[PATCH v4 0/3] Add Altera SoCFPGA Crypto Service (FCS) driver

[PATCH v4 0/3] Add Altera SoCFPGA Crypto Service (FCS) driver

[hang.suan.wang]

From: Hang Suan Wang <hang.suan.wang@altera.com>

This series adds Linux support for one of the Altera SoCFPGA Crypto Service
(FCS): Secure Data Object Service (SDOS). FCS is a runtime cryptographic
interface provided by the Secure Device Manager (SDM).

The SDM is the hardware security controller in Altera SoCFPGA devices. Host
software reaches it through the existing stratix10-svc mailbox, which uses
Arm Trusted Firmware SIP SMC calls. In this series does not expose the rest
of FCS (RNG, AES, SHA, key management, and so on).

SDOS protects data at rest. The SDM encrypts and decrypts using a key
derived from a device-unique SDOS root key that never leaves the secure
boundary. The host supplies plaintext (or an authenticated object) and
never handles raw key material. A primary use case is black-key
provisioning.

SDOS requests use the stratix10-svc asynchronous SIP SMC path. Source and
destination buffers are allocated from the service-layer memory pool, and
their physical addresses are passed to the SDM. Each request opens an SDM
crypto session, runs under a lock (one in-flight transaction), and closes
the session afterwards.

The series is organized as follows:
 - Patch 1 (prerequisite) enlarges the stratix10-svc SMC argument array so
   the asynchronous FCS SDOS command can pass its full set of parameters.

 - Patch 2 (prerequisite) extends the stratix10-svc service layer with the 
   FCS command codes and matching SIP SMC function IDs, adds the Agilex 5
   (intel,agilex5-svc) match, and registers a "stratix10-fcs" platform
   device that an FCS client driver binds to.

 - Patch 3 adds the FCS driver implementing SDOS encrypt/decrypt. It is 
   exposed as a misc device (/dev/socfpga-fcs) via ioctl FCS_IOC_SDOS. The
   crypto session is opened and closed in the kernel and is not part of the
   user ABI.

Testing:
 - Built for arm64 (defconfig + CONFIG_ALTERA_SOCFPGA_FCS=m).
 - Tested on an Agilex 5 SoC FPGA board (SDOS root key provisioned).
   SDOS encrypt/decrypt round-trip; the decrypted output matches the
   original 32-byte plaintext:

   root@agilex5e:~# hexdump -v -e '/1 "%02x "' secret.bin
   38 61 39 36 38 38 65 31 64 65 35 37 38 33 62 34
   39 37 32 65 33 31 64 37 63 65 30 37 30 63 31 35

   root@agilex5e:~# ./fcs_client -E -i secret.bin -o enc.bin -d 0x1234 -r
                    0xabcd
   root@agilex5e:~# ./fcs_client -D -i enc.bin -o sdos_decrypt.bin

   root@agilex5e:~# hexdump -v -e '/1 "%02x "' sdos_decrypt.bin
   38 61 39 36 38 38 65 31 64 65 35 37 38 33 62 34
   39 37 32 65 33 31 64 37 63 65 30 37 30 63 31 35

---
Changes since v3:
 - Rebase onto current linux-upstream; register stratix10-fcs beside the
   existing socfpga-hwmon child device.
 - Drop context_id from the ioctl UAPI; the kernel owns session and context.
 - Make FCS state per-device and kref-counted so an open fd can outlive
   driver remove (-ENODEV after unbind).
 - Copy user buffers in the front-end; the core uses kernel pointers only.
 - Use kzalloc_obj() and shorten comments.

Changes since v2:
socfpga-fcs (front-end):
 - Replace the sysfs store interface with an ioctl character device
   (/dev/socfpga_fcs) using a fixed-width UAPI struct and
   compat_ptr_ioctl(), fixing the KASAN out-of-bounds read and the
   32-bit incompatibility of casting the sysfs buffer as a pointer.
 - Add include/uapi/misc/socfpga-fcs-crypto.h and register the ioctl
   magic in Documentation/userspace-api/ioctl/ioctl-number.rst.
 - Add a .release handler so a session is torn down if the owning fd
   is closed (including on crash).
socfpga-fcs (core):
 - Manage the crypto session internally: SDOS opens and closes its own
   session; reject a concurrent open with -EBUSY. Removes the
   user-visible open/close-session interface and session UUID, fixing
   the session-exhaustion/DoS concern.
 - Harden the async poll loop: keep polling until the deadline and
   always call stratix10_svc_async_done(), fixing the teardown
   use-after-free from the previous -EINPROGRESS early-return and the
   needless full-timeout block.
 - Clear receive_cb only on the synchronous send-error path so a late
   firmware response cannot deref a NULL callback.
 - Set priv = NULL on all fcs_init() error paths so a later probe is
   not permanently rejected with -EBUSY.
 - Read the SDOS owner ID with get_unaligned_le64() for correct
   little-endian handling on big-endian hosts.
stratix10-svc:
 - Enlarge the SMC arguments array so the async SDOS command can
   pass its full parameter set (through a11).
 - In remove(), unregister the child devices before
   stratix10_svc_async_exit() so async_poll() cannot race a freed
   handle.

---
Changes since v1:
stratix10-svc:
 - Forward result registers (kaddr1) for OPEN_SESSION and SDOS_DATA_EXT
   so session ID / output length reach the client.
socfpga-fcs (front-end):
 - Publish sysfs via driver.dev_groups on the platform device instead of
   a raw kobject under /sys/kernel; callbacks now get a struct device.
socfpga-fcs (core):
 - Convert completion timeouts with msecs_to_jiffies(); drop TIMEOUT.
 - On SDM-busy timeout (-EAGAIN), abort without async_done() (no id
   reuse) and return -EINPROGRESS.
 - SDOS: on in-flight abort, leak s_buf/d_buf instead of freeing to
   avoid corruption from late firmware DMA.
 - Validate the caller UUID early in fcs_sdos_crypt().
 - Enforce single instance: -EBUSY in fcs_init() and priv NULL-guard in
   fcs_acquire_cmd_ctx().
 - Drop the always-zero platform attribute and fcs_get_platform().
 - Set/clear receive_cb only around the synchronous send.
 - Use device-lifetime priv->completion for the async path (was on-stack).
 - Use the local ctx snapshot consistently in fcs_sdos_crypt() and
   fcs_session_close().
 - Point sdos.dst_size at priv->sdos_output_size, not a stack variable.
socfpga-fcs.h:
 - Drop platform/AGILEX5_PLAT; add sdos_output_size.
---

Hang Suan Wang (3):
  firmware: stratix10-svc: increase args array
  firmware: stratix10-svc: add FCS crypto-service commands for Agilex 5
  firmware: socfpga-fcs: add Altera SoCFPGA FCS driver with SDOS

 .../userspace-api/ioctl/ioctl-number.rst      |   1 +
 MAINTAINERS                                   |   9 +
 drivers/firmware/Kconfig                      |  17 +
 drivers/firmware/Makefile                     |   2 +
 drivers/firmware/socfpga-fcs-core.c           | 684 ++++++++++++++++++
 drivers/firmware/socfpga-fcs.c                | 294 ++++++++
 drivers/firmware/stratix10-svc.c              |  65 +-
 include/linux/firmware/intel/socfpga-fcs.h    | 130 ++++
 include/linux/firmware/intel/stratix10-smc.h  |  64 ++
 .../firmware/intel/stratix10-svc-client.h     |  18 +-
 include/uapi/misc/socfpga-fcs-crypto.h        |  28 +
 11 files changed, 1304 insertions(+), 8 deletions(-)
 create mode 100644 drivers/firmware/socfpga-fcs-core.c
 create mode 100644 drivers/firmware/socfpga-fcs.c
 create mode 100644 include/linux/firmware/intel/socfpga-fcs.h
 create mode 100644 include/uapi/misc/socfpga-fcs-crypto.h

-- 
2.43.7

[PATCH v4 1/3] firmware: stratix10-svc: increase args array

[hang.suan.wang]

From: Hang Suan Wang <hang.suan.wang@altera.com>

Increase args array from 3 to 6, for the SDOS encryption to call smc
call which is used for args to be passed via registers and not
physically mapped buffer.

