[PATCH] battery.el Retrieve more information from sysfs

["Jérémy Compostella" <jeremy.compostella@gmail.com>]

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All,

I just bought a new laptop and installed a fresh Debian on it. I used to
look at my current battery status using Emacs. I like to look at the
current rate too since this laptop will be used during a long trip and I
want to take care of the consumption in real time.

The issue is that with the 2.6.32 kernel from Debian for this laptop I
do not have the /proc/acpi/battery part. However, the sysfs is able to
report all the data I need. The current Emacs battery module is not able
to retrieve the information I need from sysfs but it does from
/proc/acpi/battery. So I made a small evolution to enable the following:

- Get the current rate
- Get the current temperature (does not work on my laptop but the
  power_supply interface is able to provide it, so I added it too.
- Do the time remaining estimation using the current voltage, the
  remaining capacity and the current rate. It works on both charging and
  discharging state.

I attached the patch but I warn you that it has been generated using git
since I was unable to retrieve the bazar repository for the last two
days (it hangs during the download process). By the way, do you have any
advice which could help me ?

Please merge it or review it.

Best regards,

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From 905c2ccd805bb6be0ed11e4f85f9baf316106da1 Mon Sep 17 00:00:00 2001
From: Jeremy Compostella <jeremy.compostella@gmail.com>
Date: Sun, 18 Dec 2011 19:38:29 +0100
Subject: [PATCH] battery.el: Retrieve more information from sysfs

The sysfs power_supply interface provides more information than the
ones retrieved for now. This patch adds the rate and temperature
properties. It provides the ability to estimate the remaining time too
using the current rate, the current voltage and the remaining capacity.
The time remaining estimation works on both charging and discharging
states.
---
 lisp/battery.el |   37 ++++++++++++++++++++++++++++++++++---
 1 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/lisp/battery.el b/lisp/battery.el
index 3b245ed..b6b98d5 100644
--- a/lisp/battery.el
+++ b/lisp/battery.el
@@ -420,11 +420,16 @@ This function works only with the new `/sys/class/power_supply/'
 format introduced in Linux version 2.4.25.
 
 The following %-sequences are provided:
+%r Current rate
+%d Temperature (in degrees Celsius)
 %c Current capacity (mAh or mWh)
 %B Battery status (verbose)
 %p Battery load percentage
-%L AC line status (verbose)"
-  (let (charging-state
+%L AC line status (verbose)
+%m Remaining time (to charge or discharge) in minutes
+%h Remaining time (to charge or discharge) in hours
+%t Remaining time (to charge or discharge) in the form `h:min'"
+  (let (charging-state rate temperature hours
 	(charge-full 0.0)
 	(charge-now 0.0)
 	(energy-full 0.0)
@@ -444,6 +449,11 @@ The following %-sequences are provided:
 	  (and (re-search-forward "POWER_SUPPLY_STATUS=\\(.*\\)$" nil t)
 	       (member charging-state '("Unknown" "Full" nil))
 	       (setq charging-state (match-string 1)))
+	  (when (or (re-search-forward "POWER_SUPPLY_CURRENT_NOW=\\([0-9]*\\)$" nil t)
+		    (re-search-forward "POWER_SUPPLY_POWER_NOW=\\([0-9]*\\)$" nil t))
+	    (setq rate (float (string-to-number (match-string 1)))))
+	  (when (re-search-forward "POWER_SUPPLY_TEMP=\\([0-9]*\\)$" nil t)
+	    (setq temperature (match-string 1)))
 	  (let (full-string now-string)
 	    ;; Sysfs may list either charge (mAh) or energy (mWh).
 	    ;; Keep track of both, and choose which to report later.
@@ -466,12 +476,33 @@ The following %-sequences are provided:
 		   (setq energy-full (+ energy-full
 					(string-to-number full-string))
 			 energy-now  (+ energy-now
-					(string-to-number now-string)))))))))
+					(string-to-number now-string))))))
+	  (goto-char (point-min))
+	  (when (and energy-now rate (not (zerop rate))
+		     (re-search-forward "POWER_SUPPLY_VOLTAGE_NOW=\\([0-9]*\\)$" nil t))
+	    (let ((remaining (if (string= charging-state "Discharging")
+				 energy-now
+			       (- energy-full energy-now))))
+	      (setq hours (/ (/ (* remaining (string-to-number (match-string 1))) rate)
+			     10000000.0)))))))
     (list (cons ?c (cond ((or (> charge-full 0) (> charge-now 0))
 			  (number-to-string charge-now))
 			 ((or (> energy-full 0) (> energy-now 0))
 			  (number-to-string energy-now))
 			 (t "N/A")))
+	  (cons ?r (if rate
+		        (format "%.1f" (/ rate 1000000.0))
+		     "N/A"))
+	  (cons ?m (if hours
+		       (format "%d" (* hours 60))
+		     "N/A"))
+	  (cons ?h (if hours
+		       (format "%d" hours)
+		     "N/A"))
+	  (cons ?t (if hours
+		       (format "%d:%02d" hours (* (- hours (floor hours)) 60))
+		     "N/A"))
+	  (cons ?d (or temperature "N/A"))
 	  (cons ?B (or charging-state "N/A"))
 	  (cons ?p (cond ((> charge-full 0)
 			  (format "%.1f"
-- 
1.7.2.5


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Jeremy

PS: I signed my Emacs assignment and post it by mail 10 days ago.
--
Sent from my Emacs