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