// SPDX-License-Identifier: GPL-2.0-only
/*
 * ARM Integrator Logical Module bus driver
 * Copyright (C) 2020 Linaro Ltd.
 * Author: Linus Walleij <linus.walleij@linaro.org>
 *
 * See the device tree bindings for this block for more details on the
 * hardware.
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/bitops.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>

/* All information about the connected logic modules are in here */
#define INTEGRATOR_SC_DEC_OFFSET        0x10

/* Base address for the expansion modules */
#define INTEGRATOR_AP_EXP_BASE          0xc0000000
#define INTEGRATOR_AP_EXP_STRIDE        0x10000000

static int integrator_lm_populate(int num, struct device *dev)
{
        struct device_node *np = dev->of_node;
        struct device_node *child;
        u32 base;
        int ret;

        base = INTEGRATOR_AP_EXP_BASE + (num * INTEGRATOR_AP_EXP_STRIDE);

        /* Walk over the child nodes and see what chipselects we use */
        for_each_available_child_of_node(np, child) {
                struct resource res;

                ret = of_address_to_resource(child, 0, &res);
                if (ret) {
                        dev_info(dev, "no valid address on child\n");
                        continue;
                }

                /* First populate the syscon then any devices */
                if (res.start == base) {
                        dev_info(dev, "populate module @0x%08x from DT\n",
                                 base);
                        ret = of_platform_default_populate(child, NULL, dev);
                        if (ret) {
                                dev_err(dev, "failed to populate module\n");
                                of_node_put(child);
                                return ret;
                        }
                }
        }

        return 0;
}

static const struct of_device_id integrator_ap_syscon_match[] = {
        { .compatible = "arm,integrator-ap-syscon"},
        { },
};

static int integrator_ap_lm_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *syscon;
        static struct regmap *map;
        u32 val;
        int ret;
        int i;

        /* Look up the system controller */
        syscon = of_find_matching_node(NULL, integrator_ap_syscon_match);
        if (!syscon) {
                dev_err(dev,
                        "could not find Integrator/AP system controller\n");
                return -ENODEV;
        }
        map = syscon_node_to_regmap(syscon);
        of_node_put(syscon);
        if (IS_ERR(map)) {
                dev_err(dev,
                        "could not find Integrator/AP system controller\n");
                return PTR_ERR(map);
        }

        ret = regmap_read(map, INTEGRATOR_SC_DEC_OFFSET, &val);
        if (ret) {
                dev_err(dev, "could not read from Integrator/AP syscon\n");
                return ret;
        }

        /* Loop over the connected modules */
        for (i = 0; i < 4; i++) {
                if (!(val & BIT(4 + i)))
                        continue;

                dev_info(dev, "detected module in slot %d\n", i);
                ret = integrator_lm_populate(i, dev);
                if (ret)
                        return ret;
        }

        return 0;
}

static const struct of_device_id integrator_ap_lm_match[] = {
        { .compatible = "arm,integrator-ap-lm"},
        { },
};

static struct platform_driver integrator_ap_lm_driver = {
        .probe = integrator_ap_lm_probe,
        .driver = {
                .name = "integratorap-lm",
                .of_match_table = integrator_ap_lm_match,
        },
};
module_platform_driver(integrator_ap_lm_driver);
MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
MODULE_DESCRIPTION("Integrator AP Logical Module driver");