Signed-off-by: Hang Suan Wang <hang.suan.wang@altera.com>
---
 drivers/firmware/stratix10-svc.c                    | 6 ++++--
 include/linux/firmware/intel/stratix10-svc-client.h | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/stratix10-svc.c b/drivers/firmware/stratix10-svc.c
index f8c2da207cb4..07345efeef0c 100644
--- a/drivers/firmware/stratix10-svc.c
+++ b/drivers/firmware/stratix10-svc.c
@@ -173,7 +173,7 @@ struct stratix10_svc_data {
 	size_t size_output;
 	u32 command;
 	u32 flag;
-	u64 arg[3];
+	u64 arg[6];
 };
 
 /**
@@ -1888,7 +1888,9 @@ int stratix10_svc_send(struct stratix10_svc_chan *chan, void *msg)
 	p_data->arg[0] = p_msg->arg[0];
 	p_data->arg[1] = p_msg->arg[1];
 	p_data->arg[2] = p_msg->arg[2];
-	p_data->size = p_msg->payload_length;
+	p_data->arg[3] = p_msg->arg[3];
+	p_data->arg[4] = p_msg->arg[4];
+	p_data->arg[5] = p_msg->arg[5];
 	p_data->chan = chan;
 	pr_debug("%s: %s: put to FIFO pa=0x%016x, cmd=%x, size=%u\n",
 		 __func__,
diff --git a/include/linux/firmware/intel/stratix10-svc-client.h b/include/linux/firmware/intel/stratix10-svc-client.h
index af13dacdf5ac..9bb46c3cb0f8 100644
--- a/include/linux/firmware/intel/stratix10-svc-client.h
+++ b/include/linux/firmware/intel/stratix10-svc-client.h
@@ -215,7 +215,7 @@ struct stratix10_svc_client_msg {
 	void *payload_output;
 	size_t payload_length_output;
 	enum stratix10_svc_command_code command;
-	u64 arg[3];
+	u64 arg[6];
 };
 
 /**
-- 
2.43.7

[PATCH v4 2/3] firmware: stratix10-svc: add FCS crypto-service commands for Agilex 5

[hang.suan.wang]

From: Hang Suan Wang <hang.suan.wang@altera.com>

The Agilex 5 Secure Device Manager (SDM 1.5) exposes an FPGA Crypto
Service (FCS) over the existing SIP SMC mailbox: a session-based
interface for crypto primitives such as SDOS (Secure Data Object
Service) encrypt/decrypt. The service layer has no command to drive it
yet.

Configure stratix10-svc about this interface so an in-kernel FCS client
can use it:

  - add the client command codes COMMAND_FCS_CRYPTO_OPEN_SESSION,
    COMMAND_FCS_CRYPTO_CLOSE_SESSION and COMMAND_FCS_SDOS_DATA_EXT (all
    asynchronous)

  - add the matching asynchronous SIP SMC function IDs
    (INTEL_SIP_SMC_ASYNC_FCS_OPEN_CS_SESSION,
    INTEL_SIP_SMC_ASYNC_FCS_CLOSE_CS_SESSION and
    INTEL_SIP_SMC_ASYNC_FCS_CRYPTION_EXT) with their register-usage
    documentation;

  - match "intel,agilex5-svc" and register a "stratix10-fcs" child
    platform device, mirroring the existing RSU child, so an FCS client
    driver can bind without a dedicated device-tree node;

  - dispatch the new commands in the asynchronous send and response
    paths; for the SDOS data command, translate the source and
    destination buffers (allocated from the service-layer gen_pool) to
    physical addresses and pass them, together with the session/context
    IDs and owner ID, to the SDM.

The transport is unchanged: Agilex 5 reuses the SIP SMC calling
convention and async mailbox ABI the driver already implements, so no
new transport mechanism is required.

The SDOS SMMU-remapped address slots currently carry the buffer
physical addresses; SMMU remapping support is added in a follow-up
series.

This is a prerequisite for the SoCFPGA FCS driver, the first in-tree
consumer of these commands.

Signed-off-by: Hang Suan Wang <hang.suan.wang@altera.com>
Reviewed-by: Dinh Nguyen <dinguyen@kernel.org>
---
 drivers/firmware/stratix10-svc.c              | 59 +++++++++++++++--
 include/linux/firmware/intel/stratix10-smc.h  | 64 +++++++++++++++++++
 .../firmware/intel/stratix10-svc-client.h     | 16 +++++
 3 files changed, 134 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/stratix10-svc.c b/drivers/firmware/stratix10-svc.c
index 07345efeef0c..8ead4a3c4a1b 100644
--- a/drivers/firmware/stratix10-svc.c
+++ b/drivers/firmware/stratix10-svc.c
@@ -46,6 +46,7 @@
 
 /* stratix10 service layer clients */
 #define STRATIX10_RSU				"stratix10-rsu"
+#define STRATIX10_FCS				"stratix10-fcs"
 #define SOCFPGA_HWMON				"socfpga-hwmon"
 
 /* Maximum number of SDM client IDs. */
@@ -106,10 +107,12 @@ struct stratix10_svc_chan;
 /**
  * struct stratix10_svc - svc private data
  * @stratix10_svc_rsu: pointer to stratix10 RSU device
+ * @stratix10_svc_fcs: pointer to stratix10 FCS device
  * @stratix10_svc_hwmon: pointer to stratix10 HWMON device
  */
 struct stratix10_svc {
 	struct platform_device *stratix10_svc_rsu;
+	struct platform_device *stratix10_svc_fcs;
 	struct platform_device *stratix10_svc_hwmon;
 };
 
@@ -1398,6 +1401,30 @@ int stratix10_svc_async_send(struct stratix10_svc_chan *chan, void *msg,
 		STRATIX10_SIP_SMC_SET_TRANSACTIONID_X1(handle->transaction_id);
 
 	switch (p_msg->command) {
+	case COMMAND_FCS_CRYPTO_OPEN_SESSION:
+		args.a0 = INTEL_SIP_SMC_ASYNC_FCS_OPEN_CS_SESSION;
+		break;
+	case COMMAND_FCS_CRYPTO_CLOSE_SESSION:
+		args.a0 = INTEL_SIP_SMC_ASYNC_FCS_CLOSE_CS_SESSION;
+		args.a2 = p_msg->arg[0];
+		break;
+	case COMMAND_FCS_SDOS_DATA_EXT:
+		args.a0 = INTEL_SIP_SMC_ASYNC_FCS_CRYPTION_EXT;
+		args.a2 = p_msg->arg[0];
+		args.a3 = p_msg->arg[1];
+		args.a4 = p_msg->arg[2];
+		/* payloads are allocated from the svc gen_pool; pass phys addr */
+		args.a5 = gen_pool_virt_to_phys(ctrl->genpool,
+						(unsigned long)p_msg->payload);
+		args.a6 = p_msg->payload_length;
+		args.a7 = gen_pool_virt_to_phys(ctrl->genpool,
+						(unsigned long)p_msg->payload_output);
+		args.a8 = p_msg->payload_length_output;
+		args.a9 = p_msg->arg[3];
+		/* SMMU remapping is added later; pass phys addr for now */
+		args.a10 = args.a5;
+		args.a11 = args.a7;
+		break;
 	case COMMAND_RSU_GET_SPT_TABLE:
 		args.a0 = INTEL_SIP_SMC_ASYNC_RSU_GET_SPT;
 		break;
@@ -1495,8 +1522,13 @@ static int stratix10_svc_async_prepare_response(struct stratix10_svc_chan *chan,
 	data->status = STRATIX10_GET_SDM_STATUS_CODE(handle->res.a1);
 
 	switch (p_msg->command) {
+	case COMMAND_FCS_CRYPTO_CLOSE_SESSION:
 	case COMMAND_RSU_NOTIFY:
 		break;
+	case COMMAND_FCS_CRYPTO_OPEN_SESSION:
+	case COMMAND_FCS_SDOS_DATA_EXT:
+		data->kaddr1 = (void *)&handle->res.a2;
+		break;
 	case COMMAND_RSU_GET_SPT_TABLE:
 		data->kaddr1 = (void *)&handle->res.a2;
 		data->kaddr2 = (void *)&handle->res.a3;
@@ -2004,6 +2036,7 @@ EXPORT_SYMBOL_GPL(stratix10_svc_free_memory);
 static const struct of_device_id stratix10_svc_drv_match[] = {
 	{.compatible = "intel,stratix10-svc"},
 	{.compatible = "intel,agilex-svc"},
+	{.compatible = "intel,agilex5-svc"},
 	{},
 };
 
