linux-kernel - [PATCH v1] reset: Add devm_reset_control_get_optional_exclusive

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Date:   Sat, 23 Jan 2021 19:34:45 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        Matt Merhar <mattmerhar@...tonmail.com>,
        Peter Geis <pgwipeout@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>
Cc:     linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1] reset: Add devm_reset_control_get_optional_exclusive_released()

NVIDIA Tegra DRM and media drivers will need a resource-managed-optional
variant of reset_control_get_exclusive_released() in order to switch away
from a legacy Tegra-specific PD API to a GENPD API without much hassle.
Add the new reset helper to the reset API.

Tested-by: Peter Geis <pgwipeout@...il.com> # Ouya T30
Tested-by: Nicolas Chauvet <kwizart@...il.com> # PAZ00 T20
Tested-by: Matt Merhar <mattmerhar@...tonmail.com> # Ouya T30
Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---

Hello Philipp,

This patch is a prerequisite for a power domain enablement using
GENPD API on NVIDIA Tegra20/30 SoCs. The hardware resets are acquired
by a Tegra PMC (Power Management Controller) driver until device is
RPM-resumed if GENPD API is used, and thus, device drivers need to
request resets in a released state. The resets are also optional,
depending on hardware and DTB versions. This is why we will need the
new helper. Will be awesome if you could pick up this patch for v5.12,
this will help to avoid inter-subsystem dependencies for the driver
patches that will target v5.13. Thanks in advance!

 include/linux/reset.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/include/linux/reset.h b/include/linux/reset.h
index 439fec7112a9..b9109efa2a5c 100644
--- a/include/linux/reset.h
+++ b/include/linux/reset.h
@@ -362,6 +362,25 @@ __must_check devm_reset_control_get_exclusive_released(struct device *dev,
 	return __devm_reset_control_get(dev, id, 0, false, false, false);
 }
 
+/**
+ * devm_reset_control_get_optional_exclusive_released - resource managed
+ *                                                      reset_control_get_optional_exclusive_released()
+ * @dev: device to be reset by the controller
+ * @id: reset line name
+ *
+ * Managed-and-optional variant of reset_control_get_exclusive_released(). For
+ * reset controllers returned from this function, reset_control_put() is called
+ * automatically on driver detach.
+ *
+ * See reset_control_get_exclusive_released() for more information.
+ */
+static inline struct reset_control *
+__must_check devm_reset_control_get_optional_exclusive_released(struct device *dev,
+								const char *id)
+{
+	return __devm_reset_control_get(dev, id, 0, false, true, false);
+}
+
 /**
  * devm_reset_control_get_shared - resource managed reset_control_get_shared()
  * @dev: device to be reset by the controller
-- 
2.29.2