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Diffstat (limited to 'drivers/firmware/arm_scmi/shmem.c')
-rw-r--r--drivers/firmware/arm_scmi/shmem.c130
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 0000000000..517d52fb3b
--- /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);
+}