1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * For transport using shared mem structure.
4  *
5  * Copyright (C) 2019 ARM Ltd.
6  */
7 
8 #include <linux/io.h>
9 #include <linux/processor.h>
10 #include <linux/types.h>
11 
12 #include "common.h"
13 
14 /*
15  * SCMI specification requires all parameters, message headers, return
16  * arguments or any protocol data to be expressed in little endian
17  * format only.
18  */
19 struct scmi_shared_mem {
20 	__le32 reserved;
21 	__le32 channel_status;
22 #define SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR	BIT(1)
23 #define SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE	BIT(0)
24 	__le32 reserved1[2];
25 	__le32 flags;
26 #define SCMI_SHMEM_FLAG_INTR_ENABLED	BIT(0)
27 	__le32 length;
28 	__le32 msg_header;
29 	u8 msg_payload[];
30 };
31 
shmem_tx_prepare(struct scmi_shared_mem __iomem * shmem,struct scmi_xfer * xfer)32 void shmem_tx_prepare(struct scmi_shared_mem __iomem *shmem,
33 		      struct scmi_xfer *xfer)
34 {
35 	/*
36 	 * Ideally channel must be free by now unless OS timeout last
37 	 * request and platform continued to process the same, wait
38 	 * until it releases the shared memory, otherwise we may endup
39 	 * overwriting its response with new message payload or vice-versa
40 	 */
41 	spin_until_cond(ioread32(&shmem->channel_status) &
42 			SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE);
43 	/* Mark channel busy + clear error */
44 	iowrite32(0x0, &shmem->channel_status);
45 	iowrite32(xfer->hdr.poll_completion ? 0 : SCMI_SHMEM_FLAG_INTR_ENABLED,
46 		  &shmem->flags);
47 	iowrite32(sizeof(shmem->msg_header) + xfer->tx.len, &shmem->length);
48 	iowrite32(pack_scmi_header(&xfer->hdr), &shmem->msg_header);
49 	if (xfer->tx.buf)
50 		memcpy_toio(shmem->msg_payload, xfer->tx.buf, xfer->tx.len);
51 }
52 
shmem_read_header(struct scmi_shared_mem __iomem * shmem)53 u32 shmem_read_header(struct scmi_shared_mem __iomem *shmem)
54 {
55 	return ioread32(&shmem->msg_header);
56 }
57 
shmem_fetch_response(struct scmi_shared_mem __iomem * shmem,struct scmi_xfer * xfer)58 void shmem_fetch_response(struct scmi_shared_mem __iomem *shmem,
59 			  struct scmi_xfer *xfer)
60 {
61 	xfer->hdr.status = ioread32(shmem->msg_payload);
62 	/* Skip the length of header and status in shmem area i.e 8 bytes */
63 	xfer->rx.len = min_t(size_t, xfer->rx.len,
64 			     ioread32(&shmem->length) - 8);
65 
66 	/* Take a copy to the rx buffer.. */
67 	memcpy_fromio(xfer->rx.buf, shmem->msg_payload + 4, xfer->rx.len);
68 }
69 
shmem_fetch_notification(struct scmi_shared_mem __iomem * shmem,size_t max_len,struct scmi_xfer * xfer)70 void shmem_fetch_notification(struct scmi_shared_mem __iomem *shmem,
71 			      size_t max_len, struct scmi_xfer *xfer)
72 {
73 	/* Skip only the length of header in shmem area i.e 4 bytes */
74 	xfer->rx.len = min_t(size_t, max_len, ioread32(&shmem->length) - 4);
75 
76 	/* Take a copy to the rx buffer.. */
77 	memcpy_fromio(xfer->rx.buf, shmem->msg_payload, xfer->rx.len);
78 }
79 
shmem_clear_channel(struct scmi_shared_mem __iomem * shmem)80 void shmem_clear_channel(struct scmi_shared_mem __iomem *shmem)
81 {
82 	iowrite32(SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE, &shmem->channel_status);
83 }
84 
shmem_poll_done(struct scmi_shared_mem __iomem * shmem,struct scmi_xfer * xfer)85 bool shmem_poll_done(struct scmi_shared_mem __iomem *shmem,
86 		     struct scmi_xfer *xfer)
87 {
88 	u16 xfer_id;
89 
90 	xfer_id = MSG_XTRACT_TOKEN(ioread32(&shmem->msg_header));
91 
92 	if (xfer->hdr.seq != xfer_id)
93 		return false;
94 
95 	return ioread32(&shmem->channel_status) &
96 		(SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR |
97 		 SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE);
98 }
99