fbdev/simplefb: Add support for generic power-domains

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.

v2: - remove unnecessary call to simplefb_detach_genpds() since that's
      already done automatically by devres
    - fix crash if power-domains property is missing in DT

Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231101172017.3872242-3-thierry.reding@gmail.com

diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
index 18025f34fde71e2bb6e0a3be29477e3b806ab623..fe682af63827baa4ab3af590b368d5bb7b88c5c4 100644 (file)
--- 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 +438,89 @@ 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_genpds(struct simplefb_par *par,
+                                 struct platform_device *pdev)
+{
+       struct device *dev = &pdev->dev;
+       unsigned int i;
+       int err;
+
+       err = of_count_phandle_with_args(dev->of_node, "power-domains",
+                                        "#power-domain-cells");
+       if (err < 0) {
+               dev_info(dev, "failed to parse power-domains: %d\n", err);
+               return err;
+       }
+
+       par->num_genpds = err;
+
+       /*
+        * 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_genpds(struct simplefb_par *par,
+                                 struct platform_device *pdev)
+{
+       return 0;
+}
+#endif
+
 static int simplefb_probe(struct platform_device *pdev)
 {
        int ret;
@@ -518,6 +607,10 @@ static int simplefb_probe(struct platform_device *pdev)
        if (ret < 0)
                goto error_clocks;
 
+       ret = simplefb_attach_genpds(par, pdev);
+       if (ret < 0)
+               goto error_regulators;
+
        simplefb_clocks_enable(par, pdev);
        simplefb_regulators_enable(par, pdev);