@@ -2107,7 +2140,18 @@ static int stratix10_svc_drv_probe(struct platform_device *pdev)
 
 	ret = platform_device_add(svc->stratix10_svc_rsu);
 	if (ret)
-		goto err_put_device;
+		goto err_put_rsu;
+
+	svc->stratix10_svc_fcs = platform_device_alloc(STRATIX10_FCS, 0);
+	if (!svc->stratix10_svc_fcs) {
+		dev_err(dev, "failed to allocate %s device\n", STRATIX10_FCS);
+		ret = -ENOMEM;
+		goto err_unregister_rsu;
+	}
+
+	ret = platform_device_add(svc->stratix10_svc_fcs);
+	if (ret)
+		goto err_put_fcs;
 
 	if (IS_ENABLED(CONFIG_SENSORS_ALTERA_SOCFPGA_HWMON)) {
 		svc->stratix10_svc_hwmon =
@@ -2139,10 +2183,14 @@ static int stratix10_svc_drv_probe(struct platform_device *pdev)
 err_unregister_clients:
 	if (svc->stratix10_svc_hwmon)
 		platform_device_unregister(svc->stratix10_svc_hwmon);
-	if (svc->stratix10_svc_rsu)
-		platform_device_unregister(svc->stratix10_svc_rsu);
+	platform_device_unregister(svc->stratix10_svc_fcs);
+	goto err_unregister_rsu;
+err_put_fcs:
+	platform_device_put(svc->stratix10_svc_fcs);
+err_unregister_rsu:
+	platform_device_unregister(svc->stratix10_svc_rsu);
 	goto err_free_fifos;
-err_put_device:
+err_put_rsu:
 	platform_device_put(svc->stratix10_svc_rsu);
 err_free_fifos:
 	/* only remove from list if list_add_tail() was reached */
@@ -2164,9 +2212,10 @@ static void stratix10_svc_drv_remove(struct platform_device *pdev)
 	struct stratix10_svc_controller *ctrl = platform_get_drvdata(pdev);
 	struct stratix10_svc *svc = ctrl->svc;
 
-	platform_device_unregister(svc->stratix10_svc_rsu);
 	if (svc->stratix10_svc_hwmon)
 		platform_device_unregister(svc->stratix10_svc_hwmon);
+	platform_device_unregister(svc->stratix10_svc_fcs);
+	platform_device_unregister(svc->stratix10_svc_rsu);
 
 	stratix10_svc_async_exit(ctrl);
 
diff --git a/include/linux/firmware/intel/stratix10-smc.h b/include/linux/firmware/intel/stratix10-smc.h
index 366309260121..75a39e7190af 100644
--- a/include/linux/firmware/intel/stratix10-smc.h
+++ b/include/linux/firmware/intel/stratix10-smc.h
@@ -669,6 +669,70 @@ INTEL_SIP_SMC_FAST_CALL_VAL(INTEL_SIP_SMC_FUNCID_FPGA_CONFIG_COMPLETED_WRITE)
 #define INTEL_SIP_SMC_FCS_GET_PROVISION_DATA \
 	INTEL_SIP_SMC_STD_CALL_VAL(INTEL_SIP_SMC_FUNCID_FCS_GET_PROVISION_DATA)
 
+/**
+ * Request INTEL_SIP_SMC_ASYNC_FCS_CRYPTION_EXT
+ * Async call to perform encryption/decryption
+ *
+ * Call register usage:
+ * a0 INTEL_SIP_SMC_ASYNC_FCS_CRYPTION_EXT
+ * a1 transaction job id
+ * a2 session ID
+ * a3 context ID
+ * a4 cryption operating mode (1 for encryption and 0 for decryption)
+ * a5 physical address of source
+ * a6 size of source
+ * a7 physical address of destination
+ * a8 size of destination
+ * a9 sdos ownership
+ * a10 smmu remapped address of source
+ * a11 smmu remapped address of destination
+ * a12-a17 not used
+ *
+ * Return status:
+ * a0 INTEL_SIP_SMC_STATUS_OK or INTEL_SIP_SMC_STATUS_ERROR
+ * a1-a17 not used
+ */
+#define INTEL_SIP_SMC_ASYNC_FUNC_ID_FCS_CRYPTION_EXT (0x12F)
+#define INTEL_SIP_SMC_ASYNC_FCS_CRYPTION_EXT \
+	INTEL_SIP_SMC_ASYNC_VAL(INTEL_SIP_SMC_ASYNC_FUNC_ID_FCS_CRYPTION_EXT)
+
+/**
+ * Request INTEL_SIP_SMC_ASYNC_FCS_OPEN_CS_SESSION
+ * Async call to open and establish a crypto service session with firmware
+ *
+ * Call register usage:
+ * a0 INTEL_SIP_SMC_FCS_OPEN_CRYPTO_SERVICE_SESSION
+ * a1 transaction job id
+ * a2-a17 not used
+ *
+ * Return status:
+ * a0 INTEL_SIP_SMC_STATUS_OK ,INTEL_SIP_SMC_STATUS_REJECTED
+ * or INTEL_SIP_SMC_STATUS_BUSY
+ * a1-a17 not used
+ */
+#define INTEL_SIP_SMC_ASYNC_FUNC_ID_FCS_OPEN_CS_SESSION (0x13A)
+#define INTEL_SIP_SMC_ASYNC_FCS_OPEN_CS_SESSION \
+	INTEL_SIP_SMC_ASYNC_VAL(INTEL_SIP_SMC_ASYNC_FUNC_ID_FCS_OPEN_CS_SESSION)
+
+/**
+ * Request INTEL_SIP_SMC_ASYNC_FCS_CLOSE_CS_SESSION
+ * Async call to close a service session
+ *
+ * Call register usage:
+ * a0 INTEL_SIP_SMC_ASYNC_FCS_CLOSE_CS_SESSION
+ * a1 transaction job id
+ * a2 session ID
+ * a3-a17 not used
+ *
+ * Return status:
+ * a0 INTEL_SIP_SMC_STATUS_OK ,INTEL_SIP_SMC_STATUS_REJECTED
+ * or INTEL_SIP_SMC_STATUS_BUSY
+ * a1-a17 not used
+ */
+#define INTEL_SIP_SMC_ASYNC_FUNC_ID_FCS_CLOSE_CS_SESSION (0x13B)
+#define INTEL_SIP_SMC_ASYNC_FCS_CLOSE_CS_SESSION \
+	INTEL_SIP_SMC_ASYNC_VAL(INTEL_SIP_SMC_ASYNC_FUNC_ID_FCS_CLOSE_CS_SESSION)
+
 /**
  * Request INTEL_SIP_SMC_HWMON_READTEMP
  * Sync call to request temperature
diff --git a/include/linux/firmware/intel/stratix10-svc-client.h b/include/linux/firmware/intel/stratix10-svc-client.h
index 9bb46c3cb0f8..ffc1ac7c9785 100644
--- a/include/linux/firmware/intel/stratix10-svc-client.h
+++ b/include/linux/firmware/intel/stratix10-svc-client.h
@@ -7,6 +7,8 @@
 #ifndef __STRATIX10_SVC_CLIENT_H
 #define __STRATIX10_SVC_CLIENT_H
 
+#include <linux/types.h>
+
 /*
  * Service layer driver supports client names
  *
@@ -122,6 +124,15 @@ struct stratix10_svc_chan;
  * @COMMAND_SMC_SVC_VERSION: Non-mailbox SMC SVC API Version,
  * return status is SVC_STATUS_OK
  *
+ * @COMMAND_FCS_CRYPTO_OPEN_SESSION: open the crypto service session(s),
+ * return status is SVC_STATUS_OK or SVC_STATUS_ERROR
+ *
+ * @COMMAND_FCS_CRYPTO_CLOSE_SESSION: close the crypto service session(s),
+ * return status is SVC_STATUS_OK or SVC_STATUS_ERROR
+ *
+ * @COMMAND_FCS_SDOS_DATA_EXT: extend SDOS data encryption & decryption,
+ * return status is SVC_STATUS_OK or SVC_STATUS_ERROR
+ *
  * @COMMAND_MBOX_SEND_CMD: send generic mailbox command, return status is
  * SVC_STATUS_OK or SVC_STATUS_ERROR
  *
@@ -190,6 +201,11 @@ enum stratix10_svc_command_code {
 	COMMAND_FCS_RANDOM_NUMBER_GEN,
 	/* for general status poll */
 	COMMAND_POLL_SERVICE_STATUS = 40,
+	/* for crypto service */
+	COMMAND_FCS_CRYPTO_OPEN_SESSION = 50,
+	COMMAND_FCS_CRYPTO_CLOSE_SESSION,
+	/* for extended SDOS encrypt/decrypt */
+	COMMAND_FCS_SDOS_DATA_EXT = 82,
 	/* for generic mailbox send command */
 	COMMAND_MBOX_SEND_CMD = 100,
 	/* Non-mailbox SMC Call */
-- 
2.43.7

[PATCH v4 3/3] firmware: socfpga-fcs: add Altera SoCFPGA FCS driver with SDOS

[hang.suan.wang]

From: Hang Suan Wang <hang.suan.wang@altera.com>

Add the Altera SoCFPGA Crypto Service (FCS) driver, which exposes the
Secure Data Object Service (SDOS) encrypt/decrypt operation to
non-secure host software.

The SDOS protects data at rest: the SDM encrypts and decrypts using a key
derived from a device-unique SDOS root key plus an SDM-generated IV, so
the host never handles raw key material or IVs. It only submits plaintext
it already owns and receives authenticated ciphertext objects managed by
the SDM. A primary use case is black key, where operational keys are
installed without ever appearing in cleartext.

