platform/x86: intel_telemetry: Fix suspend stats

Suspend stats are not reported consistently due to a limitation in the PMC
firmware. This limitation causes a delay in updating the s0ix counters and
residencies in the telemetry log upon s0ix exit. As a consequence, reading
these counters from the suspend-exit notifier may result in zero read.

This patch fixes this issue by cross-verifying the s0ix residencies from
the GCR TELEM registers in case the counters are not incremented in the
telemetry log after suspend.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=197833

Reported-and-tested-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@intel.com>
Signed-off-by: Souvik Kumar Chakravarty <souvik.k.chakravarty@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/x86/intel_telemetry_debugfs.c

@@ -890,6 +890,31 @@ static int pm_suspend_exit_cb(void)
 		goto out;
 	}
 
+	/*
+	 * Due to some design limitations in the firmware, sometimes the
+	 * counters do not get updated by the time we reach here. As a
+	 * workaround, we try to see if this was a genuine case of sleep
+	 * failure or not by cross-checking from PMC GCR registers directly.
+	 */
+	if (suspend_shlw_ctr_exit == suspend_shlw_ctr_temp &&
+	    suspend_deep_ctr_exit == suspend_deep_ctr_temp) {
+		ret = intel_pmc_gcr_read64(PMC_GCR_TELEM_SHLW_S0IX_REG,
+					  &suspend_shlw_res_exit);
+		if (ret < 0)
+			goto out;
+
+		ret = intel_pmc_gcr_read64(PMC_GCR_TELEM_DEEP_S0IX_REG,
+					  &suspend_deep_res_exit);
+		if (ret < 0)
+			goto out;
+
+		if (suspend_shlw_res_exit > suspend_shlw_res_temp)
+			suspend_shlw_ctr_exit++;
+
+		if (suspend_deep_res_exit > suspend_deep_res_temp)
+			suspend_deep_ctr_exit++;
+	}
+
 	suspend_shlw_ctr_exit -= suspend_shlw_ctr_temp;
 	suspend_deep_ctr_exit -= suspend_deep_ctr_temp;
 	suspend_shlw_res_exit -= suspend_shlw_res_temp;