kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 941 insertions, 0 deletions

diff --git a/drivers/firmware/tegra/bpmp.c b/drivers/firmware/tegra/bpmp.c
new file mode 100644
index 000000000..753472b53
--- /dev/null
+++ b/drivers/firmware/tegra/bpmp.c
@@ -0,0 +1,941 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2016, NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#include <linux/clk/tegra.h>
+#include <linux/genalloc.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/semaphore.h>
+#include <linux/sched/clock.h>
+
+#include <soc/tegra/bpmp.h>
+#include <soc/tegra/bpmp-abi.h>
+#include <soc/tegra/ivc.h>
+
+#include "bpmp-private.h"
+
+#define MSG_ACK		BIT(0)
+#define MSG_RING	BIT(1)
+#define TAG_SZ		32
+
+static inline const struct tegra_bpmp_ops *
+channel_to_ops(struct tegra_bpmp_channel *channel)
+{
+	struct tegra_bpmp *bpmp = channel->bpmp;
+
+	return bpmp->soc->ops;
+}
+
+struct tegra_bpmp *tegra_bpmp_get_with_id(struct device *dev, unsigned int *id)
+{
+	struct platform_device *pdev;
+	struct of_phandle_args args;
+	struct tegra_bpmp *bpmp;
+	int err;
+
+	err = __of_parse_phandle_with_args(dev->of_node, "nvidia,bpmp", NULL,
+					   1, 0, &args);
+	if (err < 0)
+		return ERR_PTR(err);
+
+	pdev = of_find_device_by_node(args.np);
+	if (!pdev) {
+		bpmp = ERR_PTR(-ENODEV);
+		goto put;
+	}
+
+	bpmp = platform_get_drvdata(pdev);
+	if (!bpmp) {
+		bpmp = ERR_PTR(-EPROBE_DEFER);
+		put_device(&pdev->dev);
+		goto put;
+	}
+
+	if (id)
+		*id = args.args[0];
+
+put:
+	of_node_put(args.np);
+	return bpmp;
+}
+EXPORT_SYMBOL_GPL(tegra_bpmp_get_with_id);
+
+struct tegra_bpmp *tegra_bpmp_get(struct device *dev)
+{
+	struct platform_device *pdev;
+	struct tegra_bpmp *bpmp;
+	struct device_node *np;
+
+	np = of_parse_phandle(dev->of_node, "nvidia,bpmp", 0);
+	if (!np)
+		return ERR_PTR(-ENOENT);
+
+	pdev = of_find_device_by_node(np);
+	if (!pdev) {
+		bpmp = ERR_PTR(-ENODEV);
+		goto put;
+	}
+
+	bpmp = platform_get_drvdata(pdev);
+	if (!bpmp) {
+		bpmp = ERR_PTR(-EPROBE_DEFER);
+		put_device(&pdev->dev);
+		goto put;
+	}
+
+put:
+	of_node_put(np);
+	return bpmp;
+}
+EXPORT_SYMBOL_GPL(tegra_bpmp_get);
+
+void tegra_bpmp_put(struct tegra_bpmp *bpmp)
+{
+	if (bpmp)
+		put_device(bpmp->dev);
+}
+EXPORT_SYMBOL_GPL(tegra_bpmp_put);
+
+static int
+tegra_bpmp_channel_get_thread_index(struct tegra_bpmp_channel *channel)
+{
+	struct tegra_bpmp *bpmp = channel->bpmp;
+	unsigned int count;
+	int index;
+
+	count = bpmp->soc->channels.thread.count;
+
+	index = channel - channel->bpmp->threaded_channels;
+	if (index < 0 || index >= count)
+		return -EINVAL;
+
+	return index;
+}
+
+static bool tegra_bpmp_message_valid(const struct tegra_bpmp_message *msg)
+{
+	return (msg->tx.size <= MSG_DATA_MIN_SZ) &&
+	       (msg->rx.size <= MSG_DATA_MIN_SZ) &&
