[PATCH v4 06/11] firmware: samsung: acpm: Add TMU protocol support

Tudor Ambarus
2026-04-23T15:23:05Z

The Thermal Management Unit (TMU) on the Google GS101 SoC is managed
through a hybrid model shared between the kernel and the Alive Clock
and Power Manager (ACPM) firmware.

Add the protocol helpers required to communicate with the ACPM for
thermal operations, including initialization, threshold configuration,
temperature reading, and system suspend/resume handshakes.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
---
drivers/firmware/samsung/Makefile | 1 +
drivers/firmware/samsung/exynos-acpm-tmu.c | 240 +++++++++++++++++++++
drivers/firmware/samsung/exynos-acpm-tmu.h | 28 +++
drivers/firmware/samsung/exynos-acpm.c | 12 ++
.../linux/firmware/samsung/exynos-acpm-protocol.h | 18 ++
5 files changed, 299 insertions(+)

diff --git a/drivers/firmware/samsung/Makefile b/drivers/firmware/samsung/Makefile
index 80d4f89b33a9..5a6f72bececf 100644
--- a/drivers/firmware/samsung/Makefile
+++ b/drivers/firmware/samsung/Makefile
@@ -3,4 +3,5 @@
acpm-protocol-objs := exynos-acpm.o
acpm-protocol-objs += exynos-acpm-pmic.o
acpm-protocol-objs += exynos-acpm-dvfs.o
+acpm-protocol-objs += exynos-acpm-tmu.o
obj-$(CONFIG_EXYNOS_ACPM_PROTOCOL) += acpm-protocol.o
diff --git a/drivers/firmware/samsung/exynos-acpm-tmu.c b/drivers/firmware/samsung/exynos-acpm-tmu.c
new file mode 100644
index 000000000000..7d9b75be032c
--- /dev/null
+++ b/drivers/firmware/samsung/exynos-acpm-tmu.c
@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2020 Samsung Electronics Co., Ltd.
+ * Copyright 2020 Google LLC.
+ * Copyright 2026 Linaro Ltd.
+ */
+
+#include <linux/array_size.h>
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/firmware/samsung/exynos-acpm-protocol.h>
+#include <linux/ktime.h>
+#include <linux/types.h>
+#include <linux/units.h>
+
+#include "exynos-acpm.h"
+#include "exynos-acpm-tmu.h"
+
+/* IPC Request Types */
+#define ACPM_TMU_INIT 0x01
+#define ACPM_TMU_READ_TEMP 0x02
+#define ACPM_TMU_SUSPEND 0x04
+#define ACPM_TMU_RESUME 0x10
+#define ACPM_TMU_THRESHOLD 0x11
+#define ACPM_TMU_INTEN 0x12
+#define ACPM_TMU_CONTROL 0x13
+#define ACPM_TMU_IRQ_CLEAR 0x14
+
+#define ACPM_TMU_TX_DATA_LEN 8
+#define ACPM_TMU_RX_DATA_LEN 7
+
+struct acpm_tmu_tx {
+ u16 ctx;
+ u16 fw_use;
+ u8 type;
+ u8 rsvd0;
+ u8 tzid;
+ u8 rsvd1;
+ u8 data[ACPM_TMU_TX_DATA_LEN];
+} __packed;
+
+struct acpm_tmu_rx {
+ u16 ctx;
+ u16 fw_use;
+ u8 type;
+ s8 ret;
+ u8 tzid;
+ s8 temp;
+ u8 rsvd;
+ u8 data[ACPM_TMU_RX_DATA_LEN];
+} __packed;
+
+union acpm_tmu_msg {
+ u32 data[4];
+ struct acpm_tmu_tx tx;
+ struct acpm_tmu_rx rx;
+};
+
+static int acpm_tmu_to_linux_err(s8 fw_err)
+{
+ /*
+ * ACPM_TMU_INIT uses BIT(0) and BIT(1) of msg.rx.ret to flag APM
+ * capabilities. Treat zero and all positive values as success.
+ */
+ if (fw_err >= 0)
+ return 0;
+
+ if (fw_err == -1)
+ return -EACCES;
+
+ return -EIO;
+}
+
+int acpm_tmu_init(struct acpm_handle *handle, unsigned int acpm_chan_id)
+{
+ union acpm_tmu_msg msg = {0};
+ struct acpm_xfer xfer;
+ int ret;
+
+ msg.tx.type = ACPM_TMU_INIT;
+ acpm_set_xfer(&xfer, msg.data, ARRAY_SIZE(msg.data), acpm_chan_id,
+ true);
+
+ ret = acpm_do_xfer(handle, &xfer);
+ if (ret)
+ return ret;
+
+ return acpm_tmu_to_linux_err(msg.rx.ret);
+}
+
+int acpm_tmu_read_temp(struct acpm_handle *handle, unsigned int acpm_chan_id,
+ u8 tz, int *temp)
+{
+ union acpm_tmu_msg msg = {0};
+ struct acpm_xfer xfer;
+ int ret;
+
+ msg.tx.type = ACPM_TMU_READ_TEMP;
+ msg.tx.tzid = tz;
+
+ acpm_set_xfer(&xfer, msg.data, ARRAY_SIZE(msg.data), acpm_chan_id,
+ true);
+
+ ret = acpm_do_xfer(handle, &xfer);
+ if (ret)
+ return ret;
+
+ ret = acpm_tmu_to_linux_err(msg.rx.ret);
+ if (ret)
+ return ret;
+
+ *temp = msg.rx.temp;
+
+ return 0;
+}
+
+int acpm_tmu_set_threshold(struct acpm_handle *handle,
+ unsigned int acpm_chan_id, u8 tz,
+ const u8 temperature[8], size_t tlen)
+{
+ union acpm_tmu_msg msg = {0};
+ struct acpm_xfer xfer;
+ int i, ret;
+
+ if (tlen > ACPM_TMU_TX_DATA_LEN)
+ return -EINVAL;
+
