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fwctl: FWCTL_INFO to return basic information about the device

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Userspace will need to know some details about the fwctl interface being
used to locate the correct userspace code to communicate with the
kernel. Provide a simple device_type enum indicating what the kernel
driver is.

Allow the device to provide a device specific info struct that contains
any additional information that the driver may need to provide to
userspace.

Link: https://patch.msgid.link/r/3-v5-642aa0c94070+4447f-fwctl_jgg@nvidia.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Tested-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Jason Gunthorpe
2025-02-27 20:26:31 -04:00
parent 0e79a47fb1
commit fb39e9092b
3 changed files with 98 additions and 0 deletions
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55
drivers/fwctl/main.c
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@@ -27,8 +27,62 @@ struct fwctl_ucmd {
u32 user_size;
};
static int ucmd_respond(struct fwctl_ucmd *ucmd, size_t cmd_len)
{
if (copy_to_user(ucmd->ubuffer, ucmd->cmd,
min_t(size_t, ucmd->user_size, cmd_len)))
return -EFAULT;
return 0;
}
static int copy_to_user_zero_pad(void __user *to, const void *from,
size_t from_len, size_t user_len)
{
size_t copy_len;
copy_len = min(from_len, user_len);
if (copy_to_user(to, from, copy_len))
return -EFAULT;
if (copy_len < user_len) {
if (clear_user(to + copy_len, user_len - copy_len))
return -EFAULT;
}
return 0;
}
static int fwctl_cmd_info(struct fwctl_ucmd *ucmd)
{
struct fwctl_device *fwctl = ucmd->uctx->fwctl;
struct fwctl_info *cmd = ucmd->cmd;
size_t driver_info_len = 0;
if (cmd->flags)
return -EOPNOTSUPP;
if (!fwctl->ops->info && cmd->device_data_len) {
if (clear_user(u64_to_user_ptr(cmd->out_device_data),
cmd->device_data_len))
return -EFAULT;
} else if (cmd->device_data_len) {
void *driver_info __free(kfree) =
fwctl->ops->info(ucmd->uctx, &driver_info_len);
if (IS_ERR(driver_info))
return PTR_ERR(driver_info);
if (copy_to_user_zero_pad(u64_to_user_ptr(cmd->out_device_data),
driver_info, driver_info_len,
cmd->device_data_len))
return -EFAULT;
}
cmd->out_device_type = fwctl->ops->device_type;
cmd->device_data_len = driver_info_len;
return ucmd_respond(ucmd, sizeof(*cmd));
}
/* On stack memory for the ioctl structs */
union fwctl_ucmd_buffer {
struct fwctl_info info;
};
struct fwctl_ioctl_op {
@@ -48,6 +102,7 @@ struct fwctl_ioctl_op {
.execute = _fn, \
}
static const struct fwctl_ioctl_op fwctl_ioctl_ops[] = {
IOCTL_OP(FWCTL_INFO, fwctl_cmd_info, struct fwctl_info, out_device_data),
};
static long fwctl_fops_ioctl(struct file *filp, unsigned int cmd,