mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-13 14:04:05 +08:00
6f9f7f876e
Add support for the clocks in the CCU that introduce a phase shift from their parent clock. Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by: Michael Turquette <mturquette@baylibre.com> Link: lkml.kernel.org/r/20160629190535.11855-7-maxime.ripard@free-electrons.com
127 lines
3.2 KiB
C
127 lines
3.2 KiB
C
/*
|
|
* 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,
|
|
};
|