+	       (msg->tx.size == 0 || msg->tx.data) &&
+	       (msg->rx.size == 0 || msg->rx.data);
+}
+
+static bool tegra_bpmp_is_response_ready(struct tegra_bpmp_channel *channel)
+{
+	const struct tegra_bpmp_ops *ops = channel_to_ops(channel);
+
+	return ops->is_response_ready(channel);
+}
+
+static bool tegra_bpmp_is_request_ready(struct tegra_bpmp_channel *channel)
+{
+	const struct tegra_bpmp_ops *ops = channel_to_ops(channel);
+
+	return ops->is_request_ready(channel);
+}
+
+static int tegra_bpmp_wait_response(struct tegra_bpmp_channel *channel)
+{
+	unsigned long timeout = channel->bpmp->soc->channels.cpu_tx.timeout;
+	ktime_t end;
+
+	end = ktime_add_us(ktime_get(), timeout);
+
+	do {
+		if (tegra_bpmp_is_response_ready(channel))
+			return 0;
+	} while (ktime_before(ktime_get(), end));
+
+	return -ETIMEDOUT;
+}
+
+static int tegra_bpmp_ack_response(struct tegra_bpmp_channel *channel)
+{
+	const struct tegra_bpmp_ops *ops = channel_to_ops(channel);
+
+	return ops->ack_response(channel);
+}
+
+static int tegra_bpmp_ack_request(struct tegra_bpmp_channel *channel)
+{
+	const struct tegra_bpmp_ops *ops = channel_to_ops(channel);
+
+	return ops->ack_request(channel);
+}
+
+static bool
+tegra_bpmp_is_request_channel_free(struct tegra_bpmp_channel *channel)
+{
+	const struct tegra_bpmp_ops *ops = channel_to_ops(channel);
+
+	return ops->is_request_channel_free(channel);
+}
+
+static bool
+tegra_bpmp_is_response_channel_free(struct tegra_bpmp_channel *channel)
+{
+	const struct tegra_bpmp_ops *ops = channel_to_ops(channel);
+
+	return ops->is_response_channel_free(channel);
+}
+
+static int
+tegra_bpmp_wait_request_channel_free(struct tegra_bpmp_channel *channel)
+{
+	unsigned long timeout = channel->bpmp->soc->channels.cpu_tx.timeout;
+	ktime_t start, now;
+
+	start = ns_to_ktime(local_clock());
+
+	do {
+		if (tegra_bpmp_is_request_channel_free(channel))
+			return 0;
+
+		now = ns_to_ktime(local_clock());
+	} while (ktime_us_delta(now, start) < timeout);
+
+	return -ETIMEDOUT;
+}
+
+static int tegra_bpmp_post_request(struct tegra_bpmp_channel *channel)
+{
+	const struct tegra_bpmp_ops *ops = channel_to_ops(channel);
+
+	return ops->post_request(channel);
+}
+
+static int tegra_bpmp_post_response(struct tegra_bpmp_channel *channel)
+{
+	const struct tegra_bpmp_ops *ops = channel_to_ops(channel);
+
+	return ops->post_response(channel);
+}
+
+static int tegra_bpmp_ring_doorbell(struct tegra_bpmp *bpmp)
+{
+	return bpmp->soc->ops->ring_doorbell(bpmp);
+}
+
+static ssize_t __tegra_bpmp_channel_read(struct tegra_bpmp_channel *channel,
+					 void *data, size_t size, int *ret)
+{
+	int err;
+
+	if (data && size > 0)
+		tegra_bpmp_mb_read(data, &channel->ib, size);
+
+	err = tegra_bpmp_ack_response(channel);
+	if (err < 0)
+		return err;
