[PATCH v4 4/4] hwmon: (occ) Provide the SBEFIFO FFDC in binary sysfs

[Guenter Roeck]

On 10/21/21 4:09 PM, Joel Stanley wrote:
> On Tue, 19 Oct 2021 at 20:53, Eddie James <eajames at linux.ibm.com> wrote:
>>
>> Save any FFDC provided by the OCC driver, and provide it to userspace
>> through a binary sysfs entry. Notify userspace pollers when there is an
>> error too.
>>
>> Signed-off-by: Eddie James <eajames at linux.ibm.com>
>> Reviewed-by: Guenter Roeck <linux at roeck-us.net>
> 
> Guenter, I will merge this through the fsi tree unless you have objections.
> 

Go ahead.

Guenter

> Cheers,
> 
> Joel
> 
>> ---
>>   drivers/hwmon/occ/p9_sbe.c | 86 +++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 85 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/hwmon/occ/p9_sbe.c b/drivers/hwmon/occ/p9_sbe.c
>> index 9709f2b9c052..e50243580269 100644
>> --- a/drivers/hwmon/occ/p9_sbe.c
>> +++ b/drivers/hwmon/occ/p9_sbe.c
>> @@ -4,18 +4,79 @@
>>   #include <linux/device.h>
>>   #include <linux/errno.h>
>>   #include <linux/fsi-occ.h>
>> +#include <linux/mm.h>
>>   #include <linux/module.h>
>> +#include <linux/mutex.h>
>>   #include <linux/platform_device.h>
>> +#include <linux/string.h>
>> +#include <linux/sysfs.h>
>>
>>   #include "common.h"
>>
>>   struct p9_sbe_occ {
>>          struct occ occ;
>> +       bool sbe_error;
>> +       void *ffdc;
>> +       size_t ffdc_len;
>> +       size_t ffdc_size;
>> +       struct mutex sbe_error_lock;    /* lock access to ffdc data */
>>          struct device *sbe;
>>   };
>>
>>   #define to_p9_sbe_occ(x)       container_of((x), struct p9_sbe_occ, occ)
>>
>> +static ssize_t ffdc_read(struct file *filp, struct kobject *kobj,
>> +                        struct bin_attribute *battr, char *buf, loff_t pos,
>> +                        size_t count)
>> +{
>> +       ssize_t rc = 0;
>> +       struct occ *occ = dev_get_drvdata(kobj_to_dev(kobj));
>> +       struct p9_sbe_occ *ctx = to_p9_sbe_occ(occ);
>> +
>> +       mutex_lock(&ctx->sbe_error_lock);
>> +       if (ctx->sbe_error) {
>> +               rc = memory_read_from_buffer(buf, count, &pos, ctx->ffdc,
>> +                                            ctx->ffdc_len);
>> +               if (pos >= ctx->ffdc_len)
>> +                       ctx->sbe_error = false;
>> +       }
>> +       mutex_unlock(&ctx->sbe_error_lock);
>> +
>> +       return rc;
>> +}
>> +static BIN_ATTR_RO(ffdc, OCC_MAX_RESP_WORDS * 4);
>> +
>> +static bool p9_sbe_occ_save_ffdc(struct p9_sbe_occ *ctx, const void *resp,
>> +                                size_t resp_len)
>> +{
>> +       bool notify = false;
>> +
>> +       mutex_lock(&ctx->sbe_error_lock);
>> +       if (!ctx->sbe_error) {
>> +               if (resp_len > ctx->ffdc_size) {
>> +                       if (ctx->ffdc)
>> +                               kvfree(ctx->ffdc);
>> +                       ctx->ffdc = kvmalloc(resp_len, GFP_KERNEL);
>> +                       if (!ctx->ffdc) {
>> +                               ctx->ffdc_len = 0;
>> +                               ctx->ffdc_size = 0;
>> +                               goto done;
>> +                       }
>> +
>> +                       ctx->ffdc_size = resp_len;
>> +               }
>> +
>> +               notify = true;
>> +               ctx->sbe_error = true;
>> +               ctx->ffdc_len = resp_len;
>> +               memcpy(ctx->ffdc, resp, resp_len);
>> +       }
>> +
>> +done:
>> +       mutex_unlock(&ctx->sbe_error_lock);
>> +       return notify;
>> +}
>> +
>>   static int p9_sbe_occ_send_cmd(struct occ *occ, u8 *cmd, size_t len)
>>   {
>>          struct occ_response *resp = &occ->resp;
>> @@ -24,8 +85,15 @@ static int p9_sbe_occ_send_cmd(struct occ *occ, u8 *cmd, size_t len)
>>          int rc;
>>
>>          rc = fsi_occ_submit(ctx->sbe, cmd, len, resp, &resp_len);
>> -       if (rc < 0)
>> +       if (rc < 0) {
>> +               if (resp_len) {
>> +                       if (p9_sbe_occ_save_ffdc(ctx, resp, resp_len))
>> +                               sysfs_notify(&occ->bus_dev->kobj, NULL,
>> +                                            bin_attr_ffdc.attr.name);
>> +               }
>> +
>>                  return rc;
>> +       }
>>
>>          switch (resp->return_status) {
>>          case OCC_RESP_CMD_IN_PRG:
>> @@ -65,6 +133,8 @@ static int p9_sbe_occ_probe(struct platform_device *pdev)
>>          if (!ctx)
>>                  return -ENOMEM;
>>
>> +       mutex_init(&ctx->sbe_error_lock);
>> +
>>          ctx->sbe = pdev->dev.parent;
>>          occ = &ctx->occ;
>>          occ->bus_dev = &pdev->dev;
>> @@ -78,6 +148,15 @@ static int p9_sbe_occ_probe(struct platform_device *pdev)
>>          if (rc == -ESHUTDOWN)
>>                  rc = -ENODEV;   /* Host is shutdown, don't spew errors */
>>
>> +       if (!rc) {
>> +               rc = device_create_bin_file(occ->bus_dev, &bin_attr_ffdc);
>> +               if (rc) {
>> +                       dev_warn(occ->bus_dev,
>> +                                "failed to create SBE error ffdc file\n");
>> +                       rc = 0;
>> +               }
>> +       }
>> +
>>          return rc;
>>   }
>>
>> @@ -86,9 +165,14 @@ static int p9_sbe_occ_remove(struct platform_device *pdev)
>>          struct occ *occ = platform_get_drvdata(pdev);
>>          struct p9_sbe_occ *ctx = to_p9_sbe_occ(occ);
>>
>> +       device_remove_bin_file(occ->bus_dev, &bin_attr_ffdc);
>> +
>>          ctx->sbe = NULL;
>>          occ_shutdown(occ);
>>
>> +       if (ctx->ffdc)
>> +               kvfree(ctx->ffdc);
>> +
>>          return 0;
>>   }
>>
>> --
>> 2.27.0
>>