[PATCH v4 2/8] firmware: scmi: mailbox/smt agent device
Etienne Carriere
etienne.carriere at linaro.org
Wed Sep 9 18:44:01 CEST 2020
This change implements a mailbox transport using SMT format for SCMI
exchanges. This implementation follows the Linux kernel and
SCP-firmware [1] as references implementation for SCMI message
processing using SMT format for communication channel meta-data.
Use of mailboxes in SCMI FDT bindings are defined in the Linux kernel
DT bindings since v4.17.
Links: [1] https://github.com/ARM-software/SCP-firmware
Signed-off-by: Etienne Carriere <etienne.carriere at linaro.org>
Cc: Simon Glass <sjg at chromium.org>
Cc: Peng Fan <peng.fan at nxp.com>
Cc: Sudeep Holla <sudeep.holla at arm.com>
---
Changes in v4:
- Replace __arm__ with CONFIG_ARM.
- Remove cast for priv reference hence remove helper scmi_mbox_get_priv().
Changes in v3:
- This is a followup of the SCMI agent patches posted in
https://patchwork.ozlabs.org/project/uboot/list/?series=196253
The v3 splits commits and introduces a new uclass as requested.
- This patch implements the same mailbox SCMI agent proposed in v2
but split over few source files.
---
drivers/firmware/scmi/Kconfig | 6 +-
drivers/firmware/scmi/Makefile | 2 +
drivers/firmware/scmi/mailbox_agent.c | 102 +++++++++++++++++++
drivers/firmware/scmi/smt.c | 139 ++++++++++++++++++++++++++
drivers/firmware/scmi/smt.h | 86 ++++++++++++++++
5 files changed, 333 insertions(+), 2 deletions(-)
create mode 100644 drivers/firmware/scmi/mailbox_agent.c
create mode 100644 drivers/firmware/scmi/smt.c
create mode 100644 drivers/firmware/scmi/smt.h
diff --git a/drivers/firmware/scmi/Kconfig b/drivers/firmware/scmi/Kconfig
index 57e2ebbe42..c501bf4943 100644
--- a/drivers/firmware/scmi/Kconfig
+++ b/drivers/firmware/scmi/Kconfig
@@ -2,7 +2,7 @@ config SCMI_FIRMWARE
bool "Enable SCMI support"
select FIRMWARE
select OF_TRANSLATE
- depends on SANDBOX
+ depends on SANDBOX || DM_MAILBOX
help
System Control and Management Interface (SCMI) is a communication
protocol that defines standard interfaces for power, performance
@@ -14,4 +14,6 @@ config SCMI_FIRMWARE
or a companion host in the CPU system.
Communications between agent (client) and the SCMI server are
- based on message exchange.
+ based on message exchange. Messages can be exchange over tranport
+ channels as a mailbox device with some piece of identified shared
+ memory.
diff --git a/drivers/firmware/scmi/Makefile b/drivers/firmware/scmi/Makefile
index 336ea1f2a3..d22f53efe7 100644
--- a/drivers/firmware/scmi/Makefile
+++ b/drivers/firmware/scmi/Makefile
@@ -1,2 +1,4 @@
obj-y += scmi_agent-uclass.o
+obj-y += smt.o
+obj-$(CONFIG_DM_MAILBOX) += mailbox_agent.o
obj-$(CONFIG_SANDBOX) += sandbox-scmi_agent.o
diff --git a/drivers/firmware/scmi/mailbox_agent.c b/drivers/firmware/scmi/mailbox_agent.c
new file mode 100644
index 0000000000..7d9fb3622e
--- /dev/null
+++ b/drivers/firmware/scmi/mailbox_agent.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020 Linaro Limited.
