| Message ID | 20211216062405.415888-3-amitay@ozlabs.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Enable read timeout specification for sbefifo read | expand |
On Thu, Dec 16, 2021 at 05:24:05PM +1100, Amitay Isaacs wrote: > FSI_SBEFIFO_READ_TIMEOUT ioctl sets the read timeout (in seconds) for > the response received by sbefifo device from sbe. The timeout affects > only the read operation on 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. > > Signed-off-by: Amitay Isaacs <amitay@ozlabs.org> > --- > drivers/fsi/fsi-sbefifo.c | 44 +++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/fsi.h | 14 +++++++++++++ > 2 files changed, 58 insertions(+) Where is the userspace tool that uses this new ioctl? And again, why does it have to be an ioctl? Where is this now documented? What are the units of the value? greg k-h
Hi Greg, On Thu, 16 Dec 2021 at 08:04, Greg KH <gregkh@linuxfoundation.org> wrote: > > On Thu, Dec 16, 2021 at 05:24:05PM +1100, Amitay Isaacs wrote: > > FSI_SBEFIFO_READ_TIMEOUT ioctl sets the read timeout (in seconds) for > > the response received by sbefifo device from sbe. The timeout affects > > only the read operation on 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. > > > > Signed-off-by: Amitay Isaacs <amitay@ozlabs.org> > > --- > > drivers/fsi/fsi-sbefifo.c | 44 +++++++++++++++++++++++++++++++++++++++ > > include/uapi/linux/fsi.h | 14 +++++++++++++ > > 2 files changed, 58 insertions(+) I'm taking over this patch series on behalf of Amitay. > Where is the userspace tool that uses this new ioctl? The userspace is a library called 'libpdbg'. Amitay has some patches prepared that use this new ioctl here: https://github.com/amitay/pdbg/commits/ioctl > And again, why does it have to be an ioctl? Where is this now > documented? What are the units of the value? We need a way for userspace to tell the driver that subsequent operations (writes to the chardev, that cause the driver to send data to a microcontroller over a fsi link) are expected to take a longer time, so the kernel should wait longer before declaring the operation timed out. The kernel driver doesn't know about the specific operation, and we don't want to have that policy in the kernel, so userspace will set the timeout appropriately. I'll send a new version, as Amitay wants to remove the one-shot nature of the configuration, and instead have it persist. I'll update the patch to make it clear what the units are. Where do we usually stick documentation for ioctls such as this one? Cheers, Joel
diff --git a/drivers/fsi/fsi-sbefifo.c b/drivers/fsi/fsi-sbefifo.c index 1e9b326e8f67..771b1a44a61c 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 +934,50 @@ 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) +{ + u32 timeout; + + if (get_user(timeout, (__u32 __user *)argp)) + return -EFAULT; + + if (timeout == 0) { + user->read_timeout_ms = SBEFIFO_TIMEOUT_START_RSP; + return 0; + } + + 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; + int rc = -ENOTTY; + + if (!user) + return -EINVAL; + + mutex_lock(&user->file_lock); + switch (cmd) { + case FSI_SBEFIFO_READ_TIMEOUT: + 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) diff --git a/include/uapi/linux/fsi.h b/include/uapi/linux/fsi.h index da577ecd90e7..a4c886832df5 100644 --- a/include/uapi/linux/fsi.h +++ b/include/uapi/linux/fsi.h @@ -55,4 +55,18 @@ 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 + */ + +/** + * FSI_SBEFIFO_READ_TIMEOUT sets the read timeout for response from SBE. + * + * The read timeout is specified in seconds. The minimum value of read + * timeout is 10 seconds (default) and the maximum value of read timeout is + * 120 seconds. A read timeout of 0 will reset the value to the default of + * (10 seconds). + */ +#define FSI_SBEFIFO_READ_TIMEOUT _IOW('s', 0x00, __u32) + #endif /* _UAPI_LINUX_FSI_H */
FSI_SBEFIFO_READ_TIMEOUT ioctl sets the read timeout (in seconds) for the response received by sbefifo device from sbe. The timeout affects only the read operation on 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. Signed-off-by: Amitay Isaacs <amitay@ozlabs.org> --- drivers/fsi/fsi-sbefifo.c | 44 +++++++++++++++++++++++++++++++++++++++ include/uapi/linux/fsi.h | 14 +++++++++++++ 2 files changed, 58 insertions(+)