[PATCH v2 5/9] drm/panthor: Implement support for multiple power domains

[Marek Vasut <marex@denx.de>]

The driver code power domain binding to driver instances only works
for single power domain, in case there are multiple power domains,
it is necessary to explicitly attach via dev_pm_domain_attach*().
As DT bindings list support for up to 5 power domains, add support
for attaching them all. This is useful on Freescale i.MX95 which
does have two power domains.

Signed-off-by: Marek Vasut <marex@denx.de>
---
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Conor Dooley <conor+dt@kernel.org>
Cc: David Airlie <airlied@gmail.com>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Krzysztof Kozlowski <krzk+dt@kernel.org>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: Steven Price <steven.price@arm.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: devicetree@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: imx@lists.linux.dev
Cc: linux-arm-kernel@lists.infradead.org
---
V2: Exit from panthor_genpd_init() on any pm_domain_attach_by_id() failure
---
 drivers/gpu/drm/panthor/panthor_device.c | 52 ++++++++++++++++++++++++
 drivers/gpu/drm/panthor/panthor_device.h |  5 +++
 2 files changed, 57 insertions(+)

diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index 51ee9cae94504..8aa79c6d157e1 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -75,6 +75,54 @@ static int panthor_reset_init(struct panthor_device *ptdev)
 	return 0;
 }
 
+/* Generic power domain handling code, see drivers/gpu/drm/tiny/simpledrm.c */
+static void panthor_detach_genpd(void *res)
+{
+	struct panthor_device *ptdev = res;
+	int i;
+
+	if (ptdev->pwr_dom_count <= 1)
+		return;
+
+	for (i = ptdev->pwr_dom_count - 1; i >= 0; i--)
+		dev_pm_domain_detach(ptdev->pwr_dom_devs[i], true);
+}
+
+static int panthor_genpd_init(struct panthor_device *ptdev)
+{
+	struct device *dev = ptdev->base.dev;
+	int i;
+
+	ptdev->pwr_dom_count = of_count_phandle_with_args(dev->of_node, "power-domains",
+							  "#power-domain-cells");
+	/*
+	 * Single power-domain devices are handled by driver core nothing to do
+	 * here. The same for device nodes without "power-domains" property.
+	 */
+	if (ptdev->pwr_dom_count <= 1)
+		return 0;
+
+	if (ptdev->pwr_dom_count > ARRAY_SIZE(ptdev->pwr_dom_devs)) {
+		drm_warn(&ptdev->base, "Too many power domains (%d) for this device\n",
+			 ptdev->pwr_dom_count);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < ptdev->pwr_dom_count; i++) {
+		ptdev->pwr_dom_devs[i] = dev_pm_domain_attach_by_id(dev, i);
+		if (!IS_ERR(ptdev->pwr_dom_devs[i]))
+			continue;
+
+		/* Missing dependency, try again. */
+		panthor_detach_genpd(ptdev);
+		return dev_err_probe(ptdev->base.dev,
+				     PTR_ERR(ptdev->pwr_dom_devs[i]),
+				     "pm_domain_attach_by_id(%u) failed\n", i);
+	}
+
+	return devm_add_action_or_reset(dev, panthor_detach_genpd, ptdev);
+}
+
 void panthor_device_unplug(struct panthor_device *ptdev)
 {
 	/* This function can be called from two different path: the reset work
@@ -232,6 +280,10 @@ int panthor_device_init(struct panthor_device *ptdev)
 	if (ret)
 		return ret;
 
+	ret = panthor_genpd_init(ptdev);
+	if (ret)
+		return ret;
+
 	ret = panthor_devfreq_init(ptdev);
 	if (ret)
 		return ret;
diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
index fea3a05778e2e..7fb65447253e9 100644
--- a/drivers/gpu/drm/panthor/panthor_device.h
+++ b/drivers/gpu/drm/panthor/panthor_device.h
@@ -114,6 +114,11 @@ struct panthor_device {
 	/** @resets: GPU reset. */
 	struct reset_control *resets;
 
+	/** @pwr_dom_count: Power domain count */
+	int pwr_dom_count;
+	/** @pwr_dom_dev: Power domain devices */
+	struct device *pwr_dom_devs[5];
+
 	/** @coherent: True if the CPU/GPU are memory coherent. */
 	bool coherent;
 
-- 
2.47.2