+
+	*ret = tegra_bpmp_mb_read_field(&channel->ib, code);
+
+	return 0;
+}
+
+static ssize_t tegra_bpmp_channel_read(struct tegra_bpmp_channel *channel,
+				       void *data, size_t size, int *ret)
+{
+	struct tegra_bpmp *bpmp = channel->bpmp;
+	unsigned long flags;
+	ssize_t err;
+	int index;
+
+	index = tegra_bpmp_channel_get_thread_index(channel);
+	if (index < 0) {
+		err = index;
+		goto unlock;
+	}
+
+	spin_lock_irqsave(&bpmp->lock, flags);
+	err = __tegra_bpmp_channel_read(channel, data, size, ret);
+	clear_bit(index, bpmp->threaded.allocated);
+	spin_unlock_irqrestore(&bpmp->lock, flags);
+
+unlock:
+	up(&bpmp->threaded.lock);
+
+	return err;
+}
+
+static ssize_t __tegra_bpmp_channel_write(struct tegra_bpmp_channel *channel,
+					  unsigned int mrq, unsigned long flags,
+					  const void *data, size_t size)
+{
+	tegra_bpmp_mb_write_field(&channel->ob, code, mrq);
+	tegra_bpmp_mb_write_field(&channel->ob, flags, flags);
+
+	if (data && size > 0)
+		tegra_bpmp_mb_write(&channel->ob, data, size);
+
+	return tegra_bpmp_post_request(channel);
+}
+
+static struct tegra_bpmp_channel *
+tegra_bpmp_write_threaded(struct tegra_bpmp *bpmp, unsigned int mrq,
+			  const void *data, size_t size)
+{
+	unsigned long timeout = bpmp->soc->channels.thread.timeout;
+	unsigned int count = bpmp->soc->channels.thread.count;
+	struct tegra_bpmp_channel *channel;
+	unsigned long flags;
+	unsigned int index;
+	int err;
+
+	err = down_timeout(&bpmp->threaded.lock, usecs_to_jiffies(timeout));
+	if (err < 0)
+		return ERR_PTR(err);
+
+	spin_lock_irqsave(&bpmp->lock, flags);
+
+	index = find_first_zero_bit(bpmp->threaded.allocated, count);
+	if (index == count) {
+		err = -EBUSY;
+		goto unlock;
+	}
+
+	channel = &bpmp->threaded_channels[index];
+
+	if (!tegra_bpmp_is_request_channel_free(channel)) {
+		err = -EBUSY;
+		goto unlock;
+	}
+
+	set_bit(index, bpmp->threaded.allocated);
+
+	err = __tegra_bpmp_channel_write(channel, mrq, MSG_ACK | MSG_RING,
+					 data, size);
+	if (err < 0)
+		goto clear_allocated;
+
+	set_bit(index, bpmp->threaded.busy);
+
+	spin_unlock_irqrestore(&bpmp->lock, flags);
+	return channel;
+
+clear_allocated:
+	clear_bit(index, bpmp->threaded.allocated);
+unlock:
+	spin_unlock_irqrestore(&bpmp->lock, flags);
+	up(&bpmp->threaded.lock);
+
+	return ERR_PTR(err);
+}
+
+static ssize_t tegra_bpmp_channel_write(struct tegra_bpmp_channel *channel,
+					unsigned int mrq, unsigned long flags,
+					const void *data, size_t size)
+{
+	int err;
+
+	err = tegra_bpmp_wait_request_channel_free(channel);
+	if (err < 0)
+		return err;
+
+	return __tegra_bpmp_channel_write(channel, mrq, flags, data, size);
+}
+
+static int __maybe_unused tegra_bpmp_resume(struct device *dev);
+
+int tegra_bpmp_transfer_atomic(struct tegra_bpmp *bpmp,
