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From:   Sarah Walker <sarah.walker@imgtec.com>
To:     <dri-devel@lists.freedesktop.org>
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        <linux-doc@vger.kernel.org>
Subject: [PATCH v8 12/20] drm/imagination: Implement power management
Date:   Tue, 31 Oct 2023 15:12:49 +0000
Message-Id: <20231031151257.90350-13-sarah.walker@imgtec.com>
In-Reply-To: <20231031151257.90350-1-sarah.walker@imgtec.com>
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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 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>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
---
 drivers/gpu/drm/imagination/Kconfig      |   1 +
 drivers/gpu/drm/imagination/Makefile     |   1 +
 drivers/gpu/drm/imagination/pvr_device.c |  23 +-
 drivers/gpu/drm/imagination/pvr_device.h |  22 ++
 drivers/gpu/drm/imagination/pvr_drv.c    |  20 +-
 drivers/gpu/drm/imagination/pvr_power.c  | 271 +++++++++++++++++++++++
 drivers/gpu/drm/imagination/pvr_power.h  |  39 ++++
 7 files changed, 374 insertions(+), 3 deletions(-)
 create mode 100644 drivers/gpu/drm/imagination/pvr_power.c
 create mode 100644 drivers/gpu/drm/imagination/pvr_power.h

diff --git a/drivers/gpu/drm/imagination/Kconfig b/drivers/gpu/drm/imagination/Kconfig
index 3e167d5470b4..2639fbf3ebac 100644
--- a/drivers/gpu/drm/imagination/Kconfig
+++ b/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
diff --git a/drivers/gpu/drm/imagination/Makefile b/drivers/gpu/drm/imagination/Makefile
index 8fcabc1bea36..235e2d329e29 100644
--- a/drivers/gpu/drm/imagination/Makefile
+++ b/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
diff --git a/drivers/gpu/drm/imagination/pvr_device.c b/drivers/gpu/drm/imagination/pvr_device.c
index f71e400ea24e..51ff10522d23 100644
--- a/drivers/gpu/drm/imagination/pvr_device.c
+++ b/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"
 
@@ -361,6 +362,8 @@ 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. */
@@ -368,13 +371,29 @@ pvr_device_init(struct pvr_device *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;
 }
 
 /**
diff --git a/drivers/gpu/drm/imagination/pvr_device.h b/drivers/gpu/drm/imagination/pvr_device.h
index a5e62ca00737..0f37d84e9c61 100644
--- a/drivers/gpu/drm/imagination/pvr_device.h
+++ b/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;
 };
 
 /**
diff --git a/drivers/gpu/drm/imagination/pvr_drv.c b/drivers/gpu/drm/imagination/pvr_drv.c
index c3a5cc04c3de..debec785a7c0 100644
--- a/drivers/gpu/drm/imagination/pvr_drv.c
+++ b/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,
 	},
 };
diff --git a/drivers/gpu/drm/imagination/pvr_power.c b/drivers/gpu/drm/imagination/pvr_power.c
new file mode 100644
index 000000000000..a494fed92e81
--- /dev/null
+++ b/drivers/gpu/drm/imagination/pvr_power.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+/* Copyright (c) 2023 Imagination Technologies Ltd. */
+
+#include "pvr_device.h"
+#include "pvr_fw.h"
+#include "pvr_power.h"
