[PATCH v2 4/9] drm/panthor: Implement optional reset

[Marek Vasut]

The instance of the GPU populated in Freescale i.MX95 does require
release from reset by writing into a single GPUMIX block controller
GPURESET register bit 0. Implement support for one optional reset.

Signed-off-by: Marek Vasut <marex at denx.de>
---
Cc: Boris Brezillon <boris.brezillon at collabora.com>
Cc: Conor Dooley <conor+dt at kernel.org>
Cc: David Airlie <airlied at gmail.com>
Cc: Fabio Estevam <festevam at gmail.com>
Cc: Krzysztof Kozlowski <krzk+dt at kernel.org>
Cc: Liviu Dudau <liviu.dudau at arm.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Maxime Ripard <mripard at kernel.org>
Cc: Pengutronix Kernel Team <kernel at pengutronix.de>
Cc: Philipp Zabel <p.zabel at pengutronix.de>
Cc: Rob Herring <robh at kernel.org>
Cc: Sascha Hauer <s.hauer at pengutronix.de>
Cc: Sebastian Reichel <sre at kernel.org>
Cc: Shawn Guo <shawnguo at kernel.org>
Cc: Simona Vetter <simona at ffwll.ch>
Cc: Steven Price <steven.price at arm.com>
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: devicetree at vger.kernel.org
Cc: dri-devel at lists.freedesktop.org
Cc: imx at lists.linux.dev
Cc: linux-arm-kernel at lists.infradead.org
---
V2: Drop the select RESET_SIMPLE from Kconfig
---
 drivers/gpu/drm/panthor/panthor_device.c | 23 +++++++++++++++++++++++
 drivers/gpu/drm/panthor/panthor_device.h |  3 +++
 2 files changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index a9da1d1eeb707..51ee9cae94504 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -64,6 +64,17 @@ static int panthor_clk_init(struct panthor_device *ptdev)
 	return 0;
 }
 
+static int panthor_reset_init(struct panthor_device *ptdev)
+{
+	ptdev->resets = devm_reset_control_get_optional_exclusive_deasserted(ptdev->base.dev, NULL);
+	if (IS_ERR(ptdev->resets))
+		return dev_err_probe(ptdev->base.dev,
+				     PTR_ERR(ptdev->resets),
+				     "get reset failed");
+
+	return 0;
+}
+
 void panthor_device_unplug(struct panthor_device *ptdev)
 {
 	/* This function can be called from two different path: the reset work
@@ -217,6 +228,10 @@ int panthor_device_init(struct panthor_device *ptdev)
 	if (ret)
 		return ret;
 
+	ret = panthor_reset_init(ptdev);
+	if (ret)
+		return ret;
+
 	ret = panthor_devfreq_init(ptdev);
 	if (ret)
 		return ret;
@@ -470,6 +485,10 @@ int panthor_device_resume(struct device *dev)
 	if (ret)
 		goto err_disable_stacks_clk;
 
+	ret = reset_control_deassert(ptdev->resets);
+	if (ret)
+		goto err_disable_coregroup_clk;
+
 	panthor_devfreq_resume(ptdev);
 
 	if (panthor_device_is_initialized(ptdev) &&
@@ -512,6 +531,9 @@ int panthor_device_resume(struct device *dev)
 
 err_suspend_devfreq:
 	panthor_devfreq_suspend(ptdev);
+	reset_control_assert(ptdev->resets);
+
+err_disable_coregroup_clk:
 	clk_disable_unprepare(ptdev->clks.coregroup);
 
 err_disable_stacks_clk:
@@ -563,6 +585,7 @@ int panthor_device_suspend(struct device *dev)
 
 	panthor_devfreq_suspend(ptdev);
 
+	reset_control_assert(ptdev->resets);
 	clk_disable_unprepare(ptdev->clks.coregroup);
 	clk_disable_unprepare(ptdev->clks.stacks);
 	clk_disable_unprepare(ptdev->clks.core);
diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
index da6574021664b..fea3a05778e2e 100644
--- a/drivers/gpu/drm/panthor/panthor_device.h
+++ b/drivers/gpu/drm/panthor/panthor_device.h
@@ -111,6 +111,9 @@ struct panthor_device {
 		struct clk *coregroup;
 	} clks;
 
+	/** @resets: GPU reset. */
+	struct reset_control *resets;
+
 	/** @coherent: True if the CPU/GPU are memory coherent. */
 	bool coherent;
 
-- 
2.47.2