drm/imagination: Implement firmware infrastructure and META FW support

The infrastructure includes parsing of the firmware image, initialising
FW-side structures, handling the kernel and firmware command
ringbuffers and starting & stopping the firmware processor.

This patch also adds the necessary support code for the META firmware
processor.

Changes since v8:
- Fix documentation for pvr_fwccb_process()
- Corrected license identifiers

Changes since v6:
- Add a minimum retry count to pvr_kccb_reserve_slot_sync()

Changes since v5:
- Add workaround for BRN 71242
- Attempt to recover GPU on MMU flush command failure

Changes since v4:
- Remove use of drm_gem_shmem_get_pages()
- Remove interrupt resource name

Changes since v3:
- Hard reset FW processor on watchdog timeout
- Switch to threaded IRQ
- Rework FW object creation/initialisation to aid hard reset
- Added MODULE_FIRMWARE()
- Use drm_dev_{enter,exit}

Signed-off-by: Sarah Walker <sarah.walker@imgtec.com>
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Link: https://lore.kernel.org/r/bb52a8dc84f296b37dc6668dfe8fbaf2ba551139.1700668843.git.donald.robson@imgtec.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>

1 files changed, 635 insertions, 0 deletions

diff --git a/drivers/gpu/drm/imagination/pvr_ccb.c b/drivers/gpu/drm/imagination/pvr_ccb.c
new file mode 100644
index 000000000000..48f06f58f3f1
--- /dev/null
+++ b/drivers/gpu/drm/imagination/pvr_ccb.c
@@ -0,0 +1,635 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/* Copyright (c) 2023 Imagination Technologies Ltd. */
+
+#include "pvr_ccb.h"
+#include "pvr_device.h"
+#include "pvr_drv.h"
+#include "pvr_fw.h"
+#include "pvr_gem.h"
+#include "pvr_power.h"
+
+#include <drm/drm_managed.h>
+#include <linux/compiler.h>
+#include <linux/delay.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+#define RESERVE_SLOT_TIMEOUT (1 * HZ) /* 1s */
+#define RESERVE_SLOT_MIN_RETRIES 10
+
+static void
+ccb_ctrl_init(void *cpu_ptr, void *priv)
+{
+	struct rogue_fwif_ccb_ctl *ctrl = cpu_ptr;
+	struct pvr_ccb *pvr_ccb = priv;
+
+	ctrl->write_offset = 0;
+	ctrl->read_offset = 0;
+	ctrl->wrap_mask = pvr_ccb->num_cmds - 1;
+	ctrl->cmd_size = pvr_ccb->cmd_size;
+}
+
+/**
+ * pvr_ccb_init() - Initialise a CCB
+ * @pvr_dev: Device pointer.
+ * @pvr_ccb: Pointer to CCB structure to initialise.
+ * @num_cmds_log2: Log2 of number of commands in this CCB.
+ * @cmd_size: Command size for this CCB.
+ *
+ * Return:
+ *  * Zero on success, or
+ *  * Any error code returned by pvr_fw_object_create_and_map().
+ */
+static int
+pvr_ccb_init(struct pvr_device *pvr_dev, struct pvr_ccb *pvr_ccb,
+	     u32 num_cmds_log2, size_t cmd_size)
+{
+	u32 num_cmds = 1 << num_cmds_log2;
+	u32 ccb_size = num_cmds * cmd_size;
+	int err;
+
+	pvr_ccb->num_cmds = num_cmds;
+	pvr_ccb->cmd_size = cmd_size;
+
+	err = drmm_mutex_init(from_pvr_device(pvr_dev), &pvr_ccb->lock);
+	if (err)
+		return err;
+
+	/*
+	 * Map CCB and control structure as uncached, so we don't have to flush
+	 * CPU cache repeatedly when polling for space.
