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// SPDX-License-Identifier: GPL-2.0
/*
* System Control and Management Interface (SCMI) Message SMC/HVC
* Transport driver
*
* Copyright 2020 NXP
*/
#include <linux/arm-smccc.h>
#include <linux/atomic.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/processor.h>
#include <linux/slab.h>
#include "common.h"
/*
* The shmem address is split into 4K page and offset.
* This is to make sure the parameters fit in 32bit arguments of the
* smc/hvc call to keep it uniform across smc32/smc64 conventions.
* This however limits the shmem address to 44 bit.
*
* These optional parameters can be used to distinguish among multiple
* scmi instances that are using the same smc-id.
* The page parameter is passed in r1/x1/w1 register and the offset parameter
* is passed in r2/x2/w2 register.
*/
#define SHMEM_SIZE (SZ_4K)
#define SHMEM_SHIFT 12
#define SHMEM_PAGE(x) (_UL((x) >> SHMEM_SHIFT))
#define SHMEM_OFFSET(x) ((x) & (SHMEM_SIZE - 1))
/**
* struct scmi_smc - Structure representing a SCMI smc transport
*
* @irq: An optional IRQ for completion
* @cinfo: SCMI channel info
* @shmem: Transmit/Receive shared memory area
* @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
* Used when NOT operating in atomic mode.
* @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
* Used when operating in atomic mode.
* @func_id: smc/hvc call function id
* @param_page: 4K page number of the shmem channel
* @param_offset: Offset within the 4K page of the shmem channel
*/
struct scmi_smc {
int irq;
struct scmi_chan_info *cinfo;
struct scmi_shared_mem __iomem *shmem;
/* Protect access to shmem area */
struct mutex shmem_lock;
#define INFLIGHT_NONE MSG_TOKEN_MAX
atomic_t inflight;
u32 func_id;
u32 param_page;
u32 param_offset;
};
static irqreturn_t smc_msg_done_isr(int irq, void *data)
{
struct scmi_smc *scmi_info = data;
scmi_rx_callback(scmi_info->cinfo,
shmem_read_header(scmi_info->shmem), NULL);
return IRQ_HANDLED;
}
static bool smc_chan_available(struct device_node *of_node, int idx)
{
struct device_node *np = of_parse_phandle(of_node, "shmem", 0);
if (!np)
return false;
of_node_put(np);
return true;
}
static inline void smc_channel_lock_init(struct scmi_smc *scmi_info)
{
if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
else
mutex_init(&scmi_info->shmem_lock);
}
static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight)
{
int ret;
ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq);
return ret == INFLIGHT_NONE;
}
static inline void
smc_channel_lock_acquire(struct scmi_smc *scmi_info,
struct scmi_xfer *xfer __maybe_unused)
{
if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight));
else
mutex_lock(&scmi_info->shmem_lock);
}
static inline void smc_channel_lock_release(struct scmi_smc *scmi_info)
{
if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
else
mutex_unlock(&scmi_info->shmem_lock);
}
static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
bool tx)
{
struct device *cdev = cinfo->dev;
struct scmi_smc *scmi_info;
resource_size_t size;
struct resource res;
struct device_node *np;
u32 func_id;
int ret;
if (!tx)
return -ENODEV;
scmi_info = devm_kzalloc(dev, sizeof(*scmi_info), GFP_KERNEL);
if (!scmi_info)
return -ENOMEM;
np = of_parse_phandle(cdev->of_node, "shmem", 0);
if (!of_device_is_compatible(np, "arm,scmi-shmem")) {
of_node_put(np);
return -ENXIO;
}
ret = of_address_to_resource(np, 0, &res);
of_node_put(np);
if (ret) {
dev_err(cdev, "failed to get SCMI Tx shared memory\n");
return ret;
}
size = resource_size(&res);
scmi_info->shmem = devm_ioremap(dev, res.start, size);
if (!scmi_info->shmem) {
dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
return -EADDRNOTAVAIL;
}
ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
if (ret < 0)
return ret;
if (of_device_is_compatible(dev->of_node, "arm,scmi-smc-param")) {
scmi_info->param_page = SHMEM_PAGE(res.start);
scmi_info->param_offset = SHMEM_OFFSET(res.start);
}
/*
* If there is an interrupt named "a2p", then the service and
* completion of a message is signaled by an interrupt rather than by
* the return of the SMC call.
*/
scmi_info->irq = of_irq_get_byname(cdev->of_node, "a2p");
if (scmi_info->irq > 0) {
ret = request_irq(scmi_info->irq, smc_msg_done_isr,
IRQF_NO_SUSPEND, dev_name(dev), scmi_info);
if (ret) {
dev_err(dev, "failed to setup SCMI smc irq\n");
return ret;
}
} else {
cinfo->no_completion_irq = true;
}
scmi_info->func_id = func_id;
scmi_info->cinfo = cinfo;
smc_channel_lock_init(scmi_info);
cinfo->transport_info = scmi_info;
return 0;
}
static int smc_chan_free(int id, void *p, void *data)
{
struct scmi_chan_info *cinfo = p;
struct scmi_smc *scmi_info = cinfo->transport_info;
/*
* Different protocols might share the same chan info, so a previous
* smc_chan_free call might have already freed the structure.
*/
if (!scmi_info)
return 0;
/* Ignore any possible further reception on the IRQ path */
if (scmi_info->irq > 0)
free_irq(scmi_info->irq, scmi_info);
cinfo->transport_info = NULL;
scmi_info->cinfo = NULL;
return 0;
}
static int smc_send_message(struct scmi_chan_info *cinfo,
struct scmi_xfer *xfer)
{
struct scmi_smc *scmi_info = cinfo->transport_info;
struct arm_smccc_res res;
unsigned long page = scmi_info->param_page;
unsigned long offset = scmi_info->param_offset;
/*
* Channel will be released only once response has been
* surely fully retrieved, so after .mark_txdone()
*/
smc_channel_lock_acquire(scmi_info, xfer);
shmem_tx_prepare(scmi_info->shmem, xfer, cinfo);
arm_smccc_1_1_invoke(scmi_info->func_id, page, offset, 0, 0, 0, 0, 0,
&res);
/* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
if (res.a0) {
smc_channel_lock_release(scmi_info);
return -EOPNOTSUPP;
}
return 0;
}
static void smc_fetch_response(struct scmi_chan_info *cinfo,
struct scmi_xfer *xfer)
{
struct scmi_smc *scmi_info = cinfo->transport_info;
shmem_fetch_response(scmi_info->shmem, xfer);
}
static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,
struct scmi_xfer *__unused)
{
struct scmi_smc *scmi_info = cinfo->transport_info;
smc_channel_lock_release(scmi_info);
}
static const struct scmi_transport_ops scmi_smc_ops = {
.chan_available = smc_chan_available,
.chan_setup = smc_chan_setup,
.chan_free = smc_chan_free,
.send_message = smc_send_message,
.mark_txdone = smc_mark_txdone,
.fetch_response = smc_fetch_response,
};
const struct scmi_desc scmi_smc_desc = {
.ops = &scmi_smc_ops,
.max_rx_timeout_ms = 30,
.max_msg = 20,
.max_msg_size = 128,
/*
* Setting .sync_cmds_atomic_replies to true for SMC assumes that,
* once the SMC instruction has completed successfully, the issued
* SCMI command would have been already fully processed by the SCMI
* platform firmware and so any possible response value expected
* for the issued command will be immmediately ready to be fetched
* from the shared memory area.
*/
.sync_cmds_completed_on_ret = true,
.atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
};
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