drivers/scmi-msg: smt entry points for incoming messages
This change implements SCMI channels for reading a SCMI message from a
shared memory and call the SCMI message drivers to route the message
to the target platform services.
SMT refers to the shared memory management protocol which is used
to get/put message/response in shared memory. SMT is a 28byte header
stating shared memory state and exchanged protocol data.
The processing entry for a SCMI message can be a secure interrupt
or fastcall SMCCC invocation.
SMT description in this implementation is based on the OP-TEE
project [1] itself based in the SCP-firmware implementation [2].
Link: [1] https://github.com/OP-TEE/optee_os/commit/a58c4d706d2333d2b21a3eba7e2ec0cb257bca1d
Link: [2] https://github.com/ARM-software/SCP-firmware.git
Change-Id: I416c7dab5c67954c6fe80bae8d8cdfdcda66873e
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
diff --git a/drivers/st/scmi-msg/smt.c b/drivers/st/scmi-msg/smt.c
new file mode 100644
index 0000000..2d5cd73
--- /dev/null
+++ b/drivers/st/scmi-msg/smt.c
@@ -0,0 +1,206 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/*
+ * Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2019-2020, Linaro Limited
+ */
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <drivers/st/scmi-msg.h>
+#include <drivers/st/scmi.h>
+#include <lib/cassert.h>
+#include <lib/mmio.h>
+#include <lib/spinlock.h>
+#include <lib/utils.h>
+#include <plat/common/platform.h>
+
+#include "common.h"
+
+/* Legacy SMT/SCMI messages are 128 bytes at most including SMT header */
+#define SCMI_PLAYLOAD_MAX 92U
+#define SCMI_PLAYLOAD_U32_MAX (SCMI_PLAYLOAD_MAX / sizeof(uint32_t))
+
+/**
+ * struct smt_header - SMT formatted header for SMT base shared memory transfer
+ *
+ * @status: Bit flags, see SMT_STATUS_*
+ * @flags: Bit flags, see SMT_FLAG_*
+ * @length: Byte size of message payload (variable) + ::message_header (32bit)
+ * payload: SCMI message payload data
+ */
+struct smt_header {
+ uint32_t reserved0;
+ uint32_t status;
+ uint64_t reserved1;
+ uint32_t flags;
+ uint32_t length; /* message_header + payload */
+ uint32_t message_header;
+ uint32_t payload[];
+};
+
+CASSERT(SCMI_PLAYLOAD_MAX + sizeof(struct smt_header) <= SMT_BUF_SLOT_SIZE,
+ assert_scmi_message_max_length_fits_in_smt_buffer_slot);
+
+/* Flag set in smt_header::status when SMT does not contain pending message */
+#define SMT_STATUS_FREE BIT(0)
+/* Flag set in smt_header::status when SMT reports an error */
+#define SMT_STATUS_ERROR BIT(1)
+
+/* Flag set in smt_header::flags when SMT uses interrupts */
+#define SMT_FLAG_INTR_ENABLED BIT(1)
+
+/* Bit fields packed in smt_header::message_header */
+#define SMT_MSG_ID_MASK GENMASK_32(7, 0)
+#define SMT_HDR_MSG_ID(_hdr) ((_hdr) & SMT_MSG_ID_MASK)
+
+#define SMT_MSG_TYPE_MASK GENMASK_32(9, 8)
+#define SMT_HDR_TYPE_ID(_hdr) (((_hdr) & SMT_MSG_TYPE_MASK) >> 8)
+
+#define SMT_MSG_PROT_ID_MASK GENMASK_32(17, 10)
+#define SMT_HDR_PROT_ID(_hdr) (((_hdr) & SMT_MSG_PROT_ID_MASK) >> 10)
+
+/*
+ * Provision input message payload buffers for fastcall SMC context entries
+ * and for interrupt context execution entries.
+ */
+static uint32_t fast_smc_payload[PLATFORM_CORE_COUNT][SCMI_PLAYLOAD_U32_MAX];
+static uint32_t interrupt_payload[PLATFORM_CORE_COUNT][SCMI_PLAYLOAD_U32_MAX];
+
+/* SMP protection on channel access */
+static struct spinlock smt_channels_lock;
+
+/* If channel is not busy, set busy and return true, otherwise return false */
+static bool channel_set_busy(struct scmi_msg_channel *chan)
+{
+ bool channel_is_busy;
+
+ spin_lock(&smt_channels_lock);
+
+ channel_is_busy = chan->busy;
+
+ if (!channel_is_busy) {
+ chan->busy = true;
+ }
+
+ spin_unlock(&smt_channels_lock);
+
+ return !channel_is_busy;
+}
+
+static void channel_release_busy(struct scmi_msg_channel *chan)
+{
+ chan->busy = false;
+}
+
+static struct smt_header *channel_to_smt_hdr(struct scmi_msg_channel *chan)
+{
+ return (struct smt_header *)chan->shm_addr;
+}
+
+/*
+ * Creates a SCMI message instance in secure memory and pushes it in the SCMI
+ * message drivers. Message structure contains SCMI protocol meta-data and
+ * references to input payload in secure memory and output message buffer
+ * in shared memory.