+	 */
+	pvr_ccb->ctrl = pvr_fw_object_create_and_map(pvr_dev, sizeof(*pvr_ccb->ctrl),
+						     PVR_BO_FW_FLAGS_DEVICE_UNCACHED,
+						     ccb_ctrl_init, pvr_ccb, &pvr_ccb->ctrl_obj);
+	if (IS_ERR(pvr_ccb->ctrl))
+		return PTR_ERR(pvr_ccb->ctrl);
+
+	pvr_ccb->ccb = pvr_fw_object_create_and_map(pvr_dev, ccb_size,
+						    PVR_BO_FW_FLAGS_DEVICE_UNCACHED,
+						    NULL, NULL, &pvr_ccb->ccb_obj);
+	if (IS_ERR(pvr_ccb->ccb)) {
+		err = PTR_ERR(pvr_ccb->ccb);
+		goto err_free_ctrl;
+	}
+
+	pvr_fw_object_get_fw_addr(pvr_ccb->ctrl_obj, &pvr_ccb->ctrl_fw_addr);
+	pvr_fw_object_get_fw_addr(pvr_ccb->ccb_obj, &pvr_ccb->ccb_fw_addr);
+
+	WRITE_ONCE(pvr_ccb->ctrl->write_offset, 0);
+	WRITE_ONCE(pvr_ccb->ctrl->read_offset, 0);
+	WRITE_ONCE(pvr_ccb->ctrl->wrap_mask, num_cmds - 1);
+	WRITE_ONCE(pvr_ccb->ctrl->cmd_size, cmd_size);
+
+	return 0;
+
+err_free_ctrl:
+	pvr_fw_object_unmap_and_destroy(pvr_ccb->ctrl_obj);
+
+	return err;
+}
+
+/**
+ * pvr_ccb_fini() - Release CCB structure
+ * @pvr_ccb: CCB to release.
+ */
+void
+pvr_ccb_fini(struct pvr_ccb *pvr_ccb)
+{
+	pvr_fw_object_unmap_and_destroy(pvr_ccb->ccb_obj);
+	pvr_fw_object_unmap_and_destroy(pvr_ccb->ctrl_obj);
+}
+
+/**
+ * pvr_ccb_slot_available_locked() - Test whether any slots are available in CCB
+ * @pvr_ccb: CCB to test.
+ * @write_offset: Address to store number of next available slot. May be %NULL.
+ *
+ * Caller must hold @pvr_ccb->lock.
+ *
+ * Return:
+ *  * %true if a slot is available, or
+ *  * %false if no slot is available.
+ */
+static __always_inline bool
+pvr_ccb_slot_available_locked(struct pvr_ccb *pvr_ccb, u32 *write_offset)
+{
+	struct rogue_fwif_ccb_ctl *ctrl = pvr_ccb->ctrl;
+	u32 next_write_offset = (READ_ONCE(ctrl->write_offset) + 1) & READ_ONCE(ctrl->wrap_mask);
+
+	lockdep_assert_held(&pvr_ccb->lock);
+
+	if (READ_ONCE(ctrl->read_offset) != next_write_offset) {
+		if (write_offset)
+			*write_offset = next_write_offset;
+		return true;
+	}
+
+	return false;
+}
+
+static void
+process_fwccb_command(struct pvr_device *pvr_dev, struct rogue_fwif_fwccb_cmd *cmd)
+{
+	switch (cmd->cmd_type) {
+	case ROGUE_FWIF_FWCCB_CMD_REQUEST_GPU_RESTART:
+		pvr_power_reset(pvr_dev, false);
+		break;
+
+	default:
+		drm_info(from_pvr_device(pvr_dev), "Received unknown FWCCB command %x\n",
+			 cmd->cmd_type);
+		break;
+	}
+}
+
+/**
+ * pvr_fwccb_process() - Process any pending FWCCB commands
+ * @pvr_dev: Target PowerVR device
+ */
+void pvr_fwccb_process(struct pvr_device *pvr_dev)
+{
+	struct rogue_fwif_fwccb_cmd *fwccb = pvr_dev->fwccb.ccb;
+	struct rogue_fwif_ccb_ctl *ctrl = pvr_dev->fwccb.ctrl;
+	u32 read_offset;
+
+	mutex_lock(&pvr_dev->fwccb.lock);
+
+	while ((read_offset = READ_ONCE(ctrl->read_offset)) != READ_ONCE(ctrl->write_offset)) {
+		struct rogue_fwif_fwccb_cmd cmd = fwccb[read_offset];
+
+		WRITE_ONCE(ctrl->read_offset, (read_offset + 1) & READ_ONCE(ctrl->wrap_mask));
+
+		/* Drop FWCCB lock while we process command. */
+		mutex_unlock(&pvr_dev->fwccb.lock);
+
+		process_fwccb_command(pvr_dev, &cmd);
+
+		mutex_lock(&pvr_dev->fwccb.lock);
+	}
+
+	mutex_unlock(&pvr_dev->fwccb.lock);
+}
+
+/**
+ * pvr_kccb_capacity() - Returns the maximum number of usable KCCB slots.
