From patchwork Sat Jan 4 10:54:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Guido_G=C3=BCnther?= X-Patchwork-Id: 206185 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D0840C2D0C2 for ; Sat, 4 Jan 2020 10:54:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B2CF724650 for ; Sat, 4 Jan 2020 10:54:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726436AbgADKyy (ORCPT ); Sat, 4 Jan 2020 05:54:54 -0500 Received: from honk.sigxcpu.org ([24.134.29.49]:40228 "EHLO honk.sigxcpu.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726293AbgADKyk (ORCPT ); Sat, 4 Jan 2020 05:54:40 -0500 Received: from localhost (localhost [127.0.0.1]) by honk.sigxcpu.org (Postfix) with ESMTP id 69018FB02; Sat, 4 Jan 2020 11:54:39 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at honk.sigxcpu.org Received: from honk.sigxcpu.org ([127.0.0.1]) by localhost (honk.sigxcpu.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 5zpYTwW8azHf; Sat, 4 Jan 2020 11:54:38 +0100 (CET) Received: by bogon.sigxcpu.org (Postfix, from userid 1000) id 49C7149AAD; Sat, 4 Jan 2020 11:54:26 +0100 (CET) From: =?utf-8?q?Guido_G=C3=BCnther?= To: Jacek Anaszewski , Pavel Machek , Dan Murphy , Rob Herring , Mark Rutland , linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 6/9] leds: lm3692x: Make sure we don't exceed the maximum led current Date: Sat, 4 Jan 2020 11:54:22 +0100 Message-Id: <5826b77d42521595e93d01d53475a8881cad1875.1578134779.git.agx@sigxcpu.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: References: MIME-Version: 1.0 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org The current is given by the formular from page 12 of https://www.ti.com/lit/ds/symlink/lm36922.pdf. We use this to limit the led's max_brightness using the led-max-microamp DT property. The formula for the lm36923 is identical according to the data sheet. Signed-off-by: Guido Günther Acked-by: Pavel Machek --- drivers/leds/leds-lm3692x.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/drivers/leds/leds-lm3692x.c b/drivers/leds/leds-lm3692x.c index ff20560a8263..2e24316566f5 100644 --- a/drivers/leds/leds-lm3692x.c +++ b/drivers/leds/leds-lm3692x.c @@ -6,6 +6,7 @@ #include #include #include +#include #include #include #include @@ -320,11 +321,29 @@ static int lm3692x_init(struct lm3692x_led *led) return ret; } +static enum led_brightness lm3692x_max_brightness(struct lm3692x_led *led, + u32 max_cur) +{ + u32 max_code; + + /* see p.12 of LM36922 data sheet for brightness formula */ + if (led->brightness_ctrl & LM3692X_MAP_MODE_EXP) { + /* 228 =~ 1.0 / log2(1.003040572) */ + max_code = ilog2(max_cur/50) * 228; + } else { + max_code = ((max_cur * 1000) - 37806) / 12195; + } + if (max_code > 0x7FF) + max_code = 0x7FF; + + return max_code >> 3; +} + static int lm3692x_probe_dt(struct lm3692x_led *led) { struct fwnode_handle *child = NULL; struct led_init_data init_data = {}; - u32 ovp; + u32 ovp, max_cur; bool exp_mode; int ret; @@ -397,6 +416,10 @@ static int lm3692x_probe_dt(struct lm3692x_led *led) return ret; } + ret = fwnode_property_read_u32(child, "led-max-microamp", &max_cur); + led->led_dev.max_brightness = ret ? LED_FULL : + lm3692x_max_brightness(led, max_cur); + init_data.fwnode = child; init_data.devicename = led->client->name; init_data.default_label = ":";