// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2015 Endless Mobile, Inc.
* Author: Carlo Caione <carlo@endlessm.com>
*
* Copyright (c) 2018 Baylibre, SAS.
* Author: Jerome Brunet <jbrunet@baylibre.com>
*/
/*
* In the most basic form, a Meson PLL is composed as follows:
*
* PLL
* +--------------------------------+
* | |
* | +--+ |
* in >>-----[ /N ]--->| | +-----+ |
* | | |------| DCO |---->> out
* | +--------->| | +--v--+ |
* | | +--+ | |
* | | | |
* | +--[ *(M + (F/Fmax) ]<--+ |
* | |
* +--------------------------------+
*
* out = in * (m + frac / frac_max) / n
*/
#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/slab.h>
#include <linux/string.h>
#include "clkc.h"
static inline struct meson_clk_pll_data *
meson_clk_pll_data(struct clk_regmap *clk)
{
return (struct meson_clk_pll_data *)clk->data;
}
static unsigned long __pll_params_to_rate(unsigned long parent_rate,
const struct pll_params_table *pllt,
u16 frac,
struct meson_clk_pll_data *pll)
{
u64 rate = (u64)parent_rate * pllt->m;
if (frac && MESON_PARM_APPLICABLE(&pll->frac)) {
u64 frac_rate = (u64)parent_rate * frac;
rate += DIV_ROUND_UP_ULL(frac_rate,
(1 << pll->frac.width));
}
return DIV_ROUND_UP_ULL(rate, pllt->n);
}
static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct clk_regmap *clk = to_clk_regmap(hw);
struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
struct pll_params_table pllt;
u16 frac;
pllt.n = meson_parm_read(clk->map, &pll->n);
pllt.m = meson_parm_read(clk->map, &pll->m);
frac = MESON_PARM_APPLICABLE(&pll->frac) ?
meson_parm_read(clk->map, &pll->frac) :
0;
return __pll_params_to_rate(parent_rate, &pllt, frac, pll);
}
static u16 __pll_params_with_frac(unsigned long rate,
unsigned long parent_rate,
const struct pll_params_table *pllt,
struct meson_clk_pll_data *pll)
{
u16 frac_max = (1 << pll->frac.width);
u64 val = (u64)rate * pllt->n;
if (pll->flags & CLK_MESON_PLL_ROUND_CLOSEST)
val = DIV_ROUND_CLOSEST_ULL(val * frac_max, parent_rate);
else
val = div_u64(val * frac_max, parent_rate);
val -= pllt->m * frac_max;
return min((u16)val, (u16)(frac_max - 1));
}
static bool meson_clk_pll_is_better(unsigned long rate,
unsigned long best,
unsigned long now,
struct meson_clk_pll_data *pll)
{
if (!(pll->flags & CLK_MESON_PLL_ROUND_CLOSEST) ||
MESON_PARM_APPLICABLE(&pll->frac)) {
/* Round down */
if (now < rate && best < now)
return true;
} else {
/* Round Closest */
if (abs(now - rate) < abs(best - rate))
return true;
}
return false;
}
static const struct pll_params_table *
meson_clk_get_pll_settings(unsigned long rate,
unsigned long parent_rate,
struct meson_clk_pll_data *pll)
{
const struct pll_params_table *table = pll->table;
unsigned long best = 0, now = 0;
unsigned int i, best_i = 0;
if (!table)
return NULL;
for (i = 0; table[i].n; i++) {
now = __pll_params_to_rate(parent_rate, &table[i], 0, pll);
/* If we get an exact match, don't bother any further */
if (now == rate) {
return &table[i];
} else if (meson_clk_pll_is_better(rate, best, now, pll)) {
best = now;
best_i = i;
}
}
return (struct pll_params_table *)&table[best_i];
}
static long meson_clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *parent_rate)
{
struct clk_regmap *clk = to_clk_regmap(hw);
struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
const struct pll_params_table *pllt =
meson_clk_get_pll_settings(rate, *parent_rate, pll);
unsigned long round;
u16 frac;
if (!pllt)
return meson_clk_pll_recalc_rate(hw, *parent_rate);
round = __pll_params_to_rate(*parent_rate, pllt, 0, pll);
if (!MESON_PARM_APPLICABLE(&pll->frac) || rate == round)
return round;
/*