+ * @pvr_dev: Target PowerVR device
+ *
+ * Return:
+ *  * The maximum number of active slots.
+ */
+static u32 pvr_kccb_capacity(struct pvr_device *pvr_dev)
+{
+	/* Capacity is the number of slot minus one to cope with the wrapping
+	 * mechanisms. If we were to use all slots, we might end up with
+	 * read_offset == write_offset, which the FW considers as a KCCB-is-empty
+	 * condition.
+	 */
+	return pvr_dev->kccb.slot_count - 1;
+}
+
+/**
+ * pvr_kccb_used_slot_count_locked() - Get the number of used slots
+ * @pvr_dev: Device pointer.
+ *
+ * KCCB lock must be held.
+ *
+ * Return:
+ *  * The number of slots currently used.
+ */
+static u32
+pvr_kccb_used_slot_count_locked(struct pvr_device *pvr_dev)
+{
+	struct pvr_ccb *pvr_ccb = &pvr_dev->kccb.ccb;
+	struct rogue_fwif_ccb_ctl *ctrl = pvr_ccb->ctrl;
+	u32 wr_offset = READ_ONCE(ctrl->write_offset);
+	u32 rd_offset = READ_ONCE(ctrl->read_offset);
+	u32 used_count;
+
+	lockdep_assert_held(&pvr_ccb->lock);
+
+	if (wr_offset >= rd_offset)
+		used_count = wr_offset - rd_offset;
+	else
+		used_count = wr_offset + pvr_dev->kccb.slot_count - rd_offset;
+
+	return used_count;
+}
+
+/**
+ * pvr_kccb_send_cmd_reserved_powered() - Send command to the KCCB, with the PM ref
+ * held and a slot pre-reserved
+ * @pvr_dev: Device pointer.
+ * @cmd: Command to sent.
+ * @kccb_slot: Address to store the KCCB slot for this command. May be %NULL.
+ */
+void
+pvr_kccb_send_cmd_reserved_powered(struct pvr_device *pvr_dev,
+				   struct rogue_fwif_kccb_cmd *cmd,
+				   u32 *kccb_slot)
+{
+	struct pvr_ccb *pvr_ccb = &pvr_dev->kccb.ccb;
+	struct rogue_fwif_kccb_cmd *kccb = pvr_ccb->ccb;
+	struct rogue_fwif_ccb_ctl *ctrl = pvr_ccb->ctrl;
+	u32 old_write_offset;
+	u32 new_write_offset;
+
+	WARN_ON(pvr_dev->lost);
+
+	mutex_lock(&pvr_ccb->lock);
+
+	if (WARN_ON(!pvr_dev->kccb.reserved_count))
+		goto out_unlock;
+
+	old_write_offset = READ_ONCE(ctrl->write_offset);
+
+	/* We reserved the slot, we should have one available. */
+	if (WARN_ON(!pvr_ccb_slot_available_locked(pvr_ccb, &new_write_offset)))
+		goto out_unlock;
+
+	memcpy(&kccb[old_write_offset], cmd,
+	       sizeof(struct rogue_fwif_kccb_cmd));
+	if (kccb_slot) {
+		*kccb_slot = old_write_offset;
+		/* Clear return status for this slot. */
+		WRITE_ONCE(pvr_dev->kccb.rtn[old_write_offset],
+			   ROGUE_FWIF_KCCB_RTN_SLOT_NO_RESPONSE);
+	}
+	mb(); /* memory barrier */
+	WRITE_ONCE(ctrl->write_offset, new_write_offset);
+	pvr_dev->kccb.reserved_count--;
+
+	/* Kick MTS */
+	pvr_fw_mts_schedule(pvr_dev,
+			    PVR_FWIF_DM_GP & ~ROGUE_CR_MTS_SCHEDULE_DM_CLRMSK);
+
+out_unlock:
+	mutex_unlock(&pvr_ccb->lock);
+}
+
+/**
+ * pvr_kccb_try_reserve_slot() - Try to reserve a KCCB slot
+ * @pvr_dev: Device pointer.
+ *
+ * Return:
+ *  * true if a KCCB slot was reserved, or
+ *  * false otherwise.
