From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sakari Ailus Subject: [PATCH v4 2/6] ACPI: Add a convenience function to tell a device is in low power state Date: Tue, 21 Jan 2020 15:41:53 +0200 Message-ID: <20200121134157.20396-3-sakari.ailus@linux.intel.com> References: <20200121134157.20396-1-sakari.ailus@linux.intel.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: Received: from mga05.intel.com ([192.55.52.43]:8602 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728978AbgAUNlp (ORCPT ); Tue, 21 Jan 2020 08:41:45 -0500 In-Reply-To: <20200121134157.20396-1-sakari.ailus@linux.intel.com> Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: linux-i2c@vger.kernel.org Cc: Wolfram Sang , "Rafael J. Wysocki" , linux-acpi@vger.kernel.org, Bingbu Cao , linux-media@vger.kernel.org, Chiranjeevi Rapolu , Hyungwoo Yang , Bartosz Golaszewski , Arnd Bergmann , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , rajmohan.mani@intel.com, Tomasz Figa Add a convenience function to tell whether a device is in low power state, primarily for use in drivers' probe or remove functions on busses where the custom is to power on the device for the duration of both. Returns false on non-ACPI systems. Suggested-by: Mika Westerberg Signed-off-by: Sakari Ailus --- drivers/acpi/device_pm.c | 31 +++++++++++++++++++++++++++++++ include/linux/acpi.h | 5 +++++ 2 files changed, 36 insertions(+) diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c index 5e4a8860a9c0c..d3174c6edf915 100644 --- a/drivers/acpi/device_pm.c +++ b/drivers/acpi/device_pm.c @@ -1348,4 +1348,35 @@ int acpi_dev_pm_attach(struct device *dev, bool power_on) return 1; } EXPORT_SYMBOL_GPL(acpi_dev_pm_attach); + +/** + * acpi_dev_state_low_power - Check the current ACPI power state of a device. + * @dev: Physical device the ACPI power state of which to check + * + * On a system without ACPI, return false. On a system with ACPI, return true if + * the current ACPI power state of the device is not D0, or false otherwise. + * + * Note that the power state of a device is not well-defined after it has been + * passed to acpi_device_set_power() and before that function returns, so it is + * not valid to ask for the ACPI power state of the device in that time frame. + */ +bool acpi_dev_state_low_power(struct device *dev) +{ + struct acpi_device *adev = ACPI_COMPANION(dev); + int power_state; + int ret; + + if (!adev) + return false; + + ret = acpi_device_get_power(adev, &power_state); + if (ret) { + dev_dbg(dev, "Cannot obtain power state (%d)\n", ret); + return false; + } + + return power_state != ACPI_STATE_D0; +} +EXPORT_SYMBOL_GPL(acpi_dev_state_low_power); + #endif /* CONFIG_PM */ diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 0f37a7d5fa774..aa666da311444 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -926,6 +926,7 @@ int acpi_dev_resume(struct device *dev); int acpi_subsys_runtime_suspend(struct device *dev); int acpi_subsys_runtime_resume(struct device *dev); int acpi_dev_pm_attach(struct device *dev, bool power_on); +bool acpi_dev_state_low_power(struct device *dev); #else static inline int acpi_dev_runtime_suspend(struct device *dev) { return 0; } static inline int acpi_dev_runtime_resume(struct device *dev) { return 0; } @@ -935,6 +936,10 @@ static inline int acpi_dev_pm_attach(struct device *dev, bool power_on) { return 0; } +static inline bool acpi_dev_state_low_power(struct device *dev) +{ + return false; +} #endif #if defined(CONFIG_ACPI) && defined(CONFIG_PM_SLEEP) -- 2.20.1