Re: [PATCH v2 1/3] bcm-vk: add bcm_vk UAPI

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Aug 18, 2020 at 10:23:42AM -0700, Scott Branden wrote:
> Hi Greg,
> 
> On 2020-08-18 6:53 a.m., Greg Kroah-Hartman wrote:
> > On Wed, Aug 05, 2020 at 05:46:29PM -0700, Scott Branden wrote:
> >> Add user space api for bcm-vk driver.
> >>
> >> Signed-off-by: Scott Branden <scott.branden@broadcom.com>
> >> ---
> >>  include/uapi/linux/misc/bcm_vk.h | 99 ++++++++++++++++++++++++++++++++
> >>  1 file changed, 99 insertions(+)
> >>  create mode 100644 include/uapi/linux/misc/bcm_vk.h
> >>
> >> diff --git a/include/uapi/linux/misc/bcm_vk.h b/include/uapi/linux/misc/bcm_vk.h
> >> new file mode 100644
> >> index 000000000000..783087b7c31f
> >> --- /dev/null
> >> +++ b/include/uapi/linux/misc/bcm_vk.h
> >> @@ -0,0 +1,99 @@
> >> +/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) */
> >> +/*
> >> + * Copyright 2018-2020 Broadcom.
> >> + */
> >> +
> >> +#ifndef __UAPI_LINUX_MISC_BCM_VK_H
> >> +#define __UAPI_LINUX_MISC_BCM_VK_H
> >> +
> >> +#include <linux/ioctl.h>
> >> +#include <linux/types.h>
> >> +
> >> +#define BCM_VK_MAX_FILENAME 64
> >> +
> >> +struct vk_image {
> >> +	__u32 type; /* Type of image */
> >> +#define VK_IMAGE_TYPE_BOOT1 1 /* 1st stage (load to SRAM) */
> >> +#define VK_IMAGE_TYPE_BOOT2 2 /* 2nd stage (load to DDR) */
> >> +	char filename[BCM_VK_MAX_FILENAME]; /* Filename of image */
> >> +};
> >> +
> >> +struct vk_reset {
> >> +	__u32 arg1;
> >> +	__u32 arg2;
> >> +};
> >> +
> >> +#define VK_MAGIC		0x5e
> >> +
> >> +/* Load image to Valkyrie */
> >> +#define VK_IOCTL_LOAD_IMAGE	_IOW(VK_MAGIC, 0x2, struct vk_image)
> >> +
> >> +/* Send Reset to Valkyrie */
> >> +#define VK_IOCTL_RESET		_IOW(VK_MAGIC, 0x4, struct vk_reset)
> >> +
> >> +/*
> >> + * message block - basic unit in the message where a message's size is always
> >> + *		   N x sizeof(basic_block)
> >> + */
> >> +struct vk_msg_blk {
> >> +	__u8 function_id;
> >> +#define VK_FID_TRANS_BUF	5
> >> +#define VK_FID_SHUTDOWN		8
> >> +	__u8 size;
> >> +	__u16 trans_id; /* transport id, queue & msg_id */
> >> +	__u32 context_id;
> >> +	__u32 args[2];
> >> +#define VK_CMD_PLANES_MASK	0x000f /* number of planes to up/download */
> >> +#define VK_CMD_UPLOAD		0x0400 /* memory transfer to vk */
> >> +#define VK_CMD_DOWNLOAD		0x0500 /* memory transfer from vk */
> >> +#define VK_CMD_MASK		0x0f00 /* command mask */
> >> +};
> >> +
> >> +#define VK_BAR_FWSTS			0x41c
> >> +#define VK_BAR_COP_FWSTS		0x428
> >> +/* VK_FWSTS definitions */
> >> +#define VK_FWSTS_RELOCATION_ENTRY	BIT(0)
> > <snip>
> >
> > I thought BIT() was not allowed in uapi .h files, this really works
> > properly???
> I did some investigation and it looks like a few other header files in include/uapi also use the BIT() macro:
> include/uapi/misc/uacce/uacce.h
> include/uapi/linux/psci.h
> include/uapi/linux/v4l2-subdev.h

Does the header install test target now fail for these?

> tools/include/uapi/linux/pkt_sched.h

That doesn't count :)

> It does look like we end up defining the BIT() macro in our user space app that includes the header file.
> 
> So, what is the proper thing to be done?
> 1) Move the BIT() macro somewhere in include/uapi and include it in the necessary header files
> 2) Use the _BITUL macro in include/uapi/linux/const.h instead?
> 3) something else?

open-code it for now please, that's the best way as I am pretty sure we
can not contaminate the global C namespace with out BIT() macro, no
matter how much we would like to...

thanks,

greg k-h