Linux-ACPI Archive on lore.kernel.org
 help / color / Atom feed
From: Sakari Ailus <sakari.ailus@linux.intel.com>
To: linux-i2c@vger.kernel.org
Cc: Wolfram Sang <wsa@the-dreams.de>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	rajmohan.mani@intel.com, Tomasz Figa <tfiga@chromium.org>
Subject: [PATCH v3 2/5] ACPI: Add a convenience function to tell a device is suspended in probe
Date: Thu,  9 Jan 2020 17:45:26 +0200
Message-ID: <20200109154529.19484-3-sakari.ailus@linux.intel.com> (raw)
In-Reply-To: <20200109154529.19484-1-sakari.ailus@linux.intel.com>

Add a convenience function to tell whether a device is suspended for probe
or remove, for busses where the custom is that drivers don't need to
resume devices in probe, or suspend them in their remove handlers.

Returns false on non-ACPI systems.

Suggested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/acpi/device_pm.c | 35 +++++++++++++++++++++++++++++++++++
 include/linux/acpi.h     |  5 +++++
 2 files changed, 40 insertions(+)

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index 5e4a8860a9c0c..87393020276d8 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -1348,4 +1348,39 @@ int acpi_dev_pm_attach(struct device *dev, bool power_on)
 	return 1;
 }
 EXPORT_SYMBOL_GPL(acpi_dev_pm_attach);
+
+/**
+ * acpi_dev_low_power_state_probe - Tell if a device is in a low power state
+ *				    during probe
+ * @dev: The device
+ *
+ * Tell whether a given device is in a low power state during the driver's probe
+ * or remove operation.
+ *
+ * Drivers of devices on certain busses such as I²C can generally assume (on
+ * ACPI based systems) that the devices they control are powered on without
+ * driver having to do anything about it. Using struct
+ * device_driver.probe_low_power and "probe-low-power" property, this can be
+ * negated and the driver has full control of the device power management.
+ * Always returns false on non-ACPI based systems. True is returned on ACPI
+ * based systems iff the device is in a low power state during probe or remove.
+ */
+bool acpi_dev_low_power_state_probe(struct device *dev)
+{
+	int power_state;
+	int ret;
+
+	if (!is_acpi_device_node(dev_fwnode(dev)))
+		return false;
+
+	ret = acpi_device_get_power(ACPI_COMPANION(dev), &power_state);
+	if (ret) {
+		dev_warn(dev, "Cannot obtain power state (%d)\n", ret);
+		return false;
+	}
+
+	return power_state != ACPI_STATE_D0;
+}
+EXPORT_SYMBOL_GPL(acpi_dev_low_power_state_probe);
+
 #endif /* CONFIG_PM */
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 0f37a7d5fa774..fd00853074e1a 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_low_power_state_probe(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_low_power_state_probe(struct device *dev)
+{
+	return false;
+}
 #endif
 
 #if defined(CONFIG_ACPI) && defined(CONFIG_PM_SLEEP)
-- 
2.20.1


  parent reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-09 15:45 [PATCH v3 0/5] Support running driver's probe for a device powered off Sakari Ailus
2020-01-09 15:45 ` [PATCH v3 1/5] i2c: Allow driver to manage the device's power state during probe Sakari Ailus
2020-01-09 15:45 ` Sakari Ailus [this message]
2020-01-13 10:41   ` [PATCH v3 2/5] ACPI: Add a convenience function to tell a device is suspended in probe Rafael J. Wysocki
2020-01-21  9:09     ` Sakari Ailus
2020-01-21 16:02       ` Rafael J. Wysocki
2020-01-09 15:45 ` [PATCH v3 3/5] ov5670: Support probe whilst the device is in a low power state Sakari Ailus
2020-01-09 15:45 ` [PATCH v3 4/5] media: i2c: imx319: Support probe while the device is off Sakari Ailus
2020-01-09 15:45 ` [PATCH v3 5/5] at24: Support probing while off Sakari Ailus
2020-01-10 11:16   ` Bartosz Golaszewski
2020-01-10 11:28     ` Sakari Ailus
2020-01-10 11:31       ` Bartosz Golaszewski

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200109154529.19484-3-sakari.ailus@linux.intel.com \
    --to=sakari.ailus@linux.intel.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-acpi@vger.kernel.org \
    --cc=linux-i2c@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=rafael@kernel.org \
    --cc=rajmohan.mani@intel.com \
    --cc=tfiga@chromium.org \
    --cc=wsa@the-dreams.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-ACPI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-acpi/0 linux-acpi/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-acpi linux-acpi/ https://lore.kernel.org/linux-acpi \
		linux-acpi@vger.kernel.org
	public-inbox-index linux-acpi

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-acpi


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git