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>

1 files changed, 271 insertions, 0 deletions

diff --git a/drivers/gpu/drm/imagination/pvr_power.c b/drivers/gpu/drm/imagination/pvr_power.c
new file mode 100644
index 000000000000..88f14a4d31ab
--- /dev/null
+++ b/drivers/gpu/drm/imagination/pvr_power.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0-only 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);
+}