[PATCH 2/2] fbdev/simplefb: Add support for generic power-domains

[Thierry Reding <thierry.reding@gmail.com>]

From: Thierry Reding <treding@nvidia.com>

The simple-framebuffer device tree bindings document the power-domains
property, so make sure that simplefb supports it. This ensures that the
power domains remain enabled as long as simplefb is active.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/video/fbdev/simplefb.c | 93 +++++++++++++++++++++++++++++++++-
 1 file changed, 91 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
index 18025f34fde7..e69fb0ad2d54 100644
--- a/drivers/video/fbdev/simplefb.c
+++ b/drivers/video/fbdev/simplefb.c
@@ -25,6 +25,7 @@
 #include <linux/of_clk.h>
 #include <linux/of_platform.h>
 #include <linux/parser.h>
+#include <linux/pm_domain.h>
 #include <linux/regulator/consumer.h>
 
 static const struct fb_fix_screeninfo simplefb_fix = {
@@ -78,6 +79,11 @@ struct simplefb_par {
 	unsigned int clk_count;
 	struct clk **clks;
 #endif
+#if defined CONFIG_OF && defined CONFIG_PM_GENERIC_DOMAINS
+	unsigned int num_genpds;
+	struct device **genpds;
+	struct device_link **genpd_links;
+#endif
 #if defined CONFIG_OF && defined CONFIG_REGULATOR
 	bool regulators_enabled;
 	u32 regulator_count;
@@ -432,6 +438,83 @@ static void simplefb_regulators_enable(struct simplefb_par *par,
 static void simplefb_regulators_destroy(struct simplefb_par *par) { }
 #endif
 
+#if defined CONFIG_OF && defined CONFIG_PM_GENERIC_DOMAINS
+static void simplefb_detach_genpds(void *res)
+{
+	struct simplefb_par *par = res;
+	unsigned int i = par->num_genpds;
+
+	if (par->num_genpds <= 1)
+		return;
+
+	while (i--) {
+		if (par->genpd_links[i])
+			device_link_del(par->genpd_links[i]);
+
+		if (!IS_ERR_OR_NULL(par->genpds[i]))
+			dev_pm_domain_detach(par->genpds[i], true);
+	}
+}
+
+static int simplefb_attach_genpd(struct simplefb_par *par,
+				 struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	unsigned int i;
+	int err;
+
+	par->num_genpds = of_count_phandle_with_args(dev->of_node,
+						     "power-domains",
+						     "#power-domain-cells");
+	/*
+	 * Single power-domain devices are handled by the driver core, so
+	 * nothing to do here.
+	 */
+	if (par->num_genpds <= 1)
+		return 0;
+
+	par->genpds = devm_kcalloc(dev, par->num_genpds, sizeof(*par->genpds),
+				   GFP_KERNEL);
+	if (!par->genpds)
+		return -ENOMEM;
+
+	par->genpd_links = devm_kcalloc(dev, par->num_genpds,
+					sizeof(*par->genpd_links),
+					GFP_KERNEL);
+	if (!par->genpd_links)
+		return -ENOMEM;
+
+	for (i = 0; i < par->num_genpds; i++) {
+		par->genpds[i] = dev_pm_domain_attach_by_id(dev, i);
+		if (IS_ERR(par->genpds[i])) {
+			err = PTR_ERR(par->genpds[i]);
+			if (err == -EPROBE_DEFER) {
+				simplefb_detach_genpds(par);
+				return err;
+			}
+
+			dev_warn(dev, "failed to attach domain %u: %d\n", i, err);
+			continue;
+		}
+
+		par->genpd_links[i] = device_link_add(dev, par->genpds[i],
+						      DL_FLAG_STATELESS |
+						      DL_FLAG_PM_RUNTIME |
+						      DL_FLAG_RPM_ACTIVE);
+		if (!par->genpd_links[i])
+			dev_warn(dev, "failed to link power-domain %u\n", i);
+	}
+
+	return devm_add_action_or_reset(dev, simplefb_detach_genpds, par);
+}
+#else
+static int simplefb_attach_genpd(struct simplefb_par *par,
+				 struct platform_device *pdev)
+{
+	return 0;
+}
+#endif
+
 static int simplefb_probe(struct platform_device *pdev)
 {
 	int ret;
@@ -518,6 +601,10 @@ static int simplefb_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto error_clocks;
 
+	ret = simplefb_attach_genpd(par, pdev);
+	if (ret < 0)
+		goto error_regulators;
+
 	simplefb_clocks_enable(par, pdev);
 	simplefb_regulators_enable(par, pdev);
 
@@ -534,18 +621,20 @@ static int simplefb_probe(struct platform_device *pdev)
 	ret = devm_aperture_acquire_for_platform_device(pdev, par->base, par->size);
 	if (ret) {
 		dev_err(&pdev->dev, "Unable to acquire aperture: %d\n", ret);
-		goto error_regulators;
+		goto error_genpds;
 	}
 	ret = register_framebuffer(info);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "Unable to register simplefb: %d\n", ret);
-		goto error_regulators;
+		goto error_genpds;
 	}
 
 	dev_info(&pdev->dev, "fb%d: simplefb registered!\n", info->node);
 
 	return 0;
 
+error_genpds:
+	simplefb_detach_genpds(par);
 error_regulators:
 	simplefb_regulators_destroy(par);
 error_clocks:
-- 
2.42.0