drivers/clk/ti/clk-am3-dpll.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * TI DPLL clock support
 *
 * Copyright (C) 2020 Dario Binacchi <dariobin@libero.it>
 *
 * Loosely based on Linux kernel drivers/clk/ti/dpll.c
 */

#include <common.h>
#include <clk.h>
#include <clk-uclass.h>
#include <div64.h>
#include <dm.h>
#include <dm/device_compat.h>
#include <hang.h>
#include <asm/arch/clock.h>
#include <asm/arch/sys_proto.h>
#include <asm/io.h>
#include "clk.h"

struct clk_ti_am3_dpll_drv_data {
	ulong max_rate;
};

struct clk_ti_am3_dpll_priv {
	struct clk_ti_reg clkmode_reg;
	struct clk_ti_reg idlest_reg;
	struct clk_ti_reg clksel_reg;
	struct clk_ti_reg ssc_deltam_reg;
	struct clk_ti_reg ssc_modfreq_reg;
	struct clk clk_bypass;
	struct clk clk_ref;
	u16 last_rounded_mult;
	u8 last_rounded_div;
	u8 min_div;
	ulong max_rate;
	u32 ssc_modfreq;
	u32 ssc_deltam;
	bool ssc_downspread;
};

static ulong clk_ti_am3_dpll_round_rate(struct clk *clk, ulong rate)
{
	struct clk_ti_am3_dpll_priv *priv = dev_get_priv(clk->dev);
	ulong ret, ref_rate, r;
	int m, d, err_min, err;
	int mult = INT_MAX, div = INT_MAX;

	if (priv->max_rate && rate > priv->max_rate) {
		dev_warn(clk->dev, "%ld is to high a rate, lowered to %ld\n",
			 rate, priv->max_rate);
		rate = priv->max_rate;
	}

	ret = -EFAULT;
	err = rate;
	err_min = rate;
	ref_rate = clk_get_rate(&priv->clk_ref);
	for (d = priv->min_div; err_min && d <= 128; d++) {
		for (m = 2; m <= 2047; m++) {
			r = (ref_rate * m) / d;
			err = abs(r - rate);
			if (err < err_min) {
				err_min = err;
				ret = r;
				mult = m;
				div = d;

				if (err == 0)
					break;
			} else if (r > rate) {
				break;
			}
		}
	}

	priv->last_rounded_mult = mult;
	priv->last_rounded_div = div;
	dev_dbg(clk->dev, "rate=%ld, min-div: %d, best_rate=%ld, mult=%d, div=%d\n",
		rate, priv->min_div, ret, mult, div);
	return ret;
}

static void clk_ti_am3_dpll_clken(struct clk_ti_am3_dpll_priv *priv,
				  u8 clken_bits)
{
	u32 v;

	v = clk_ti_readl(&priv->clkmode_reg);
	v &= ~CM_CLKMODE_DPLL_DPLL_EN_MASK;
	v |= clken_bits << CM_CLKMODE_DPLL_EN_SHIFT;
	clk_ti_writel(v, &priv->clkmode_reg);
}

static int clk_ti_am3_dpll_state(struct clk *clk, u8 state)
{
	struct clk_ti_am3_dpll_priv *priv = dev_get_priv(clk->dev);
	u32 i = 0, v;

	do {
		v = clk_ti_readl(&priv->idlest_reg) & ST_DPLL_CLK_MASK;
		if (v == state) {
			dev_dbg(clk->dev, "transition to '%s' in %d loops\n",
				state ? "locked" : "bypassed", i);
			return 1;
		}

	} while (++i < LDELAY);

	dev_err(clk->dev, "failed transition to '%s'\n",
		state ? "locked" : "bypassed");
	return 0;
}