+ */
+static bool pvr_kccb_try_reserve_slot(struct pvr_device *pvr_dev)
+{
+	bool reserved = false;
+	u32 used_count;
+
+	mutex_lock(&pvr_dev->kccb.ccb.lock);
+
+	used_count = pvr_kccb_used_slot_count_locked(pvr_dev);
+	if (pvr_dev->kccb.reserved_count < pvr_kccb_capacity(pvr_dev) - used_count) {
+		pvr_dev->kccb.reserved_count++;
+		reserved = true;
+	}
+
+	mutex_unlock(&pvr_dev->kccb.ccb.lock);
+
+	return reserved;
+}
+
+/**
+ * pvr_kccb_reserve_slot_sync() - Try to reserve a slot synchronously
+ * @pvr_dev: Device pointer.
+ *
+ * Return:
+ *  * 0 on success, or
+ *  * -EBUSY if no slots were reserved after %RESERVE_SLOT_TIMEOUT, with a minimum of
+ *    %RESERVE_SLOT_MIN_RETRIES retries.
+ */
+static int pvr_kccb_reserve_slot_sync(struct pvr_device *pvr_dev)
+{
+	unsigned long start_timestamp = jiffies;
+	bool reserved = false;
+	u32 retries = 0;
+
+	while ((jiffies - start_timestamp) < (u32)RESERVE_SLOT_TIMEOUT ||
+	       retries < RESERVE_SLOT_MIN_RETRIES) {
+		reserved = pvr_kccb_try_reserve_slot(pvr_dev);
+		if (reserved)
+			break;
+
+		usleep_range(1, 50);
+
+		if (retries < U32_MAX)
+			retries++;
+	}
+
+	return reserved ? 0 : -EBUSY;
+}
+
+/**
+ * pvr_kccb_send_cmd_powered() - Send command to the KCCB, with a PM ref held
+ * @pvr_dev: Device pointer.
+ * @cmd: Command to sent.
+ * @kccb_slot: Address to store the KCCB slot for this command. May be %NULL.
+ *
+ * Returns:
+ *  * Zero on success, or
+ *  * -EBUSY if timeout while waiting for a free KCCB slot.
+ */
+int
+pvr_kccb_send_cmd_powered(struct pvr_device *pvr_dev, struct rogue_fwif_kccb_cmd *cmd,
+			  u32 *kccb_slot)
+{
+	int err;
+
+	err = pvr_kccb_reserve_slot_sync(pvr_dev);
+	if (err)
+		return err;
+
+	pvr_kccb_send_cmd_reserved_powered(pvr_dev, cmd, kccb_slot);
+	return 0;
+}
+
+/**
+ * pvr_kccb_send_cmd() - Send command to the KCCB
+ * @pvr_dev: Device pointer.
+ * @cmd: Command to sent.
+ * @kccb_slot: Address to store the KCCB slot for this command. May be %NULL.
+ *
+ * Returns:
+ *  * Zero on success, or
+ *  * -EBUSY if timeout while waiting for a free KCCB slot.
+ */
+int
+pvr_kccb_send_cmd(struct pvr_device *pvr_dev, struct rogue_fwif_kccb_cmd *cmd,
+		  u32 *kccb_slot)
+{
+	int err;
+
+	err = pvr_power_get(pvr_dev);
+	if (err)
+		return err;
+
+	err = pvr_kccb_send_cmd_powered(pvr_dev, cmd, kccb_slot);
+
+	pvr_power_put(pvr_dev);
+
+	return err;
+}
+
+/**
+ * pvr_kccb_wait_for_completion() - Wait for a KCCB command to complete
+ * @pvr_dev: Device pointer.
+ * @slot_nr: KCCB slot to wait on.
+ * @timeout: Timeout length (in jiffies).
+ * @rtn_out: Location to store KCCB command result. May be %NULL.
+ *
+ * Returns:
+ *  * Zero on success, or
+ *  * -ETIMEDOUT on timeout.
+ */
+int
+pvr_kccb_wait_for_completion(struct pvr_device *pvr_dev, u32 slot_nr,
+			     u32 timeout, u32 *rtn_out)
+{
+	int ret = wait_event_timeout(pvr_dev->kccb.rtn_q, READ_ONCE(pvr_dev->kccb.rtn[slot_nr]) &
+				     ROGUE_FWIF_KCCB_RTN_SLOT_CMD_EXECUTED, timeout);
+
+	if (ret && rtn_out)
+		*rtn_out = READ_ONCE(pvr_dev->kccb.rtn[slot_nr]);
+
+	return ret ? 0 : -ETIMEDOUT;
+}
+
+/**
+ * pvr_kccb_is_idle() - Returns whether the device's KCCB is idle
+ * @pvr_dev: Device pointer
+ *
+ * Returns:
+ *  * %true if the KCCB is idle (contains no commands), or
+ *  * %false if the KCCB contains pending commands.
