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.wal...@imgtec.com>
Reviewed-by: Maxime Ripard <mrip...@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_mmu.c    |   6 +-
 drivers/gpu/drm/imagination/pvr_power.c  | 271 +++++++++++++++++++++++
 drivers/gpu/drm/imagination/pvr_power.h  |  39 ++++
 8 files changed, 378 insertions(+), 5 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 350e894a2939..f7eb14942195 100644
--- a/drivers/gpu/drm/imagination/pvr_device.h
+++ b/drivers/gpu/drm/imagination/pvr_device.h
@@ -135,6 +135,28 @@ struct pvr_device {
 
        /** @fw_dev: Firmware related data. */
        struct pvr_fw_device fw_dev;
+
+       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 4b0c52118735..cfd4cea5a69c 100644
--- a/drivers/gpu/drm/imagination/pvr_drv.c
+++ b/drivers/gpu/drm/imagination/pvr_drv.c
@@ -4,6 +4,7 @@
 #include "pvr_device.h"
 #include "pvr_drv.h"
 #include "pvr_gem.h"
+#include "pvr_power.h"
 #include "pvr_rogue_defs.h"
 #include "pvr_rogue_fwif_client.h"
 #include "pvr_rogue_fwif_shared.h"
@@ -1277,9 +1278,16 @@ 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)
@@ -1290,6 +1298,9 @@ 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;
 }
 
@@ -1299,8 +1310,10 @@ 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);
        drm_dev_unplug(drm_dev);
        pvr_device_fini(pvr_dev);
+       pvr_watchdog_fini(pvr_dev);
 
        return 0;
 }
@@ -1311,11 +1324,16 @@ 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_mmu.c 
b/drivers/gpu/drm/imagination/pvr_mmu.c
index 895e206fe555..34a290136f74 100644
--- a/drivers/gpu/drm/imagination/pvr_mmu.c
+++ b/drivers/gpu/drm/imagination/pvr_mmu.c
@@ -61,8 +61,10 @@
  * pvr_mmu_flush() - Request flush of all MMU caches.
  * @pvr_dev: Target PowerVR device.
  *
- * This function must be called following any possible change to the MMU page
- * tables.
+ * This function must be called following any possible change to the MMU page 
tables.
+ *
+ * As a failure to flush the MMU caches could risk memory corruption, if the 
flush fails (implying
+ * the firmware is not responding) then the GPU device is marked as lost.
  *
  * Returns:
  *  * 0 on success, or
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

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