The driver is a standalone module and describes no hardware of its own.
It binds by name to the "stratix10-fcs" platform device registered by
stratix10-svc, so no device-tree node is required. SDOS requests go to
the SDM through the stratix10-svc asynchronous SIP SMC path using
service-layer memory pool buffers that the SDM can reach via physical or
SMMU-remapped addresses. Userspace talks to /dev/socfpga-fcs via ioctl
and sysfs exposes atf_version.

For encryption the SDM returns a structured object (header, ciphertext,
HMAC). For decryption the SDM validates the HMAC and enforces the 64-bit
owner ID from the object header so only the creator can decrypt it.

Each SDOS request opens an SDM crypto session, runs under priv->lock
(one in-flight transaction), and closes the session afterwards.

Signed-off-by: Hang Suan Wang <hang.suan.wang@altera.com>
---
 .../userspace-api/ioctl/ioctl-number.rst      |   1 +
 MAINTAINERS                                   |   9 +
 drivers/firmware/Kconfig                      |  17 +
 drivers/firmware/Makefile                     |   2 +
 drivers/firmware/socfpga-fcs-core.c           | 684 ++++++++++++++++++
 drivers/firmware/socfpga-fcs.c                | 294 ++++++++
 include/linux/firmware/intel/socfpga-fcs.h    | 130 ++++
 include/uapi/misc/socfpga-fcs-crypto.h        |  28 +
 8 files changed, 1165 insertions(+)
 create mode 100644 drivers/firmware/socfpga-fcs-core.c
 create mode 100644 drivers/firmware/socfpga-fcs.c
 create mode 100644 include/linux/firmware/intel/socfpga-fcs.h
 create mode 100644 include/uapi/misc/socfpga-fcs-crypto.h

diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index 2fc53093752d..a1e07f7f6870 100644
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -348,6 +348,7 @@ Code  Seq#    Include File                                             Comments
                                                                        <mailto:luzmaximilian@gmail.com>
 0xA6  00-0F  uapi/linux/alloc_tag.h                                    Memory allocation profiling
                                                                        <mailto:surenb@google.com>
+0xA6  00-1F  uapi/misc/socfpga-fcs-crypto.h                            Altera SoCFPGA FCS (Crypto Service)
 0xAA  00-3F  linux/uapi/linux/userfaultfd.h
 0xAB  00-1F  linux/nbd.h
 0xAC  00-1F  linux/raw.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 627595e245f3..1960094f284d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -945,6 +945,15 @@ ALPS PS/2 TOUCHPAD DRIVER
 R:	Pali Rohár <pali@kernel.org>
 F:	drivers/input/mouse/alps.*
 
+ALTERA FCS DRIVER
+M:	Hang Suan Wang <hang.suan.wang@altera.com>
+M:	Genevieve Chan <genevieve.chan@altera.com>
+L:	linux-arm-kernel@lists.infradead.org
+S:	Maintained
+F:	drivers/firmware/socfpga-fcs*
+F:	include/linux/firmware/intel/socfpga-fcs*
+F:	include/uapi/misc/socfpga-fcs*
+
 ALTERA MAILBOX DRIVER
 M:	Tien Sung Ang <tiensung.ang@altera.com>
 S:	Maintained
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index b7cc11e4fbfa..15727855fd5f 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -193,6 +193,23 @@ config INTEL_STRATIX10_RSU
 
 	  Say Y here if you want Intel RSU support.
 