+ msg.tx.type = ACPM_TMU_THRESHOLD;
+ msg.tx.tzid = tz;
+
+ for (i = 0; i < tlen; i++)
+ msg.tx.data[i] = temperature[i];
+
+ acpm_set_xfer(&xfer, msg.data, ARRAY_SIZE(msg.data), acpm_chan_id,
+ true);
+
+ ret = acpm_do_xfer(handle, &xfer);
+ if (ret)
+ return ret;
+
+ return acpm_tmu_to_linux_err(msg.rx.ret);
+}
+
+int acpm_tmu_set_interrupt_enable(struct acpm_handle *handle,
+ unsigned int acpm_chan_id, u8 tz, u8 inten)
+{
+ union acpm_tmu_msg msg = {0};
+ struct acpm_xfer xfer;
+ int ret;
+
+ msg.tx.type = ACPM_TMU_INTEN;
+ msg.tx.tzid = tz;
+ msg.tx.data[0] = inten;
+
+ acpm_set_xfer(&xfer, msg.data, ARRAY_SIZE(msg.data), acpm_chan_id,
+ true);
+
+ ret = acpm_do_xfer(handle, &xfer);
+ if (ret)
+ return ret;
+
+ return acpm_tmu_to_linux_err(msg.rx.ret);
+}
+
+int acpm_tmu_tz_control(struct acpm_handle *handle, unsigned int acpm_chan_id,
+ u8 tz, bool enable)
+{
+ union acpm_tmu_msg msg = {0};
+ struct acpm_xfer xfer;
+ int ret;
+
+ msg.tx.type = ACPM_TMU_CONTROL;
+ msg.tx.tzid = tz;
+ msg.tx.data[0] = enable ? 1 : 0;
+
+ acpm_set_xfer(&xfer, msg.data, ARRAY_SIZE(msg.data), acpm_chan_id,
+ true);
+
+ ret = acpm_do_xfer(handle, &xfer);
+ if (ret)
+ return ret;
+
+ return acpm_tmu_to_linux_err(msg.rx.ret);
+}
+
+int acpm_tmu_clear_tz_irq(struct acpm_handle *handle, unsigned int acpm_chan_id,
+ u8 tz)
+{
+ union acpm_tmu_msg msg = {0};
+ struct acpm_xfer xfer;
+ int ret;
+
+ msg.tx.type = ACPM_TMU_IRQ_CLEAR;
+ msg.tx.tzid = tz;
+
+ acpm_set_xfer(&xfer, msg.data, ARRAY_SIZE(msg.data), acpm_chan_id,
+ true);
+
+ ret = acpm_do_xfer(handle, &xfer);
+ if (ret)
+ return ret;
+
+ return acpm_tmu_to_linux_err(msg.rx.ret);
+}
+
+int acpm_tmu_suspend(struct acpm_handle *handle, unsigned int acpm_chan_id)
+{
+ union acpm_tmu_msg msg = {0};
+ struct acpm_xfer xfer;
+ int ret;
+
+ msg.tx.type = ACPM_TMU_SUSPEND;
+
+ acpm_set_xfer(&xfer, msg.data, ARRAY_SIZE(msg.data), acpm_chan_id,
+ true);
+
+ ret = acpm_do_xfer(handle, &xfer);
+ if (ret)
+ return ret;
+
+ return acpm_tmu_to_linux_err(msg.rx.ret);
+}
+
+int acpm_tmu_resume(struct acpm_handle *handle, unsigned int acpm_chan_id)
+{
+ union acpm_tmu_msg msg = {0};
+ struct acpm_xfer xfer;
+ int ret;
+
+ msg.tx.type = ACPM_TMU_RESUME;
+
+ acpm_set_xfer(&xfer, msg.data, ARRAY_SIZE(msg.data), acpm_chan_id,
+ true);
+
+ ret = acpm_do_xfer(handle, &xfer);
+ if (ret)
+ return ret;
+
+ return acpm_tmu_to_linux_err(msg.rx.ret);
+}
diff --git a/drivers/firmware/samsung/exynos-acpm-tmu.h b/drivers/firmware/samsung/exynos-acpm-tmu.h
new file mode 100644
index 000000000000..8b89f29fda67
--- /dev/null
+++ b/drivers/firmware/samsung/exynos-acpm-tmu.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2020 Samsung Electronics Co., Ltd.
+ * Copyright 2020 Google LLC.
+ * Copyright 2026 Linaro Ltd.
+ */
+#ifndef __EXYNOS_ACPM_TMU_H__
+#define __EXYNOS_ACPM_TMU_H__
+
+#include <linux/types.h>
+
+struct acpm_handle;
+
+int acpm_tmu_init(struct acpm_handle *handle, unsigned int acpm_chan_id);
+int acpm_tmu_read_temp(struct acpm_handle *handle, unsigned int acpm_chan_id,
+ u8 tz, int *temp);
+int acpm_tmu_set_threshold(struct acpm_handle *handle,
+ unsigned int acpm_chan_id, u8 tz,
+ const u8 temperature[8], size_t tlen);
+int acpm_tmu_set_interrupt_enable(struct acpm_handle *handle,
+ unsigned int acpm_chan_id, u8 tz, u8 inten);
+int acpm_tmu_tz_control(struct acpm_handle *handle, unsigned int acpm_chan_id,
+ u8 tz, bool enable);
+int acpm_tmu_clear_tz_irq(struct acpm_handle *handle, unsigned int acpm_chan_id,
+ u8 tz);
+int acpm_tmu_suspend(struct acpm_handle *handle, unsigned int acpm_chan_id);
+int acpm_tmu_resume(struct acpm_handle *handle, unsigned int acpm_chan_id);
+#endif /* __EXYNOS_ACPM_TMU_H__ */
diff --git a/drivers/firmware/samsung/exynos-acpm.c b/drivers/firmware/samsung/exynos-acpm.c
index 38f40fb67ea7..655b80fc635f 100644
--- a/drivers/firmware/samsung/exynos-acpm.c
+++ b/drivers/firmware/samsung/exynos-acpm.c
@@ -31,6 +31,7 @@
#include "exynos-acpm.h"
#include "exynos-acpm-dvfs.h"
#include "exynos-acpm-pmic.h"
+#include "exynos-acpm-tmu.h"

