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Diffstat (limited to '')
-rw-r--r-- | drivers/clk/sunxi-ng/ccu_phase.c | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/drivers/clk/sunxi-ng/ccu_phase.c b/drivers/clk/sunxi-ng/ccu_phase.c new file mode 100644 index 000000000..400c58ad7 --- /dev/null +++ b/drivers/clk/sunxi-ng/ccu_phase.c @@ -0,0 +1,126 @@ +/* + * 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, +}; |