[PATCH v3 5/7] drm/panfrost: Add support for multiple power domains

[Nicolas Boichat]

When there is a single power domain per device, the core will
ensure the power domain is switched on (so it is technically
equivalent to having not power domain specified at all).

However, when there are multiple domains, as in MT8183 Bifrost
GPU, we need to handle them in driver code.

Signed-off-by: Nicolas Boichat <drinkcat@xxxxxxxxxxxx>

---

The downstream driver we use on chromeos-4.19 currently uses 2
additional devices in device tree to accomodate for this [1], but
I believe this solution is cleaner.

[1] https://chromium.googlesource.com/chromiumos/third_party/kernel/+/refs/heads/chromeos-4.19/drivers/gpu/arm/midgard/platform/mediatek/mali_kbase_runtime_pm.c#31

v3:
 - Use the compatible matching data to specify the number of power
   domains. Note that setting 0 or 1 in num_pm_domains is equivalent
   as the core will handle these 2 cases in the exact same way
   (automatically, without driver intervention), and there should
   be no adverse consequence in this case (the concern is about
   switching on only some power domains and not others).

 drivers/gpu/drm/panfrost/panfrost_device.c | 95 ++++++++++++++++++++--
 drivers/gpu/drm/panfrost/panfrost_device.h |  9 ++
 drivers/gpu/drm/panfrost/panfrost_drv.c    |  1 +
 3 files changed, 97 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
index c30e0a3772a4f57..7c9766f76cc7689 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.c
+++ b/drivers/gpu/drm/panfrost/panfrost_device.c
@@ -5,6 +5,7 @@
 #include <linux/clk.h>
 #include <linux/reset.h>
 #include <linux/platform_device.h>
+#include <linux/pm_domain.h>
 #include <linux/regulator/consumer.h>
 
 #include "panfrost_device.h"
@@ -119,6 +120,75 @@ static void panfrost_regulator_fini(struct panfrost_device *pfdev)
 			pfdev->regulators);
 }
 
+static void panfrost_pm_domain_fini(struct panfrost_device *pfdev)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(pfdev->pm_domain_devs); i++) {
+		if (!pfdev->pm_domain_devs[i])
+			break;
+
+		if (pfdev->pm_domain_links[i])
+			device_link_del(pfdev->pm_domain_links[i]);
+
+		dev_pm_domain_detach(pfdev->pm_domain_devs[i], true);
+	}
+}
+
+static int panfrost_pm_domain_init(struct panfrost_device *pfdev)
+{
+	int err;
+	int i, num_domains;
+
+	num_domains = of_count_phandle_with_args(pfdev->dev->of_node,
+						 "power-domains",
+						 "#power-domain-cells");
+
+	/*
+	 * Single domain is handled by the core, and, if only a single power
+	 * the power domain is requested, the property is optional.
+	 */
+	if (num_domains < 2 && pfdev->comp->num_pm_domains < 2)
+		return 0;
+
+	if (num_domains != pfdev->comp->num_pm_domains) {
+		dev_err(pfdev->dev,
+			"Incorrect number of power domains: %d provided, %d needed\n",
+			num_domains, pfdev->comp->num_pm_domains);
+		return -EINVAL;
+	}
+
+	BUG_ON(num_domains > ARRAY_SIZE(pfdev->pm_domain_devs));
+
+	for (i = 0; i < num_domains; i++) {
+		pfdev->pm_domain_devs[i] =
+			dev_pm_domain_attach_by_id(pfdev->dev, i);
+		if (IS_ERR(pfdev->pm_domain_devs[i])) {
+			err = PTR_ERR(pfdev->pm_domain_devs[i]);
+			pfdev->pm_domain_devs[i] = NULL;
+			dev_err(pfdev->dev,
+				"failed to get pm-domain %d: %d\n", i, err);
+			goto err;
+		}
+
+		pfdev->pm_domain_links[i] = device_link_add(pfdev->dev,
+				pfdev->pm_domain_devs[i], DL_FLAG_PM_RUNTIME |
+				DL_FLAG_STATELESS | DL_FLAG_RPM_ACTIVE);
+		if (!pfdev->pm_domain_links[i]) {
+			dev_err(pfdev->pm_domain_devs[i],
+				"adding device link failed!\n");
+			err = -ENODEV;
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	panfrost_pm_domain_fini(pfdev);
+	return err;
+}
+
 int panfrost_device_init(struct panfrost_device *pfdev)
 {
 	int err;
@@ -149,37 +219,45 @@ int panfrost_device_init(struct panfrost_device *pfdev)
 		goto err_out1;
 	}
 
