Re: [RFC PATCH 5/5] fsi/scom: Major overhaul

[Joel Stanley]

On 12 June 2018 at 14:49, Benjamin Herrenschmidt
<benh@xxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxx>

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.

> +++ 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 */


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
>