// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Hisilicon clock driver
 *
 * Copyright (c) 2013-2017 Hisilicon Limited.
 * Copyright (c) 2017 Linaro Limited.
 *
 * Author: Kai Zhao <zhaokai1@hisilicon.com>
 *          Tao Wang <kevin.wangtao@hisilicon.com>
 *          Leo Yan <leo.yan@linaro.org>
 */

#include <linux/clk-provider.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/mailbox_client.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <dt-bindings/clock/hi3660-clock.h>

#define HI3660_STUB_CLOCK_DATA          (0x70)
#define MHZ                             (1000 * 1000)

#define DEFINE_CLK_STUB(_id, _cmd, _name)                       \
        {                                                       \
                .id = (_id),                                    \
                .cmd = (_cmd),                                  \
                .hw.init = &(struct clk_init_data) {            \
                        .name = #_name,                         \
                        .ops = &hi3660_stub_clk_ops,            \
                        .num_parents = 0,                       \
                        .flags = CLK_GET_RATE_NOCACHE,          \
                },                                              \
        }

#define to_stub_clk(_hw) container_of(_hw, struct hi3660_stub_clk, hw)

struct hi3660_stub_clk_chan {
        struct mbox_client cl;
        struct mbox_chan *mbox;
};

struct hi3660_stub_clk {
        unsigned int id;
        struct clk_hw hw;
        unsigned int cmd;
        unsigned int msg[8];
        unsigned int rate;
};

static void __iomem *freq_reg;
static struct hi3660_stub_clk_chan stub_clk_chan;

static unsigned long hi3660_stub_clk_recalc_rate(struct clk_hw *hw,
                                                 unsigned long parent_rate)
{
        struct hi3660_stub_clk *stub_clk = to_stub_clk(hw);

        /*
         * LPM3 writes back the CPU frequency in shared SRAM so read
         * back the frequency.
         */
        stub_clk->rate = readl(freq_reg + (stub_clk->id << 2)) * MHZ;
        return stub_clk->rate;
}

static int hi3660_stub_clk_determine_rate(struct clk_hw *hw,
                                          struct clk_rate_request *req)
{
        /*
         * LPM3 handles rate rounding so just return whatever
         * rate is requested.
         */
        return 0;
}

static int hi3660_stub_clk_set_rate(struct clk_hw *hw, unsigned long rate,
                                    unsigned long parent_rate)
{
        struct hi3660_stub_clk *stub_clk = to_stub_clk(hw);

        stub_clk->msg[0] = stub_clk->cmd;
        stub_clk->msg[1] = rate / MHZ;

        dev_dbg(stub_clk_chan.cl.dev, "set rate msg[0]=0x%x msg[1]=0x%x\n",
                stub_clk->msg[0], stub_clk->msg[1]);

        mbox_send_message(stub_clk_chan.mbox, stub_clk->msg);
        mbox_client_txdone(stub_clk_chan.mbox, 0);

        stub_clk->rate = rate;
        return 0;
}

static const struct clk_ops hi3660_stub_clk_ops = {
        .recalc_rate    = hi3660_stub_clk_recalc_rate,
        .determine_rate = hi3660_stub_clk_determine_rate,
        .set_rate       = hi3660_stub_clk_set_rate,
};

static struct hi3660_stub_clk hi3660_stub_clks[HI3660_CLK_STUB_NUM] = {
        DEFINE_CLK_STUB(HI3660_CLK_STUB_CLUSTER0, 0x0001030A, "cpu-cluster.0"),
        DEFINE_CLK_STUB(HI3660_CLK_STUB_CLUSTER1, 0x0002030A, "cpu-cluster.1"),
        DEFINE_CLK_STUB(HI3660_CLK_STUB_GPU, 0x0003030A, "clk-g3d"),
        DEFINE_CLK_STUB(HI3660_CLK_STUB_DDR, 0x00040309, "clk-ddrc"),
};

static struct clk_hw *hi3660_stub_clk_hw_get(struct of_phandle_args *clkspec,
                                             void *data)
{
        unsigned int idx = clkspec->args[0];

        if (idx >= HI3660_CLK_STUB_NUM) {
                pr_err("%s: invalid index %u\n", __func__, idx);
                return ERR_PTR(-EINVAL);
        }

        return &hi3660_stub_clks[idx].hw;
}

static int hi3660_stub_clk_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct resource *res;
        unsigned int i;
        int ret;

        /* Use mailbox client without blocking */
        stub_clk_chan.cl.dev = dev;
        stub_clk_chan.cl.tx_done = NULL;
        stub_clk_chan.cl.tx_block = false;
        stub_clk_chan.cl.knows_txdone = false;

        /* Allocate mailbox channel */
        stub_clk_chan.mbox = mbox_request_channel(&stub_clk_chan.cl, 0);
        if (IS_ERR(stub_clk_chan.mbox))
                return PTR_ERR(stub_clk_chan.mbox);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -EINVAL;
        freq_reg = devm_ioremap(dev, res->start, resource_size(res));
        if (!freq_reg)
                return -ENOMEM;

        freq_reg += HI3660_STUB_CLOCK_DATA;

        for (i = 0; i < HI3660_CLK_STUB_NUM; i++) {
                ret = devm_clk_hw_register(&pdev->dev, &hi3660_stub_clks[i].hw);
                if (ret)
                        return ret;
        }

        return devm_of_clk_add_hw_provider(&pdev->dev, hi3660_stub_clk_hw_get,
                                           hi3660_stub_clks);
}

static const struct of_device_id hi3660_stub_clk_of_match[] = {
        { .compatible = "hisilicon,hi3660-stub-clk", },
        {}
};

static struct platform_driver hi3660_stub_clk_driver = {
        .probe  = hi3660_stub_clk_probe,
        .driver = {
                .name = "hi3660-stub-clk",
                .of_match_table = hi3660_stub_clk_of_match,
        },
};

static int __init hi3660_stub_clk_init(void)
{
        return platform_driver_register(&hi3660_stub_clk_driver);
}
subsys_initcall(hi3660_stub_clk_init);