+			       struct tegra_bpmp_message *msg)
+{
+	struct tegra_bpmp_channel *channel;
+	int err;
+
+	if (WARN_ON(!irqs_disabled()))
+		return -EPERM;
+
+	if (!tegra_bpmp_message_valid(msg))
+		return -EINVAL;
+
+	if (bpmp->suspended) {
+		/* Reset BPMP IPC channels during resume based on flags passed */
+		if (msg->flags & TEGRA_BPMP_MESSAGE_RESET)
+			tegra_bpmp_resume(bpmp->dev);
+		else
+			return -EAGAIN;
+	}
+
+	channel = bpmp->tx_channel;
+
+	spin_lock(&bpmp->atomic_tx_lock);
+
+	err = tegra_bpmp_channel_write(channel, msg->mrq, MSG_ACK,
+				       msg->tx.data, msg->tx.size);
+	if (err < 0) {
+		spin_unlock(&bpmp->atomic_tx_lock);
+		return err;
+	}
+
+	spin_unlock(&bpmp->atomic_tx_lock);
+
+	err = tegra_bpmp_ring_doorbell(bpmp);
+	if (err < 0)
+		return err;
+
+	err = tegra_bpmp_wait_response(channel);
+	if (err < 0)
+		return err;
+
+	return __tegra_bpmp_channel_read(channel, msg->rx.data, msg->rx.size,
+					 &msg->rx.ret);
+}
+EXPORT_SYMBOL_GPL(tegra_bpmp_transfer_atomic);
+
+int tegra_bpmp_transfer(struct tegra_bpmp *bpmp,
+			struct tegra_bpmp_message *msg)
+{
+	struct tegra_bpmp_channel *channel;
+	unsigned long timeout;
+	int err;
+
+	if (WARN_ON(irqs_disabled()))
+		return -EPERM;
+
+	if (!tegra_bpmp_message_valid(msg))
+		return -EINVAL;
+
+	if (bpmp->suspended) {
+		/* Reset BPMP IPC channels during resume based on flags passed */
+		if (msg->flags & TEGRA_BPMP_MESSAGE_RESET)
+			tegra_bpmp_resume(bpmp->dev);
+		else
+			return -EAGAIN;
+	}
+
+	channel = tegra_bpmp_write_threaded(bpmp, msg->mrq, msg->tx.data,
+					    msg->tx.size);
+	if (IS_ERR(channel))
+		return PTR_ERR(channel);
+
+	err = tegra_bpmp_ring_doorbell(bpmp);
+	if (err < 0)
+		return err;
+
+	timeout = usecs_to_jiffies(bpmp->soc->channels.thread.timeout);
+
+	err = wait_for_completion_timeout(&channel->completion, timeout);
+	if (err == 0)
+		return -ETIMEDOUT;
+
+	return tegra_bpmp_channel_read(channel, msg->rx.data, msg->rx.size,
+				       &msg->rx.ret);
+}
+EXPORT_SYMBOL_GPL(tegra_bpmp_transfer);
+
+static struct tegra_bpmp_mrq *tegra_bpmp_find_mrq(struct tegra_bpmp *bpmp,
+						  unsigned int mrq)
+{
+	struct tegra_bpmp_mrq *entry;
+
+	list_for_each_entry(entry, &bpmp->mrqs, list)
+		if (entry->mrq == mrq)
+			return entry;
+
+	return NULL;
+}
+
+void tegra_bpmp_mrq_return(struct tegra_bpmp_channel *channel, int code,
+			   const void *data, size_t size)
+{
+	unsigned long flags = tegra_bpmp_mb_read_field(&channel->ib, flags);
+	struct tegra_bpmp *bpmp = channel->bpmp;
+	int err;
+
+	if (WARN_ON(size > MSG_DATA_MIN_SZ))
+		return;
+
+	err = tegra_bpmp_ack_request(channel);
+	if (WARN_ON(err < 0))
+		return;
+
+	if ((flags & MSG_ACK) == 0)
+		return;
+
+	if (WARN_ON(!tegra_bpmp_is_response_channel_free(channel)))
+		return;
+
+	tegra_bpmp_mb_write_field(&channel->ob, code, code);
