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linux/drivers/firmware/arm_scmi/shmem.c
Cristian Marussi fc789363c9 firmware: arm_scmi: Remove legacy transport-layer code
Since all SCMI transports have been made standalone drivers, remove all the
core SCMI stack legacy support that was needed to run transports as built
into the stack.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Message-Id: <20240812173340.3912830-10-cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
2024-08-16 10:26:58 +01:00

195 lines
5.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* For transport using shared mem structure.
*
* Copyright (C) 2019-2024 ARM Ltd.
*/
#include <linux/ktime.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.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[];
};
static 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);
}
static u32 shmem_read_header(struct scmi_shared_mem __iomem *shmem)
{
return ioread32(&shmem->msg_header);
}
static 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);
}
static 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);
}
static void shmem_clear_channel(struct scmi_shared_mem __iomem *shmem)
{
iowrite32(SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE, &shmem->channel_status);
}
static 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);
}
static bool shmem_channel_free(struct scmi_shared_mem __iomem *shmem)
{
return (ioread32(&shmem->channel_status) &
SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE);
}
static bool shmem_channel_intr_enabled(struct scmi_shared_mem __iomem *shmem)
{
return ioread32(&shmem->flags) & SCMI_SHMEM_FLAG_INTR_ENABLED;
}
static void __iomem *shmem_setup_iomap(struct scmi_chan_info *cinfo,
struct device *dev, bool tx,
struct resource *res)
{
struct device_node *shmem __free(device_node);
const char *desc = tx ? "Tx" : "Rx";
int ret, idx = tx ? 0 : 1;
struct device *cdev = cinfo->dev;
struct resource lres = {};
resource_size_t size;
void __iomem *addr;
shmem = of_parse_phandle(cdev->of_node, "shmem", idx);
if (!shmem)
return IOMEM_ERR_PTR(-ENODEV);
if (!of_device_is_compatible(shmem, "arm,scmi-shmem"))
return IOMEM_ERR_PTR(-ENXIO);
/* Use a local on-stack as a working area when not provided */
if (!res)
res = &lres;
ret = of_address_to_resource(shmem, 0, res);
if (ret) {
dev_err(cdev, "failed to get SCMI %s shared memory\n", desc);
return IOMEM_ERR_PTR(ret);
}
size = resource_size(res);
addr = devm_ioremap(dev, res->start, size);
if (!addr) {
dev_err(dev, "failed to ioremap SCMI %s shared memory\n", desc);
return IOMEM_ERR_PTR(-EADDRNOTAVAIL);
}
return addr;
}
static const struct scmi_shared_mem_operations scmi_shmem_ops = {
.tx_prepare = shmem_tx_prepare,
.read_header = shmem_read_header,
.fetch_response = shmem_fetch_response,
.fetch_notification = shmem_fetch_notification,
.clear_channel = shmem_clear_channel,
.poll_done = shmem_poll_done,
.channel_free = shmem_channel_free,
.channel_intr_enabled = shmem_channel_intr_enabled,
.setup_iomap = shmem_setup_iomap,
};
const struct scmi_shared_mem_operations *scmi_shared_mem_operations_get(void)
{
return &scmi_shmem_ops;
}