/**
 * clk_ti_am3_dpll_ssc_program - set spread-spectrum clocking registers
 * @clk:	struct clk * of DPLL to set
 *
 * Enable the DPLL spread spectrum clocking if frequency modulation and
 * frequency spreading have been set, otherwise disable it.
 */
static void clk_ti_am3_dpll_ssc_program(struct clk *clk)
{
	struct clk_ti_am3_dpll_priv *priv = dev_get_priv(clk->dev);
	unsigned long ref_rate;
	u32 v, ctrl, mod_freq_divider, exponent, mantissa;
	u32 deltam_step, deltam_ceil;

	ctrl = clk_ti_readl(&priv->clkmode_reg);

	if (priv->ssc_modfreq && priv->ssc_deltam) {
		ctrl |= CM_CLKMODE_DPLL_SSC_EN_MASK;

		if (priv->ssc_downspread)
			ctrl |= CM_CLKMODE_DPLL_SSC_DOWNSPREAD_MASK;
		else
			ctrl &= ~CM_CLKMODE_DPLL_SSC_DOWNSPREAD_MASK;

		ref_rate = clk_get_rate(&priv->clk_ref);
		mod_freq_divider =
		    (ref_rate / priv->last_rounded_div) / (4 * priv->ssc_modfreq);
		if (priv->ssc_modfreq > (ref_rate / 70))
			dev_warn(clk->dev,
				 "clock: SSC modulation frequency of DPLL %s greater than %ld\n",
				 clk->dev->name, ref_rate / 70);

		exponent = 0;
		mantissa = mod_freq_divider;
		while ((mantissa > 127) && (exponent < 7)) {
			exponent++;
			mantissa /= 2;
		}
		if (mantissa > 127)
			mantissa = 127;

		v = clk_ti_readl(&priv->ssc_modfreq_reg);
		v &= ~(CM_SSC_MODFREQ_DPLL_MANT_MASK | CM_SSC_MODFREQ_DPLL_EXP_MASK);
		v |= mantissa << __ffs(CM_SSC_MODFREQ_DPLL_MANT_MASK);
		v |= exponent << __ffs(CM_SSC_MODFREQ_DPLL_EXP_MASK);
		clk_ti_writel(v, &priv->ssc_modfreq_reg);
		dev_dbg(clk->dev,
			"mod_freq_divider: %u, exponent: %u, mantissa: %u, modfreq_reg: 0x%x\n",
			mod_freq_divider, exponent, mantissa, v);

		deltam_step = priv->last_rounded_mult * priv->ssc_deltam;
		deltam_step /= 10;
		if (priv->ssc_downspread)
			deltam_step /= 2;

		deltam_step <<= __ffs(CM_SSC_DELTAM_DPLL_INT_MASK);
		deltam_step /= 100;
		deltam_step /= mod_freq_divider;
		if (deltam_step > 0xFFFFF)
			deltam_step = 0xFFFFF;

		deltam_ceil = (deltam_step & CM_SSC_DELTAM_DPLL_INT_MASK) >>
			__ffs(CM_SSC_DELTAM_DPLL_INT_MASK);
		if (deltam_step & CM_SSC_DELTAM_DPLL_FRAC_MASK)
			deltam_ceil++;

		if ((priv->ssc_downspread &&
		     ((priv->last_rounded_mult - (2 * deltam_ceil)) < 20 ||
		      priv->last_rounded_mult > 2045)) ||
		    ((priv->last_rounded_mult - deltam_ceil) < 20 ||
		     (priv->last_rounded_mult + deltam_ceil) > 2045))
			dev_warn(clk->dev,
				 "clock: SSC multiplier of DPLL %s is out of range\n",
				 clk->dev->name);

		v = clk_ti_readl(&priv->ssc_deltam_reg);
		v &= ~(CM_SSC_DELTAM_DPLL_INT_MASK | CM_SSC_DELTAM_DPLL_FRAC_MASK);
		v |= deltam_step << __ffs(CM_SSC_DELTAM_DPLL_INT_MASK |
					  CM_SSC_DELTAM_DPLL_FRAC_MASK);
		clk_ti_writel(v, &priv->ssc_deltam_reg);
		dev_dbg(clk->dev,
			"deltam_step: %u, deltam_ceil: %u, deltam_reg: 0x%x\n",
			deltam_step, deltam_ceil, v);
	} else {
		ctrl &= ~CM_CLKMODE_DPLL_SSC_EN_MASK;
	}

