From 86f8670d0b35e713931065611e8e40c16ebcba63 Mon Sep 17 00:00:00 2001
From: CTCaer <ctcaer@gmail.com>
Date: Mon, 31 May 2021 18:36:49 +0300
Subject: [PATCH] plat: unix: get better battery stats on sysfs nodes

This addresses 2 issues:

1. Input controllers report battery supplies.
   That causes wrong charging status or capacities if they report percentages instead of levels.
   Such supplies normally report scope attributes that report Unknown or Device type of power supply.
   If reported value is System or the attribute is missing, it's considered a System supply and used.

2. Various systems have backup batteries.
   That causes the wrong capacity to be reported depending on order of node creation.
   This is addressed by keeping track of these and calculating an average.
---
 frontend/drivers/platform_unix.c | 37 ++++++++++++++++++++++++++------
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/frontend/drivers/platform_unix.c b/frontend/drivers/platform_unix.c
index 43e818494f..8cc3231c2c 100644
--- a/frontend/drivers/platform_unix.c
+++ b/frontend/drivers/platform_unix.c
@@ -818,8 +818,8 @@ end:
    buf_info = NULL;
 }
 static void check_proc_acpi_sysfs_battery(const char *node,
-      bool *have_battery, bool *charging,
-      int *seconds, int *percent)
+      bool *have_battery, bool *charging, int *seconds,
+      int *percent, int *valid_pct_idx)
 {
    char path[1024];
    const char *base  = proc_acpi_sysfs_battery_path;
@@ -838,6 +838,22 @@ static void check_proc_acpi_sysfs_battery(const char *node,
 
    path[0]           = '\0';
 
+   /* Stat type. Avoid unknown or device supplies. Missing is considered System. */
+   snprintf(path, sizeof(path), "%s/%s/%s", base, node, "scope");
+
+   if (filestream_exists(path) != 0)
+   {
+      if (filestream_read_file(path, (void**)&buf, &length) == 1 && buf)
+      {
+         if (strstr((char*)buf, "Unknown"))
+            goto end;
+         else if (strstr((char*)buf, "Device"))
+            goto end;
+         free(buf);
+         buf = NULL;
+      }
+   }
+
    snprintf(path, sizeof(path), "%s/%s/%s", base, node, "status");
 
    if (!filestream_exists(path))
@@ -858,17 +874,21 @@ static void check_proc_acpi_sysfs_battery(const char *node,
       else if (strstr((char*)buf, "Full"))
          *have_battery = true;
       free(buf);
+      buf = NULL;
    }
 
-   buf = NULL;
-
    snprintf(path, sizeof(path), "%s/%s/%s", base, node, "capacity");
    if (filestream_read_file(path, (void**)&buf, &length) != 1)
       goto end;
 
    capacity = atoi(buf);
 
-   *percent = capacity;
+   /*
+    * Keep record of valid capacities for calculating an average
+    * on systems with backup battery supplies.
+    */
+   (*valid_pct_idx)++;
+   (*percent) += capacity;
 
 end:
    free(buf);
@@ -1103,6 +1123,7 @@ static bool frontend_unix_powerstate_check_acpi_sysfs(
    bool have_battery   = false;
    bool have_ac        = false;
    bool charging       = false;
+   int  valid_pct_idx  = 0;
    struct RDIR *entry  = retro_opendir(proc_acpi_sysfs_battery_path);
    if (!entry)
       goto error;
@@ -1116,9 +1137,13 @@ static bool frontend_unix_powerstate_check_acpi_sysfs(
 
       if (node && (strstr(node, "BAT") || strstr(node, "battery")))
          check_proc_acpi_sysfs_battery(node,
-               &have_battery, &charging, seconds, percent);
+               &have_battery, &charging, seconds, percent, &valid_pct_idx);
    }
 
+   /* Get average percentage */
+   if (valid_pct_idx)
+      (*percent) /= valid_pct_idx;
+
    retro_closedir(entry);
 
    entry = retro_opendir(proc_acpi_sysfs_ac_adapter_path);