+
+	if (data && size > 0)
+		tegra_bpmp_mb_write(&channel->ob, data, size);
+
+	err = tegra_bpmp_post_response(channel);
+	if (WARN_ON(err < 0))
+		return;
+
+	if (flags & MSG_RING) {
+		err = tegra_bpmp_ring_doorbell(bpmp);
+		if (WARN_ON(err < 0))
+			return;
+	}
+}
+EXPORT_SYMBOL_GPL(tegra_bpmp_mrq_return);
+
+static void tegra_bpmp_handle_mrq(struct tegra_bpmp *bpmp,
+				  unsigned int mrq,
+				  struct tegra_bpmp_channel *channel)
+{
+	struct tegra_bpmp_mrq *entry;
+	u32 zero = 0;
+
+	spin_lock(&bpmp->lock);
+
+	entry = tegra_bpmp_find_mrq(bpmp, mrq);
+	if (!entry) {
+		spin_unlock(&bpmp->lock);
+		tegra_bpmp_mrq_return(channel, -EINVAL, &zero, sizeof(zero));
+		return;
+	}
+
+	entry->handler(mrq, channel, entry->data);
+
+	spin_unlock(&bpmp->lock);
+}
+
+int tegra_bpmp_request_mrq(struct tegra_bpmp *bpmp, unsigned int mrq,
+			   tegra_bpmp_mrq_handler_t handler, void *data)
+{
+	struct tegra_bpmp_mrq *entry;
+	unsigned long flags;
+
+	if (!handler)
+		return -EINVAL;
+
+	entry = devm_kzalloc(bpmp->dev, sizeof(*entry), GFP_KERNEL);
+	if (!entry)
+		return -ENOMEM;
+
+	spin_lock_irqsave(&bpmp->lock, flags);
+
+	entry->mrq = mrq;
+	entry->handler = handler;
+	entry->data = data;
+	list_add(&entry->list, &bpmp->mrqs);
+
+	spin_unlock_irqrestore(&bpmp->lock, flags);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tegra_bpmp_request_mrq);
+
+void tegra_bpmp_free_mrq(struct tegra_bpmp *bpmp, unsigned int mrq, void *data)
+{
+	struct tegra_bpmp_mrq *entry;
+	unsigned long flags;
+
+	spin_lock_irqsave(&bpmp->lock, flags);
+
+	entry = tegra_bpmp_find_mrq(bpmp, mrq);
+	if (!entry)
+		goto unlock;
+
+	list_del(&entry->list);
+	devm_kfree(bpmp->dev, entry);
+
+unlock:
+	spin_unlock_irqrestore(&bpmp->lock, flags);
+}
+EXPORT_SYMBOL_GPL(tegra_bpmp_free_mrq);
+
+bool tegra_bpmp_mrq_is_supported(struct tegra_bpmp *bpmp, unsigned int mrq)
+{
+	struct mrq_query_abi_request req = { .mrq = mrq };
+	struct mrq_query_abi_response resp;
+	struct tegra_bpmp_message msg = {
+		.mrq = MRQ_QUERY_ABI,
+		.tx = {
+			.data = &req,
+			.size = sizeof(req),
+		},
+		.rx = {
+			.data = &resp,
+			.size = sizeof(resp),
+		},
+	};
+	int err;
+
+	err = tegra_bpmp_transfer(bpmp, &msg);
+	if (err || msg.rx.ret)
+		return false;
+
+	return resp.status == 0;
+}
+EXPORT_SYMBOL_GPL(tegra_bpmp_mrq_is_supported);
+
+static void tegra_bpmp_mrq_handle_ping(unsigned int mrq,
+				       struct tegra_bpmp_channel *channel,
+				       void *data)
+{
+	struct mrq_ping_request request;
+	struct mrq_ping_response response;
+
+	tegra_bpmp_mb_read(&request, &channel->ib, sizeof(request));
+
+	memset(&response, 0, sizeof(response));
+	response.reply = request.challenge << 1;
+
+	tegra_bpmp_mrq_return(channel, 0, &response, sizeof(response));
+}
+
