linux-kernel - [PATCH 2/2] drm/imagination: add reset control support

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Message-Id: <20241125-pvr-reset-v1-2-b437b8052948@linumiz.com>
Date: Mon, 25 Nov 2024 22:07:04 +0530
From: Parthiban Nallathambi <parthiban@...umiz.com>
To: Frank Binns <frank.binns@...tec.com>, 
 Matt Coster <matt.coster@...tec.com>, David Airlie <airlied@...il.com>, 
 Simona Vetter <simona@...ll.ch>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>
Cc: dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Parthiban Nallathambi <parthiban@...umiz.com>
Subject: [PATCH 2/2] drm/imagination: add reset control support

On some platforms like Allwinner A133 with GE8300 includes
reset control from reset control unit. Add reset control
optionally from the devicetree.

Signed-off-by: Parthiban Nallathambi <parthiban@...umiz.com>
---
 drivers/gpu/drm/imagination/pvr_device.h |  8 ++++++++
 drivers/gpu/drm/imagination/pvr_drv.c    |  5 +++++
 drivers/gpu/drm/imagination/pvr_power.c  | 16 +++++++++++++++-
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/imagination/pvr_device.h b/drivers/gpu/drm/imagination/pvr_device.h
index 6d0dfacb677b..21ec7dd64415 100644
--- a/drivers/gpu/drm/imagination/pvr_device.h
+++ b/drivers/gpu/drm/imagination/pvr_device.h
@@ -23,6 +23,7 @@
 #include <linux/kernel.h>
 #include <linux/math.h>
 #include <linux/mutex.h>
+#include <linux/reset.h>
 #include <linux/spinlock_types.h>
 #include <linux/timer.h>
 #include <linux/types.h>
@@ -131,6 +132,13 @@ struct pvr_device {
 	 */
 	struct clk *mem_clk;
 
+	/**
+	 * @reset: Optional reset control
+	 *
+	 * This may be used on some platforms to reset the GPU module/IP.
+	 */
+	struct reset_control *reset;
+
 	/** @irq: IRQ number. */
 	int irq;
 
diff --git a/drivers/gpu/drm/imagination/pvr_drv.c b/drivers/gpu/drm/imagination/pvr_drv.c
index fb17196e05f4..d9b918410ea9 100644
--- a/drivers/gpu/drm/imagination/pvr_drv.c
+++ b/drivers/gpu/drm/imagination/pvr_drv.c
@@ -36,6 +36,7 @@
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 #include <linux/xarray.h>
 
 /**
@@ -1427,6 +1428,10 @@ pvr_probe(struct platform_device *plat_dev)
 	pm_runtime_use_autosuspend(&plat_dev->dev);
 	pvr_watchdog_init(pvr_dev);
 
+	pvr_dev->reset = devm_reset_control_get_optional_exclusive(&plat_dev->dev, "ahb");
+	if (PTR_ERR(pvr_dev->reset) == -EPROBE_DEFER)
+		return PTR_ERR(pvr_dev->reset);
+
 	err = pvr_device_init(pvr_dev);
 	if (err)
 		goto err_watchdog_fini;
diff --git a/drivers/gpu/drm/imagination/pvr_power.c b/drivers/gpu/drm/imagination/pvr_power.c
index ba7816fd28ec..a24ed85f36c7 100644
--- a/drivers/gpu/drm/imagination/pvr_power.c
+++ b/drivers/gpu/drm/imagination/pvr_power.c
@@ -15,6 +15,7 @@
 #include <linux/mutex.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 #include <linux/timer.h>
 #include <linux/types.h>
 #include <linux/workqueue.h>
@@ -252,6 +253,9 @@ pvr_power_device_suspend(struct device *dev)
 	clk_disable_unprepare(pvr_dev->sys_clk);
 	clk_disable_unprepare(pvr_dev->core_clk);
 
+	if (!IS_ERR(pvr_dev->reset))
+		reset_control_assert(pvr_dev->reset);
+
 err_drm_dev_exit:
 	drm_dev_exit(idx);
 
@@ -270,9 +274,15 @@ pvr_power_device_resume(struct device *dev)
 	if (!drm_dev_enter(drm_dev, &idx))
 		return -EIO;
 
+	if (!IS_ERR(pvr_dev->reset)) {
+		err = reset_control_reset(pvr_dev->reset);
+		if (err)
+			goto err_drm_dev_exit;
+	}
+
 	err = clk_prepare_enable(pvr_dev->core_clk);
 	if (err)
-		goto err_drm_dev_exit;
+		goto err_reset_exit;
 
 	err = clk_prepare_enable(pvr_dev->sys_clk);
 	if (err)
@@ -301,6 +311,10 @@ pvr_power_device_resume(struct device *dev)
 err_core_clk_disable:
 	clk_disable_unprepare(pvr_dev->core_clk);
 
+err_reset_exit:
+	if (!IS_ERR(pvr_dev->reset))
+		reset_control_assert(pvr_dev->reset);
+
 err_drm_dev_exit:
 	drm_dev_exit(idx);
 

-- 
2.39.2