Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752884AbbBXEgJ (ORCPT ); Mon, 23 Feb 2015 23:36:09 -0500 Received: from cantor2.suse.de ([195.135.220.15]:34437 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752364AbbBXEgE (ORCPT ); Mon, 23 Feb 2015 23:36:04 -0500 From: NeilBrown To: Samuel Ortiz , Tony Lindgren , Lee Jones , Sebastian Reichel , Dmitry Eremin-Solenikov , David Woodhouse Date: Tue, 24 Feb 2015 15:33:51 +1100 Subject: [PATCH 06/15] twl4030_charger: split uA calculation into a function. Cc: GTA04 owners , linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Message-ID: <20150224043351.4243.86053.stgit@notabene.brown> In-Reply-To: <20150224043341.4243.23291.stgit@notabene.brown> References: <20150224043341.4243.23291.stgit@notabene.brown> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2433 Lines: 88 We will need this calculation in other places, so create functions to map between register value and uA value. Signed-off-by: NeilBrown --- drivers/power/twl4030_charger.c | 48 ++++++++++++++++++++++++++++----------- 1 file changed, 35 insertions(+), 13 deletions(-) diff --git a/drivers/power/twl4030_charger.c b/drivers/power/twl4030_charger.c index db8931a17541..0b6fb06a0c01 100644 --- a/drivers/power/twl4030_charger.c +++ b/drivers/power/twl4030_charger.c @@ -178,6 +178,40 @@ static int twl4030_is_battery_present(struct twl4030_bci *bci) } /* + * 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 + * Here we use integer approximation of: + * CGAIN == 0: val * 1.6618 - 0.85 * 1000 + * CGAIN == 1: (val * 1.6618 - 0.85 * 1000) * 2 + */ +/* + * convert twl register value for currents into uA + */ +static int regval2ua(int regval, bool cgain) +{ + if (cgain) + return (regval * 16618 - 8500 * 1000) / 5; + else + return (regval * 16618 - 8500 * 1000) / 10; +} + +/* + * convert uA currents into twl register value + */ +static int ua2regval(int ua, bool cgain) +{ + int ret; + if (cgain) + ua /= 2; + ret = (ua * 10 + 8500 * 1000) / 16618; + /* rounding problems */ + if (ret < 512) + ret = 512; + return ret; +} + +/* * Enable/Disable USB Charge functionality. */ static int twl4030_charger_enable_usb(struct twl4030_bci *bci, bool enable) @@ -366,14 +400,6 @@ static int twl4030_bci_usb_ncb(struct notifier_block *nb, unsigned long val, return NOTIFY_OK; } -/* - * 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 - * Here we use integer approximation of: - * CGAIN == 0: val * 1.6618 - 0.85 - * CGAIN == 1: (val * 1.6618 - 0.85) * 2 - */ static int twl4030_charger_get_current(void) { int curr; @@ -388,11 +414,7 @@ static int twl4030_charger_get_current(void) if (ret) return ret; - ret = (curr * 16618 - 850 * 10000) / 10; - if (bcictl1 & TWL4030_CGAIN) - ret *= 2; - - return ret; + return regval2ua(curr, bcictl1 & TWL4030_CGAIN); } /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/