+static int tegra_bpmp_ping(struct tegra_bpmp *bpmp)
+{
+	struct mrq_ping_response response;
+	struct mrq_ping_request request;
+	struct tegra_bpmp_message msg;
+	unsigned long flags;
+	ktime_t start, end;
+	int err;
+
+	memset(&request, 0, sizeof(request));
+	request.challenge = 1;
+
+	memset(&response, 0, sizeof(response));
+
+	memset(&msg, 0, sizeof(msg));
+	msg.mrq = MRQ_PING;
+	msg.tx.data = &request;
+	msg.tx.size = sizeof(request);
+	msg.rx.data = &response;
+	msg.rx.size = sizeof(response);
+
+	local_irq_save(flags);
+	start = ktime_get();
+	err = tegra_bpmp_transfer_atomic(bpmp, &msg);
+	end = ktime_get();
+	local_irq_restore(flags);
+
+	if (!err)
+		dev_dbg(bpmp->dev,
+			"ping ok: challenge: %u, response: %u, time: %lld\n",
+			request.challenge, response.reply,
+			ktime_to_us(ktime_sub(end, start)));
+
+	return err;
+}
+
+/* deprecated version of tag query */
+static int tegra_bpmp_get_firmware_tag_old(struct tegra_bpmp *bpmp, char *tag,
+					   size_t size)
+{
+	struct mrq_query_tag_request request;
+	struct tegra_bpmp_message msg;
+	unsigned long flags;
+	dma_addr_t phys;
+	void *virt;
+	int err;
+
+	if (size != TAG_SZ)
+		return -EINVAL;
+
+	virt = dma_alloc_coherent(bpmp->dev, TAG_SZ, &phys,
+				  GFP_KERNEL | GFP_DMA32);
+	if (!virt)
+		return -ENOMEM;
+
+	memset(&request, 0, sizeof(request));
+	request.addr = phys;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.mrq = MRQ_QUERY_TAG;
+	msg.tx.data = &request;
+	msg.tx.size = sizeof(request);
+
+	local_irq_save(flags);
+	err = tegra_bpmp_transfer_atomic(bpmp, &msg);
+	local_irq_restore(flags);
+
+	if (err == 0)
+		memcpy(tag, virt, TAG_SZ);
+
+	dma_free_coherent(bpmp->dev, TAG_SZ, virt, phys);
+
+	return err;
+}
+
+static int tegra_bpmp_get_firmware_tag(struct tegra_bpmp *bpmp, char *tag,
+				       size_t size)
+{
+	if (tegra_bpmp_mrq_is_supported(bpmp, MRQ_QUERY_FW_TAG)) {
+		struct mrq_query_fw_tag_response resp;
+		struct tegra_bpmp_message msg = {
+			.mrq = MRQ_QUERY_FW_TAG,
+			.rx = {
+				.data = &resp,
+				.size = sizeof(resp),
+			},
+		};
+		int err;
+
+		if (size != sizeof(resp.tag))
+			return -EINVAL;
+
+		err = tegra_bpmp_transfer(bpmp, &msg);
+
+		if (err)
+			return err;
+		if (msg.rx.ret < 0)
+			return -EINVAL;
+
+		memcpy(tag, resp.tag, sizeof(resp.tag));
+		return 0;
+	}
+
+	return tegra_bpmp_get_firmware_tag_old(bpmp, tag, size);
+}
+
+static void tegra_bpmp_channel_signal(struct tegra_bpmp_channel *channel)
+{
+	unsigned long flags = tegra_bpmp_mb_read_field(&channel->ob, flags);
+
+	if ((flags & MSG_RING) == 0)
+		return;
+
+	complete(&channel->completion);
+}
+
+void tegra_bpmp_handle_rx(struct tegra_bpmp *bpmp)
+{
+	struct tegra_bpmp_channel *channel;
+	unsigned int i, count;
+	unsigned long *busy;
+
+	channel = bpmp->rx_channel;
