/*
 * OMAP2xxx DVFS virtual clock functions
 *
 * Copyright (C) 2005-2008, 2012 Texas Instruments, Inc.
 * Copyright (C) 2004-2010 Nokia Corporation
 *
 * Contacts:
 * Richard Woodruff <r-woodruff2@ti.com>
 * Paul Walmsley
 *
 * Based on earlier work by Tuukka Tikkanen, Tony Lindgren,
 * Gordon McNutt and RidgeRun, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * XXX Some of this code should be replaceable by the upcoming OPP layer
 * code.  However, some notion of "rate set" is probably still necessary
 * for OMAP2xxx at least.  Rate sets should be generalized so they can be
 * used for any OMAP chip, not just OMAP2xxx.  In particular, Richard Woodruff
 * has in the past expressed a preference to use rate sets for OPP changes,
 * rather than dynamically recalculating the clock tree, so if someone wants
 * this badly enough to write the code to handle it, we should support it
 * as an option.
 */
#undef DEBUG

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/cpufreq.h>
#include <linux/slab.h>

#include "soc.h"
#include "clock.h"
#include "clock2xxx.h"
#include "opp2xxx.h"
#include "cm2xxx.h"
#include "cm-regbits-24xx.h"
#include "sdrc.h"
#include "sram.h"

const struct prcm_config *curr_prcm_set;
const struct prcm_config *rate_table;

/*
 * sys_ck_rate: the rate of the external high-frequency clock
 * oscillator on the board.  Set by the SoC-specific clock init code.
 * Once set during a boot, will not change.
 */
static unsigned long sys_ck_rate;

/**
 * omap2_table_mpu_recalc - just return the MPU speed
 * @clk: virt_prcm_set struct clk
 *
 * Set virt_prcm_set's rate to the mpu_speed field of the current PRCM set.
 */
unsigned long omap2_table_mpu_recalc(struct clk_hw *clk,
                                     unsigned long parent_rate)
{
        return curr_prcm_set->mpu_speed;
}

/*
 * Look for a rate equal or less than the target rate given a configuration set.
 *
 * What's not entirely clear is "which" field represents the key field.
 * Some might argue L3-DDR, others ARM, others IVA. This code is simple and
 * just uses the ARM rates.
 */
long omap2_round_to_table_rate(struct clk_hw *hw, unsigned long rate,
                               unsigned long *parent_rate)
{
        const struct prcm_config *ptr;
        long highest_rate;

        highest_rate = -EINVAL;

        for (ptr = rate_table; ptr->mpu_speed; ptr++) {
                if (!(ptr->flags & cpu_mask))
                        continue;
                if (ptr->xtal_speed != sys_ck_rate)
                        continue;

                highest_rate = ptr->mpu_speed;

                /* Can check only after xtal frequency check */
                if (ptr->mpu_speed <= rate)
                        break;
        }
        return highest_rate;
}

/* Sets basic clocks based on the specified rate */
int omap2_select_table_rate(struct clk_hw *hw, unsigned long rate,
                            unsigned long parent_rate)
{
        u32 cur_rate, done_rate, bypass = 0;
        const struct prcm_config *prcm;
        unsigned long found_speed = 0;
        unsigned long flags;

        for (prcm = rate_table; prcm->mpu_speed; prcm++) {
                if (!(prcm->flags & cpu_mask))
                        continue;

                if (prcm->xtal_speed != sys_ck_rate)
                        continue;

                if (prcm->mpu_speed <= rate) {
                        found_speed = prcm->mpu_speed;
                        break;
                }
        }

        if (!found_speed) {
                printk(KERN_INFO "Could not set MPU rate to %luMHz\n",
                       rate / 1000000);
                return -EINVAL;
        }

        curr_prcm_set = prcm;
        cur_rate = omap2xxx_clk_get_core_rate();

        if (prcm->dpll_speed == cur_rate / 2) {
                omap2xxx_sdrc_reprogram(CORE_CLK_SRC_DPLL, 1);
        } else if (prcm->dpll_speed == cur_rate * 2) {
                omap2xxx_sdrc_reprogram(CORE_CLK_SRC_DPLL_X2, 1);
        } else if (prcm->dpll_speed != cur_rate) {
                local_irq_save(flags);

