1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
|
// 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 <linux/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);
}
bool shmem_channel_intr_enabled(struct scmi_shared_mem __iomem *shmem)
{
return ioread32(&shmem->flags) & SCMI_SHMEM_FLAG_INTR_ENABLED;
}
|
