[PATCH v5 05/18] drm/imagination: Add power domain control

[Matt Coster <matt.coster@imgtec.com>]

The first supported GPU only used a single power domain so this was
automatically handled by the device runtime.

In order to support multiple power domains, they must be enumerated from
devicetree and linked to both the GPU device and each other to ensure
correct power sequencing at start time.

For all Imagination Rogue GPUs, power domains are named "a", "b", etc. and
the sequence A->B->... is always valid for startup with the reverse true
for shutdown. Note this is not always the *only* valid sequence, but it's
simple and does not require special-casing for different GPU power
topologies.

Signed-off-by: Matt Coster <matt.coster@imgtec.com>
---
Changes in v5:
- None
- Link to v4: https://lore.kernel.org/r/20250320-sets-bxs-4-64-patch-v1-v4-5-d987cf4ca439@imgtec.com
Changes in v4:
- None
- Link to v3: https://lore.kernel.org/r/20250310-sets-bxs-4-64-patch-v1-v3-5-143b3dbef02f@imgtec.com
Changes in v3:
- None
- Link to v2: https://lore.kernel.org/r/20241118-sets-bxs-4-64-patch-v1-v2-6-3fd45d9fb0cf@imgtec.com
Changes in v2:
- None
- Link to v1: https://lore.kernel.org/r/20241105-sets-bxs-4-64-patch-v1-v1-6-4ed30e865892@imgtec.com
---
 drivers/gpu/drm/imagination/pvr_device.h |   8 +++
 drivers/gpu/drm/imagination/pvr_drv.c    |   7 ++
 drivers/gpu/drm/imagination/pvr_power.c  | 114 +++++++++++++++++++++++++++++++
 drivers/gpu/drm/imagination/pvr_power.h  |   3 +
 4 files changed, 132 insertions(+)

diff --git a/drivers/gpu/drm/imagination/pvr_device.h b/drivers/gpu/drm/imagination/pvr_device.h
index 6d0dfacb677b46a880f37f419dfa7b67c68fe63d..2dd8a8885fe07078896d669d822525fb2b7bab51 100644
--- a/drivers/gpu/drm/imagination/pvr_device.h
+++ b/drivers/gpu/drm/imagination/pvr_device.h
@@ -18,6 +18,7 @@
 #include <linux/bits.h>
 #include <linux/compiler_attributes.h>
 #include <linux/compiler_types.h>
+#include <linux/device.h>
 #include <linux/io.h>
 #include <linux/iopoll.h>
 #include <linux/kernel.h>
@@ -131,6 +132,13 @@ struct pvr_device {
 	 */
 	struct clk *mem_clk;
 
+	struct pvr_device_power {
+		struct device **domain_devs;
+		struct device_link **domain_links;
+
+		u32 domain_count;
+	} power;
+
 	/** @irq: IRQ number. */
 	int irq;
 
diff --git a/drivers/gpu/drm/imagination/pvr_drv.c b/drivers/gpu/drm/imagination/pvr_drv.c
index 3130193f8fffc185e630a293be53374bdc4b7ce0..ac4f5855c5692f0956862cebdbf76b16d8da9a81 100644
--- a/drivers/gpu/drm/imagination/pvr_drv.c
+++ b/drivers/gpu/drm/imagination/pvr_drv.c
@@ -1411,6 +1411,10 @@ pvr_probe(struct platform_device *plat_dev)
 
 	platform_set_drvdata(plat_dev, drm_dev);
 
+	err = pvr_power_domains_init(pvr_dev);
+	if (err)
+		return err;
+
 	init_rwsem(&pvr_dev->reset_sem);
 
 	pvr_context_device_init(pvr_dev);
@@ -1450,6 +1454,8 @@ pvr_probe(struct platform_device *plat_dev)
 err_context_fini:
 	pvr_context_device_fini(pvr_dev);
 
+	pvr_power_domains_fini(pvr_dev);
+
 	return err;
 }
 
@@ -1470,6 +1476,7 @@ static void pvr_remove(struct platform_device *plat_dev)
 	pvr_watchdog_fini(pvr_dev);
 	pvr_queue_device_fini(pvr_dev);
 	pvr_context_device_fini(pvr_dev);
+	pvr_power_domains_fini(pvr_dev);
 }
 
 static const struct of_device_id dt_match[] = {
diff --git a/drivers/gpu/drm/imagination/pvr_power.c b/drivers/gpu/drm/imagination/pvr_power.c
index ba7816fd28ec77e6ca5ce408302a413ce1afeb6e..19b079b357df78e8bcdecfa377fc9c05b6e8e4b0 100644
--- a/drivers/gpu/drm/imagination/pvr_power.c
+++ b/drivers/gpu/drm/imagination/pvr_power.c
@@ -10,10 +10,13 @@
 
