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Message-Id: <5003354d-75e1-3ef3-a641-28a128677783@linux.vnet.ibm.com>
Date: Thu, 14 Jun 2018 09:12:25 -0500
From: Eddie James <eajames@...ux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
openbmc@...ts.ozlabs.org
Cc: Andrew Jeffery <andrew@...id.au>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 5/5] fsi/scom: Major overhaul
On 06/13/2018 06:00 PM, Benjamin Herrenschmidt wrote:
> 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@...nel.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.
Cool, thanks.
Reviewed-by: Eddie James <eajames@...ux.vnet.ibm.com>
>
>> 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 */
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