// SPDX-License-Identifier: GPL-2.0
//
// Copyright (c) 2015 Samsung Electronics Co., Ltd.
//            http://www.samsung.com/
//
// Exynos - SROM Controller support
// Author: Pankaj Dubey <pankaj.dubey@samsung.com>

#include <linux/io.h>
#include <linux/init.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include "exynos-srom.h"

static const unsigned long exynos_srom_offsets[] = {
        /* SROM side */
        EXYNOS_SROM_BW,
        EXYNOS_SROM_BC0,
        EXYNOS_SROM_BC1,
        EXYNOS_SROM_BC2,
        EXYNOS_SROM_BC3,
};

/**
 * struct exynos_srom_reg_dump: register dump of SROM Controller registers.
 * @offset: srom register offset from the controller base address.
 * @value: the value of register under the offset.
 */
struct exynos_srom_reg_dump {
        u32     offset;
        u32     value;
};

/**
 * struct exynos_srom: platform data for exynos srom controller driver.
 * @dev: platform device pointer
 * @reg_base: srom base address
 * @reg_offset: exynos_srom_reg_dump pointer to hold offset and its value.
 */
struct exynos_srom {
        struct device *dev;
        void __iomem *reg_base;
        struct exynos_srom_reg_dump *reg_offset;
};

static struct exynos_srom_reg_dump *
exynos_srom_alloc_reg_dump(const unsigned long *rdump,
                           unsigned long nr_rdump)
{
        struct exynos_srom_reg_dump *rd;
        unsigned int i;

        rd = kzalloc_objs(*rd, nr_rdump);
        if (!rd)
                return NULL;

        for (i = 0; i < nr_rdump; ++i)
                rd[i].offset = rdump[i];

        return rd;
}

static int exynos_srom_configure_bank(struct exynos_srom *srom,
                                      struct device_node *np)
{
        u32 bank, width, pmc = 0;
        u32 timing[6];
        u32 cs, bw;

        if (of_property_read_u32(np, "reg", &bank))
                return -EINVAL;
        if (of_property_read_u32(np, "reg-io-width", &width))
                width = 1;
        if (of_property_read_bool(np, "samsung,srom-page-mode"))
                pmc = 1 << EXYNOS_SROM_BCX__PMC__SHIFT;
        if (of_property_read_u32_array(np, "samsung,srom-timing", timing,
                                       ARRAY_SIZE(timing)))
                return -EINVAL;

        bank *= 4; /* Convert bank into shift/offset */

        cs = 1 << EXYNOS_SROM_BW__BYTEENABLE__SHIFT;
        if (width == 2)
                cs |= 1 << EXYNOS_SROM_BW__DATAWIDTH__SHIFT;

        bw = readl_relaxed(srom->reg_base + EXYNOS_SROM_BW);
        bw = (bw & ~(EXYNOS_SROM_BW__CS_MASK << bank)) | (cs << bank);
        writel_relaxed(bw, srom->reg_base + EXYNOS_SROM_BW);

        writel_relaxed(pmc | (timing[0] << EXYNOS_SROM_BCX__TACP__SHIFT) |
                       (timing[1] << EXYNOS_SROM_BCX__TCAH__SHIFT) |
                       (timing[2] << EXYNOS_SROM_BCX__TCOH__SHIFT) |
                       (timing[3] << EXYNOS_SROM_BCX__TACC__SHIFT) |
                       (timing[4] << EXYNOS_SROM_BCX__TCOS__SHIFT) |
                       (timing[5] << EXYNOS_SROM_BCX__TACS__SHIFT),
                       srom->reg_base + EXYNOS_SROM_BC0 + bank);

        return 0;
}

static int exynos_srom_probe(struct platform_device *pdev)
{
        struct device_node *np, *child;
        struct exynos_srom *srom;
        struct device *dev = &pdev->dev;
        bool bad_bank_config = false;

        np = dev->of_node;
        if (!np) {
                dev_err(&pdev->dev, "could not find device info\n");
                return -EINVAL;
        }

        srom = devm_kzalloc(&pdev->dev,
                            sizeof(struct exynos_srom), GFP_KERNEL);
        if (!srom)
                return -ENOMEM;

        srom->dev = dev;
        srom->reg_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(srom->reg_base)) {
                dev_err(&pdev->dev, "iomap of exynos srom controller failed\n");
                return PTR_ERR(srom->reg_base);
        }

        platform_set_drvdata(pdev, srom);

        srom->reg_offset = exynos_srom_alloc_reg_dump(exynos_srom_offsets,
                                                      ARRAY_SIZE(exynos_srom_offsets));
        if (!srom->reg_offset)
                return -ENOMEM;

        for_each_child_of_node(np, child) {
                if (exynos_srom_configure_bank(srom, child)) {
                        dev_err(dev,
                                "Could not decode bank configuration for %pOFn\n",
                                child);
                        bad_bank_config = true;
                }
        }

        /*
         * If any bank failed to configure, we still provide suspend/resume,
         * but do not probe child devices
         */
        if (bad_bank_config)
                return 0;

        return of_platform_populate(np, NULL, NULL, dev);
}

#ifdef CONFIG_PM_SLEEP
static void exynos_srom_save(void __iomem *base,
                             struct exynos_srom_reg_dump *rd,
                             unsigned int num_regs)
{
        for (; num_regs > 0; --num_regs, ++rd)
                rd->value = readl(base + rd->offset);
}

static void exynos_srom_restore(void __iomem *base,
                                const struct exynos_srom_reg_dump *rd,
                                unsigned int num_regs)
{
        for (; num_regs > 0; --num_regs, ++rd)
                writel(rd->value, base + rd->offset);
}

static int exynos_srom_suspend(struct device *dev)
{
        struct exynos_srom *srom = dev_get_drvdata(dev);

        exynos_srom_save(srom->reg_base, srom->reg_offset,
                         ARRAY_SIZE(exynos_srom_offsets));
        return 0;
}

static int exynos_srom_resume(struct device *dev)
{
        struct exynos_srom *srom = dev_get_drvdata(dev);

        exynos_srom_restore(srom->reg_base, srom->reg_offset,
                            ARRAY_SIZE(exynos_srom_offsets));
        return 0;
}
#endif

static const struct of_device_id of_exynos_srom_ids[] = {
        {
                .compatible     = "samsung,exynos4210-srom",
        },
        {},
};

static SIMPLE_DEV_PM_OPS(exynos_srom_pm_ops, exynos_srom_suspend, exynos_srom_resume);

static struct platform_driver exynos_srom_driver = {
        .probe = exynos_srom_probe,
        .driver = {
                .name = "exynos-srom",
                .of_match_table = of_exynos_srom_ids,
                .pm = &exynos_srom_pm_ops,
                .suppress_bind_attrs = true,
        },
};
builtin_platform_driver(exynos_srom_driver);