fsi: sbefifo: Implement FSI_SBEFIFO_READ_TIMEOUT_SECONDS ioctl

FSI_SBEFIFO_READ_TIMEOUT_SECONDS ioctl sets the read timeout (in
seconds) for the response received by sbefifo device from sbe.  The
timeout affects only the read operation on current sbefifo device fd.

Certain SBE operations can take long time to complete and the default
timeout of 10 seconds might not be sufficient to start receiving
response from SBE.  In such cases, allow the timeout to be set to the
maximum of 120 seconds.

The kernel does not contain the definition of the various SBE
operations, so we must expose an interface to userspace to set the
timeout for the given operation.

Signed-off-by: Amitay Isaacs <amitay@ozlabs.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20220121053816.82253-3-joel@jms.id.au
Signed-off-by: Joel Stanley <joel@jms.id.au>

1 files changed, 49 insertions, 0 deletions

diff --git a/drivers/fsi/fsi-sbefifo.c b/drivers/fsi/fsi-sbefifo.c
index 1e9b326e8f67..f52a912cdf16 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;
+	u32			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 +842,9 @@ 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);
+	sbefifo->timeout_start_rsp_ms = SBEFIFO_TIMEOUT_START_RSP;
 	mutex_unlock(&sbefifo->lock);
 	if (rc < 0)
 		goto bail;
@@ -928,12 +934,55 @@ 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)
+{
+	struct device *dev = &user->sbefifo->dev;
+	u32 timeout;
+
+	if (get_user(timeout, (__u32 __user *)argp))
+		return -EFAULT;
+
+	if (timeout == 0) {
+		user->read_timeout_ms = SBEFIFO_TIMEOUT_START_RSP;
+		dev_dbg(dev, "Timeout reset to %d\n", user->read_timeout_ms);
+		return 0;
+	}
+
+	if (timeout < 10 || timeout > 120)
+		return -EINVAL;
+
+	user->read_timeout_ms = timeout * 1000; /* user timeout is in sec */
+
+	dev_dbg(dev, "Timeout set to %d\n", user->read_timeout_ms);
+
+	return 0;
+}
+
+static long sbefifo_user_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct sbefifo_user *user = file->private_data;
+	int rc = -ENOTTY;
+
+	if (!user)
+		return -EINVAL;
+
+	mutex_lock(&user->file_lock);
+	switch (cmd) {
+	case FSI_SBEFIFO_READ_TIMEOUT_SECONDS:
+		rc = sbefifo_read_timeout(user, (void __user *)arg);
+		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)