clkt2xxx_virt_prcm_set.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * OMAP2xxx DVFS virtual clock functions
 *
 * Copyright (C) 2005-2008, 2012 Texas Instruments, Inc.
 * Copyright (C) 2004-2010 Nokia Corporation
 *
 * Contacts:
 * Richard Woodruff <[email protected]>
 * Paul Walmsley
 *
 * Based on earlier work by Tuukka Tikkanen, Tony Lindgren,
 * Gordon McNutt and RidgeRun, Inc.
 *
 * 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"

static u16 cpu_mask;

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.
 */
static 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.
 */
static int omap2_determine_rate_to_table(struct clk_hw *hw,
					 struct clk_rate_request *req)
{
	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 <= req->rate)
			break;
	}
	req->rate = highest_rate;

	return 0;
}

/* Sets basic clocks based on the specified rate */
static 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_rates - 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;
 */
static 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.
 */
static 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,
	.determine_rate = &omap2_determine_rate_to_table,
};

/**
 * 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)
		return;
	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);
	if (IS_ERR(clk)) {
		printk(KERN_ERR "Failed to register clock\n");
		kfree(hw);
		return;
	}

	clkdev_create(clk, "cpufreq_ck", NULL);
}
#endif