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SubjectRe: [RFC PATCH 5/5] fsi/scom: Major overhaul
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On Sat, 2018-06-16 at 14:34 +0930, Joel Stanley wrote:
> On 12 June 2018 at 14:49, Benjamin Herrenschmidt
> <benh@kernel.crashing.org> wrote:
> > This was too hard to split ... this adds a number of features
> > to the SCOM user interface:
> >
> > - Support for indirect SCOMs
> >
> > - read()/write() interface now handle errors and retries
> >
> > - New ioctl() "raw" interface for use by debuggers
> >
> > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>
> Looks okay to me. I will put it in the openbmc tree with Eddie's ack
> for more testing.
>
> I got a warning from the 0day infra, I made comments below.
>
> We should get Alistair review the ioctl interface to ensure we have
> everything that pdbg might need.

We have everything that cronus needs and more than pdbg needs afaik :-)

That said, cronus does a bunch of other stupid things that I'm still
trying to figure out how to fix.

We might need to create a /dev/cfam rather than going through that
magic sysfs "raw" file, and I wouldn't mind using a single IDA so that
all the devices below a given FSI slace (cfam itself, sbefifo, occ,
...) have the same "number".

>
> > +++ b/include/uapi/linux/fsi.h
> > @@ -0,0 +1,56 @@
> > +#ifndef _UAPI_LINUX_FSI_H
> > +#define _UAPI_LINUX_FSI_H
> > +
> > +#include <linux/ioctl.h>
>
> This needs to include <linux/types.h> for the __u64 etc types.
>
> We should also put a licence in the header. Probably:
>
> /* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */

Yup.

Cheers,
Ben.

>
> Cheers,
>
> Joel
>
> > +
> > +/*
> > + * /dev/scom "raw" ioctl interface
> > + *
> > + * The driver supports a high level "read/write" interface which
> > + * handles retries and converts the status to Linux error codes,
> > + * however low level tools an debugger need to access the "raw"
> > + * HW status information and interpret it themselves, so this
> > + * ioctl interface is also provided for their use case.
> > + */
> > +
> > +/* Structure for SCOM read/write */
> > +struct scom_access {
> > + __u64 addr; /* SCOM address, supports indirect */
> > + __u64 data; /* SCOM data (in for write, out for read) */
> > + __u64 mask; /* Data mask for writes */
> > + __u32 intf_errors; /* Interface error flags */
> > +#define SCOM_INTF_ERR_PARITY 0x00000001 /* Parity error */
> > +#define SCOM_INTF_ERR_PROTECTION 0x00000002 /* Blocked by secure boot */
> > +#define SCOM_INTF_ERR_ABORT 0x00000004 /* PIB reset during access */
> > +#define SCOM_INTF_ERR_UNKNOWN 0x80000000 /* Unknown error */
> > + /*
> > + * Note: Any other bit set in intf_errors need to be considered as an
> > + * error. Future implementations may define new error conditions. The
> > + * pib_status below is only valid if intf_errors is 0.
> > + */
> > + __u8 pib_status; /* 3-bit PIB status */
> > +#define SCOM_PIB_SUCCESS 0 /* Access successful */
> > +#define SCOM_PIB_BLOCKED 1 /* PIB blocked, pls retry */
> > +#define SCOM_PIB_OFFLINE 2 /* Chiplet offline */
> > +#define SCOM_PIB_PARTIAL 3 /* Partial good */
> > +#define SCOM_PIB_BAD_ADDR 4 /* Invalid address */
> > +#define SCOM_PIB_CLK_ERR 5 /* Clock error */
> > +#define SCOM_PIB_PARITY_ERR 6 /* Parity error on the PIB bus */
> > +#define SCOM_PIB_TIMEOUT 7 /* Bus timeout */
> > + __u8 pad;
> > +};
> > +
> > +/* Flags for SCOM check */
> > +#define SCOM_CHECK_SUPPORTED 0x00000001 /* Interface supported */
> > +#define SCOM_CHECK_PROTECTED 0x00000002 /* Interface blocked by secure boot */
> > +
> > +/* Flags for SCOM reset */
> > +#define SCOM_RESET_INTF 0x00000001 /* Reset interface */
> > +#define SCOM_RESET_PIB 0x00000002 /* Reset PIB */
> > +
> > +#define FSI_SCOM_CHECK _IOR('s', 0x00, __u32)
> > +#define FSI_SCOM_READ _IOWR('s', 0x01, struct scom_access)
> > +#define FSI_SCOM_WRITE _IOWR('s', 0x02, struct scom_access)
> > +#define FSI_SCOM_RESET _IOW('s', 0x03, __u32)
> > +
> > +#endif /* _UAPI_LINUX_FSI_H */
> > --
> > 2.17.0
> >

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