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <mailbox.h>
+#include <scmi_agent.h>
+#include <scmi_agent-uclass.h>
+#include <dm/devres.h>
+#include <linux/compat.h>
+
+#include "smt.h"
+
+#define TIMEOUT_US_10MS 10000
+
+/**
+ * struct scmi_mbox_channel - Description of an SCMI mailbox transport
+ * @smt: Shared memory buffer
+ * @mbox: Mailbox channel description
+ * @timeout_us: Timeout in microseconds for the mailbox transfer
+ */
+struct scmi_mbox_channel {
+ struct scmi_smt smt;
+ struct mbox_chan mbox;
+ ulong timeout_us;
+};
+
+static int scmi_mbox_process_msg(struct udevice *dev, struct scmi_msg *msg)
+{
+ struct scmi_mbox_channel *chan = dev_get_priv(dev);
+ int ret;
+
+ ret = scmi_write_msg_to_smt(dev, &chan->smt, msg);
+ if (ret)
+ return ret;
+
+ /* Give shm addr to mbox in case it is meaningful */
+ ret = mbox_send(&chan->mbox, chan->smt.buf);
+ if (ret) {
+ dev_err(dev, "Message send failed: %d\n", ret);
+ goto out;
+ }
+
+ /* Receive the response */
+ ret = mbox_recv(&chan->mbox, chan->smt.buf, chan->timeout_us);
+ if (ret) {
+ dev_err(dev, "Response failed: %d, abort\n", ret);
+ goto out;
+ }
+
+ ret = scmi_read_resp_from_smt(dev, &chan->smt, msg);
+
+out:
+ scmi_clear_smt_channel(&chan->smt);
+
+ return ret;
+}
+
+int scmi_mbox_probe(struct udevice *dev)
+{
+ struct scmi_mbox_channel *chan = dev_get_priv(dev);
+ int ret;
+
+ chan->timeout_us = TIMEOUT_US_10MS;
+
+ ret = mbox_get_by_index(dev, 0, &chan->mbox);
+ if (ret) {
+ dev_err(dev, "Failed to find mailbox: %d\n", ret);
+ goto out;
+ }
+
+ ret = scmi_dt_get_smt_buffer(dev, &chan->smt);
+ if (ret)
+ dev_err(dev, "Failed to get shm resources: %d\n", ret);
+
+out:
+ if (ret)
+ devm_kfree(dev, chan);
+
+ return ret;
+}
+
+static const struct udevice_id scmi_mbox_ids[] = {
+ { .compatible = "arm,scmi" },
+ { }
+};
+
+static const struct scmi_agent_ops scmi_mbox_ops = {
+ .process_msg = scmi_mbox_process_msg,
+};
+
+U_BOOT_DRIVER(scmi_mbox) = {
+ .name = "scmi-over-mailbox",
+ .id = UCLASS_SCMI_AGENT,
+ .of_match = scmi_mbox_ids,
+ .priv_auto_alloc_size = sizeof(struct scmi_mbox_channel),
+ .probe = scmi_mbox_probe,
+ .ops = &scmi_mbox_ops,
+};
diff --git a/drivers/firmware/scmi/smt.c b/drivers/firmware/scmi/smt.c
new file mode 100644
index 0000000000..ce8fe49939
--- /dev/null
+++ b/drivers/firmware/scmi/smt.c
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
+ * Copyright (C) 2019-2020 Linaro Limited.
+ */
+
+#include <common.h>
+#include <cpu_func.h>
+#include <dm.h>
+#include <errno.h>
+#include <scmi_agent.h>
+#include <asm/cache.h>
+#include <asm/system.h>
+#include <dm/ofnode.h>
+#include <linux/compat.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+
+#include "smt.h"
+
+/**
+ * Get shared memory configuration defined by the referred DT phandle
+ * Return with a errno compliant value.
+ */
+int scmi_dt_get_smt_buffer(struct udevice *dev, struct scmi_smt *smt)
+{
+ int ret;
+ struct ofnode_phandle_args args;
+ struct resource resource;
+ fdt32_t faddr;
+ phys_addr_t paddr;
+
+ ret = dev_read_phandle_with_args(dev, "shmem", NULL, 0, 0, &args);
+ if (ret)
+ return ret;
+
+ ret = ofnode_read_resource(args.node, 0, &resource);
+ if (ret)
+ return ret;
+
+ faddr = cpu_to_fdt32(resource.start);
+ paddr = ofnode_translate_address(args.node, &faddr);
+
+ smt->size = resource_size(&resource);
+ if (smt->size < sizeof(struct scmi_smt_header)) {
+ dev_err(dev, "Shared memory buffer too small\n");
+ return -EINVAL;
+ }
+
+ smt->buf = devm_ioremap(dev, paddr, smt->size);
+ if (!smt->buf)
+ return -ENOMEM;
+
+#ifdef CONFIG_ARM
+ if (dcache_status())
+ mmu_set_region_dcache_behaviour((uintptr_t)smt->buf,
+ smt->size, DCACHE_OFF);
+#endif
+
+ return 0;
+}
+
+/**
+ * Write SCMI message @msg into a SMT shared buffer @smt.
+ * Return 0 on success and with a negative errno in case of error.
+ */
+int scmi_write_msg_to_smt(struct udevice *dev, struct scmi_smt *smt,
+ struct scmi_msg *msg)
+{
+ struct scmi_smt_header *hdr = (void *)smt->buf;
+
+ if ((!msg->in_msg && msg->in_msg_sz) ||
+ (!msg->out_msg && msg->out_msg_sz))
+ return -EINVAL;
+
+ if (!(hdr->channel_status & SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE)) {
+ dev_dbg(dev, "Channel busy\n");
+ return -EBUSY;
+ }
+
+ if (smt->size < (sizeof(*hdr) + msg->in_msg_sz) ||
+ smt->size < (sizeof(*hdr) + msg->out_msg_sz)) {
+ dev_dbg(dev, "Buffer too small\n");
+ return -ETOOSMALL;
+ }
+
+ /* Load message in shared memory */
+ hdr->channel_status &= ~SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE;
+ hdr->length = msg->in_msg_sz + sizeof(hdr->msg_header);
+ hdr->msg_header = SMT_HEADER_TOKEN(0) |
+ SMT_HEADER_MESSAGE_TYPE(0) |
+ SMT_HEADER_PROTOCOL_ID(msg->protocol_id) |
+ SMT_HEADER_MESSAGE_ID(msg->message_id);
+
+ memcpy_toio(hdr->msg_payload, msg->in_msg, msg->in_msg_sz);
+
+ return 0;
+}
+
+/**
+ * Read SCMI message from a SMT shared buffer @smt and copy it into @msg.