#define ACPM_PROTOCOL_SEQNUM GENMASK(21, 16)

@@ -639,6 +640,17 @@ static const struct acpm_ops exynos_acpm_driver_ops = {
.bulk_write = acpm_pmic_bulk_write,
.update_reg = acpm_pmic_update_reg,
},
+
+ .tmu = {
+ .init = acpm_tmu_init,
+ .read_temp = acpm_tmu_read_temp,
+ .set_threshold = acpm_tmu_set_threshold,
+ .set_interrupt_enable = acpm_tmu_set_interrupt_enable,
+ .tz_control = acpm_tmu_tz_control,
+ .clear_tz_irq = acpm_tmu_clear_tz_irq,
+ .suspend = acpm_tmu_suspend,
+ .resume = acpm_tmu_resume,
+ },
};

static int acpm_probe(struct platform_device *pdev)
diff --git a/include/linux/firmware/samsung/exynos-acpm-protocol.h b/include/linux/firmware/samsung/exynos-acpm-protocol.h
index fbf1829b33db..08d9f5c95701 100644
--- a/include/linux/firmware/samsung/exynos-acpm-protocol.h
+++ b/include/linux/firmware/samsung/exynos-acpm-protocol.h
@@ -35,9 +35,27 @@ struct acpm_pmic_ops {
u8 type, u8 reg, u8 chan, u8 value, u8 mask);
};

+struct acpm_tmu_ops {
+ int (*init)(struct acpm_handle *handle, unsigned int acpm_chan_id);
+ int (*read_temp)(struct acpm_handle *handle, unsigned int acpm_chan_id,
+ u8 tz, int *temp);
+ int (*set_threshold)(struct acpm_handle *handle,
+ unsigned int acpm_chan_id, u8 tz,
+ const u8 temperature[8], size_t tlen);
+ int (*set_interrupt_enable)(struct acpm_handle *handle,
+ unsigned int acpm_chan_id, u8 tz, u8 inten);
+ int (*tz_control)(struct acpm_handle *handle, unsigned int acpm_chan_id,
+ u8 tz, bool enable);
+ int (*clear_tz_irq)(struct acpm_handle *handle,
+ unsigned int acpm_chan_id, u8 tz);
+ int (*suspend)(struct acpm_handle *handle, unsigned int acpm_chan_id);
+ int (*resume)(struct acpm_handle *handle, unsigned int acpm_chan_id);
+};
+
struct acpm_ops {
struct acpm_dvfs_ops dvfs;
struct acpm_pmic_ops pmic;
+ struct acpm_tmu_ops tmu;
};

/**

--
2.54.0.545.g6539524ca2-goog