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: 13374903 Received: from mail-lj1-f175.google.com (mail-lj1-f175.google.com [209.85.208.175]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 25868D53B for ; Tue, 5 Sep 2023 18:53:32 +0000 (UTC) Received: by mail-lj1-f175.google.com with SMTP id 38308e7fff4ca-2b95d5ee18dso48744371fa.1 for ; Tue, 05 Sep 2023 11:53:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20230601.gappssmtp.com; s=20230601; t=1693940011; x=1694544811; darn=lists.linux.dev; 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=fr4zCHHJ+feU9jTNsyfRrzBIF+qEP5h5Yl1n9FFjDMte8SJGgAHvXxNdGJYVjXI9Dr hkWPftz07SAhcL63MgklLxu0QnacCdZWvhCnhFEOYGiQz33JflpY7cTDq/veKi/KiPjJ Aia1PmbfCLsrcnniiCL/xVjKeSsR8hzlUcvggwYahw8KSggLwtHHxWZW8e6xHJBOpFIZ wiVm+K+PGa2VAnJihIK9VsokpEQZZ6q1QIPWIXbvx37NT0QWYGi8NvGxNwzcfoINfBCo SoFOhfgiJVKT4+ey5fcuoCE2mVJ6md1GUZcnNgr7r1Mngb8tQJFkI+Ty8FBeNxGdzB1r 9Xxw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693940011; x=1694544811; 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=Z5aA4d0XVDqAa04VVu8/QnBSPq1TCfH/jh6eSLzZS3Az0+N1aVGYHo20xSfYr7pC/x kfDHIBqb07dCEOmor93EnsIm0qhiYu67N4F/zP8Z7Xne1CDb24Ov2SfdGi/jkGUdzfRO lll7X7cyUwMUb50zI/rzopHsJxvJ2CPG4XidXTea548IeKRwECVz4lOzN47uTvojo+SK WVCpSWjiuaiLTaYYpOz8Qz0CN+fSTcuOJVyLdgAQPU9lfqTBNdLepsoU/nqzgzNTj2FP F+E7/aOkAkHPjOAS47g8eb+/4BCquxkxigfTw3vJidJBZ3hJGH9E7jL+pLujwM0MEi2c WstQ== X-Gm-Message-State: AOJu0YwVGrZurS5w7HtScXqHi43kmgqN+NlgmfXlZryFEpi2r8Ihm9Oo 1jcVdm463k7qOvp5FiNGuC1PIg== 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> Precedence: bulk X-Mailing-List: timestamp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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