// SPDX-License-Identifier: GPL-2.0-only
/*
 * OMAP4-specific DPLL control functions
 *
 * Copyright (C) 2011 Texas Instruments, Inc.
 * Rajendra Nayak
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/bitops.h>
#include <linux/clk/ti.h>

#include "clock.h"

/*
 * Maximum DPLL input frequency (FINT) and output frequency (FOUT) that
 * can supported when using the DPLL low-power mode. Frequencies are
 * defined in OMAP4430/60 Public TRM section 3.6.3.3.2 "Enable Control,
 * Status, and Low-Power Operation Mode".
 */
#define OMAP4_DPLL_LP_FINT_MAX  1000000
#define OMAP4_DPLL_LP_FOUT_MAX  100000000

/*
 * Bitfield declarations
 */
#define OMAP4430_DPLL_CLKOUT_GATE_CTRL_MASK             BIT(8)
#define OMAP4430_DPLL_CLKOUTX2_GATE_CTRL_MASK           BIT(10)
#define OMAP4430_DPLL_REGM4XEN_MASK                     BIT(11)

/* Static rate multiplier for OMAP4 REGM4XEN clocks */
#define OMAP4430_REGM4XEN_MULT                          4

static void omap4_dpllmx_allow_gatectrl(struct clk_hw_omap *clk)
{
        u32 v;
        u32 mask;

        if (!clk)
                return;

        mask = clk->flags & CLOCK_CLKOUTX2 ?
                        OMAP4430_DPLL_CLKOUTX2_GATE_CTRL_MASK :
                        OMAP4430_DPLL_CLKOUT_GATE_CTRL_MASK;

        v = ti_clk_ll_ops->clk_readl(&clk->clksel_reg);
        /* Clear the bit to allow gatectrl */
        v &= ~mask;
        ti_clk_ll_ops->clk_writel(v, &clk->clksel_reg);
}

static void omap4_dpllmx_deny_gatectrl(struct clk_hw_omap *clk)
{
        u32 v;
        u32 mask;

        if (!clk)
                return;

        mask = clk->flags & CLOCK_CLKOUTX2 ?
                        OMAP4430_DPLL_CLKOUTX2_GATE_CTRL_MASK :
                        OMAP4430_DPLL_CLKOUT_GATE_CTRL_MASK;

        v = ti_clk_ll_ops->clk_readl(&clk->clksel_reg);
        /* Set the bit to deny gatectrl */
        v |= mask;
        ti_clk_ll_ops->clk_writel(v, &clk->clksel_reg);
}

const struct clk_hw_omap_ops clkhwops_omap4_dpllmx = {
        .allow_idle     = omap4_dpllmx_allow_gatectrl,
        .deny_idle      = omap4_dpllmx_deny_gatectrl,
};

/**
 * omap4_dpll_lpmode_recalc - compute DPLL low-power setting
 * @dd: pointer to the dpll data structure
 *
 * Calculates if low-power mode can be enabled based upon the last
 * multiplier and divider values calculated. If low-power mode can be
 * enabled, then the bit to enable low-power mode is stored in the
 * last_rounded_lpmode variable. This implementation is based upon the
 * criteria for enabling low-power mode as described in the OMAP4430/60
 * Public TRM section 3.6.3.3.2 "Enable Control, Status, and Low-Power
 * Operation Mode".
 */
static void omap4_dpll_lpmode_recalc(struct dpll_data *dd)
{
        long fint, fout;

        fint = clk_hw_get_rate(dd->clk_ref) / (dd->last_rounded_n + 1);
        fout = fint * dd->last_rounded_m;

        if ((fint < OMAP4_DPLL_LP_FINT_MAX) && (fout < OMAP4_DPLL_LP_FOUT_MAX))
                dd->last_rounded_lpmode = 1;
        else
                dd->last_rounded_lpmode = 0;
}

/**
 * omap4_dpll_regm4xen_recalc - compute DPLL rate, considering REGM4XEN bit
 * @hw: pointer to the clock to compute the rate for
 * @parent_rate: clock rate of the DPLL parent
 *
 * Compute the output rate for the OMAP4 DPLL represented by @clk.
 * Takes the REGM4XEN bit into consideration, which is needed for the
 * OMAP4 ABE DPLL.  Returns the DPLL's output rate (before M-dividers)
 * upon success, or 0 upon error.
 */
unsigned long omap4_dpll_regm4xen_recalc(struct clk_hw *hw,
                                         unsigned long parent_rate)
{
        struct clk_hw_omap *clk = to_clk_hw_omap(hw);
        u32 v;
        unsigned long rate;
        struct dpll_data *dd;

        if (!clk || !clk->dpll_data)
                return 0;

        dd = clk->dpll_data;

        rate = omap2_get_dpll_rate(clk);

        /* regm4xen adds a multiplier of 4 to DPLL calculations */
        v = ti_clk_ll_ops->clk_readl(&dd->control_reg);
        if (v & OMAP4430_DPLL_REGM4XEN_MASK)
                rate *= OMAP4430_REGM4XEN_MULT;

        return rate;
}

/**
 * omap4_dpll_regm4xen_determine_rate - determine rate for a DPLL
 * @hw: pointer to the clock to determine rate for
 * @req: target rate request
 *
 * Determines which DPLL mode to use for reaching a desired rate.
 * Checks whether the DPLL shall be in bypass or locked mode, and if
 * locked, calculates the M,N values for the DPLL.
 * Returns 0 on success and a negative error value otherwise.
 */
int omap4_dpll_regm4xen_determine_rate(struct clk_hw *hw,
                                       struct clk_rate_request *req)
{
        struct clk_hw_omap *clk = to_clk_hw_omap(hw);
        struct dpll_data *dd;

        if (!req->rate)
                return -EINVAL;

        dd = clk->dpll_data;
        if (!dd)
                return -EINVAL;

        if (clk_hw_get_rate(dd->clk_bypass) == req->rate &&
            (dd->modes & (1 << DPLL_LOW_POWER_BYPASS))) {
                req->best_parent_hw = dd->clk_bypass;
        } else {
                struct clk_rate_request tmp_req;
                long r;

                clk_hw_init_rate_request(hw, &tmp_req, req->rate);
                dd->last_rounded_m4xen = 0;

                /*
                 * First try to compute the DPLL configuration for
                 * target rate without using the 4X multiplier.
                 */

                r = omap2_dpll_determine_rate(hw, &tmp_req);
                if (r < 0) {
                        /*
                         * If we did not find a valid DPLL configuration, try again, but
                         * this time see if using the 4X multiplier can help. Enabling the
                         * 4X multiplier is equivalent to dividing the target rate by 4.
                         */
                        tmp_req.rate /= OMAP4430_REGM4XEN_MULT;
                        r = omap2_dpll_determine_rate(hw, &tmp_req);
                        if (r < 0)
                                return r;

                        dd->last_rounded_rate *= OMAP4430_REGM4XEN_MULT;
                        dd->last_rounded_m4xen = 1;
                }

                omap4_dpll_lpmode_recalc(dd);

                req->rate = dd->last_rounded_rate;
                req->best_parent_hw = dd->clk_ref;
        }

        req->best_parent_rate = req->rate;

        return 0;
}