drm/imagination: Implement power management

Add power management to the driver, using runtime pm. The power off
sequence depends on firmware commands which are not implemented in this
patch.

Changes since v8:
- Corrected license identifiers

Changes since v5:
- Use RUNTIME_PM_OPS() to declare PM callbacks
- Add Kconfig dependency on CONFIG_PM

Changes since v4:
- Suspend runtime PM before unplugging device on rmmod

Changes since v3:
- Don't power device when calling pvr_device_gpu_fini()
- Documentation for pvr_dev->lost has been improved
- pvr_power_init() renamed to pvr_watchdog_init()
- Use drm_dev_{enter,exit}

Changes since v2:
- Use runtime PM
- Implement watchdog

Signed-off-by: Sarah Walker <sarah.walker@imgtec.com>
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/e09af4ef1ff514e1d6d7f97c7c5032c643c56f9c.1700668843.git.donald.robson@imgtec.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>

drivers/gpu/drm/imagination/Kconfig

@@ -5,6 +5,7 @@ config DRM_POWERVR
 	tristate "Imagination Technologies PowerVR (Series 6 and later) & IMG Graphics"
 	depends on ARM64
 	depends on DRM
+	depends on PM
 	select DRM_GEM_SHMEM_HELPER
 	select DRM_SCHED
 	select DRM_GPUVM

drivers/gpu/drm/imagination/Makefile

@@ -10,6 +10,7 @@ powervr-y := \
 	pvr_fw.o \
 	pvr_gem.o \
 	pvr_mmu.o \
+	pvr_power.o \
 	pvr_vm.o
 
 obj-$(CONFIG_DRM_POWERVR) += powervr.o

drivers/gpu/drm/imagination/pvr_device.c

@@ -5,6 +5,7 @@
 #include "pvr_device_info.h"
 
 #include "pvr_fw.h"
+#include "pvr_power.h"
 #include "pvr_rogue_cr_defs.h"
 #include "pvr_vm.h"
 
@@ -361,20 +362,38 @@ pvr_device_gpu_fini(struct pvr_device *pvr_dev)
 int
 pvr_device_init(struct pvr_device *pvr_dev)
 {
+	struct drm_device *drm_dev = from_pvr_device(pvr_dev);
+	struct device *dev = drm_dev->dev;
 	int err;
 
 	/* Enable and initialize clocks required for the device to operate. */
 	err = pvr_device_clk_init(pvr_dev);
 	if (err)
 		return err;
 
+	/* Explicitly power the GPU so we can access control registers before the FW is booted. */
+	err = pm_runtime_resume_and_get(dev);
+	if (err)
+		return err;
+
 	/* Map the control registers into memory. */
 	err = pvr_device_reg_init(pvr_dev);
 	if (err)
-		return err;
+		goto err_pm_runtime_put;
 
 	/* Perform GPU-specific initialization steps. */
-	return pvr_device_gpu_init(pvr_dev);
+	err = pvr_device_gpu_init(pvr_dev);
+	if (err)
+		goto err_pm_runtime_put;
+
+	pm_runtime_put(dev);
+
+	return 0;
+
+err_pm_runtime_put:
+	pm_runtime_put_sync_suspend(dev);
+
+	return err;
 }
 
 /**

drivers/gpu/drm/imagination/pvr_device.h

@@ -141,6 +141,28 @@ struct pvr_device {
 	 * before submitting the next job.
 	 */
 	atomic_t mmu_flush_cache_flags;
+
+	struct {
+		/** @work: Work item for watchdog callback. */
+		struct delayed_work work;
+
+		/** @old_kccb_cmds_executed: KCCB command execution count at last watchdog poll. */
+		u32 old_kccb_cmds_executed;
+
+		/** @kccb_stall_count: Number of watchdog polls KCCB has been stalled for. */
+		u32 kccb_stall_count;
+	} watchdog;
+
+	/**
+	 * @lost: %true if the device has been lost.
+	 *
+	 * This variable is set if the device has become irretrievably unavailable, e.g. if the
+	 * firmware processor has stopped responding and can not be revived via a hard reset.
+	 */
+	bool lost;
+
+	/** @sched_wq: Workqueue for schedulers. */
+	struct workqueue_struct *sched_wq;
 };
 
 /**

drivers/gpu/drm/imagination/pvr_drv.c

@@ -5,6 +5,7 @@
 #include "pvr_drv.h"
 #include "pvr_gem.h"
 #include "pvr_mmu.h"
+#include "pvr_power.h"
 #include "pvr_rogue_defs.h"
 #include "pvr_rogue_fwif_client.h"
 #include "pvr_rogue_fwif_shared.h"
@@ -1265,9 +1266,16 @@ pvr_probe(struct platform_device *plat_dev)
 
 	platform_set_drvdata(plat_dev, drm_dev);
 
+	devm_pm_runtime_enable(&plat_dev->dev);
+	pm_runtime_mark_last_busy(&plat_dev->dev);
+
+	pm_runtime_set_autosuspend_delay(&plat_dev->dev, 50);
+	pm_runtime_use_autosuspend(&plat_dev->dev);
+	pvr_watchdog_init(pvr_dev);
+
 	err = pvr_device_init(pvr_dev);
 	if (err)
-		return err;
+		goto err_watchdog_fini;
 
 	err = drm_dev_register(drm_dev, 0);
 	if (err)
@@ -1278,6 +1286,9 @@ pvr_probe(struct platform_device *plat_dev)
 err_device_fini:
 	pvr_device_fini(pvr_dev);
 
+err_watchdog_fini:
+	pvr_watchdog_fini(pvr_dev);
+
 	return err;
 }
 
@@ -1287,8 +1298,10 @@ pvr_remove(struct platform_device *plat_dev)
 	struct drm_device *drm_dev = platform_get_drvdata(plat_dev);
 	struct pvr_device *pvr_dev = to_pvr_device(drm_dev);
 
+	pm_runtime_suspend(drm_dev->dev);
 	pvr_device_fini(pvr_dev);
 	drm_dev_unplug(drm_dev);
+	pvr_watchdog_fini(pvr_dev);
 
 	return 0;
 }
@@ -1299,11 +1312,16 @@ static const struct of_device_id dt_match[] = {
 };
 MODULE_DEVICE_TABLE(of, dt_match);
 
+static const struct dev_pm_ops pvr_pm_ops = {
+	RUNTIME_PM_OPS(pvr_power_device_suspend, pvr_power_device_resume, pvr_power_device_idle)
+};
+
 static struct platform_driver pvr_driver = {
 	.probe = pvr_probe,
 	.remove = pvr_remove,
 	.driver = {
 		.name = PVR_DRIVER_NAME,
+		.pm = &pvr_pm_ops,
 		.of_match_table = dt_match,
 	},
 };