 #include <drm/drm_drv.h>
 #include <drm/drm_managed.h>
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/interrupt.h>
 #include <linux/mutex.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
+#include <linux/pm_domain.h>
 #include <linux/pm_runtime.h>
 #include <linux/timer.h>
 #include <linux/types.h>
@@ -431,3 +434,114 @@ pvr_watchdog_fini(struct pvr_device *pvr_dev)
 {
 	cancel_delayed_work_sync(&pvr_dev->watchdog.work);
 }
+
+int pvr_power_domains_init(struct pvr_device *pvr_dev)
+{
+	struct device *dev = from_pvr_device(pvr_dev)->dev;
+
+	struct device_link **domain_links __free(kfree) = NULL;
+	struct device **domain_devs __free(kfree) = NULL;
+	int domain_count;
+	int link_count;
+
+	char dev_name[2] = "a";
+	int err;
+	int i;
+
+	domain_count = of_count_phandle_with_args(dev->of_node, "power-domains",
+						  "#power-domain-cells");
+	if (domain_count < 0)
+		return domain_count;
+
+	if (domain_count <= 1)
+		return 0;
+
+	link_count = domain_count + (domain_count - 1);
+
+	domain_devs = kcalloc(domain_count, sizeof(*domain_devs), GFP_KERNEL);
+	if (!domain_devs)
+		return -ENOMEM;
+
+	domain_links = kcalloc(link_count, sizeof(*domain_links), GFP_KERNEL);
+	if (!domain_links)
+		return -ENOMEM;
+
+	for (i = 0; i < domain_count; i++) {
+		struct device *domain_dev;
+
+		dev_name[0] = 'a' + i;
+		domain_dev = dev_pm_domain_attach_by_name(dev, dev_name);
+		if (IS_ERR_OR_NULL(domain_dev)) {
+			err = domain_dev ? PTR_ERR(domain_dev) : -ENODEV;
+			goto err_detach;
+		}
+
+		domain_devs[i] = domain_dev;
+	}
+
+	for (i = 0; i < domain_count; i++) {
+		struct device_link *link;
+
+		link = device_link_add(dev, domain_devs[i], DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
+		if (!link) {
+			err = -ENODEV;
+			goto err_unlink;
+		}
+
+		domain_links[i] = link;
+	}
+
+	for (i = domain_count; i < link_count; i++) {
+		struct device_link *link;
+
+		link = device_link_add(domain_devs[i - domain_count + 1],
+				       domain_devs[i - domain_count],
+				       DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
+		if (!link) {
+			err = -ENODEV;
+			goto err_unlink;
+		}
+
+		domain_links[i] = link;
+	}
+
+	pvr_dev->power = (struct pvr_device_power){
+		.domain_devs = no_free_ptr(domain_devs),
+		.domain_links = no_free_ptr(domain_links),
+		.domain_count = domain_count,
+	};
+
+	return 0;
+
+err_unlink:
+	while (--i >= 0)
+		device_link_del(domain_links[i]);
+
+	i = domain_count;
+
+err_detach:
+	while (--i >= 0)
+		dev_pm_domain_detach(domain_devs[i], true);
+
+	return err;
+}
+
+void pvr_power_domains_fini(struct pvr_device *pvr_dev)
+{
+	const int domain_count = pvr_dev->power.domain_count;
+
+	int i = domain_count + (domain_count - 1);
+
+	while (--i >= 0)
+		device_link_del(pvr_dev->power.domain_links[i]);
+
+	i = domain_count;
+
+	while (--i >= 0)
+		dev_pm_domain_detach(pvr_dev->power.domain_devs[i], true);
+
+	kfree(pvr_dev->power.domain_links);
+	kfree(pvr_dev->power.domain_devs);
+
+	pvr_dev->power = (struct pvr_device_power){ 0 };
+}
diff --git a/drivers/gpu/drm/imagination/pvr_power.h b/drivers/gpu/drm/imagination/pvr_power.h
index 9a9312dcb2dab7d36ee8ff7f69e69d126c5469a9..ada85674a7ca762dcf92df40424230e1c3910342 100644
--- a/drivers/gpu/drm/imagination/pvr_power.h
+++ b/drivers/gpu/drm/imagination/pvr_power.h
@@ -38,4 +38,7 @@ pvr_power_put(struct pvr_device *pvr_dev)
 	return pm_runtime_put(drm_dev->dev);
 }
 
+int pvr_power_domains_init(struct pvr_device *pvr_dev);
+void pvr_power_domains_fini(struct pvr_device *pvr_dev);
+
 #endif /* PVR_POWER_H */

-- 
2.49.0