// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2014 Chen-Yu Tsai
 * Author: Chen-Yu Tsai <wens@csie.org>
 *
 * Allwinner A23 APB0 clock driver
 *
 * Based on clk-sun6i-apb0.c
 * Allwinner A31 APB0 clock driver
 *
 * Copyright (C) 2014 Free Electrons
 * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
 */

#include <linux/clk-provider.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>

static struct clk *sun8i_a23_apb0_register(struct device_node *node,
                                           void __iomem *reg)
{
        const char *clk_name = node->name;
        const char *clk_parent;
        struct clk *clk;
        int ret;

        clk_parent = of_clk_get_parent_name(node, 0);
        if (!clk_parent)
                return ERR_PTR(-EINVAL);

        of_property_read_string(node, "clock-output-names", &clk_name);

        /* The A23 APB0 clock is a standard 2 bit wide divider clock */
        clk = clk_register_divider(NULL, clk_name, clk_parent, 0, reg,
                                   0, 2, 0, NULL);
        if (IS_ERR(clk))
                return clk;

        ret = of_clk_add_provider(node, of_clk_src_simple_get, clk);
        if (ret)
                goto err_unregister;

        return clk;

err_unregister:
        clk_unregister_divider(clk);

        return ERR_PTR(ret);
}

static void sun8i_a23_apb0_setup(struct device_node *node)
{
        void __iomem *reg;
        struct resource res;
        struct clk *clk;

        reg = of_io_request_and_map(node, 0, of_node_full_name(node));
        if (IS_ERR(reg)) {
                /*
                 * This happens with clk nodes instantiated through mfd,
                 * as those do not have their resources assigned in the
                 * device tree. Do not print an error in this case.
                 */
                if (PTR_ERR(reg) != -EINVAL)
                        pr_err("Could not get registers for a23-apb0-clk\n");

                return;
        }

        clk = sun8i_a23_apb0_register(node, reg);
        if (IS_ERR(clk))
                goto err_unmap;

        return;

err_unmap:
        iounmap(reg);
        of_address_to_resource(node, 0, &res);
        release_mem_region(res.start, resource_size(&res));
}
CLK_OF_DECLARE_DRIVER(sun8i_a23_apb0, "allwinner,sun8i-a23-apb0-clk",
                      sun8i_a23_apb0_setup);

static int sun8i_a23_apb0_clk_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        void __iomem *reg;
        struct clk *clk;

        reg = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(reg))
                return PTR_ERR(reg);

        clk = sun8i_a23_apb0_register(np, reg);
        return PTR_ERR_OR_ZERO(clk);
}

static const struct of_device_id sun8i_a23_apb0_clk_dt_ids[] = {
        { .compatible = "allwinner,sun8i-a23-apb0-clk" },
        { /* sentinel */ }
};

static struct platform_driver sun8i_a23_apb0_clk_driver = {
        .driver = {
                .name = "sun8i-a23-apb0-clk",
                .of_match_table = sun8i_a23_apb0_clk_dt_ids,
        },
        .probe = sun8i_a23_apb0_clk_probe,
};
builtin_platform_driver(sun8i_a23_apb0_clk_driver);