+config ALTERA_SOCFPGA_FCS
+	tristate "Altera SoCFPGA Crypto Services (FCS)"
+	depends on INTEL_STRATIX10_SERVICE
+	help
+	  Altera SoCFPGA Crypto Services (FCS) driver gives user space
+	  access to the crypto services of the Secure Device Manager (SDM)
+	  through the Intel Service Layer, with requests forwarded to Arm
+	  Trusted Firmware.
+
+	  The SDM executes or authorizes the requests using device-rooted
+	  security resources. Protected key material stays within the
+	  secure firmware boundary and is never exposed to non-secure host
+	  software.
+
+	  Say Y here to add support for Altera SoCFPGA Crypto Services
+	  (FCS).
+
 config MTK_ADSP_IPC
 	tristate "MTK ADSP IPC Protocol driver"
 	depends on MTK_ADSP_MBOX
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index be46f1e1dc77..10431273e401 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -11,6 +11,8 @@ obj-$(CONFIG_EDD)		+= edd.o
 obj-$(CONFIG_DMIID)		+= dmi-id.o
 obj-$(CONFIG_INTEL_STRATIX10_SERVICE) += stratix10-svc.o
 obj-$(CONFIG_INTEL_STRATIX10_RSU)     += stratix10-rsu.o
+obj-$(CONFIG_ALTERA_SOCFPGA_FCS) += altera-fcs.o
+altera-fcs-y := socfpga-fcs.o socfpga-fcs-core.o
 obj-$(CONFIG_ISCSI_IBFT_FIND)	+= iscsi_ibft_find.o
 obj-$(CONFIG_ISCSI_IBFT)	+= iscsi_ibft.o
 obj-$(CONFIG_FIRMWARE_MEMMAP)	+= memmap.o
diff --git a/drivers/firmware/socfpga-fcs-core.c b/drivers/firmware/socfpga-fcs-core.c
new file mode 100644
index 000000000000..bb8d8fa9546f
--- /dev/null
+++ b/drivers/firmware/socfpga-fcs-core.c
@@ -0,0 +1,684 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2026 Altera Corporation
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+#include <linux/unaligned.h>
+#include <linux/firmware/intel/socfpga-fcs.h>
+#include <linux/firmware/intel/stratix10-svc-client.h>
+
+#define OWNER_ID_OFFSET				12
+
+#define SDOS_DECRYPTION_REPROVISION_KEY_WARN	0x102
+#define SDOS_DECRYPTION_NOT_LATEST_KEY_WARN	0x103
+
+#define MSG_RETRY				3
+#define FCS_RETRY_SLEEP_MS			1
+
+struct fcs_cmd_params {
+	const void	*src;
+	void		*dst;
+	u32		src_len;
+	u32		dst_len;
+	u32		op_mode;
+	u64		own;
+};
+
+/**
+ * fcs_atf_version_callback() - service-layer callback for the ATF version query
+ * @client: pointer to the stratix10-svc client
+ * @data: pointer to the service-layer callback data
+ */
+static void fcs_atf_version_callback(struct stratix10_svc_client *client,
+				     struct stratix10_svc_cb_data *data)
+{
+	struct socfpga_fcs_priv *p = client->priv;
+
+	p->status = data->status;
+	if (data->status == BIT(SVC_STATUS_OK)) {
+		p->status = 0;
+		p->atf_version[0] = *((unsigned int *)data->kaddr1);
+		p->atf_version[1] = *((unsigned int *)data->kaddr2);
+		p->atf_version[2] = *((unsigned int *)data->kaddr3);
+		p->atf_version_valid = true;
+	} else if (data->status == BIT(SVC_STATUS_ERROR)) {
+		p->status = *((unsigned int *)data->kaddr1);
+		dev_err(client->dev, "mbox_error=0x%x\n", p->status);
+	}
+
+	complete(&p->completion);
+}
+
+/**
+ * fcs_async_callback() - completion callback for an async service request
+ * @ptr: pointer to the completion to signal
+ */
+static void fcs_async_callback(void *ptr)
+{
+	if (ptr)
+		complete(ptr);
+}
+
+/**
+ * fcs_svc_send_sync() - run a command on the synchronous service path
+ * @msg: service-layer message to send
+ * @timeout: time to wait for the response
+ * Return: 0 on success, negative errno on failure.
+ */
+static int fcs_svc_send_sync(struct socfpga_fcs_priv *priv,
+			     struct stratix10_svc_client_msg *msg,
+			     unsigned long timeout)
+{
+	int ret;
+
+	reinit_completion(&priv->completion);
+
+	/*
+	 * receive_cb is only used by the sync send path; leave it set so a
+	 * late response cannot find a NULL callback.
+	 */
+	priv->client.receive_cb = fcs_atf_version_callback;
+
+	ret = stratix10_svc_send(priv->chan, msg);
+	if (ret) {
+		pr_err("failed to send message to service channel\n");
+		priv->client.receive_cb = NULL;
+		return ret;
+	}
+
+	if (!wait_for_completion_timeout(&priv->completion,
+					 msecs_to_jiffies(timeout))) {
+		pr_err("svc timeout to get completed status\n");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+/**
+ * fcs_svc_send_async() - run a command on the asynchronous mailbox path
+ * @msg: service-layer message to send
+ * @timeout: time to wait for the response
+ *
+ * Return: 0 once the transaction completed, negative errno on transport
+ *         failure or timeout.
+ */
+static int fcs_svc_send_async(struct socfpga_fcs_priv *priv,
+			      struct stratix10_svc_client_msg *msg,
+			      unsigned long timeout)
+{
+	unsigned long deadline = jiffies + msecs_to_jiffies(timeout);
+	struct stratix10_svc_cb_data data;
+	void *handle = NULL;
+	int status, index;
+	int ret;
+
+	/*
+	 * Use priv->completion, not a stack one: on timeout this function
+	 * returns while the svc layer still holds a pointer to it.
+	 */
+	reinit_completion(&priv->completion);
+
+	for (index = 0; index < MSG_RETRY; index++) {
+		status = stratix10_svc_async_send(priv->chan, msg, &handle,
+						  fcs_async_callback,
+						  &priv->completion);
+		if (status == 0)
+			break;
+		msleep(FCS_RETRY_SLEEP_MS);
+	}
+
+	if (status || !handle) {
+		pr_err("Failed to send async message\n");
+		/*
+		 * A NULL handle with a success status would otherwise be
+		 * reported as a completed transaction that never ran.
+		 */
+		return status ? status : -EIO;
+	}
+
+	ret = -ETIMEDOUT;
+	while (!time_after(jiffies, deadline)) {
+		status = stratix10_svc_async_poll(priv->chan, handle, &data);
+
+		if (status == 0) {
+			ret = 0;
+			break;
+		}
+
+		/*
+		 * Keep polling until the deadline. Leaving an in-flight
+		 * transaction orphans the SDM crypto session.
+		 */
+		ret = status;
+		msleep(FCS_RETRY_SLEEP_MS);
+	}
+
+	if (ret) {
+		pr_err("Failed to poll async message\n");
+		goto out;
+	}
+
+	priv->status = data.status;
+
+	/*
+	 * Non-zero SDM status is a firmware result, not a transport failure.
+	 * Store it in priv->status and return success to the caller.
+	 */
+	if (data.status) {
+		pr_err("%s: SDM mailbox status 0x%x\n", __func__, data.status);
+		goto out;
+	}
+
+	if (data.kaddr1)
+		priv->resp = *((u32 *)data.kaddr1);
+
+out:
+	stratix10_svc_async_done(priv->chan, handle);
+
+	return ret;
+}
+
+/**
+ * fcs_svc_send_request() - build and send an FCS command to the service layer
+ * @command: FCS command code to dispatch
+ * @timeout: time to wait for completion, in milliseconds
+ * @params: payload and arguments for @command, or NULL for commands that
+ *          carry none
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+static int fcs_svc_send_request(struct socfpga_fcs_priv *priv,
+				enum fcs_command_code command,
+				unsigned long timeout,
+				const struct fcs_cmd_params *params)
+{
+	struct stratix10_svc_client_msg *msg;
+	int ret = 0;
+
+	/*
+	 * The service layer keeps this message alive in its transaction handle
+	 * and still dereferences it from stratix10_svc_async_done(), so it
+	 * cannot live on our stack.
+	 */
+	msg = kzalloc_obj(*msg);
+	if (!msg)
+		return -ENOMEM;
+
+	priv->status = 0;
+	priv->resp = 0;
+
+	switch (command) {
+	case FCS_DEV_CRYPTO_OPEN_SESSION:
+		pr_debug("Sending command: COMMAND_FCS_CRYPTO_OPEN_SESSION\n");
+		msg->command = COMMAND_FCS_CRYPTO_OPEN_SESSION;
+		break;
+
+	case FCS_DEV_CRYPTO_CLOSE_SESSION:
+		pr_debug("Sending command: COMMAND_FCS_CRYPTO_CLOSE_SESSION with session_id: 0x%x\n",
+			 priv->session_id);
+		msg->arg[0] = priv->session_id;
+		msg->command = COMMAND_FCS_CRYPTO_CLOSE_SESSION;
+		break;
+
+	case FCS_DEV_ATF_VERSION:
+		pr_debug("Sending command: COMMAND_SMC_ATF_BUILD_VER\n");
+		msg->command = COMMAND_SMC_ATF_BUILD_VER;
+		break;
+
+	case FCS_DEV_SDOS_DATA_EXT:
+		if (!params) {
+			ret = -EINVAL;
+			break;
+		}
+		pr_debug("Sending command: COMMAND_FCS_SDOS_DATA_EXT with session_id: 0x%x, context_id: 0x%x, op_mode: 0x%x, own: 0x%llx\n",
+			 priv->session_id, priv->context_id,
+			 params->op_mode, params->own);
+		msg->arg[0] = priv->session_id;
+		msg->arg[1] = priv->context_id;
+		msg->arg[2] = params->op_mode;
+		msg->arg[3] = params->own;
+		msg->payload = (void *)params->src;
+		msg->payload_length = params->src_len;