+ * Return 0 on success and with a negative errno in case of error.
+ */
+int scmi_read_resp_from_smt(struct udevice *dev, struct scmi_smt *smt,
+ struct scmi_msg *msg)
+{
+ struct scmi_smt_header *hdr = (void *)smt->buf;
+
+ if (!(hdr->channel_status & SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE)) {
+ dev_err(dev, "Channel unexpectedly busy\n");
+ return -EBUSY;
+ }
+
+ if (hdr->channel_status & SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR) {
+ dev_err(dev, "Channel error reported, reset channel\n");
+ return -ECOMM;
+ }
+
+ if (hdr->length > msg->out_msg_sz + sizeof(hdr->msg_header)) {
+ dev_err(dev, "Buffer to small\n");
+ return -ETOOSMALL;
+ }
+
+ /* Get the data */
+ msg->out_msg_sz = hdr->length - sizeof(hdr->msg_header);
+ memcpy_fromio(msg->out_msg, hdr->msg_payload, msg->out_msg_sz);
+
+ return 0;
+}
+
+/**
+ * Clear SMT flags in shared buffer to allow further message exchange
+ */
+void scmi_clear_smt_channel(struct scmi_smt *smt)
+{
+ struct scmi_smt_header *hdr = (void *)smt->buf;
+
+ hdr->channel_status &= ~SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR;
+}
diff --git a/drivers/firmware/scmi/smt.h b/drivers/firmware/scmi/smt.h
new file mode 100644
index 0000000000..a8c0987bd3
--- /dev/null
+++ b/drivers/firmware/scmi/smt.h
@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
+ * Copyright (C) 2019-2020 Linaro Limited.
+ */
+#ifndef SCMI_SMT_H
+#define SCMI_SMT_H
+
+#include <asm/types.h>
+
+/**
+ * struct scmi_smt_header - Description of the shared memory message buffer
+ *
+ * SMT stands for Shared Memory based Transport.
+ * SMT uses 28 byte header prior message payload to handle the state of
+ * the communication channel realized by the shared memory area and
+ * to define SCMI protocol information the payload relates to.
+ */
+struct scmi_smt_header {
+ __le32 reserved;
+ __le32 channel_status;
+#define SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR BIT(1)
+#define SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE BIT(0)
+ __le32 reserved1[2];
+ __le32 flags;
+#define SCMI_SHMEM_FLAG_INTR_ENABLED BIT(0)
+ __le32 length;
+ __le32 msg_header;
+ u8 msg_payload[0];
+};
+
+#define SMT_HEADER_TOKEN(token) (((token) << 18) & GENMASK(31, 18))
+#define SMT_HEADER_PROTOCOL_ID(proto) (((proto) << 10) & GENMASK(17, 10))
+#define SMT_HEADER_MESSAGE_TYPE(type) (((type) << 18) & GENMASK(9, 8))
+#define SMT_HEADER_MESSAGE_ID(id) ((id) & GENMASK(7, 0))
+
+/**
+ * struct scmi_smt - Description of a SMT memory buffer
+ * @buf: Shared memory base address
+ * @size: Shared memory byte size
+ */
+struct scmi_smt {
+ u8 *buf;
+ size_t size;
+};
+
+static inline bool scmi_smt_channel_is_free(struct scmi_smt *smt)
+{
+ struct scmi_smt_header *hdr = (void *)smt->buf;
+
+ return hdr->channel_status & SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE;
+}
+
+static inline bool scmi_smt_channel_reports_error(struct scmi_smt *smt)
+{
+ struct scmi_smt_header *hdr = (void *)smt->buf;
+
+ return hdr->channel_status & SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR;
+}
+
+static inline void scmi_smt_get_channel(struct scmi_smt *smt)
+{
+ struct scmi_smt_header *hdr = (void *)smt->buf;
+
+ hdr->channel_status &= ~SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE;
+}
+
+static inline void scmi_smt_put_channel(struct scmi_smt *smt)
+{
+ struct scmi_smt_header *hdr = (void *)smt->buf;
+
+ hdr->channel_status |= SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE;
+ hdr->channel_status &= ~SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR;
+}
+
+int scmi_dt_get_smt_buffer(struct udevice *dev, struct scmi_smt *smt);
+
+int scmi_write_msg_to_smt(struct udevice *dev, struct scmi_smt *smt,
+ struct scmi_msg *msg);
+
+int scmi_read_resp_from_smt(struct udevice *dev, struct scmi_smt *smt,
+ struct scmi_msg *msg);
+
+void scmi_clear_smt_channel(struct scmi_smt *smt);
+
+#endif /* SCMI_SMT_H */
--
2.17.1
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