	clk_ti_writel(ctrl, &priv->clkmode_reg);
}

static ulong clk_ti_am3_dpll_set_rate(struct clk *clk, ulong rate)
{
	struct clk_ti_am3_dpll_priv *priv = dev_get_priv(clk->dev);
	u32 v;
	ulong round_rate;

	round_rate = clk_ti_am3_dpll_round_rate(clk, rate);
	if (IS_ERR_VALUE(round_rate))
		return round_rate;

	v = clk_ti_readl(&priv->clksel_reg);

	/* enter bypass mode */
	clk_ti_am3_dpll_clken(priv, DPLL_EN_MN_BYPASS);

	/* wait for bypass mode */
	clk_ti_am3_dpll_state(clk, 0);

	/* set M & N */
	v &= ~CM_CLKSEL_DPLL_M_MASK;
	v |= (priv->last_rounded_mult << CM_CLKSEL_DPLL_M_SHIFT) &
		CM_CLKSEL_DPLL_M_MASK;

	v &= ~CM_CLKSEL_DPLL_N_MASK;
	v |= ((priv->last_rounded_div - 1) << CM_CLKSEL_DPLL_N_SHIFT) &
		CM_CLKSEL_DPLL_N_MASK;

	clk_ti_writel(v, &priv->clksel_reg);

	clk_ti_am3_dpll_ssc_program(clk);

	/* lock dpll */
	clk_ti_am3_dpll_clken(priv, DPLL_EN_LOCK);

	/* wait till the dpll locks */
	if (!clk_ti_am3_dpll_state(clk, ST_DPLL_CLK_MASK))
		hang();

	return round_rate;
}

static ulong clk_ti_am3_dpll_get_rate(struct clk *clk)
{
	struct clk_ti_am3_dpll_priv *priv = dev_get_priv(clk->dev);
	u64 rate;
	u32 m, n, v;

	/* Return bypass rate if DPLL is bypassed */
	v = clk_ti_readl(&priv->clkmode_reg);
	v &= CM_CLKMODE_DPLL_EN_MASK;
	v >>= CM_CLKMODE_DPLL_EN_SHIFT;

	switch (v) {
	case DPLL_EN_MN_BYPASS:
	case DPLL_EN_LOW_POWER_BYPASS:
	case DPLL_EN_FAST_RELOCK_BYPASS:
		rate = clk_get_rate(&priv->clk_bypass);
		dev_dbg(clk->dev, "rate=%lld\n", rate);
		return rate;
	}

	v = clk_ti_readl(&priv->clksel_reg);
	m = v & CM_CLKSEL_DPLL_M_MASK;
	m >>= CM_CLKSEL_DPLL_M_SHIFT;
	n = v & CM_CLKSEL_DPLL_N_MASK;
	n >>= CM_CLKSEL_DPLL_N_SHIFT;

	rate = clk_get_rate(&priv->clk_ref) * m;
	do_div(rate, n + 1);
	dev_dbg(clk->dev, "rate=%lld\n", rate);
	return rate;
}

const struct clk_ops clk_ti_am3_dpll_ops = {
	.round_rate = clk_ti_am3_dpll_round_rate,
	.get_rate = clk_ti_am3_dpll_get_rate,
	.set_rate = clk_ti_am3_dpll_set_rate,
};

static int clk_ti_am3_dpll_remove(struct udevice *dev)
{
	struct clk_ti_am3_dpll_priv *priv = dev_get_priv(dev);
	int err;

	err = clk_release_all(&priv->clk_bypass, 1);
	if (err) {
		dev_err(dev, "failed to release bypass clock\n");
		return err;
	}

	err = clk_release_all(&priv->clk_ref, 1);
	if (err) {
		dev_err(dev, "failed to release reference clock\n");
		return err;
	}

