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 <ma...@denx.de>
---
Cc: Boris Brezillon <boris.brezil...@collabora.com>
Cc: Conor Dooley <conor...@kernel.org>
Cc: David Airlie <airl...@gmail.com>
Cc: Fabio Estevam <feste...@gmail.com>
Cc: Krzysztof Kozlowski <krzk...@kernel.org>
Cc: Liviu Dudau <liviu.du...@arm.com>
Cc: Maarten Lankhorst <maarten.lankho...@linux.intel.com>
Cc: Maxime Ripard <mrip...@kernel.org>
Cc: Pengutronix Kernel Team <ker...@pengutronix.de>
Cc: Philipp Zabel <p.za...@pengutronix.de>
Cc: Rob Herring <r...@kernel.org>
Cc: Sascha Hauer <s.ha...@pengutronix.de>
Cc: Sebastian Reichel <s...@kernel.org>
Cc: Shawn Guo <shawn...@kernel.org>
Cc: Simona Vetter <sim...@ffwll.ch>
Cc: Steven Price <steven.pr...@arm.com>
Cc: Thomas Zimmermann <tzimmerm...@suse.de>
Cc: devicet...@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: i...@lists.linux.dev
Cc: linux-arm-ker...@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

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