUT ioctl sets the read timeout (in seconds) for
the response to *the next* chip-op sent to sbe.  The timeout value is
reset to default after the chip-op.  The timeout affects only the read()
operation on sbefifo device fd.

Signed-off-by: Amitay Isaacs <amitay@...abs.org>
---
 drivers/fsi/fsi-sbefifo.c | 42 +++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/fsi.h  |  6 ++++++
 2 files changed, 48 insertions(+)

diff --git a/drivers/fsi/fsi-sbefifo.c b/drivers/fsi/fsi-sbefifo.c
index 9188161f440c..b2654b143b85 100644
--- a/drivers/fsi/fsi-sbefifo.c
+++ b/drivers/fsi/fsi-sbefifo.c
@@ -32,6 +32,8 @@
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
 
+#include <uapi/linux/fsi.h>
+
 /*
  * The SBEFIFO is a pipe-like FSI device for communicating with
  * the self boot engine on POWER processors.
@@ -134,6 +136,7 @@ struct sbefifo_user {
 	void			*cmd_page;
 	void			*pending_cmd;
 	size_t			pending_len;
+	uint32_t		read_timeout_ms;
 };
 
 static DEFINE_MUTEX(sbefifo_ffdc_mutex);
@@ -796,6 +799,7 @@ static int sbefifo_user_open(struct inode *inode, struct file *file)
 		return -ENOMEM;
 	}
 	mutex_init(&user->file_lock);
+	user->read_timeout_ms = SBEFIFO_TIMEOUT_START_RSP;
 
 	return 0;
 }
@@ -838,7 +842,11 @@ static ssize_t sbefifo_user_read(struct file *file, char __user *buf,
 	rc = mutex_lock_interruptible(&sbefifo->lock);
 	if (rc)
 		goto bail;
+	sbefifo->timeout_start_rsp_ms = user->read_timeout_ms;
 	rc = __sbefifo_submit(sbefifo, user->pending_cmd, cmd_len, &resp_iter);
+	/* Reset the read timeout after a single chip-op */
+	sbefifo->timeout_start_rsp_ms = SBEFIFO_TIMEOUT_START_RSP;
+	user->read_timeout_ms = SBEFIFO_TIMEOUT_START_RSP;
 	mutex_unlock(&sbefifo->lock);
 	if (rc < 0)
 		goto bail;
@@ -847,6 +855,7 @@ static ssize_t sbefifo_user_read(struct file *file, char __user *buf,
 	rc = len - iov_iter_count(&resp_iter);
  bail:
 	sbefifo_release_command(user);
+	user->read_timeout_ms = 0;
 	mutex_unlock(&user->file_lock);
 	return rc;
 }
@@ -928,12 +937,45 @@ static int sbefifo_user_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static int sbefifo_read_timeout(struct sbefifo_user *user, void __user **argp)
+{
+	uint32_t timeout;
+
+	if (get_user(timeout, (__u32 __user *)argp))
+		return -EFAULT;
+	if (timeout < 10 || timeout > 120)
+		return -EINVAL;
+
+	user->read_timeout_ms = timeout * 1000; /* user timeout is in sec */
+	return 0;
+}
+
+static long sbefifo_user_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct sbefifo_user *user = file->private_data;
+	void __user **argp = (void __user *)arg;
+	int rc = -ENOTTY;
+
+	if (!user)
+		return -EINVAL;
+
+	mutex_lock(&user->file_lock);
+	switch (cmd) {
+	case FSI_SBEFIFO_READ_TIMEOUT:
+		rc = sbefifo_read_timeout(user, argp);
+		break;
+	}
+	mutex_unlock(&user->file_lock);
+	return rc;
+}
+
 static const struct file_operations sbefifo_fops = {
 	.owner		= THIS_MODULE,
 	.open		= sbefifo_user_open,
 	.read		= sbefifo_user_read,
 	.write		= sbefifo_user_write,
 	.release	= sbefifo_user_release,
+	.unlocked_ioctl = sbefifo_user_ioctl,
 };
 
 static void sbefifo_free(struct device *dev)
diff --git a/include/uapi/linux/fsi.h b/include/uapi/linux/fsi.h
index da577ecd90e7..3e00874ace22 100644
--- a/include/uapi/linux/fsi.h
+++ b/include/uapi/linux/fsi.h
@@ -55,4 +55,10 @@ struct scom_access {
 #define FSI_SCOM_WRITE	_IOWR('s', 0x02, struct scom_access)
 #define FSI_SCOM_RESET	_IOW('s', 0x03, __u32)
 
+/*
+ * /dev/sbefifo* ioctl interface
+ */
+
+#define FSI_SBEFIFO_READ_TIMEOUT	_IOW('s', 0x00, __u32)
+
 #endif /* _UAPI_LINUX_FSI_H */
-- 
2.33.1