+ */
+static void scmi_proccess_smt(unsigned int agent_id, uint32_t *payload_buf)
+{
+ struct scmi_msg_channel *chan;
+ struct smt_header *smt_hdr;
+ size_t in_payload_size;
+ uint32_t smt_status;
+ struct scmi_msg msg;
+ bool error = true;
+
+ chan = plat_scmi_get_channel(agent_id);
+ if (chan == NULL) {
+ return;
+ }
+
+ smt_hdr = channel_to_smt_hdr(chan);
+ assert(smt_hdr);
+
+ smt_status = __atomic_load_n(&smt_hdr->status, __ATOMIC_RELAXED);
+
+ if (!channel_set_busy(chan)) {
+ VERBOSE("SCMI channel %u busy", agent_id);
+ goto out;
+ }
+
+ in_payload_size = __atomic_load_n(&smt_hdr->length, __ATOMIC_RELAXED) -
+ sizeof(smt_hdr->message_header);
+
+ if (in_payload_size > SCMI_PLAYLOAD_MAX) {
+ VERBOSE("SCMI payload too big %u", in_payload_size);
+ goto out;
+ }
+
+ if ((smt_status & (SMT_STATUS_ERROR | SMT_STATUS_FREE)) != 0U) {
+ VERBOSE("SCMI channel bad status 0x%x",
+ smt_hdr->status & (SMT_STATUS_ERROR | SMT_STATUS_FREE));
+ goto out;
+ }
+
+ /* Fill message */
+ zeromem(&msg, sizeof(msg));
+ msg.in = (char *)payload_buf;
+ msg.in_size = in_payload_size;
+ msg.out = (char *)smt_hdr->payload;
+ msg.out_size = chan->shm_size - sizeof(*smt_hdr);
+
+ assert((msg.out != NULL) && (msg.out_size >= sizeof(int32_t)));
+
+ /* Here the payload is copied in secure memory */
+ memcpy(msg.in, smt_hdr->payload, in_payload_size);
+
+ msg.protocol_id = SMT_HDR_PROT_ID(smt_hdr->message_header);
+ msg.message_id = SMT_HDR_MSG_ID(smt_hdr->message_header);
+ msg.agent_id = agent_id;
+
+ scmi_process_message(&msg);
+
+ /* Update message length with the length of the response message */
+ smt_hdr->length = msg.out_size_out + sizeof(smt_hdr->message_header);
+
+ channel_release_busy(chan);
+ error = false;
+
+out:
+ if (error) {
+ VERBOSE("SCMI error");
+ smt_hdr->status |= SMT_STATUS_ERROR | SMT_STATUS_FREE;
+ } else {
+ smt_hdr->status |= SMT_STATUS_FREE;
+ }
+}
+
+void scmi_smt_fastcall_smc_entry(unsigned int agent_id)
+{
+ scmi_proccess_smt(agent_id,
+ fast_smc_payload[plat_my_core_pos()]);
+}
+
+void scmi_smt_interrupt_entry(unsigned int agent_id)
+{
+ scmi_proccess_smt(agent_id,
+ interrupt_payload[plat_my_core_pos()]);
+}
+
+/* Init a SMT header for a shared memory buffer: state it a free/no-error */
+void scmi_smt_init_agent_channel(struct scmi_msg_channel *chan)
+{
+ if (chan != NULL) {
+ struct smt_header *smt_header = channel_to_smt_hdr(chan);
+
+ if (smt_header != NULL) {
+ memset(smt_header, 0, sizeof(*smt_header));
+ smt_header->status = SMT_STATUS_FREE;
+
+ return;
+ }
+ }
+
+ panic();
+}
diff --git a/include/drivers/st/scmi-msg.h b/include/drivers/st/scmi-msg.h
index 8f7a788..a9a99cf 100644
--- a/include/drivers/st/scmi-msg.h
+++ b/include/drivers/st/scmi-msg.h
@@ -32,6 +32,32 @@
const char *agent_name;
};
+/*
+ * Initialize SMT memory buffer, called by platform at init for each
+ * agent channel using the SMT header format.
+ *
+ * @chan: Pointer to the channel shared memory to be initialized
+ */
+void scmi_smt_init_agent_channel(struct scmi_msg_channel *chan);
+
+/*
+ * Process SMT formatted message in a fastcall SMC execution context.
+ * Called by platform on SMC entry. When returning, output message is
+ * available in shared memory for agent to read the response.
+ *
+ * @agent_id: SCMI agent ID the SMT belongs to
+ */
+void scmi_smt_fastcall_smc_entry(unsigned int agent_id);
+
+/*
+ * Process SMT formatted message in a secure interrupt execution context.
+ * Called by platform interrupt handler. When returning, output message is
+ * available in shared memory for agent to read the response.
+ *
+ * @agent_id: SCMI agent ID the SMT belongs to
+ */
+void scmi_smt_interrupt_entry(unsigned int agent_id);
+
/* Platform callback functions */
/*