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/*
* Copyright (C) 2016 Maxime Ripard
* Maxime Ripard <maxime.ripard@free-electrons.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*/
#include <linux/clk-provider.h>
#include <linux/spinlock.h>
#include "ccu_phase.h"
static int ccu_phase_get_phase(struct clk_hw *hw)
{
struct ccu_phase *phase = hw_to_ccu_phase(hw);
struct clk_hw *parent, *grandparent;
unsigned int parent_rate, grandparent_rate;
u16 step, parent_div;
u32 reg;
u8 delay;
reg = readl(phase->common.base + phase->common.reg);
delay = (reg >> phase->shift);
delay &= (1 << phase->width) - 1;
if (!delay)
return 180;
/* Get our parent clock, it's the one that can adjust its rate */
parent = clk_hw_get_parent(hw);
if (!parent)
return -EINVAL;
/* And its rate */
parent_rate = clk_hw_get_rate(parent);
if (!parent_rate)
return -EINVAL;
/* Now, get our parent's parent (most likely some PLL) */
grandparent = clk_hw_get_parent(parent);
if (!grandparent)
return -EINVAL;
/* And its rate */
grandparent_rate = clk_hw_get_rate(grandparent);
if (!grandparent_rate)
return -EINVAL;
/* Get our parent clock divider */
parent_div = grandparent_rate / parent_rate;
step = DIV_ROUND_CLOSEST(360, parent_div);
return delay * step;
}
static int ccu_phase_set_phase(struct clk_hw *hw, int degrees)
{
struct ccu_phase *phase = hw_to_ccu_phase(hw);
struct clk_hw *parent, *grandparent;
unsigned int parent_rate, grandparent_rate;
unsigned long flags;
u32 reg;
u8 delay;
/* Get our parent clock, it's the one that can adjust its rate */
parent = clk_hw_get_parent(hw);
if (!parent)
return -EINVAL;
/* And its rate */
parent_rate = clk_hw_get_rate(parent);
if (!parent_rate)
return -EINVAL;
/* Now, get our parent's parent (most likely some PLL) */
grandparent = clk_hw_get_parent(parent);
if (!grandparent)
return -EINVAL;
/* And its rate */
grandparent_rate = clk_hw_get_rate(grandparent);
if (!grandparent_rate)
return -EINVAL;
if (degrees != 180) {
u16 step, parent_div;
/* Get our parent divider */
parent_div = grandparent_rate / parent_rate;
/*
* We can only outphase the clocks by multiple of the
* PLL's period.
*
* Since our parent clock is only a divider, and the
* formula to get the outphasing in degrees is deg =
* 360 * delta / period
*
* If we simplify this formula, we can see that the
* only thing that we're concerned about is the number
* of period we want to outphase our clock from, and
* the divider set by our parent clock.
*/
step = DIV_ROUND_CLOSEST(360, parent_div);
delay = DIV_ROUND_CLOSEST(degrees, step);
} else {
delay = 0;
}
spin_lock_irqsave(phase->common.lock, flags);
reg = readl(phase->common.base + phase->common.reg);
reg &= ~GENMASK(phase->width + phase->shift - 1, phase->shift);
writel(reg | (delay << phase->shift),
phase->common.base + phase->common.reg);
spin_unlock_irqrestore(phase->common.lock, flags);
return 0;
}
const struct clk_ops ccu_phase_ops = {
.get_phase = ccu_phase_get_phase,
.set_phase = ccu_phase_set_phase,
};
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