hwmon: (occ) Provide the SBEFIFO FFDC in binary sysfs

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>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20211019205307.36946-5-eajames@linux.ibm.com
Signed-off-by: Joel Stanley <joel@jms.id.au>

diff --git a/drivers/hwmon/occ/p9_sbe.c b/drivers/hwmon/occ/p9_sbe.c
index 9709f2b..e502435 100644 (file)
--- 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;
 }