	return 0;
}

static int clk_ti_am3_dpll_probe(struct udevice *dev)
{
	struct clk_ti_am3_dpll_priv *priv = dev_get_priv(dev);
	int err;

	err = clk_get_by_index(dev, 0, &priv->clk_ref);
	if (err) {
		dev_err(dev, "failed to get reference clock\n");
		return err;
	}

	err = clk_get_by_index(dev, 1, &priv->clk_bypass);
	if (err) {
		dev_err(dev, "failed to get bypass clock\n");
		return err;
	}

	return 0;
}

static int clk_ti_am3_dpll_of_to_plat(struct udevice *dev)
{
	struct clk_ti_am3_dpll_priv *priv = dev_get_priv(dev);
	struct clk_ti_am3_dpll_drv_data *data =
		(struct clk_ti_am3_dpll_drv_data *)dev_get_driver_data(dev);
	u32 min_div;
	int err;

	priv->max_rate = data->max_rate;

	err = clk_ti_get_reg_addr(dev, 0, &priv->clkmode_reg);
	if (err) {
		dev_err(dev, "failed to get clkmode register address\n");
		return err;
	}

	err = clk_ti_get_reg_addr(dev, 1, &priv->idlest_reg);
	if (err) {
		dev_err(dev, "failed to get idlest register\n");
		return -EINVAL;
	}

	err = clk_ti_get_reg_addr(dev, 2, &priv->clksel_reg);
	if (err) {
		dev_err(dev, "failed to get clksel register\n");
		return err;
	}

	err = clk_ti_get_reg_addr(dev, 3, &priv->ssc_deltam_reg);
	if (err) {
		dev_err(dev, "failed to get SSC deltam register\n");
		return err;
	}

	err = clk_ti_get_reg_addr(dev, 4, &priv->ssc_modfreq_reg);
	if (err) {
		dev_err(dev, "failed to get SSC modfreq register\n");
		return err;
	}

	if (dev_read_u32(dev, "ti,ssc-modfreq-hz", &priv->ssc_modfreq))
		priv->ssc_modfreq = 0;

	if (dev_read_u32(dev, "ti,ssc-deltam", &priv->ssc_deltam))
		priv->ssc_deltam = 0;

	priv->ssc_downspread = dev_read_bool(dev, "ti,ssc-downspread");

	if (dev_read_u32(dev, "ti,min-div", &min_div) || min_div == 0 ||
	    min_div > 128)
		priv->min_div = 1;
	else
		priv->min_div = min_div;

	return 0;
}

static const struct clk_ti_am3_dpll_drv_data dpll_no_gate_data = {
	.max_rate = 1000000000
};

static const struct clk_ti_am3_dpll_drv_data dpll_no_gate_j_type_data = {
	.max_rate = 2000000000
};

static const struct clk_ti_am3_dpll_drv_data dpll_core_data = {
	.max_rate = 1000000000
};

static const struct udevice_id clk_ti_am3_dpll_of_match[] = {
	{.compatible = "ti,am3-dpll-core-clock",
	 .data = (ulong)&dpll_core_data},
	{.compatible = "ti,am3-dpll-no-gate-clock",
	 .data = (ulong)&dpll_no_gate_data},
	{.compatible = "ti,am3-dpll-no-gate-j-type-clock",
	 .data = (ulong)&dpll_no_gate_j_type_data},
	{}
};

U_BOOT_DRIVER(clk_ti_am3_dpll) = {
	.name = "ti_am3_dpll_clock",
	.id = UCLASS_CLK,
	.of_match = clk_ti_am3_dpll_of_match,
	.of_to_plat = clk_ti_am3_dpll_of_to_plat,
	.probe = clk_ti_am3_dpll_probe,
	.remove = clk_ti_am3_dpll_remove,
	.priv_auto = sizeof(struct clk_ti_am3_dpll_priv),
	.ops = &clk_ti_am3_dpll_ops,
};