131 lines
3.8 KiB
C
131 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* For transport using shared mem structure.
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*
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* Copyright (C) 2019 ARM Ltd.
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*/
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#include <linux/ktime.h>
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#include <linux/io.h>
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#include <linux/processor.h>
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#include <linux/types.h>
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#include <asm-generic/bug.h>
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#include "common.h"
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/*
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* SCMI specification requires all parameters, message headers, return
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* arguments or any protocol data to be expressed in little endian
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* format only.
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*/
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struct scmi_shared_mem {
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__le32 reserved;
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__le32 channel_status;
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#define SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR BIT(1)
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#define SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE BIT(0)
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__le32 reserved1[2];
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__le32 flags;
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#define SCMI_SHMEM_FLAG_INTR_ENABLED BIT(0)
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__le32 length;
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__le32 msg_header;
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u8 msg_payload[];
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};
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void shmem_tx_prepare(struct scmi_shared_mem __iomem *shmem,
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struct scmi_xfer *xfer, struct scmi_chan_info *cinfo)
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{
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ktime_t stop;
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/*
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* Ideally channel must be free by now unless OS timeout last
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* request and platform continued to process the same, wait
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* until it releases the shared memory, otherwise we may endup
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* overwriting its response with new message payload or vice-versa.
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* Giving up anyway after twice the expected channel timeout so as
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* not to bail-out on intermittent issues where the platform is
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* occasionally a bit slower to answer.
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*
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* Note that after a timeout is detected we bail-out and carry on but
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* the transport functionality is probably permanently compromised:
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* this is just to ease debugging and avoid complete hangs on boot
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* due to a misbehaving SCMI firmware.
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*/
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stop = ktime_add_ms(ktime_get(), 2 * cinfo->rx_timeout_ms);
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spin_until_cond((ioread32(&shmem->channel_status) &
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SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE) ||
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ktime_after(ktime_get(), stop));
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if (!(ioread32(&shmem->channel_status) &
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SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE)) {
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WARN_ON_ONCE(1);
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dev_err(cinfo->dev,
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"Timeout waiting for a free TX channel !\n");
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return;
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}
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/* Mark channel busy + clear error */
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iowrite32(0x0, &shmem->channel_status);
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iowrite32(xfer->hdr.poll_completion ? 0 : SCMI_SHMEM_FLAG_INTR_ENABLED,
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&shmem->flags);
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iowrite32(sizeof(shmem->msg_header) + xfer->tx.len, &shmem->length);
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iowrite32(pack_scmi_header(&xfer->hdr), &shmem->msg_header);
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if (xfer->tx.buf)
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memcpy_toio(shmem->msg_payload, xfer->tx.buf, xfer->tx.len);
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}
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u32 shmem_read_header(struct scmi_shared_mem __iomem *shmem)
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{
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return ioread32(&shmem->msg_header);
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}
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void shmem_fetch_response(struct scmi_shared_mem __iomem *shmem,
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struct scmi_xfer *xfer)
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{
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size_t len = ioread32(&shmem->length);
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xfer->hdr.status = ioread32(shmem->msg_payload);
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/* Skip the length of header and status in shmem area i.e 8 bytes */
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xfer->rx.len = min_t(size_t, xfer->rx.len, len > 8 ? len - 8 : 0);
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/* Take a copy to the rx buffer.. */
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memcpy_fromio(xfer->rx.buf, shmem->msg_payload + 4, xfer->rx.len);
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}
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void shmem_fetch_notification(struct scmi_shared_mem __iomem *shmem,
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size_t max_len, struct scmi_xfer *xfer)
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{
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size_t len = ioread32(&shmem->length);
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/* Skip only the length of header in shmem area i.e 4 bytes */
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xfer->rx.len = min_t(size_t, max_len, len > 4 ? len - 4 : 0);
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/* Take a copy to the rx buffer.. */
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memcpy_fromio(xfer->rx.buf, shmem->msg_payload, xfer->rx.len);
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}
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void shmem_clear_channel(struct scmi_shared_mem __iomem *shmem)
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{
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iowrite32(SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE, &shmem->channel_status);
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}
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bool shmem_poll_done(struct scmi_shared_mem __iomem *shmem,
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struct scmi_xfer *xfer)
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{
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u16 xfer_id;
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xfer_id = MSG_XTRACT_TOKEN(ioread32(&shmem->msg_header));
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if (xfer->hdr.seq != xfer_id)
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return false;
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return ioread32(&shmem->channel_status) &
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(SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR |
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SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE);
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}
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bool shmem_channel_free(struct scmi_shared_mem __iomem *shmem)
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{
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return (ioread32(&shmem->channel_status) &
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SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE);
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}
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