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@linaro.org Cc: Simon Glass sjg@chromium.org Cc: Peng Fan peng.fan@nxp.com Cc: Sudeep Holla sudeep.holla@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 */