+ */
+bool
+pvr_kccb_is_idle(struct pvr_device *pvr_dev)
+{
+	struct rogue_fwif_ccb_ctl *ctrl = pvr_dev->kccb.ccb.ctrl;
+	bool idle;
+
+	mutex_lock(&pvr_dev->kccb.ccb.lock);
+
+	idle = (READ_ONCE(ctrl->write_offset) == READ_ONCE(ctrl->read_offset));
+
+	mutex_unlock(&pvr_dev->kccb.ccb.lock);
+
+	return idle;
+}
+
+static const char *
+pvr_kccb_fence_get_driver_name(struct dma_fence *f)
+{
+	return PVR_DRIVER_NAME;
+}
+
+static const char *
+pvr_kccb_fence_get_timeline_name(struct dma_fence *f)
+{
+	return "kccb";
+}
+
+static const struct dma_fence_ops pvr_kccb_fence_ops = {
+	.get_driver_name = pvr_kccb_fence_get_driver_name,
+	.get_timeline_name = pvr_kccb_fence_get_timeline_name,
+};
+
+/**
+ * struct pvr_kccb_fence - Fence object used to wait for a KCCB slot
+ */
+struct pvr_kccb_fence {
+	/** @base: Base dma_fence object. */
+	struct dma_fence base;
+
+	/** @node: Node used to insert the fence in the pvr_device::kccb::waiters list. */
+	struct list_head node;
+};
+
+/**
+ * pvr_kccb_wake_up_waiters() - Check the KCCB waiters
+ * @pvr_dev: Target PowerVR device
+ *
+ * Signal as many KCCB fences as we have slots available.
+ */
+void pvr_kccb_wake_up_waiters(struct pvr_device *pvr_dev)
+{
+	struct pvr_kccb_fence *fence, *tmp_fence;
+	u32 used_count, available_count;
+
+	/* Wake up those waiting for KCCB slot execution. */
+	wake_up_all(&pvr_dev->kccb.rtn_q);
+
+	/* Then iterate over all KCCB fences and signal as many as we can. */
+	mutex_lock(&pvr_dev->kccb.ccb.lock);
+	used_count = pvr_kccb_used_slot_count_locked(pvr_dev);
+
+	if (WARN_ON(used_count + pvr_dev->kccb.reserved_count > pvr_kccb_capacity(pvr_dev)))
+		goto out_unlock;
+
+	available_count = pvr_kccb_capacity(pvr_dev) - used_count - pvr_dev->kccb.reserved_count;
+	list_for_each_entry_safe(fence, tmp_fence, &pvr_dev->kccb.waiters, node) {
+		if (!available_count)
+			break;
+
+		list_del(&fence->node);
+		pvr_dev->kccb.reserved_count++;
+		available_count--;
+		dma_fence_signal(&fence->base);
+		dma_fence_put(&fence->base);
+	}
+
+out_unlock:
+	mutex_unlock(&pvr_dev->kccb.ccb.lock);
+}
+
+/**
+ * pvr_kccb_fini() - Cleanup device KCCB
+ * @pvr_dev: Target PowerVR device
+ */
+void pvr_kccb_fini(struct pvr_device *pvr_dev)
+{
+	pvr_ccb_fini(&pvr_dev->kccb.ccb);
+	WARN_ON(!list_empty(&pvr_dev->kccb.waiters));
+	WARN_ON(pvr_dev->kccb.reserved_count);
+}
+
+/**
+ * pvr_kccb_init() - Initialise device KCCB
+ * @pvr_dev: Target PowerVR device
+ *
+ * Returns:
+ *  * 0 on success, or
+ *  * Any error returned by pvr_ccb_init().
+ */
+int
+pvr_kccb_init(struct pvr_device *pvr_dev)
+{
+	pvr_dev->kccb.slot_count = 1 << ROGUE_FWIF_KCCB_NUMCMDS_LOG2_DEFAULT;
+	INIT_LIST_HEAD(&pvr_dev->kccb.waiters);
+	pvr_dev->kccb.fence_ctx.id = dma_fence_context_alloc(1);
+	spin_lock_init(&pvr_dev->kccb.fence_ctx.lock);
+
+	return pvr_ccb_init(pvr_dev, &pvr_dev->kccb.ccb,
+			    ROGUE_FWIF_KCCB_NUMCMDS_LOG2_DEFAULT,
+			    sizeof(struct rogue_fwif_kccb_cmd));
+}
+
+/**
+ * pvr_kccb_fence_alloc() - Allocate a pvr_kccb_fence object
+ *
+ * Return:
+ *  * NULL if the allocation fails, or
+ *  * A valid dma_fence pointer otherwise.