                if (prcm->dpll_speed == prcm->xtal_speed)
                        bypass = 1;

                if ((prcm->cm_clksel2_pll & OMAP24XX_CORE_CLK_SRC_MASK) ==
                    CORE_CLK_SRC_DPLL_X2)
                        done_rate = CORE_CLK_SRC_DPLL_X2;
                else
                        done_rate = CORE_CLK_SRC_DPLL;

                omap2xxx_cm_set_mod_dividers(prcm->cm_clksel_mpu,
                                             prcm->cm_clksel_dsp,
                                             prcm->cm_clksel_gfx,
                                             prcm->cm_clksel1_core,
                                             prcm->cm_clksel_mdm);

                /* x2 to enter omap2xxx_sdrc_init_params() */
                omap2xxx_sdrc_reprogram(CORE_CLK_SRC_DPLL_X2, 1);

                omap2_set_prcm(prcm->cm_clksel1_pll, prcm->base_sdrc_rfr,
                               bypass);

                omap2xxx_sdrc_init_params(omap2xxx_sdrc_dll_is_unlocked());
                omap2xxx_sdrc_reprogram(done_rate, 0);

                local_irq_restore(flags);
        }

        return 0;
}

/**
 * omap2xxx_clkt_vps_check_bootloader_rate - determine which of the rate
 * table sets matches the current CORE DPLL hardware rate
 *
 * Check the MPU rate set by bootloader.  Sets the 'curr_prcm_set'
 * global to point to the active rate set when found; otherwise, sets
 * it to NULL.  No return value;
 */
void omap2xxx_clkt_vps_check_bootloader_rates(void)
{
        const struct prcm_config *prcm = NULL;
        unsigned long rate;

        rate = omap2xxx_clk_get_core_rate();
        for (prcm = rate_table; prcm->mpu_speed; prcm++) {
                if (!(prcm->flags & cpu_mask))
                        continue;
                if (prcm->xtal_speed != sys_ck_rate)
                        continue;
                if (prcm->dpll_speed <= rate)
                        break;
        }
        curr_prcm_set = prcm;
}

/**
 * omap2xxx_clkt_vps_late_init - store a copy of the sys_ck rate
 *
 * Store a copy of the sys_ck rate for later use by the OMAP2xxx DVFS
 * code.  (The sys_ck rate does not -- or rather, must not -- change
 * during kernel runtime.)  Must be called after we have a valid
 * sys_ck rate, but before the virt_prcm_set clock rate is
 * recalculated.  No return value.
 */
void omap2xxx_clkt_vps_late_init(void)
{
        struct clk *c;

        c = clk_get(NULL, "sys_ck");
        if (IS_ERR(c)) {
                WARN(1, "could not locate sys_ck\n");
        } else {
                sys_ck_rate = clk_get_rate(c);
                clk_put(c);
        }
}

#ifdef CONFIG_OF
#include <linux/clk-provider.h>
#include <linux/clkdev.h>

static const struct clk_ops virt_prcm_set_ops = {
        .recalc_rate    = &omap2_table_mpu_recalc,
        .set_rate       = &omap2_select_table_rate,
        .round_rate     = &omap2_round_to_table_rate,
};

/**
 * omap2xxx_clkt_vps_init - initialize virt_prcm_set clock
 *
 * Does a manual init for the virtual prcm DVFS clock for OMAP2. This
 * function is called only from omap2 DT clock init, as the virtual
 * node is not modelled in the DT clock data.
 */
void omap2xxx_clkt_vps_init(void)
{
        struct clk_init_data init = { NULL };
        struct clk_hw_omap *hw = NULL;
        struct clk *clk;
        const char *parent_name = "mpu_ck";

        omap2xxx_clkt_vps_late_init();
        omap2xxx_clkt_vps_check_bootloader_rates();

        hw = kzalloc(sizeof(*hw), GFP_KERNEL);
        if (!hw)
                goto cleanup;
        init.name = "virt_prcm_set";
        init.ops = &virt_prcm_set_ops;
        init.parent_names = &parent_name;
        init.num_parents = 1;

        hw->hw.init = &init;

        clk = clk_register(NULL, &hw->hw);
        clkdev_create(clk, "cpufreq_ck", NULL);
        return;
cleanup:
        kfree(hw);
}
#endif