From patchwork Tue Sep 5 18:52:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 13374973 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E55C5CA0FFF for ; Tue, 5 Sep 2023 19:07:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229803AbjIETHF (ORCPT ); Tue, 5 Sep 2023 15:07:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34640 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239286AbjIETHE (ORCPT ); Tue, 5 Sep 2023 15:07:04 -0400 Received: from mail-wm1-x330.google.com (mail-wm1-x330.google.com [IPv6:2a00:1450:4864:20::330]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4002810D9 for ; Tue, 5 Sep 2023 12:06:28 -0700 (PDT) Received: by mail-wm1-x330.google.com with SMTP id 5b1f17b1804b1-401b0d97850so30150435e9.2 for ; Tue, 05 Sep 2023 12:06:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20230601.gappssmtp.com; s=20230601; t=1693940725; x=1694545525; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=fLtpoodGmmx9hsi2x1jr+x7uccK8YI9bvvMsLPIMWWk=; b=I7OSPyKBxHXdz0ldBsWlbwDT21tHcW9fvUgR/ob2pSfo5V/5dYhI5XuQYP9ytM1Hjo 9hYhKBGi4WBmKRwAB2dCrT2lYsVTVni0tuf8M2Zuh4rTb3Qt4NJuwG4rOq35lXQRGaPk fkKzO2cJoBKNvFpytQEl7tHygalv/BwEUGej8ldfb5w8ji1/n1EdtLyrU5oIBbpGIZeN bDmPCYeyTxUxxEfHphd3ycoKSjY0I+nJAxS8IlIImO0OKk3FeoVodfGavJORXdkPamZD DJtdR5OW+z9uORcOMXbyUbckfiUvXufVEG0T0yfl2IBL9Qh6yoXimiw438N6knfak5iB wpvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693940725; x=1694545525; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=fLtpoodGmmx9hsi2x1jr+x7uccK8YI9bvvMsLPIMWWk=; b=MYS86AUdYcpPbRP+6ZdqTYyoWdbed/FWuHga4MCwFldb0wclWx3XoeioJvWyiM6UGP nAQ1ElzpSKR3ZFxaR+uNQ9NIr2E4wv5gnnqpODC1Oh5xiPMq+T4lbYTUgSfAHkdXzb5N xZ/5itJvMMLKqGRyvD9XSbuyErV1YiuhajGGhBLQHPevc8YPQGw7F8zFumd7zfmz4Ksn r5xaA3WlSm2XeMnQ+/fQAFygk81cqbysDjpDjeZ+bEyE7zMeZfweLmQ27CIb7pAKuEKp 96nTDUG30AiDlbZEJ3SR1rpOzNwLSo6GajHzx98B8e7nJNVg0M/hp3Et4KVCvaZCmepz W65w== X-Gm-Message-State: AOJu0YzpUAZyVdApx/omQffnnit5ZU8+MjhULI5udOW2DlCkdXgxdPVN 9sC6JtFqi3KOuJlg2L1W1tvil3C4GF+i7EqLVOw= X-Google-Smtp-Source: AGHT+IFpB/13m0/nwakUzQdaNfC4LZV+lJxvCkU4V9X8PY52XKoEKpYjuE+lOSYCuwIRrrXtGPQ9RA== X-Received: by 2002:a2e:9f04:0:b0:2b9:ecab:d924 with SMTP id u4-20020a2e9f04000000b002b9ecabd924mr463291ljk.18.1693940010976; Tue, 05 Sep 2023 11:53:30 -0700 (PDT) Received: from brgl-uxlite.home ([2a01:cb1d:334:ac00:7a54:5dbc:6d09:48b7]) by smtp.gmail.com with ESMTPSA id 17-20020a05600c249100b003fbc30825fbsm17550010wms.39.2023.09.05.11.53.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Sep 2023 11:53:30 -0700 (PDT) From: Bartosz Golaszewski To: Aaro Koskinen , Janusz Krzysztofik , Tony Lindgren , Russell King , Mika Westerberg , Andy Shevchenko , Linus Walleij , Bartosz Golaszewski , Dipen Patel , Thierry Reding , Jonathan Hunter , Hans de Goede , Mark Gross Cc: linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, linux-acpi@vger.kernel.org, timestamp@lists.linux.dev, linux-tegra@vger.kernel.org, platform-driver-x86@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH 04/21] gpiolib: provide gpio_device_get_desc() Date: Tue, 5 Sep 2023 20:52:52 +0200 Message-Id: <20230905185309.131295-5-brgl@bgdev.pl> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230905185309.131295-1-brgl@bgdev.pl> References: <20230905185309.131295-1-brgl@bgdev.pl> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: platform-driver-x86@vger.kernel.org From: Bartosz Golaszewski Getting the GPIO descriptor directly from the gpio_chip struct is dangerous as we don't take the reference to the underlying GPIO device. In order to start working towards removing gpiochip_get_desc(), let's provide a safer variant that works with an existing reference to struct gpio_device. Signed-off-by: Bartosz Golaszewski Reviewed-by: Linus Walleij --- drivers/gpio/gpiolib.c | 45 +++++++++++++++++++++++++++---------- include/linux/gpio/driver.h | 2 ++ 2 files changed, 35 insertions(+), 12 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 74b837671d30..4a9af6bfc6d4 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -147,27 +147,48 @@ struct gpio_desc *gpio_to_desc(unsigned gpio) } EXPORT_SYMBOL_GPL(gpio_to_desc); -/** - * gpiochip_get_desc - get the GPIO descriptor corresponding to the given - * hardware number for this chip - * @gc: GPIO chip - * @hwnum: hardware number of the GPIO for this chip - * - * Returns: - * A pointer to the GPIO descriptor or ``ERR_PTR(-EINVAL)`` if no GPIO exists - * in the given chip for the specified hardware number. - */ +/* This function is deprecated and will be removed soon, don't use. */ struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc, unsigned int hwnum) { - struct gpio_device *gdev = gc->gpiodev; + return gpio_device_get_desc(gc->gpiodev, hwnum); +} +EXPORT_SYMBOL_GPL(gpiochip_get_desc); + +/** + * gpio_device_get_desc() - get the GPIO descriptor corresponding to the given + * hardware number for this GPIO device + * @gdev: GPIO device to get the descriptor from + * @hwnum: hardware number of the GPIO for this chip + * + * Returns: + * A pointer to the GPIO descriptor or ``ERR_PTR(-EINVAL)`` if no GPIO exists + * in the given chip for the specified hardware number or ``ERR_PTR(-ENODEV)`` + * if the underlying chip already vanished. + * + * The reference count of struct gpio_device is *NOT* increased like when the + * GPIO is being requested for exclusive usage. It's up to the caller to make + * sure the GPIO device will stay alive together with the descriptor returned + * by this function. + */ +struct gpio_desc * +gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum) +{ + struct gpio_chip *gc = gdev->chip; + + /* + * FIXME: This will be locked once we protect gdev->chip everywhere + * with SRCU. + */ + if (!gc) + return ERR_PTR(-ENODEV); if (hwnum >= gdev->ngpio) return ERR_PTR(-EINVAL); return &gdev->descs[hwnum]; } -EXPORT_SYMBOL_GPL(gpiochip_get_desc); +EXPORT_SYMBOL_GPL(gpio_device_get_desc); /** * desc_to_gpio - convert a GPIO descriptor to the integer namespace diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index 92f7143bad3e..a769baf3d731 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -766,6 +766,8 @@ struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *gc, void gpiochip_free_own_desc(struct gpio_desc *desc); struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc, unsigned int hwnum); +struct gpio_desc * +gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum); #ifdef CONFIG_GPIOLIB