+ */
+struct dma_fence *pvr_kccb_fence_alloc(void)
+{
+	struct pvr_kccb_fence *kccb_fence;
+
+	kccb_fence = kzalloc(sizeof(*kccb_fence), GFP_KERNEL);
+	if (!kccb_fence)
+		return NULL;
+
+	return &kccb_fence->base;
+}
+
+/**
+ * pvr_kccb_fence_put() - Drop a KCCB fence reference
+ * @fence: The fence to drop the reference on.
+ *
+ * If the fence hasn't been initialized yet, dma_fence_free() is called. This
+ * way we have a single function taking care of both cases.
+ */
+void pvr_kccb_fence_put(struct dma_fence *fence)
+{
+	if (!fence)
+		return;
+
+	if (!fence->ops) {
+		dma_fence_free(fence);
+	} else {
+		WARN_ON(fence->ops != &pvr_kccb_fence_ops);
+		dma_fence_put(fence);
+	}
+}
+
+/**
+ * pvr_kccb_reserve_slot() - Reserve a KCCB slot for later use
+ * @pvr_dev: Target PowerVR device
+ * @f: KCCB fence object previously allocated with pvr_kccb_fence_alloc()
+ *
+ * Try to reserve a KCCB slot, and if there's no slot available,
+ * initializes the fence object and queue it to the waiters list.
+ *
+ * If NULL is returned, that means the slot is reserved. In that case,
+ * the @f is freed and shouldn't be accessed after that point.
+ *
+ * Return:
+ *  * NULL if a slot was available directly, or
+ *  * A valid dma_fence object to wait on if no slot was available.
+ */
+struct dma_fence *
+pvr_kccb_reserve_slot(struct pvr_device *pvr_dev, struct dma_fence *f)
+{
+	struct pvr_kccb_fence *fence = container_of(f, struct pvr_kccb_fence, base);
+	struct dma_fence *out_fence = NULL;
+	u32 used_count;
+
+	mutex_lock(&pvr_dev->kccb.ccb.lock);
+
+	used_count = pvr_kccb_used_slot_count_locked(pvr_dev);
+	if (pvr_dev->kccb.reserved_count >= pvr_kccb_capacity(pvr_dev) - used_count) {
+		dma_fence_init(&fence->base, &pvr_kccb_fence_ops,
+			       &pvr_dev->kccb.fence_ctx.lock,
+			       pvr_dev->kccb.fence_ctx.id,
+			       atomic_inc_return(&pvr_dev->kccb.fence_ctx.seqno));
+		out_fence = dma_fence_get(&fence->base);
+		list_add_tail(&fence->node, &pvr_dev->kccb.waiters);
+	} else {
+		pvr_kccb_fence_put(f);
+		pvr_dev->kccb.reserved_count++;
+	}
+
+	mutex_unlock(&pvr_dev->kccb.ccb.lock);
+
+	return out_fence;
+}
+
+/**
+ * pvr_kccb_release_slot() - Release a KCCB slot reserved with
+ * pvr_kccb_reserve_slot()
+ * @pvr_dev: Target PowerVR device
+ *
+ * Should only be called if something failed after the
+ * pvr_kccb_reserve_slot() call and you know you won't call
+ * pvr_kccb_send_cmd_reserved().
+ */
+void pvr_kccb_release_slot(struct pvr_device *pvr_dev)
+{
+	mutex_lock(&pvr_dev->kccb.ccb.lock);
+	if (!WARN_ON(!pvr_dev->kccb.reserved_count))
+		pvr_dev->kccb.reserved_count--;
+	mutex_unlock(&pvr_dev->kccb.ccb.lock);
+}
+
+/**
+ * pvr_fwccb_init() - Initialise device FWCCB
+ * @pvr_dev: Target PowerVR device
+ *
+ * Returns:
+ *  * 0 on success, or
+ *  * Any error returned by pvr_ccb_init().
+ */
+int
+pvr_fwccb_init(struct pvr_device *pvr_dev)
+{
+	return pvr_ccb_init(pvr_dev, &pvr_dev->fwccb,
+			    ROGUE_FWIF_FWCCB_NUMCMDS_LOG2,
+			    sizeof(struct rogue_fwif_fwccb_cmd));
+}