// SPDX-License-Identifier: GPL-2.0+
/* Microchip Sparx5 Switch Reset driver
 *
 * Copyright (c) 2020 Microchip Technology Inc. and its subsidiaries.
 *
 * The Sparx5 Chip Register Model can be browsed at this location:
 * https://github.com/microchip-ung/sparx-5_reginfo
 */
#include <linux/mfd/syscon.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/reset-controller.h>

struct reset_props {
        u32 protect_reg;
        u32 protect_bit;
        u32 reset_reg;
        u32 reset_bit;
};

struct mchp_reset_context {
        struct regmap *cpu_ctrl;
        struct regmap *gcb_ctrl;
        struct reset_controller_dev rcdev;
        const struct reset_props *props;
};

static struct regmap_config sparx5_reset_regmap_config = {
        .reg_bits       = 32,
        .val_bits       = 32,
        .reg_stride     = 4,
};

static int sparx5_switch_reset(struct mchp_reset_context *ctx)
{
        u32 val;

        /* Make sure the core is PROTECTED from reset */
        regmap_update_bits(ctx->cpu_ctrl, ctx->props->protect_reg,
                           ctx->props->protect_bit, ctx->props->protect_bit);

        /* Start soft reset */
        regmap_write(ctx->gcb_ctrl, ctx->props->reset_reg,
                     ctx->props->reset_bit);

        /* Wait for soft reset done */
        return regmap_read_poll_timeout(ctx->gcb_ctrl, ctx->props->reset_reg, val,
                                        (val & ctx->props->reset_bit) == 0,
                                        1, 100);
}

static int sparx5_reset_noop(struct reset_controller_dev *rcdev,
                             unsigned long id)
{
        return 0;
}

static const struct reset_control_ops sparx5_reset_ops = {
        .reset = sparx5_reset_noop,
};

static const struct regmap_config mchp_lan966x_syscon_regmap_config = {
        .reg_bits = 32,
        .val_bits = 32,
        .reg_stride = 4,
};

static struct regmap *mchp_lan966x_syscon_to_regmap(struct device *dev,
                                                    struct device_node *syscon_np)
{
        struct regmap_config regmap_config = mchp_lan966x_syscon_regmap_config;
        struct resource res;
        void __iomem *base;
        int err;

        err = of_address_to_resource(syscon_np, 0, &res);
        if (err)
                return ERR_PTR(err);

        /* It is not possible to use devm_of_iomap because this resource is
         * shared with other drivers.
         */
        base = devm_ioremap(dev, res.start, resource_size(&res));
        if (!base)
                return ERR_PTR(-ENOMEM);

        regmap_config.max_register =  resource_size(&res) - 4;

        return devm_regmap_init_mmio(dev, base, &regmap_config);
}

static int mchp_sparx5_map_syscon(struct platform_device *pdev, char *name,
                                  struct regmap **target)
{
        struct device_node *syscon_np;
        struct regmap *regmap;
        int err;

        syscon_np = of_parse_phandle(pdev->dev.of_node, name, 0);
        if (!syscon_np)
                return -ENODEV;

        /*
         * The syscon API doesn't support syscon device removal.
         * When used in LAN966x PCI device, the cpu-syscon device needs to be
         * removed when the PCI device is removed.
         * In case of LAN966x, map the syscon device locally to support the
         * device removal.
         */
        if (of_device_is_compatible(pdev->dev.of_node, "microchip,lan966x-switch-reset"))
                regmap = mchp_lan966x_syscon_to_regmap(&pdev->dev, syscon_np);
        else
                regmap = syscon_node_to_regmap(syscon_np);
        of_node_put(syscon_np);
        if (IS_ERR(regmap)) {
                err = PTR_ERR(regmap);
                dev_err(&pdev->dev, "No '%s' map: %d\n", name, err);
                return err;
        }
        *target = regmap;
        return 0;
}

static int mchp_sparx5_map_io(struct platform_device *pdev, int index,
                              struct regmap **target)
{
        struct resource *res;
        struct regmap *map;
        void __iomem *mem;

        mem = devm_platform_get_and_ioremap_resource(pdev, index, &res);
        if (IS_ERR(mem)) {
                dev_err(&pdev->dev, "Could not map resource %d\n", index);
                return PTR_ERR(mem);
        }
        sparx5_reset_regmap_config.name = res->name;
        map = devm_regmap_init_mmio(&pdev->dev, mem, &sparx5_reset_regmap_config);
        if (IS_ERR(map))
                return PTR_ERR(map);
        *target = map;
        return 0;
}

static int mchp_sparx5_reset_probe(struct platform_device *pdev)
{
        struct device_node *dn = pdev->dev.of_node;
        struct mchp_reset_context *ctx;
        int err;

        ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
        if (!ctx)
                return -ENOMEM;

        err = mchp_sparx5_map_syscon(pdev, "cpu-syscon", &ctx->cpu_ctrl);
        if (err)
                return err;
        err = mchp_sparx5_map_io(pdev, 0, &ctx->gcb_ctrl);
        if (err)
                return err;

        ctx->rcdev.owner = THIS_MODULE;
        ctx->rcdev.dev = &pdev->dev;
        ctx->rcdev.nr_resets = 1;
        ctx->rcdev.ops = &sparx5_reset_ops;
        ctx->rcdev.of_node = dn;
        ctx->props = device_get_match_data(&pdev->dev);

        /* Issue the reset very early, our actual reset callback is a noop. */
        err = sparx5_switch_reset(ctx);
        if (err)
                return err;

        return devm_reset_controller_register(&pdev->dev, &ctx->rcdev);
}

static const struct reset_props reset_props_sparx5 = {
        .protect_reg    = 0x84,
        .protect_bit    = BIT(10),
        .reset_reg      = 0x0,
        .reset_bit      = BIT(1),
};

static const struct reset_props reset_props_lan966x = {
        .protect_reg    = 0x88,
        .protect_bit    = BIT(5),
        .reset_reg      = 0x0,
        .reset_bit      = BIT(1),
};

static const struct of_device_id mchp_sparx5_reset_of_match[] = {
        {
                .compatible = "microchip,sparx5-switch-reset",
                .data = &reset_props_sparx5,
        }, {
                .compatible = "microchip,lan966x-switch-reset",
                .data = &reset_props_lan966x,
        },
        { }
};
MODULE_DEVICE_TABLE(of, mchp_sparx5_reset_of_match);

static struct platform_driver mchp_sparx5_reset_driver = {
        .probe = mchp_sparx5_reset_probe,
        .driver = {
                .name = "sparx5-switch-reset",
                .of_match_table = mchp_sparx5_reset_of_match,
        },
};

static int __init mchp_sparx5_reset_init(void)
{
        return platform_driver_register(&mchp_sparx5_reset_driver);
}

/*
 * Because this is a global reset, keep this postcore_initcall() to issue the
 * reset as early as possible during the kernel startup.
 */
postcore_initcall(mchp_sparx5_reset_init);

MODULE_DESCRIPTION("Microchip Sparx5 switch reset driver");
MODULE_AUTHOR("Steen Hegelund <steen.hegelund@microchip.com>");
MODULE_LICENSE("GPL");