+		msg->payload_output = params->dst;
+		msg->payload_length_output = params->dst_len;
+		msg->command = COMMAND_FCS_SDOS_DATA_EXT;
+		break;
+
+	default:
+		pr_err("Unknown command: 0x%x\n", command);
+		ret = -EINVAL;
+		break;
+	}
+
+	if (!ret) {
+		if (command == FCS_DEV_ATF_VERSION)
+			/* ATF fast call for simple command */
+			ret = fcs_svc_send_sync(priv, msg, timeout);
+		else
+			ret = fcs_svc_send_async(priv, msg, timeout);
+	}
+
+	kfree(msg);
+
+	return ret;
+}
+
+/**
+ * fcs_open_session_locked() - open a crypto session on the SDM
+ *
+ * Enforce the single-session rule and, on success, record the SDM session
+ * handle in @priv->session_id. The caller must hold @priv->lock.
+ * @priv->status carries the mailbox status.
+ *
+ * Return: 0 on success, -EBUSY if a session is already open, or negative
+ *         errno on transport/mailbox failure.
+ */
+static int fcs_open_session_locked(struct socfpga_fcs_priv *priv)
+{
+	int ret;
+
+	lockdep_assert_held(&priv->lock);
+
+	if (priv->session_id)
+		/* SDM allows one crypto session at a time */
+		return -EBUSY;
+
+	ret = fcs_svc_send_request(priv, FCS_DEV_CRYPTO_OPEN_SESSION,
+				   SVC_FCS_REQUEST_TIMEOUT_MS, NULL);
+	if (ret)
+		return ret;
+
+	if (priv->status)
+		return -EIO;
+
+	priv->session_id = priv->resp;
+
+	return 0;
+}
+
+/**
+ * fcs_close_session_locked() - close the crypto session on the SDM
+ *
+ * Caller must hold @priv->lock. The local session id is cleared even if
+ * close fails, so a stuck session cannot block future opens.
+ *
+ * Return: 0 on success or when no session is open, negative errno otherwise.
+ */
+static int fcs_close_session_locked(struct socfpga_fcs_priv *priv)
+{
+	int ret;
+
+	lockdep_assert_held(&priv->lock);
+
+	if (!priv->session_id)
+		/* nothing to close */
+		return 0;
+
+	ret = fcs_svc_send_request(priv, FCS_DEV_CRYPTO_CLOSE_SESSION,
+				   SVC_FCS_REQUEST_TIMEOUT_MS, NULL);
+
+	priv->session_id = 0;
+
+	if (!ret && priv->status)
+		ret = -EIO;
+
+	return ret;
+}
+
+/**
+ * fcs_ctx_begin() - open a crypto session and start a context on it
+ *
+ * The SDM runs one crypto context at a time and will not start another until
+ * the current one finishes, so the caller must hold @priv->lock for the whole
+ * operation. Every command issued in between then picks up
+ * @priv->context_id.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+static int fcs_ctx_begin(struct socfpga_fcs_priv *priv)
+{
+	int ret;
+
+	lockdep_assert_held(&priv->lock);
+
+	ret = fcs_open_session_locked(priv);
+	if (ret)
+		return ret;
+
+	/*
+	 * SDM requires a non-zero context ID per request. A random value
+	 * also avoids mistaking a late response from a retired context.
+	 */
+	priv->context_id = get_random_u32_above(0);
+
+	return 0;
+}
+
+/**
+ * fcs_ctx_end() - finish the current context and close the session
+ *
+ * Closing the session is what reclaims the SDM context, so this runs on every
+ * exit path of an operation whether it succeeded or not.
+ *
+ * Return: 0 on success, negative errno otherwise.
+ */
+static int fcs_ctx_end(struct socfpga_fcs_priv *priv)
+{
+	lockdep_assert_held(&priv->lock);
+
+	priv->context_id = 0;
+
+	return fcs_close_session_locked(priv);
+}
+
+/**
+ * fcs_get_atf_version() - return the cached Arm Trusted Firmware version
+ * @version: array of three u32 entries to receive the major, minor and patch
+ *           version numbers
+ *
+ * Return: 0 on success, -ENODEV if the driver is not initialised, -ENODATA if
+ *         the probe-time query produced no version.
+ */
+int fcs_get_atf_version(struct socfpga_fcs_priv *priv, u32 *version)
+{
+	if (!priv->atf_version_valid)
+		return -ENODATA;
+
+	memcpy(version, priv->atf_version, sizeof(priv->atf_version));
+
+	return 0;
+}
+
+/**
+ * fcs_alloc_buf() - allocate a service-layer buffer for a mailbox payload
+ * Wraps the stratix10-svc allocator so front-ends can stage payloads without
+ * touching the service channel themselves.
+ *
+ * @len: size of the buffer in bytes
+ * Return: pointer to the buffer, or an ERR_PTR on failure.
+ */
+void *fcs_alloc_buf(struct socfpga_fcs_priv *priv, size_t len)
+{
+	return stratix10_svc_allocate_memory(priv->chan, len);
+}
+
+/**
+ * fcs_free_buf() - release a buffer obtained from fcs_alloc_buf()
+ * @buf: buffer to release; NULL and error pointers are ignored
+ */
+void fcs_free_buf(struct socfpga_fcs_priv *priv, void *buf)
+{
+	if (!IS_ERR_OR_NULL(buf))
+		stratix10_svc_free_memory(priv->chan, buf);
+}
+
+/**
+ * fcs_sdos_output_size() - validate an SDOS input length and size its output
+ * @op_mode: non-zero to encrypt, zero to decrypt
+ * @src_len: length of the input, including the SDOS header
+ * @out_len: receives the output capacity the SDM may need
+ *
+ * Return: 0 on success, -EINVAL if @src_len is out of range for @op_mode.
+ */
+int fcs_sdos_output_size(u32 op_mode, u32 src_len, u32 *out_len)
+{
+	if (op_mode) {
+		/* encrypt: input is header + plaintext */
+		if (src_len < SDOS_DECRYPTED_MIN_SZ ||
+		    src_len > SDOS_DECRYPTED_MAX_SZ)
+			return -EINVAL;
+
+		*out_len = SDOS_ENCRYPTED_MAX_SZ;
+	} else {
+		/* decrypt: input is header + plaintext + HMAC */
+		if (src_len < SDOS_ENCRYPTED_MIN_SZ ||
+		    src_len > SDOS_ENCRYPTED_MAX_SZ)
+			return -EINVAL;
+
+		*out_len = SDOS_DECRYPTED_MAX_SZ;
+	}
+
+	return 0;
+}
+
+/**
+ * fcs_sdos_crypt() - perform an SDOS encrypt or decrypt operation
+ * @req: request describing the operation
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int fcs_sdos_crypt(struct socfpga_fcs_priv *priv, struct fcs_sdos_req *req)
+{
+	struct fcs_cmd_params params = { };
+	u32 output_size;
+	int ret;
+
+	if (!req->src || !req->dst)
+		return -EINVAL;
+
+	ret = fcs_sdos_output_size(req->op_mode, req->src_len, &output_size);
+	if (ret) {
+		pr_err("Invalid SDOS src_size %u\n", req->src_len);
+		return ret;
+	}
+
+	/* The caller must have sized the output buffer for the worst case. */
+	if (req->dst_len < output_size)
+		return -EINVAL;
+
+	params.op_mode = req->op_mode;
+	params.src = req->src;
+	params.src_len = req->src_len;
+	params.dst = req->dst;
+	params.dst_len = req->dst_len;
+	/* Owner ID is stored little-endian in the SDOS header (offset 12) */
+	params.own = get_unaligned_le64((const u8 *)req->src + OWNER_ID_OFFSET);
+
+	/*
+	 * Only one SDM transaction may be in flight. Wait interruptibly so
+	 * a blocked caller remains killable.
+	 */
+	if (mutex_lock_interruptible(&priv->lock))
+		return -ERESTARTSYS;
+
+	/*
+	 * The device may have been removed while this caller held only a file
+	 * reference.
+	 */
+	if (priv->removed) {
+		mutex_unlock(&priv->lock);
+		return -ENODEV;
+	}
+
+	/*
+	 * SDOS is a single-command request: start a context, run the command
+	 * and finish the context before returning.
+	 */
+	ret = fcs_ctx_begin(priv);
+	if (ret) {
+		pr_err("SDOS: failed to start crypto context ret: %d\n", ret);
+		mutex_unlock(&priv->lock);
+		return ret;
+	}
+
+	ret = fcs_svc_send_request(priv, FCS_DEV_SDOS_DATA_EXT,
+				   SVC_FCS_REQUEST_TIMEOUT_MS, &params);
+	if (ret) {
+		pr_err("Failed to send the cmd=%d,ret=%d\n", FCS_DEV_SDOS_DATA_EXT, ret);
+		goto end_ctx;
+	}
+
+	req->status = priv->status;
+	req->status_valid = true;
+
+	if (priv->status &&
+	    priv->status != SDOS_DECRYPTION_REPROVISION_KEY_WARN &&
+	    priv->status != SDOS_DECRYPTION_NOT_LATEST_KEY_WARN) {
+		ret = -EIO;
+		pr_err("Failed to perform SDOS operation ret: %d Mailbox Status = 0x%x\n",
+		       ret, priv->status);
+		goto end_ctx;
+	}
+
+	if (priv->resp > req->dst_len) {
+		pr_err("SDOS output %u exceeds kernel buffer %u\n",
+		       priv->resp, req->dst_len);
+		ret = -EIO;
+		goto end_ctx;
+	}
+
+	req->dst_len = priv->resp;
+
+end_ctx:
+	/* Best-effort; the local session and context state is dropped regardless. */
+	fcs_ctx_end(priv);
+	mutex_unlock(&priv->lock);
+
+	return ret;
+}
+
+/**
+ * fcs_read_version_from_atf() - query the Arm Trusted Firmware build version
+ * Send the ATF version command to the SDM and cache the result in @priv.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+static int fcs_read_version_from_atf(struct socfpga_fcs_priv *priv)
+{
+	int ret;
