diff options
Diffstat (limited to 'drivers/firmware/arm_scmi/shmem.c')
| -rw-r--r-- | drivers/firmware/arm_scmi/shmem.c | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/drivers/firmware/arm_scmi/shmem.c b/drivers/firmware/arm_scmi/shmem.c new file mode 100644 index 000000000..517d52fb3 --- /dev/null +++ b/drivers/firmware/arm_scmi/shmem.c @@ -0,0 +1,130 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * For transport using shared mem structure. + * + * Copyright (C) 2019 ARM Ltd. + */ + +#include <linux/ktime.h> +#include <linux/io.h> +#include <linux/processor.h> +#include <linux/types.h> + +#include <asm-generic/bug.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, struct scmi_chan_info *cinfo) +{ + ktime_t stop; + + /* + * 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. + * Giving up anyway after twice the expected channel timeout so as + * not to bail-out on intermittent issues where the platform is + * occasionally a bit slower to answer. + * + * Note that after a timeout is detected we bail-out and carry on but + * the transport functionality is probably permanently compromised: + * this is just to ease debugging and avoid complete hangs on boot + * due to a misbehaving SCMI firmware. + */ + stop = ktime_add_ms(ktime_get(), 2 * cinfo->rx_timeout_ms); + spin_until_cond((ioread32(&shmem->channel_status) & + SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE) || + ktime_after(ktime_get(), stop)); + if (!(ioread32(&shmem->channel_status) & + SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE)) { + WARN_ON_ONCE(1); + dev_err(cinfo->dev, + "Timeout waiting for a free TX channel !\n"); + return; + } + + /* 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) +{ + size_t len = ioread32(&shmem->length); + + 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, len > 8 ? len - 8 : 0); + + /* 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) +{ + size_t len = ioread32(&shmem->length); + + /* Skip only the length of header in shmem area i.e 4 bytes */ + xfer->rx.len = min_t(size_t, max_len, len > 4 ? len - 4 : 0); + + /* 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); +} + +bool shmem_channel_free(struct scmi_shared_mem __iomem *shmem) +{ + return (ioread32(&shmem->channel_status) & + SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE); +} |