+	count = bpmp->soc->channels.thread.count;
+	busy = bpmp->threaded.busy;
+
+	if (tegra_bpmp_is_request_ready(channel)) {
+		unsigned int mrq = tegra_bpmp_mb_read_field(&channel->ib, code);
+
+		tegra_bpmp_handle_mrq(bpmp, mrq, channel);
+	}
+
+	spin_lock(&bpmp->lock);
+
+	for_each_set_bit(i, busy, count) {
+		struct tegra_bpmp_channel *channel;
+
+		channel = &bpmp->threaded_channels[i];
+
+		if (tegra_bpmp_is_response_ready(channel)) {
+			tegra_bpmp_channel_signal(channel);
+			clear_bit(i, busy);
+		}
+	}
+
+	spin_unlock(&bpmp->lock);
+}
+
+static int tegra_bpmp_probe(struct platform_device *pdev)
+{
+	struct tegra_bpmp *bpmp;
+	char tag[TAG_SZ];
+	size_t size;
+	int err;
+
+	bpmp = devm_kzalloc(&pdev->dev, sizeof(*bpmp), GFP_KERNEL);
+	if (!bpmp)
+		return -ENOMEM;
+
+	bpmp->soc = of_device_get_match_data(&pdev->dev);
+	bpmp->dev = &pdev->dev;
+
+	INIT_LIST_HEAD(&bpmp->mrqs);
+	spin_lock_init(&bpmp->lock);
+
+	bpmp->threaded.count = bpmp->soc->channels.thread.count;
+	sema_init(&bpmp->threaded.lock, bpmp->threaded.count);
+
+	size = BITS_TO_LONGS(bpmp->threaded.count) * sizeof(long);
+
+	bpmp->threaded.allocated = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
+	if (!bpmp->threaded.allocated)
+		return -ENOMEM;
+
+	bpmp->threaded.busy = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
+	if (!bpmp->threaded.busy)
+		return -ENOMEM;
+
+	spin_lock_init(&bpmp->atomic_tx_lock);
+	bpmp->tx_channel = devm_kzalloc(&pdev->dev, sizeof(*bpmp->tx_channel),
+					GFP_KERNEL);
+	if (!bpmp->tx_channel)
+		return -ENOMEM;
+
+	bpmp->rx_channel = devm_kzalloc(&pdev->dev, sizeof(*bpmp->rx_channel),
+	                                GFP_KERNEL);
+	if (!bpmp->rx_channel)
+		return -ENOMEM;
+
+	bpmp->threaded_channels = devm_kcalloc(&pdev->dev, bpmp->threaded.count,
+					       sizeof(*bpmp->threaded_channels),
+					       GFP_KERNEL);
+	if (!bpmp->threaded_channels)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, bpmp);
+
+	err = bpmp->soc->ops->init(bpmp);
+	if (err < 0)
+		return err;
+
+	err = tegra_bpmp_request_mrq(bpmp, MRQ_PING,
+				     tegra_bpmp_mrq_handle_ping, bpmp);
+	if (err < 0)
+		goto deinit;
+
+	err = tegra_bpmp_ping(bpmp);
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to ping BPMP: %d\n", err);
+		goto free_mrq;
+	}
+
+	err = tegra_bpmp_get_firmware_tag(bpmp, tag, sizeof(tag));
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to get firmware tag: %d\n", err);
+		goto free_mrq;
+	}
+
+	dev_info(&pdev->dev, "firmware: %.*s\n", (int)sizeof(tag), tag);
+
+	err = of_platform_default_populate(pdev->dev.of_node, NULL, &pdev->dev);
+	if (err < 0)
+		goto free_mrq;
+
+	if (of_property_present(pdev->dev.of_node, "#clock-cells")) {
+		err = tegra_bpmp_init_clocks(bpmp);
+		if (err < 0)
+			goto free_mrq;
+	}
+
