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- // SPDX-License-Identifier: GPL-2.0
- /*
- * For transport using shared mem structure.
- *
- * Copyright (C) 2019 ARM Ltd.
- */
- #include <linux/io.h>
- #include <linux/processor.h>
- #include <linux/types.h>
- #include "common.h"
- /*
- * SCMI specification requires all parameters, message headers, return
- * arguments or any protocol data to be expressed in little endian
- * format only.
- */
- struct scmi_shared_mem {
- __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[];
- };
- void shmem_tx_prepare(struct scmi_shared_mem __iomem *shmem,
- struct scmi_xfer *xfer)
- {
- /*
- * Ideally channel must be free by now unless OS timeout last
- * request and platform continued to process the same, wait
- * until it releases the shared memory, otherwise we may endup
- * overwriting its response with new message payload or vice-versa
- */
- spin_until_cond(ioread32(&shmem->channel_status) &
- SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE);
- /* Mark channel busy + clear error */
- iowrite32(0x0, &shmem->channel_status);
- iowrite32(xfer->hdr.poll_completion ? 0 : SCMI_SHMEM_FLAG_INTR_ENABLED,
- &shmem->flags);
- iowrite32(sizeof(shmem->msg_header) + xfer->tx.len, &shmem->length);
- iowrite32(pack_scmi_header(&xfer->hdr), &shmem->msg_header);
- if (xfer->tx.buf)
- memcpy_toio(shmem->msg_payload, xfer->tx.buf, xfer->tx.len);
- }
- u32 shmem_read_header(struct scmi_shared_mem __iomem *shmem)
- {
- return ioread32(&shmem->msg_header);
- }
- void shmem_fetch_response(struct scmi_shared_mem __iomem *shmem,
- struct scmi_xfer *xfer)
- {
- xfer->hdr.status = ioread32(shmem->msg_payload);
- /* Skip the length of header and status in shmem area i.e 8 bytes */
- xfer->rx.len = min_t(size_t, xfer->rx.len,
- ioread32(&shmem->length) - 8);
- /* Take a copy to the rx buffer.. */
- memcpy_fromio(xfer->rx.buf, shmem->msg_payload + 4, xfer->rx.len);
- }
- void shmem_fetch_notification(struct scmi_shared_mem __iomem *shmem,
- size_t max_len, struct scmi_xfer *xfer)
- {
- /* Skip only the length of header in shmem area i.e 4 bytes */
- xfer->rx.len = min_t(size_t, max_len, ioread32(&shmem->length) - 4);
- /* Take a copy to the rx buffer.. */
- memcpy_fromio(xfer->rx.buf, shmem->msg_payload, xfer->rx.len);
- }
- void shmem_clear_channel(struct scmi_shared_mem __iomem *shmem)
- {
- iowrite32(SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE, &shmem->channel_status);
- }
- bool shmem_poll_done(struct scmi_shared_mem __iomem *shmem,
- struct scmi_xfer *xfer)
- {
- u16 xfer_id;
- xfer_id = MSG_XTRACT_TOKEN(ioread32(&shmem->msg_header));
- if (xfer->hdr.seq != xfer_id)
- return false;
- return ioread32(&shmem->channel_status) &
- (SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR |
- SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE);
- }
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