drivers/clk/sunxi/clk-sun6i-ar100.c

root/drivers/clk/sunxi/clk-sun6i-ar100.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2014 Free Electrons
 *
 * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
 *
 * Allwinner A31 AR100 clock driver
 */

#include <linux/bitops.h>
#include <linux/clk-provider.h>
#include <linux/init.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>

#include "clk-factors.h"

/*
 * sun6i_get_ar100_factors - Calculates factors p, m for AR100
 *
 * AR100 rate is calculated as follows
 * rate = (parent_rate >> p) / (m + 1);
 */
static void sun6i_get_ar100_factors(struct factors_request *req)
{
        unsigned long div;
        int shift;

        /* clock only divides */
        if (req->rate > req->parent_rate)
                req->rate = req->parent_rate;

        div = DIV_ROUND_UP(req->parent_rate, req->rate);

        if (div < 32)
                shift = 0;
        else if (div >> 1 < 32)
                shift = 1;
        else if (div >> 2 < 32)
                shift = 2;
        else
                shift = 3;

        div >>= shift;

        if (div > 32)
                div = 32;

        req->rate = (req->parent_rate >> shift) / div;
        req->m = div - 1;
        req->p = shift;
}

static const struct clk_factors_config sun6i_ar100_config = {
        .mwidth = 5,
        .mshift = 8,
        .pwidth = 2,
        .pshift = 4,
};

static const struct factors_data sun6i_ar100_data = {
        .mux = 16,
        .muxmask = GENMASK(1, 0),
        .table = &sun6i_ar100_config,
        .getter = sun6i_get_ar100_factors,
};

static DEFINE_SPINLOCK(sun6i_ar100_lock);

static int sun6i_a31_ar100_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 = sunxi_factors_register(np, &sun6i_ar100_data, &sun6i_ar100_lock,
                                     reg);
        if (!clk)
                return -ENOMEM;

        platform_set_drvdata(pdev, clk);

        return 0;
}

static const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = {
        { .compatible = "allwinner,sun6i-a31-ar100-clk" },
        { /* sentinel */ }
};

static struct platform_driver sun6i_a31_ar100_clk_driver = {
        .driver = {
                .name = "sun6i-a31-ar100-clk",
                .of_match_table = sun6i_a31_ar100_clk_dt_ids,
                .suppress_bind_attrs = true,
        },
        .probe = sun6i_a31_ar100_clk_probe,
};
builtin_platform_driver(sun6i_a31_ar100_clk_driver);
Linux