* The rate provided by the setting is not an exact match, let's
* try to improve the result using the fractional parameter
*/
frac = __pll_params_with_frac(rate, *parent_rate, pllt, pll);
return __pll_params_to_rate(*parent_rate, pllt, frac, pll);
}
static int meson_clk_pll_wait_lock(struct clk_hw *hw)
{
struct clk_regmap *clk = to_clk_regmap(hw);
struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
int delay = 24000000;
do {
/* Is the clock locked now ? */
if (meson_parm_read(clk->map, &pll->l))
return 0;
delay--;
} while (delay > 0);
return -ETIMEDOUT;
}
static void meson_clk_pll_init(struct clk_hw *hw)
{
struct clk_regmap *clk = to_clk_regmap(hw);
struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
if (pll->init_count) {
meson_parm_write(clk->map, &pll->rst, 1);
regmap_multi_reg_write(clk->map, pll->init_regs,
pll->init_count);
meson_parm_write(clk->map, &pll->rst, 0);
}
}
static int meson_clk_pll_is_enabled(struct clk_hw *hw)
{
struct clk_regmap *clk = to_clk_regmap(hw);
struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
if (meson_parm_read(clk->map, &pll->rst) ||
!meson_parm_read(clk->map, &pll->en) ||
!meson_parm_read(clk->map, &pll->l))
return 0;
return 1;
}
static int meson_clk_pll_enable(struct clk_hw *hw)
{
struct clk_regmap *clk = to_clk_regmap(hw);
struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
/* do nothing if the PLL is already enabled */
if (clk_hw_is_enabled(hw))
return 0;
/* Make sure the pll is in reset */
meson_parm_write(clk->map, &pll->rst, 1);
/* Enable the pll */
meson_parm_write(clk->map, &pll->en, 1);
/* Take the pll out reset */
meson_parm_write(clk->map, &pll->rst, 0);
if (meson_clk_pll_wait_lock(hw))
return -EIO;
return 0;
}
static void meson_clk_pll_disable(struct clk_hw *hw)
{
struct clk_regmap *clk = to_clk_regmap(hw);
struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
/* Put the pll is in reset */
meson_parm_write(clk->map, &pll->rst, 1);
/* Disable the pll */
meson_parm_write(clk->map, &pll->en, 0);
}
static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct clk_regmap *clk = to_clk_regmap(hw);
struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
const struct pll_params_table *pllt;
unsigned int enabled;
unsigned long old_rate;
u16 frac = 0;
if (parent_rate == 0 || rate == 0)
return -EINVAL;
old_rate = rate;
pllt = meson_clk_get_pll_settings(rate, parent_rate, pll);
if (!pllt)
return -EINVAL;
enabled = meson_parm_read(clk->map, &pll->en);
if (enabled)
meson_clk_pll_disable(hw);
meson_parm_write(clk->map, &pll->n, pllt->n);
meson_parm_write(clk->map, &pll->m, pllt->m);
if (MESON_PARM_APPLICABLE(&pll->frac)) {
frac = __pll_params_with_frac(rate, parent_rate, pllt, pll);
meson_parm_write(clk->map, &pll->frac, frac);
}
/* If the pll is stopped, bail out now */
if (!enabled)
return 0;
if (meson_clk_pll_enable(hw)) {
pr_warn("%s: pll did not lock, trying to restore old rate %lu\n",
__func__, old_rate);
/*
* FIXME: Do we really need/want this HACK ?
* It looks unsafe. what happens if the clock gets into a
* broken state and we can't lock back on the old_rate ? Looks
* like an infinite recursion is possible
*/
meson_clk_pll_set_rate(hw, old_rate, parent_rate);
}
return 0;
}
const struct clk_ops meson_clk_pll_ops = {
.init = meson_clk_pll_init,
.recalc_rate = meson_clk_pll_recalc_rate,
.round_rate = meson_clk_pll_round_rate,
.set_rate = meson_clk_pll_set_rate,
.is_enabled = meson_clk_pll_is_enabled,
.enable = meson_clk_pll_enable,
.disable = meson_clk_pll_disable
};
const struct clk_ops meson_clk_pll_ro_ops = {
.recalc_rate = meson_clk_pll_recalc_rate,
.is_enabled = meson_clk_pll_is_enabled,
};
