lkml.org 
[lkml]   [2018]   [Jun]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC PATCH 5/5] fsi/scom: Major overhaul
From
Date
On Wed, 2018-06-13 at 09:57 -0500, Eddie James wrote:
>
> On 06/12/2018 12:19 AM, Benjamin Herrenschmidt 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>
> > ---
> > drivers/fsi/fsi-scom.c | 424 ++++++++++++++++++++++++++++++++++++---
> > include/uapi/linux/fsi.h | 56 ++++++
> > 2 files changed, 450 insertions(+), 30 deletions(-)
> > create mode 100644 include/uapi/linux/fsi.h
> >
> > diff --git a/drivers/fsi/fsi-scom.c b/drivers/fsi/fsi-scom.c
> > index e98573ecdae1..39c74351f1bf 100644
> > --- a/drivers/fsi/fsi-scom.c
> > +++ b/drivers/fsi/fsi-scom.c
> > @@ -24,6 +24,8 @@
> > #include <linux/list.h>
> > #include <linux/idr.h>
> > +
> > +static int scom_reset(struct scom_device *scom, void __user *argp)
> > +{
> > + uint32_t flags, dummy = -1;
> > + int rc = 0;
> > +
> > + if (get_user(flags, (__u32 __user *)argp))
> > + return -EFAULT;
> > + if (flags & SCOM_RESET_PIB)
> > + rc = fsi_device_write(scom->fsi_dev, SCOM_PIB_RESET_REG, &dummy,
> > + sizeof(uint32_t));
>
> I realize this is a user requested flag but I believe the BMC is never
> supposed to issue this type of reset, due to the possibility of breaking
> stuff on the host side. Not sure if it should even be available?

It's for use by cronus or similar low level system debuggers.

Cheers,
Ben.

> Otherwise, looks good!
> Thanks,
> Eddie
>
> > + if (!rc && (flags & (SCOM_RESET_PIB | SCOM_RESET_INTF)))
> > + rc = fsi_device_write(scom->fsi_dev, SCOM_FSI2PIB_RESET_REG, &dummy,
> > + sizeof(uint32_t));
> > + return rc;
> > +}
> > +
> > +static int scom_check(struct scom_device *scom, void __user *argp)
> > +{
> > + /* Still need to find out how to get "protected" */
> > + return put_user(SCOM_CHECK_SUPPORTED, (__u32 __user *)argp);
> > +}
> > +
> > +static long scom_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> > +{
> > + struct miscdevice *mdev = file->private_data;
> > + struct scom_device *scom = to_scom_dev(mdev);
> > + void __user *argp = (void __user *)arg;
> > + int rc = -ENOTTY;
> > +
> > + mutex_lock(&scom->lock);
> > + switch(cmd) {
> > + case FSI_SCOM_CHECK:
> > + rc = scom_check(scom, argp);
> > + break;
> > + case FSI_SCOM_READ:
> > + rc = scom_raw_read(scom, argp);
> > + break;
> > + case FSI_SCOM_WRITE:
> > + rc = scom_raw_write(scom, argp);
> > + break;
> > + case FSI_SCOM_RESET:
> > + rc = scom_reset(scom, argp);
> > + break;
> > + }
> > + mutex_unlock(&scom->lock);
> > + return rc;
> > +}
> > +
> > static const struct file_operations scom_fops = {
> > - .owner = THIS_MODULE,
> > - .llseek = scom_llseek,
> > - .read = scom_read,
> > - .write = scom_write,
> > + .owner = THIS_MODULE,
> > + .llseek = scom_llseek,
> > + .read = scom_read,
> > + .write = scom_write,
> > + .unlocked_ioctl = scom_ioctl,
> > };
> >
> > static int scom_probe(struct device *dev)
> > diff --git a/include/uapi/linux/fsi.h b/include/uapi/linux/fsi.h
> > new file mode 100644
> > index 000000000000..6008d93f2e48
> > --- /dev/null
> > +++ b/include/uapi/linux/fsi.h
> > @@ -0,0 +1,56 @@
> > +#ifndef _UAPI_LINUX_FSI_H
> > +#define _UAPI_LINUX_FSI_H
> > +
> > +#include <linux/ioctl.h>
> > +
> > +/*
> > + * /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 */

\
 
 \ /
  Last update: 2018-06-14 01:01    [W:0.035 / U:1.808 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site