+
+	ret = fcs_svc_send_request(priv, FCS_DEV_ATF_VERSION,
+				   SVC_FCS_REQUEST_TIMEOUT_MS, NULL);
+	if (ret) {
+		pr_err("Failed to send the cmd=%d,ret=%d\n", FCS_DEV_ATF_VERSION, ret);
+		return ret;
+	}
+
+	if (priv->status) {
+		ret = -EIO;
+		pr_err("Mailbox error, Failed to read ATF version ret: %d\n", ret);
+	}
+
+	stratix10_svc_done(priv->chan);
+
+	return ret;
+}
+
+/**
+ * fcs_release() - final teardown, run when the last reference is dropped
+ * @kref: reference counter embedded in the FCS state
+
+ */
+static void fcs_release(struct kref *kref)
+{
+	struct socfpga_fcs_priv *priv =
+		container_of(kref, struct socfpga_fcs_priv, refcount);
+
+	if (priv->session_id) {
+		int ret;
+
+		mutex_lock(&priv->lock);
+		ret = fcs_close_session_locked(priv);
+		mutex_unlock(&priv->lock);
+
+		if (ret)
+			dev_err(priv->client.dev,
+				"Failed to close FCS service session,ret=%d\n",
+				ret);
+	}
+
+	stratix10_svc_remove_async_client(priv->chan);
+	stratix10_svc_free_channel(priv->chan);
+	mutex_destroy(&priv->lock);
+	kfree(priv);
+}
+
+/**
+ * fcs_get() - take a reference on the FCS state
+ * @priv: state returned by fcs_init()
+
+ */
+void fcs_get(struct socfpga_fcs_priv *priv)
+{
+	kref_get(&priv->refcount);
+}
+
+/**
+ * fcs_put() - drop a reference on the FCS state
+ * @priv: state returned by fcs_init()
+ */
+void fcs_put(struct socfpga_fcs_priv *priv)
+{
+	kref_put(&priv->refcount, fcs_release);
+}
+
+/**
+ * fcs_mark_removed() - refuse further operations after the device is gone
+ * @priv: state returned by fcs_init()
+ */
+void fcs_mark_removed(struct socfpga_fcs_priv *priv)
+{
+	mutex_lock(&priv->lock);
+	priv->removed = true;
+	mutex_unlock(&priv->lock);
+}
+
+/**
+ * fcs_init() - allocate and initialise the FCS private state
+ * @dev: pointer to fcs device
+
+ *
+ * Return: the new state, or an ERR_PTR on failure (which may be
+ *         -EPROBE_DEFER from the service layer).
+ */
+struct socfpga_fcs_priv *fcs_init(struct device *dev)
+{
+	struct socfpga_fcs_priv *priv;
+	int ret;
+
+	priv = kzalloc_obj(*priv);
+	if (!priv)
+		return ERR_PTR(-ENOMEM);
+
+	kref_init(&priv->refcount);
+	mutex_init(&priv->lock);
+
+	/* kzalloc() already cleared client.receive_cb. */
+	priv->client.dev = dev;
+	priv->client.priv = priv;
+
+	priv->chan = stratix10_svc_request_channel_byname(&priv->client,
+							  SVC_CLIENT_FCS);
+	if (IS_ERR(priv->chan)) {
+		dev_err(dev, "couldn't get service channel %s\n", SVC_CLIENT_FCS);
+		ret = PTR_ERR(priv->chan);
+		goto err_free;
+	}
+
+	ret = stratix10_svc_add_async_client(priv->chan, true);
+	if (ret) {
+		dev_err(dev, "Failed to add async client\n");
+		stratix10_svc_free_channel(priv->chan);
+		goto err_free;
+	}
+
+	init_completion(&priv->completion);
+
+	/*
+	 * Version query failure is non-fatal; sysfs reports -ENODATA.
+	 */
+	fcs_read_version_from_atf(priv);
+
+	return priv;
+
+err_free:
+	mutex_destroy(&priv->lock);
+	kfree(priv);
+
+	return ERR_PTR(ret);
+}
diff --git a/drivers/firmware/socfpga-fcs.c b/drivers/firmware/socfpga-fcs.c
new file mode 100644
index 000000000000..c6cf03432307
--- /dev/null
+++ b/drivers/firmware/socfpga-fcs.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2026, Altera Corporation
+ */
+
+#include <linux/err.h>
+#include <linux/firmware/intel/socfpga-fcs.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/sysfs.h>
+#include <linux/uaccess.h>
+#include <linux/util_macros.h>
+#include <uapi/misc/socfpga-fcs-crypto.h>
+
+/**
+ * atf_version_show() - report the Arm Trusted Firmware build version
+ * @dev: pointer to fcs device
+ * @attr: device attribute
+ * @buf: pointer to character buffer to receive the version string
+ *
+ * Return: number of bytes written to @buf.
+ */
+static ssize_t atf_version_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct socfpga_fcs_priv *priv = dev_get_drvdata(dev);
+	u32 version[3];
+	int ret;
+
+	ret = fcs_get_atf_version(priv, version);
+	if (ret)
+		return ret;
+
+	return sysfs_emit(buf, "%u.%u.%u\n", version[0], version[1], version[2]);
+}
+
+/**
+ * fcs_sdos() - perform an SDOS encrypt/decrypt operation
+ * @priv: FCS state of the device this request arrived on
+ * @uarg: user pointer to a struct fcs_ioc_sdos
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+static long fcs_sdos(struct socfpga_fcs_priv *priv, void __user *uarg)
+{
+	u32 __user *dst_size_uptr;
+	s32 __user *status_uptr;
+	struct fcs_sdos_req req = { };
+	struct fcs_ioc_sdos u;
+	void *s_buf, *d_buf;
+	u32 output_size;
+	u32 dst_cap;
+	long ret;
+
+	if (copy_from_user(&u, uarg, sizeof(u)))
+		return -EFAULT;
+
+	if (!u.dst || !u.dst_size)
+		return -EINVAL;
+
+	dst_size_uptr = u64_to_user_ptr(u.dst_size);
+	status_uptr = u64_to_user_ptr(u.error_code);
+
+	/* Caller-provided output buffer capacity (in/out parameter) */
+	if (get_user(dst_cap, dst_size_uptr))
+		return -EFAULT;
+
+	ret = fcs_sdos_output_size(u.op_mode, u.src_size, &output_size);
+	if (ret)
+		return ret;
+
+	s_buf = fcs_alloc_buf(priv, u.src_size);
+	if (IS_ERR(s_buf))
+		return PTR_ERR(s_buf);
+
+	d_buf = fcs_alloc_buf(priv, output_size);
+	if (IS_ERR(d_buf)) {
+		ret = PTR_ERR(d_buf);
+		goto free_sbuf;
+	}
+
+	/*
+	 * Copy before the engine takes its lock, so a slow or faulting source
+	 * buffer cannot stall unrelated FCS callers.
+	 */
+	if (copy_from_user(s_buf, u64_to_user_ptr(u.src), u.src_size)) {
+		ret = -EFAULT;
+		goto free_dbuf;
+	}
+
+	req.op_mode	= u.op_mode;
+	req.src		= s_buf;
+	req.src_len	= u.src_size;
+	req.dst		= d_buf;
+	req.dst_len	= output_size;
+
+	ret = fcs_sdos_crypt(priv, &req);
+	if (ret)
+		goto relay_status;
+
+	if (req.dst_len > dst_cap) {
+		pr_debug("SDOS output %u exceeds caller buffer %u\n",
+			 req.dst_len, dst_cap);
+		ret = -EMSGSIZE;
+		goto relay_status;
+	}
+
+	if (copy_to_user(u64_to_user_ptr(u.dst), d_buf, req.dst_len)) {
+		ret = -EFAULT;
+		goto relay_status;
+	}
+
+	if (put_user(req.dst_len, dst_size_uptr))
+		ret = -EFAULT;
+
+relay_status:
+	if (req.status_valid && put_user(req.status, status_uptr)) {
+		/* surface the copy failure only if nothing failed earlier */
+		if (!ret)
+			ret = -EFAULT;
+	}
+free_dbuf:
+	fcs_free_buf(priv, d_buf);
+free_sbuf:
+	fcs_free_buf(priv, s_buf);
+
+	return ret;
+}
+
+/**
+ * fcs_open() - take a reference on the device state for this file
+ * @inode: inode of the FCS misc device
+ * @file: open file being created
+ *
+ * Return: 0 always.
+ */
+static int fcs_open(struct inode *inode, struct file *file)
+{
+	struct miscdevice *miscdev = file->private_data;
+	struct socfpga_fcs_priv *priv =
+		container_of(miscdev, struct socfpga_fcs_priv, miscdev);
+
+	fcs_get(priv);
+	file->private_data = priv;
+
+	return 0;
+}
+
+/**
+ * fcs_release() - drop this file's reference on the device state to
+ * guarantees the crypto session is torn down when its owning fd is closed,
+ * including on process crash/exit
+ * @inode: inode of the FCS misc device
+ * @file: open file being released
+ *
+ * Return: 0 always.
+ */
+static int fcs_release(struct inode *inode, struct file *file)
+{
+	fcs_put(file->private_data);
+
+	return 0;
+}
+
+/**
+ * fcs_ioctl() - dispatch an FCS ioctl command
+ * @file: open file for the FCS misc device
+ * @cmd: ioctl command code
+ * @arg: user pointer to the command-specific argument structure
+ *
+ * Return: 0 on success, -ENOTTY for an unknown command, or a negative errno
+ *         from the handler.
+ */
+static long fcs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct socfpga_fcs_priv *priv = file->private_data;
+	void __user *uarg = (void __user *)arg;
+
+	switch (cmd) {
+	case FCS_IOC_SDOS:
+		return fcs_sdos(priv, uarg);
+	default:
+		return -ENOTTY;
+	}
+}
+
+static const struct file_operations fcs_fops = {
+	.owner		= THIS_MODULE,
+	.open		= fcs_open,
+	.release	= fcs_release,
+	.unlocked_ioctl	= fcs_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
+};
+
+static DEVICE_ATTR_RO(atf_version);
+
+static struct attribute *fcs_attrs[] = {
+	&dev_attr_atf_version.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(fcs);
+
+/**
+ * fcs_driver_probe() - probe the FCS platform device
+ * @pdev: pointer to the FCS platform device