+	err = panfrost_pm_domain_init(pfdev);
+	if (err) {
+		dev_err(pfdev->dev, "pm_domain init failed %d\n", err);
+		goto err_out2;
+	}
+
 	res = platform_get_resource(pfdev->pdev, IORESOURCE_MEM, 0);
 	pfdev->iomem = devm_ioremap_resource(pfdev->dev, res);
 	if (IS_ERR(pfdev->iomem)) {
 		dev_err(pfdev->dev, "failed to ioremap iomem\n");
 		err = PTR_ERR(pfdev->iomem);
-		goto err_out2;
+		goto err_out3;
 	}
 
 	err = panfrost_gpu_init(pfdev);
 	if (err)
-		goto err_out2;
+		goto err_out3;
 
 	err = panfrost_mmu_init(pfdev);
 	if (err)
-		goto err_out3;
+		goto err_out4;
 
 	err = panfrost_job_init(pfdev);
 	if (err)
-		goto err_out4;
+		goto err_out5;
 
 	err = panfrost_perfcnt_init(pfdev);
 	if (err)
-		goto err_out5;
+		goto err_out6;
 
 	return 0;
-err_out5:
+err_out6:
 	panfrost_job_fini(pfdev);
-err_out4:
+err_out5:
 	panfrost_mmu_fini(pfdev);
-err_out3:
+err_out4:
 	panfrost_gpu_fini(pfdev);
+err_out3:
+	panfrost_pm_domain_fini(pfdev);
 err_out2:
 	panfrost_reset_fini(pfdev);
 err_out1:
@@ -196,6 +274,7 @@ void panfrost_device_fini(struct panfrost_device *pfdev)
 	panfrost_mmu_fini(pfdev);
 	panfrost_gpu_fini(pfdev);
 	panfrost_reset_fini(pfdev);
+	panfrost_pm_domain_fini(pfdev);
 	panfrost_regulator_fini(pfdev);
 	panfrost_clk_fini(pfdev);
 }
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
index 021f063ffb3747f..143eab57180a2e1 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -21,6 +21,7 @@ struct panfrost_perfcnt;
 
 #define NUM_JOB_SLOTS 3
 #define MAX_REGULATORS 2
+#define MAX_PM_DOMAINS 3
 
 struct panfrost_features {
 	u16 id;
@@ -61,6 +62,11 @@ struct panfrost_compatible {
 	/* Supplies count and names. */
 	int num_supplies;
 	const char * const *supply_names;
+	/*
+	 * Number of power domains required, note that values 0 and 1 are
+	 * handled identically, as only values > 1 need special handling.
+	 */
+	int num_pm_domains;
 };
 
 struct panfrost_device {
@@ -73,6 +79,9 @@ struct panfrost_device {
 	struct clk *bus_clock;
 	struct regulator_bulk_data regulators[MAX_REGULATORS];
 	struct reset_control *rstc;
+	/* pm_domains for devices with more than one. */
+	struct device *pm_domain_devs[MAX_PM_DOMAINS];
+	struct device_link *pm_domain_links[MAX_PM_DOMAINS];
 
 	struct panfrost_features features;
 	const struct panfrost_compatible* comp;
diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
index db3563b80150c9d..42b87e29e605149 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -589,6 +589,7 @@ const char * const default_supplies[] = { "mali" };
 static const struct panfrost_compatible default_data = {
 	.num_supplies = ARRAY_SIZE(default_supplies),
 	.supply_names = default_supplies,
+	.num_pm_domains = 1, /* optional */
 };
 
 static const struct of_device_id dt_match[] = {
-- 
2.25.0.rc1.283.g88dfdc4193-goog