[PATCH v3 4/4] hwmon: (occ) Provide the SBEFIFO FFDC in binary sysfs

Eddie James
2021-09-27T16:00:16Z

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@linux.ibm.com>
---
Changes since v1:
- Remove "collected" error state in favor of a boolean
- Clear the error flag once the FFDC has been completely read once
- Only store FFDC if there is no FFDC waiting to be retrieved

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