+	if (of_property_present(pdev->dev.of_node, "#reset-cells")) {
+		err = tegra_bpmp_init_resets(bpmp);
+		if (err < 0)
+			goto free_mrq;
+	}
+
+	if (of_property_present(pdev->dev.of_node, "#power-domain-cells")) {
+		err = tegra_bpmp_init_powergates(bpmp);
+		if (err < 0)
+			goto free_mrq;
+	}
+
+	err = tegra_bpmp_init_debugfs(bpmp);
+	if (err < 0)
+		dev_err(&pdev->dev, "debugfs initialization failed: %d\n", err);
+
+	return 0;
+
+free_mrq:
+	tegra_bpmp_free_mrq(bpmp, MRQ_PING, bpmp);
+deinit:
+	if (bpmp->soc->ops->deinit)
+		bpmp->soc->ops->deinit(bpmp);
+
+	return err;
+}
+
+static int __maybe_unused tegra_bpmp_suspend(struct device *dev)
+{
+	struct tegra_bpmp *bpmp = dev_get_drvdata(dev);
+
+	bpmp->suspended = true;
+
+	return 0;
+}
+
+static int __maybe_unused tegra_bpmp_resume(struct device *dev)
+{
+	struct tegra_bpmp *bpmp = dev_get_drvdata(dev);
+
+	bpmp->suspended = false;
+
+	if (bpmp->soc->ops->resume)
+		return bpmp->soc->ops->resume(bpmp);
+	else
+		return 0;
+}
+
+static const struct dev_pm_ops tegra_bpmp_pm_ops = {
+	.suspend_noirq = tegra_bpmp_suspend,
+	.resume_noirq = tegra_bpmp_resume,
+};
+
+#if IS_ENABLED(CONFIG_ARCH_TEGRA_186_SOC) || \
+    IS_ENABLED(CONFIG_ARCH_TEGRA_194_SOC) || \
+    IS_ENABLED(CONFIG_ARCH_TEGRA_234_SOC) || \
+    IS_ENABLED(CONFIG_ARCH_TEGRA_264_SOC)
+static const struct tegra_bpmp_soc tegra186_soc = {
+	.channels = {
+		.cpu_tx = {
+			.offset = 3,
+			.timeout = 60 * USEC_PER_SEC,
+		},
+		.thread = {
+			.offset = 0,
+			.count = 3,
+			.timeout = 600 * USEC_PER_SEC,
+		},
+		.cpu_rx = {
+			.offset = 13,
+			.timeout = 0,
+		},
+	},
+	.ops = &tegra186_bpmp_ops,
+	.num_resets = 193,
+};
+#endif
+
+#if IS_ENABLED(CONFIG_ARCH_TEGRA_210_SOC)
+static const struct tegra_bpmp_soc tegra210_soc = {
+	.channels = {
+		.cpu_tx = {
+			.offset = 0,
+			.count = 1,
+			.timeout = 60 * USEC_PER_SEC,
+		},
+		.thread = {
+			.offset = 4,
+			.count = 1,
+			.timeout = 600 * USEC_PER_SEC,
+		},
+		.cpu_rx = {
+			.offset = 8,
+			.count = 1,
+			.timeout = 0,
+		},
+	},
+	.ops = &tegra210_bpmp_ops,
+};
+#endif
+
+static const struct of_device_id tegra_bpmp_match[] = {
+#if IS_ENABLED(CONFIG_ARCH_TEGRA_186_SOC) || \
+    IS_ENABLED(CONFIG_ARCH_TEGRA_194_SOC) || \
+    IS_ENABLED(CONFIG_ARCH_TEGRA_234_SOC) || \
+    IS_ENABLED(CONFIG_ARCH_TEGRA_264_SOC)
+	{ .compatible = "nvidia,tegra186-bpmp", .data = &tegra186_soc },
+#endif
+#if IS_ENABLED(CONFIG_ARCH_TEGRA_210_SOC)
+	{ .compatible = "nvidia,tegra210-bpmp", .data = &tegra210_soc },
+#endif
+	{ }
+};
+
+static struct platform_driver tegra_bpmp_driver = {
+	.driver = {
+		.name = "tegra-bpmp",
+		.of_match_table = tegra_bpmp_match,
+		.pm = &tegra_bpmp_pm_ops,
+		.suppress_bind_attrs = true,
+	},
+	.probe = tegra_bpmp_probe,
+};
+builtin_platform_driver(tegra_bpmp_driver);