// SPDX-License-Identifier: GPL-2.0-only OR MIT
/*
 * Apple Silicon hardware tunable support
 *
 * Each tunable is a list with each entry containing a offset into the MMIO
 * region, a mask of bits to be cleared and a set of bits to be set. These
 * tunables are passed along by the previous boot stages and vary from device
 * to device such that they cannot be hardcoded in the individual drivers.
 *
 * Copyright (C) The Asahi Linux Contributors
 */

#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/overflow.h>
#include <linux/soc/apple/tunable.h>

struct apple_tunable *devm_apple_tunable_parse(struct device *dev,
                                               struct device_node *np,
                                               const char *name,
                                               struct resource *res)
{
        struct apple_tunable *tunable;
        struct property *prop;
        const __be32 *p;
        size_t sz;
        int i;

        if (resource_size(res) < 4)
                return ERR_PTR(-EINVAL);

        prop = of_find_property(np, name, NULL);
        if (!prop)
                return ERR_PTR(-ENOENT);

        if (prop->length % (3 * sizeof(u32)))
                return ERR_PTR(-EINVAL);
        sz = prop->length / (3 * sizeof(u32));

        tunable = devm_kzalloc(dev, struct_size(tunable, values, sz), GFP_KERNEL);
        if (!tunable)
                return ERR_PTR(-ENOMEM);
        tunable->sz = sz;

        for (i = 0, p = NULL; i < tunable->sz; ++i) {
                p = of_prop_next_u32(prop, p, &tunable->values[i].offset);
                p = of_prop_next_u32(prop, p, &tunable->values[i].mask);
                p = of_prop_next_u32(prop, p, &tunable->values[i].value);

                /* Sanity checks to catch bugs in our bootloader */
                if (tunable->values[i].offset % 4)
                        return ERR_PTR(-EINVAL);
                if (tunable->values[i].offset > (resource_size(res) - 4))
                        return ERR_PTR(-EINVAL);
        }

        return tunable;
}
EXPORT_SYMBOL(devm_apple_tunable_parse);

void apple_tunable_apply(void __iomem *regs, struct apple_tunable *tunable)
{
        size_t i;

        for (i = 0; i < tunable->sz; ++i) {
                u32 val, old_val;

                old_val = readl(regs + tunable->values[i].offset);
                val = old_val & ~tunable->values[i].mask;
                val |= tunable->values[i].value;
                if (val != old_val)
                        writel(val, regs + tunable->values[i].offset);
        }
}
EXPORT_SYMBOL(apple_tunable_apply);

MODULE_LICENSE("Dual MIT/GPL");
MODULE_AUTHOR("Sven Peter <sven@kernel.org>");
MODULE_DESCRIPTION("Apple Silicon hardware tunable support");