linux-kernel - [PATCH RESEND 1/3 v4] drivers:power:twl4030-charger: don't check if battery is present

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 14 Apr 2017 21:29:38 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Sebastian Reichel <sre@...nel.org>,
        Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
        David Woodhouse <dwmw2@...radead.org>
Cc:     Grazvydas Ignotas <notasas@...il.com>,
        Andreas Kemnade <andreas@...nade.info>,
        linux-pm@...r.kernel.org, letux-kernel@...nphoenux.org,
        linux-kernel@...r.kernel.org,
        "H. Nikolaus Schaller" <hns@...delico.com>
Subject: [PATCH RESEND 1/3 v4] drivers:power:twl4030-charger: don't check if battery is present

We can't assume that the battery is or stays present after probing
on devices with replaceable battery.

On some devices (e.g. GTA04 or OpenPanodra) it can be removed
and even be hot swapped by the user while device continues to operate
through external AC or USB power (as long as system power consumption
remains below ca. 500mA as provided by USB). Under certain conditions
it is possible to boot without battery.

So it makes no sense to check for this situation during probe and make
the charger driver (and its status reports) completely non-operational if
the battery can be inserted later.

Tested on: GTA04 and OpenPandora.

Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
---
 drivers/power/supply/twl4030_charger.c | 36 ----------------------------------
 1 file changed, 36 deletions(-)

diff --git a/drivers/power/supply/twl4030_charger.c b/drivers/power/supply/twl4030_charger.c
index bcd4dc3..e7fc9b0 100644
--- a/drivers/power/supply/twl4030_charger.c
+++ b/drivers/power/supply/twl4030_charger.c
@@ -206,35 +206,6 @@ static int twl4030bci_read_adc_val(u8 reg)
 }
 
 /*
- * Check if Battery Pack was present
- */
-static int twl4030_is_battery_present(struct twl4030_bci *bci)
-{
-	int ret;
-	u8 val = 0;
-
-	/* Battery presence in Main charge? */
-	ret = twl_i2c_read_u8(TWL_MODULE_MAIN_CHARGE, &val, TWL4030_BCIMFSTS3);
-	if (ret)
-		return ret;
-	if (val & TWL4030_BATSTSMCHG)
-		return 0;
-
-	/*
-	 * OK, It could be that bootloader did not enable main charger,
-	 * pre-charge is h/w auto. So, Battery presence in Pre-charge?
-	 */
-	ret = twl_i2c_read_u8(TWL4030_MODULE_PRECHARGE, &val,
-			      TWL4030_BCIMFSTS1);
-	if (ret)
-		return ret;
-	if (val & TWL4030_BATSTSPCHG)
-		return 0;
-
-	return -ENODEV;
-}
-
-/*
  * TI provided formulas:
  * CGAIN == 0: ICHG = (BCIICHG * 1.7) / (2^10 - 1) - 0.85
  * CGAIN == 1: ICHG = (BCIICHG * 3.4) / (2^10 - 1) - 1.7
@@ -1009,13 +980,6 @@ static int twl4030_bci_probe(struct platform_device *pdev)
 	bci->irq_chg = platform_get_irq(pdev, 0);
 	bci->irq_bci = platform_get_irq(pdev, 1);
 
-	/* Only proceed further *IF* battery is physically present */
-	ret = twl4030_is_battery_present(bci);
-	if  (ret) {
-		dev_crit(&pdev->dev, "Battery was not detected:%d\n", ret);
-		return ret;
-	}
-
 	platform_set_drvdata(pdev, bci);
 
 	bci->ac = devm_power_supply_register(&pdev->dev, &twl4030_bci_ac_desc,
-- 
2.7.3