+#include "pvr_rogue_fwif.h"
+
+#include <drm/drm_drv.h>
+#include <drm/drm_managed.h>
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/timer.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+#define POWER_SYNC_TIMEOUT_US (1000000) /* 1s */
+
+#define WATCHDOG_TIME_MS (500)
+
+static int
+pvr_power_send_command(struct pvr_device *pvr_dev, struct rogue_fwif_kccb_cmd *pow_cmd)
+{
+	/* TODO: implement */
+	return -ENODEV;
+}
+
+static int
+pvr_power_request_idle(struct pvr_device *pvr_dev)
+{
+	struct rogue_fwif_kccb_cmd pow_cmd;
+
+	/* Send FORCED_IDLE request to FW. */
+	pow_cmd.cmd_type = ROGUE_FWIF_KCCB_CMD_POW;
+	pow_cmd.cmd_data.pow_data.pow_type = ROGUE_FWIF_POW_FORCED_IDLE_REQ;
+	pow_cmd.cmd_data.pow_data.power_req_data.pow_request_type = ROGUE_FWIF_POWER_FORCE_IDLE;
+
+	return pvr_power_send_command(pvr_dev, &pow_cmd);
+}
+
+static int
+pvr_power_request_pwr_off(struct pvr_device *pvr_dev)
+{
+	struct rogue_fwif_kccb_cmd pow_cmd;
+
+	/* Send POW_OFF request to firmware. */
+	pow_cmd.cmd_type = ROGUE_FWIF_KCCB_CMD_POW;
+	pow_cmd.cmd_data.pow_data.pow_type = ROGUE_FWIF_POW_OFF_REQ;
+	pow_cmd.cmd_data.pow_data.power_req_data.forced = true;
+
+	return pvr_power_send_command(pvr_dev, &pow_cmd);
+}
+
+static int
+pvr_power_fw_disable(struct pvr_device *pvr_dev, bool hard_reset)
+{
+	if (!hard_reset) {
+		int err;
+
+		cancel_delayed_work_sync(&pvr_dev->watchdog.work);
+
+		err = pvr_power_request_idle(pvr_dev);
+		if (err)
+			return err;
+
+		err = pvr_power_request_pwr_off(pvr_dev);
+		if (err)
+			return err;
+	}
+
+	/* TODO: stop firmware */
+	return -ENODEV;
+}
+
+static int
+pvr_power_fw_enable(struct pvr_device *pvr_dev)
+{
+	int err;
+
+	/* TODO: start firmware */
+	err = -ENODEV;
+	if (err)
+		return err;
+
+	queue_delayed_work(pvr_dev->sched_wq, &pvr_dev->watchdog.work,
+			   msecs_to_jiffies(WATCHDOG_TIME_MS));
+
+	return 0;
+}
+
+bool
+pvr_power_is_idle(struct pvr_device *pvr_dev)
+{
+	/* TODO: implement */
+	return true;
+}
+
+static bool
+pvr_watchdog_kccb_stalled(struct pvr_device *pvr_dev)
+{
+	/* TODO: implement */
+	return false;
+}
+
+static void
+pvr_watchdog_worker(struct work_struct *work)
+{
+	struct pvr_device *pvr_dev = container_of(work, struct pvr_device,
+						  watchdog.work.work);
+	bool stalled;
+
+	if (pvr_dev->lost)
+		return;
+
+	if (pm_runtime_get_if_in_use(from_pvr_device(pvr_dev)->dev) <= 0)
+		goto out_requeue;
+
+	stalled = pvr_watchdog_kccb_stalled(pvr_dev);
+
+	if (stalled) {
+		drm_err(from_pvr_device(pvr_dev), "FW stalled, trying hard reset");
+
+		pvr_power_reset(pvr_dev, true);
+		/* Device may be lost at this point. */
+	}
+
+	pm_runtime_put(from_pvr_device(pvr_dev)->dev);
+
+out_requeue:
+	if (!pvr_dev->lost) {
+		queue_delayed_work(pvr_dev->sched_wq, &pvr_dev->watchdog.work,
+				   msecs_to_jiffies(WATCHDOG_TIME_MS));
+	}
+}
+
+/**
+ * pvr_watchdog_init() - Initialise watchdog for device
+ * @pvr_dev: Target PowerVR device.
+ *
+ * Returns:
+ *  * 0 on success, or
+ *  * -%ENOMEM on out of memory.