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+static int fcs_driver_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct socfpga_fcs_priv *priv;
+	int ret;
+
+	priv = fcs_init(dev);
+	if (IS_ERR(priv))
+		return dev_err_probe(dev, PTR_ERR(priv),
+				     "Failed to initialize FCS\n");
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->miscdev.minor = MISC_DYNAMIC_MINOR;
+	priv->miscdev.name = "socfpga-fcs";
+	priv->miscdev.fops = &fcs_fops;
+	priv->miscdev.parent = dev;
+
+	ret = misc_register(&priv->miscdev);
+	if (ret) {
+		fcs_put(priv);
+		return dev_err_probe(dev, ret, "Failed to register misc device\n");
+	}
+
+	return 0;
+}
+
+/**
+ * fcs_driver_remove() - remove the FCS platform device
+ * @pdev: pointer to the FCS platform device
+ */
+static void fcs_driver_remove(struct platform_device *pdev)
+{
+	struct socfpga_fcs_priv *priv = platform_get_drvdata(pdev);
+
+	/*
+	 * misc_deregister() does not wait for open files. Drop the driver's
+	 * reference; the channel lives until the last close if any remain.
+	 */
+	misc_deregister(&priv->miscdev);
+	fcs_mark_removed(priv);
+	fcs_put(priv);
+}
+
+static struct platform_driver fcs_driver = {
+	.probe = fcs_driver_probe,
+	.remove = fcs_driver_remove,
+	.driver = {
+		.name = "stratix10-fcs",
+		.dev_groups = fcs_groups,
+	},
+};
+
+/**
+ * socfpga_fcs_init() - register the FCS platform driver
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+static int __init socfpga_fcs_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&fcs_driver);
+	if (ret)
+		pr_err("Failed to register platform driver: %d\n", ret);
+
+	return ret;
+}
+
+/**
+ * socfpga_fcs_exit() - unregister the FCS platform driver
+ */
+static void __exit socfpga_fcs_exit(void)
+{
+	platform_driver_unregister(&fcs_driver);
+}
+
+module_init(socfpga_fcs_init);
+module_exit(socfpga_fcs_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Altera SoCFPGA FCS SDOS encrypt/decrypt driver");
+MODULE_AUTHOR("Altera Corporation");
+MODULE_ALIAS("platform:stratix10-fcs");
diff --git a/include/linux/firmware/intel/socfpga-fcs.h b/include/linux/firmware/intel/socfpga-fcs.h
new file mode 100644
index 000000000000..824870f8a553
--- /dev/null
+++ b/include/linux/firmware/intel/socfpga-fcs.h
@@ -0,0 +1,130 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2026 Altera Corporation
+ *
+ * SDOS-only subset of the SoCFPGA FCS (FPGA Crypto Service) interface,
+ * shared between the driver front-end (socfpga-fcs.c) and the command
+ * engine (socfpga-fcs-core.c).
+ *
+ * The command engine deals in kernel pointers only: front-ends own every
+ * transfer to and from user space. In-kernel consumers can therefore drive
+ * the same engine directly.
+ */
+#ifndef __SOCFPGA_FCS_H
+#define __SOCFPGA_FCS_H
+
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/kref.h>
+#include <linux/miscdevice.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+#include <linux/firmware/intel/stratix10-svc-client.h>
+
+#define SDOS_HEADER_SZ		40
+#define SDOS_HMAC_SZ		48
+#define SDOS_PLAINDATA_MIN_SZ	32
+#define SDOS_PLAINDATA_MAX_SZ	32672
+#define SDOS_DECRYPTED_MIN_SZ	(SDOS_PLAINDATA_MIN_SZ + SDOS_HEADER_SZ)
+#define SDOS_DECRYPTED_MAX_SZ	(SDOS_PLAINDATA_MAX_SZ + SDOS_HEADER_SZ)
+#define SDOS_ENCRYPTED_MIN_SZ	(SDOS_PLAINDATA_MIN_SZ + SDOS_HEADER_SZ + SDOS_HMAC_SZ)
+#define SDOS_ENCRYPTED_MAX_SZ	(SDOS_PLAINDATA_MAX_SZ + SDOS_HEADER_SZ + SDOS_HMAC_SZ)
+
+/**
+ * struct fcs_sdos_req - parameters for one SDOS encrypt/decrypt operation
+ * @op_mode: non-zero to encrypt, zero to decrypt
+ * @src: input buffer, obtained from fcs_alloc_buf()
+ * @src_len: number of valid bytes in @src
+ * @dst: output buffer, obtained from fcs_alloc_buf()
+ * @dst_len: on entry the capacity of @dst, on return the number of bytes the
+ *           SDM produced
+ * @status: SDM mailbox status, valid only when @status_valid is set
+ * @status_valid: set by the engine once the mailbox transaction completed,
+ *                whether it succeeded or reported a firmware error. Clear
+ *                after a transport failure, where no firmware status exists.
+ *
+ * Every pointer is a kernel address, so the engine never touches user memory.
+ */
+struct fcs_sdos_req {
+	u32		op_mode;
+	const void	*src;
+	u32		src_len;
+	void		*dst;
+	u32		dst_len;
+	s32		status;
+	bool		status_valid;
+};
+
+/**
+ * Private driver state for the SoCFPGA FCS that holds the SDM/ATF service
+ * channel, the lock serialising command submission, and the latest mailbox
+ * status/response.
+ */
+struct socfpga_fcs_priv {
+	/* Communication channel */
+	struct stratix10_svc_chan *chan;
+	struct stratix10_svc_client client;
+	struct miscdevice miscdev;
+	/*
+	 * Held by the driver and by every open file. An fd may outlive driver
+	 * detach, so this state is not devm-managed: the firmware channel and
+	 * the allocation are released only when the last reference goes.
+	 */
+	struct kref refcount;
+	/* Set on remove(); further operations fail with -ENODEV. */
+	bool removed;
+	struct completion completion;
+	/*
+	 * Serializes FCS command submission: guards the session state and the
+	 * single in-flight mailbox transaction (completion/status/resp) so only
+	 * one SDM request is outstanding at a time. The engine takes it around
+	 * the session and mailbox work of each operation; buffer allocation and
+	 * user-space copying happen outside it.
+	 */
+	struct mutex lock;
+	int status;
+	u32 resp;
+	u32 session_id;
+	/* non-zero while a crypto context is active */
+	u32 context_id;
+	u32 atf_version[3];
+	bool atf_version_valid;
+};
+
+enum fcs_command_code {
+	FCS_DEV_CRYPTO_OPEN_SESSION,
+	FCS_DEV_CRYPTO_CLOSE_SESSION,
+	FCS_DEV_SDOS_DATA_EXT,
+	FCS_DEV_ATF_VERSION,
+};
+
+/*
+ * Allocate a service-layer buffer usable as fcs_sdos_req.src or .dst.
+ * Returns an ERR_PTR on failure; release with fcs_free_buf().
+ */
+void *fcs_alloc_buf(struct socfpga_fcs_priv *priv, size_t len);
+
+/* Release a buffer from fcs_alloc_buf(); tolerates NULL and error pointers. */
+void fcs_free_buf(struct socfpga_fcs_priv *priv, void *buf);
+int fcs_sdos_output_size(u32 op_mode, u32 src_len, u32 *out_len);
+
+/*
+ * Allocate the per-device FCS state and set up the service channel; reads the
+ * ATF version. The state is reference counted; release the driver's reference
+ * with fcs_put(). Returns an ERR_PTR on failure.
+ */
+struct socfpga_fcs_priv *fcs_init(struct device *dev);
+
+/* Take/drop a reference; the last put closes the session and frees the state. */
+void fcs_get(struct socfpga_fcs_priv *priv);
+void fcs_put(struct socfpga_fcs_priv *priv);
+
+/* Refuse further operations with -ENODEV; call from the remove path. */
+void fcs_mark_removed(struct socfpga_fcs_priv *priv);
+
+int fcs_get_atf_version(struct socfpga_fcs_priv *priv, u32 *version);
+
+/* Perform an SDOS (Secure Data Object Service) encrypt/decrypt operation. */
+int fcs_sdos_crypt(struct socfpga_fcs_priv *priv, struct fcs_sdos_req *req);
+
+#endif /* SOCFPGA_FCS_H */
diff --git a/include/uapi/misc/socfpga-fcs-crypto.h b/include/uapi/misc/socfpga-fcs-crypto.h
new file mode 100644
index 000000000000..a96aa21b0baf
--- /dev/null
+++ b/include/uapi/misc/socfpga-fcs-crypto.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
+/*
+ * Description:
+ * This driver is developed for the SDM SoCFPGA Crypto Service (FCS). It
+ * provides an ioctl interface for the SDOS (Secure Data Object Service)
+ * encrypt/decrypt operation. The crypto session and the per-request context
+ * ID are managed by the kernel internally, so neither is part of the user
+ * ABI.
+ */
+#ifndef __SOCFPGA_FCS_CRYPTO_H
+#define __SOCFPGA_FCS_CRYPTO_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+struct fcs_ioc_sdos {
+	__u64 error_code;	/* __user ptr to __s32 (out)              */
+	__u64 src;		/* __user ptr to input buffer (in)        */
+	__u64 dst;		/* __user ptr to output buffer (out)      */
+	__u64 dst_size;		/* __user ptr to __u32 capacity/len (in/out) */
+	__u32 op_mode;		/* (in)  */
+	__u32 src_size;		/* (in)  */
+};
+
+#define FCS_IOC_MAGIC		0xA6
+#define FCS_IOC_SDOS		_IOWR(FCS_IOC_MAGIC, 1, struct fcs_ioc_sdos)
+
+#endif /* __SOCFPGA_FCS_CRYPTO_H */
-- 
2.43.7