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// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2025 Arm Ltd.
#define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__
#include <linux/acpi.h>
#include <linux/arm_mpam.h>
#include <linux/cacheinfo.h>
#include <linux/cpumask.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/gfp.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <linux/srcu.h>
#include <linux/types.h>
#include "mpam_internal.h"
/*
* mpam_list_lock protects the SRCU lists when writing. Once the
* mpam_enabled key is enabled these lists are read-only,
* unless the error interrupt disables the driver.
*/
static DEFINE_MUTEX(mpam_list_lock);
static LIST_HEAD(mpam_all_msc);
struct srcu_struct mpam_srcu;
/*
* Number of MSCs that have been probed. Once all MSCs have been probed MPAM
* can be enabled.
*/
static atomic_t mpam_num_msc;
/*
* An MSC can control traffic from a set of CPUs, but may only be accessible
* from a (hopefully wider) set of CPUs. The common reason for this is power
* management. If all the CPUs in a cluster are in PSCI:CPU_SUSPEND, the
* corresponding cache may also be powered off. By making accesses from
* one of those CPUs, we ensure we don't access a cache that's powered off.
*/
static void update_msc_accessibility(struct mpam_msc *msc)
{
u32 affinity_id;
int err;
err = device_property_read_u32(&msc->pdev->dev, "cpu_affinity",
&affinity_id);
if (err)
cpumask_copy(&msc->accessibility, cpu_possible_mask);
else
acpi_pptt_get_cpus_from_container(affinity_id, &msc->accessibility);
}
static void mpam_msc_destroy(struct mpam_msc *msc)
{
struct platform_device *pdev = msc->pdev;
lockdep_assert_held(&mpam_list_lock);
list_del_rcu(&msc->all_msc_list);
platform_set_drvdata(pdev, NULL);
}
static void mpam_msc_drv_remove(struct platform_device *pdev)
{
struct mpam_msc *msc = platform_get_drvdata(pdev);
mutex_lock(&mpam_list_lock);
mpam_msc_destroy(msc);
mutex_unlock(&mpam_list_lock);
synchronize_srcu(&mpam_srcu);
}
static struct mpam_msc *do_mpam_msc_drv_probe(struct platform_device *pdev)
{
int err;
u32 tmp;
struct mpam_msc *msc;
struct resource *msc_res;
struct device *dev = &pdev->dev;
lockdep_assert_held(&mpam_list_lock);
msc = devm_kzalloc(&pdev->dev, sizeof(*msc), GFP_KERNEL);
if (!msc)
return ERR_PTR(-ENOMEM);
err = devm_mutex_init(dev, &msc->probe_lock);
if (err)
return ERR_PTR(err);
err = devm_mutex_init(dev, &msc->part_sel_lock);
if (err)
return ERR_PTR(err);
msc->id = pdev->id;
msc->pdev = pdev;
INIT_LIST_HEAD_RCU(&msc->all_msc_list);
INIT_LIST_HEAD_RCU(&msc->ris);
update_msc_accessibility(msc);
if (cpumask_empty(&msc->accessibility)) {
dev_err_once(dev, "MSC is not accessible from any CPU!");
return ERR_PTR(-EINVAL);
}
if (device_property_read_u32(&pdev->dev, "pcc-channel", &tmp))
msc->iface = MPAM_IFACE_MMIO;
else
msc->iface = MPAM_IFACE_PCC;
if (msc->iface == MPAM_IFACE_MMIO) {
void __iomem *io;
io = devm_platform_get_and_ioremap_resource(pdev, 0,
&msc_res);
if (IS_ERR(io)) {
dev_err_once(dev, "Failed to map MSC base address\n");
return ERR_CAST(io);
}
msc->mapped_hwpage_sz = msc_res->end - msc_res->start;
msc->mapped_hwpage = io;
} else {
return ERR_PTR(-EINVAL);
}
list_add_rcu(&msc->all_msc_list, &mpam_all_msc);
platform_set_drvdata(pdev, msc);
return msc;
}
static int fw_num_msc;
static int mpam_msc_drv_probe(struct platform_device *pdev)
{
int err;
struct mpam_msc *msc = NULL;
void *plat_data = pdev->dev.platform_data;
mutex_lock(&mpam_list_lock);
msc = do_mpam_msc_drv_probe(pdev);
mutex_unlock(&mpam_list_lock);
if (IS_ERR(msc))
return PTR_ERR(msc);
/* Create RIS entries described by firmware */
err = acpi_mpam_parse_resources(msc, plat_data);
if (err) {
mpam_msc_drv_remove(pdev);
return err;
}
if (atomic_add_return(1, &mpam_num_msc) == fw_num_msc)
pr_info("Discovered all MSCs\n");
return 0;
}
static struct platform_driver mpam_msc_driver = {
.driver = {
.name = "mpam_msc",
},
.probe = mpam_msc_drv_probe,
.remove = mpam_msc_drv_remove,
};
static int __init mpam_msc_driver_init(void)
{
if (!system_supports_mpam())
return -EOPNOTSUPP;
init_srcu_struct(&mpam_srcu);
fw_num_msc = acpi_mpam_count_msc();
if (fw_num_msc <= 0) {
pr_err("No MSC devices found in firmware\n");
return -EINVAL;
}
return platform_driver_register(&mpam_msc_driver);
}
subsys_initcall(mpam_msc_driver_init);
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