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

[Joel Stanley]

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.

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
>