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/*
* Copyright (c) 2017 AmLogic, Inc.
* Author: Jerome Brunet <jbrunet@baylibre.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* i2s master clock divider: The algorithm of the generic clk-divider used with
* a very precise clock parent such as the mpll tends to select a low divider
* factor. This gives poor results with this particular divider, especially with
* high frequencies (> 100 MHz)
*
* This driver try to select the maximum possible divider with the rate the
* upstream clock can provide.
*/
#include <linux/clk-provider.h>
#include "clkc.h"
#define to_meson_clk_audio_divider(_hw) container_of(_hw, \
struct meson_clk_audio_divider, hw)
static int _div_round(unsigned long parent_rate, unsigned long rate,
unsigned long flags)
{
if (flags & CLK_DIVIDER_ROUND_CLOSEST)
return DIV_ROUND_CLOSEST_ULL((u64)parent_rate, rate);
return DIV_ROUND_UP_ULL((u64)parent_rate, rate);
}
static int _get_val(unsigned long parent_rate, unsigned long rate)
{
return DIV_ROUND_UP_ULL((u64)parent_rate, rate) - 1;
}
static int _valid_divider(struct clk_hw *hw, int divider)
{
struct meson_clk_audio_divider *adiv =
to_meson_clk_audio_divider(hw);
int max_divider;
u8 width;
width = adiv->div.width;
max_divider = 1 << width;
return clamp(divider, 1, max_divider);
}
static unsigned long audio_divider_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct meson_clk_audio_divider *adiv =
to_meson_clk_audio_divider(hw);
struct parm *p;
unsigned long reg, divider;
p = &adiv->div;
reg = readl(adiv->base + p->reg_off);
divider = PARM_GET(p->width, p->shift, reg) + 1;
return DIV_ROUND_UP_ULL((u64)parent_rate, divider);
}
static long audio_divider_round_rate(struct clk_hw *hw,
unsigned long rate,
unsigned long *parent_rate)
{
struct meson_clk_audio_divider *adiv =
to_meson_clk_audio_divider(hw);
unsigned long max_prate;
int divider;
if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
divider = _div_round(*parent_rate, rate, adiv->flags);
divider = _valid_divider(hw, divider);
return DIV_ROUND_UP_ULL((u64)*parent_rate, divider);
}
/* Get the maximum parent rate */
max_prate = clk_hw_round_rate(clk_hw_get_parent(hw), ULONG_MAX);
/* Get the corresponding rounded down divider */
divider = max_prate / rate;
divider = _valid_divider(hw, divider);
/* Get actual rate of the parent */
*parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw),
divider * rate);
return DIV_ROUND_UP_ULL((u64)*parent_rate, divider);
}
static int audio_divider_set_rate(struct clk_hw *hw,
unsigned long rate,
unsigned long parent_rate)
{
struct meson_clk_audio_divider *adiv =
to_meson_clk_audio_divider(hw);
struct parm *p;
unsigned long reg, flags = 0;
int val;
val = _get_val(parent_rate, rate);
if (adiv->lock)
spin_lock_irqsave(adiv->lock, flags);
else
__acquire(adiv->lock);
p = &adiv->div;
reg = readl(adiv->base + p->reg_off);
reg = PARM_SET(p->width, p->shift, reg, val);
writel(reg, adiv->base + p->reg_off);
if (adiv->lock)
spin_unlock_irqrestore(adiv->lock, flags);
else
__release(adiv->lock);
return 0;
}
const struct clk_ops meson_clk_audio_divider_ro_ops = {
.recalc_rate = audio_divider_recalc_rate,
.round_rate = audio_divider_round_rate,
};
const struct clk_ops meson_clk_audio_divider_ops = {
.recalc_rate = audio_divider_recalc_rate,
.round_rate = audio_divider_round_rate,
.set_rate = audio_divider_set_rate,
};
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