+ */
+int
+pvr_watchdog_init(struct pvr_device *pvr_dev)
+{
+	INIT_DELAYED_WORK(&pvr_dev->watchdog.work, pvr_watchdog_worker);
+
+	return 0;
+}
+
+int
+pvr_power_device_suspend(struct device *dev)
+{
+	struct platform_device *plat_dev = to_platform_device(dev);
+	struct drm_device *drm_dev = platform_get_drvdata(plat_dev);
+	struct pvr_device *pvr_dev = to_pvr_device(drm_dev);
+	int idx;
+
+	if (!drm_dev_enter(drm_dev, &idx))
+		return -EIO;
+
+	clk_disable_unprepare(pvr_dev->mem_clk);
+	clk_disable_unprepare(pvr_dev->sys_clk);
+	clk_disable_unprepare(pvr_dev->core_clk);
+
+	drm_dev_exit(idx);
+
+	return 0;
+}
+
+int
+pvr_power_device_resume(struct device *dev)
+{
+	struct platform_device *plat_dev = to_platform_device(dev);
+	struct drm_device *drm_dev = platform_get_drvdata(plat_dev);
+	struct pvr_device *pvr_dev = to_pvr_device(drm_dev);
+	int idx;
+	int err;
+
+	if (!drm_dev_enter(drm_dev, &idx))
+		return -EIO;
+
+	err = clk_prepare_enable(pvr_dev->core_clk);
+	if (err)
+		goto err_drm_dev_exit;
+
+	err = clk_prepare_enable(pvr_dev->sys_clk);
+	if (err)
+		goto err_core_clk_disable;
+
+	err = clk_prepare_enable(pvr_dev->mem_clk);
+	if (err)
+		goto err_sys_clk_disable;
+
+	drm_dev_exit(idx);
+
+	return 0;
+
+err_sys_clk_disable:
+	clk_disable_unprepare(pvr_dev->sys_clk);
+
+err_core_clk_disable:
+	clk_disable_unprepare(pvr_dev->core_clk);
+
+err_drm_dev_exit:
+	drm_dev_exit(idx);
+
+	return err;
+}
+
+int
+pvr_power_device_idle(struct device *dev)
+{
+	struct platform_device *plat_dev = to_platform_device(dev);
+	struct drm_device *drm_dev = platform_get_drvdata(plat_dev);
+	struct pvr_device *pvr_dev = to_pvr_device(drm_dev);
+
+	return pvr_power_is_idle(pvr_dev) ? 0 : -EBUSY;
+}
+
+/**
+ * pvr_power_reset() - Reset the GPU
+ * @pvr_dev: Device pointer
+ * @hard_reset: %true for hard reset, %false for soft reset
+ *
+ * If @hard_reset is %false and the FW processor fails to respond during the reset process, this
+ * function will attempt a hard reset.
+ *
+ * If a hard reset fails then the GPU device is reported as lost.
+ *
+ * Returns:
+ *  * 0 on success, or
+ *  * Any error code returned by pvr_power_get, pvr_power_fw_disable or pvr_power_fw_enable().
+ */
+int
+pvr_power_reset(struct pvr_device *pvr_dev, bool hard_reset)
+{
+	/* TODO: Implement hard reset. */
+	int err;
+
+	/*
+	 * Take a power reference during the reset. This should prevent any interference with the
+	 * power state during reset.
+	 */
+	WARN_ON(pvr_power_get(pvr_dev));
+
+	err = pvr_power_fw_disable(pvr_dev, false);
+	if (err)
+		goto err_power_put;
+
+	err = pvr_power_fw_enable(pvr_dev);
+
+err_power_put:
+	pvr_power_put(pvr_dev);
+
+	return err;
+}
+
+/**
+ * pvr_watchdog_fini() - Shutdown watchdog for device
+ * @pvr_dev: Target PowerVR device.
+ */
+void
+pvr_watchdog_fini(struct pvr_device *pvr_dev)
+{
+	cancel_delayed_work_sync(&pvr_dev->watchdog.work);
+}
diff --git a/drivers/gpu/drm/imagination/pvr_power.h b/drivers/gpu/drm/imagination/pvr_power.h
new file mode 100644
index 000000000000..439f08d13655
--- /dev/null
+++ b/drivers/gpu/drm/imagination/pvr_power.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+/* Copyright (c) 2023 Imagination Technologies Ltd. */
+
+#ifndef PVR_POWER_H
+#define PVR_POWER_H
+
+#include "pvr_device.h"
+
+#include <linux/mutex.h>
+#include <linux/pm_runtime.h>
+
+int pvr_watchdog_init(struct pvr_device *pvr_dev);
+void pvr_watchdog_fini(struct pvr_device *pvr_dev);
+
+bool pvr_power_is_idle(struct pvr_device *pvr_dev);
+
+int pvr_power_device_suspend(struct device *dev);
+int pvr_power_device_resume(struct device *dev);
+int pvr_power_device_idle(struct device *dev);
+
+int pvr_power_reset(struct pvr_device *pvr_dev, bool hard_reset);
+
+static __always_inline int
+pvr_power_get(struct pvr_device *pvr_dev)
+{
+	struct drm_device *drm_dev = from_pvr_device(pvr_dev);
+
+	return pm_runtime_resume_and_get(drm_dev->dev);
+}
+
+static __always_inline int
+pvr_power_put(struct pvr_device *pvr_dev)
+{
+	struct drm_device *drm_dev = from_pvr_device(pvr_dev);
+
+	return pm_runtime_put(drm_dev->dev);
+}
+
+#endif /* PVR_POWER_H */
-- 
2.42.0