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author | Maxime Ripard <maxime.ripard@free-electrons.com> | 2015-05-19 22:19:33 +0200 |
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committer | Maxime Ripard <maxime.ripard@free-electrons.com> | 2015-10-21 21:51:27 +0200 |
commit | f2e0a53271a439a2ab142645867f0cde45b2b3cd (patch) | |
tree | 9ac4820d6b1c42452e3a80ea8667822318c6a486 /drivers | |
parent | 7d6ddad659f7220438b863977b0c4032e3d77dda (diff) | |
download | linux-f2e0a53271a439a2ab142645867f0cde45b2b3cd.tar.bz2 |
clk: Add a basic multiplier clock
Some clocks are using a multiplier component, however, unlike their mux,
gate or divider counterpart, these factors don't have a basic clock
implementation.
This leads to code duplication across platforms that want to use that kind
of clocks, and the impossibility to use the composite clocks with such a
clock without defining your own rate operations.
Create such a driver in order to remove these issues, and hopefully factor
the implementations, reducing code size across platforms and consolidating
the various implementations.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/clk/Makefile | 1 | ||||
-rw-r--r-- | drivers/clk/clk-multiplier.c | 181 |
2 files changed, 182 insertions, 0 deletions
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile index d08b3e5985be..0b2101039508 100644 --- a/drivers/clk/Makefile +++ b/drivers/clk/Makefile @@ -6,6 +6,7 @@ obj-$(CONFIG_COMMON_CLK) += clk-divider.o obj-$(CONFIG_COMMON_CLK) += clk-fixed-factor.o obj-$(CONFIG_COMMON_CLK) += clk-fixed-rate.o obj-$(CONFIG_COMMON_CLK) += clk-gate.o +obj-$(CONFIG_COMMON_CLK) += clk-multiplier.o obj-$(CONFIG_COMMON_CLK) += clk-mux.o obj-$(CONFIG_COMMON_CLK) += clk-composite.o obj-$(CONFIG_COMMON_CLK) += clk-fractional-divider.o diff --git a/drivers/clk/clk-multiplier.c b/drivers/clk/clk-multiplier.c new file mode 100644 index 000000000000..43ec269fcbff --- /dev/null +++ b/drivers/clk/clk-multiplier.c @@ -0,0 +1,181 @@ +/* + * Copyright (C) 2015 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 version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/bitops.h> +#include <linux/clk-provider.h> +#include <linux/err.h> +#include <linux/export.h> +#include <linux/kernel.h> +#include <linux/of.h> +#include <linux/slab.h> + +#define to_clk_multiplier(_hw) container_of(_hw, struct clk_multiplier, hw) + +static unsigned long __get_mult(struct clk_multiplier *mult, + unsigned long rate, + unsigned long parent_rate) +{ + if (mult->flags & CLK_MULTIPLIER_ROUND_CLOSEST) + return DIV_ROUND_CLOSEST(rate, parent_rate); + + return rate / parent_rate; +} + +static unsigned long clk_multiplier_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_multiplier *mult = to_clk_multiplier(hw); + unsigned long val; + + val = clk_readl(mult->reg) >> mult->shift; + val &= GENMASK(mult->width - 1, 0); + + if (!val && mult->flags & CLK_MULTIPLIER_ZERO_BYPASS) + val = 1; + + return parent_rate * val; +} + +static bool __is_best_rate(unsigned long rate, unsigned long new, + unsigned long best, unsigned long flags) +{ + if (flags & CLK_MULTIPLIER_ROUND_CLOSEST) + return abs(rate - new) < abs(rate - best); + + return new >= rate && new < best; +} + +static unsigned long __bestmult(struct clk_hw *hw, unsigned long rate, + unsigned long *best_parent_rate, + u8 width, unsigned long flags) +{ + unsigned long orig_parent_rate = *best_parent_rate; + unsigned long parent_rate, current_rate, best_rate = ~0; + unsigned int i, bestmult = 0; + + if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) + return rate / *best_parent_rate; + + for (i = 1; i < ((1 << width) - 1); i++) { + if (rate == orig_parent_rate * i) { + /* + * This is the best case for us if we have a + * perfect match without changing the parent + * rate. + */ + *best_parent_rate = orig_parent_rate; + return i; + } + + parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw), + rate / i); + current_rate = parent_rate * i; + + if (__is_best_rate(rate, current_rate, best_rate, flags)) { + bestmult = i; + best_rate = current_rate; + *best_parent_rate = parent_rate; + } + } + + return bestmult; +} + +static long clk_multiplier_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *parent_rate) +{ + struct clk_multiplier *mult = to_clk_multiplier(hw); + unsigned long factor = __bestmult(hw, rate, parent_rate, + mult->width, mult->flags); + + return *parent_rate * factor; +} + +static int clk_multiplier_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct clk_multiplier *mult = to_clk_multiplier(hw); + unsigned long factor = __get_mult(mult, rate, parent_rate); + unsigned long flags = 0; + unsigned long val; + + if (mult->lock) + spin_lock_irqsave(mult->lock, flags); + else + __acquire(mult->lock); + + val = clk_readl(mult->reg); + val &= ~GENMASK(mult->width + mult->shift - 1, mult->shift); + val |= factor << mult->shift; + clk_writel(val, mult->reg); + + if (mult->lock) + spin_unlock_irqrestore(mult->lock, flags); + else + __release(mult->lock); + + return 0; +} + +const struct clk_ops clk_multiplier_ops = { + .recalc_rate = clk_multiplier_recalc_rate, + .round_rate = clk_multiplier_round_rate, + .set_rate = clk_multiplier_set_rate, +}; +EXPORT_SYMBOL_GPL(clk_multiplier_ops); + +struct clk *clk_register_multiplier(struct device *dev, const char *name, + const char *parent_name, + unsigned long flags, + void __iomem *reg, u8 shift, u8 width, + u8 clk_mult_flags, spinlock_t *lock) +{ + struct clk_init_data init; + struct clk_multiplier *mult; + struct clk *clk; + + mult = kmalloc(sizeof(*mult), GFP_KERNEL); + if (!mult) + return ERR_PTR(-ENOMEM); + + init.name = name; + init.ops = &clk_multiplier_ops; + init.flags = flags | CLK_IS_BASIC; + init.parent_names = &parent_name; + init.num_parents = 1; + + mult->reg = reg; + mult->shift = shift; + mult->width = width; + mult->flags = clk_mult_flags; + mult->lock = lock; + mult->hw.init = &init; + + clk = clk_register(dev, &mult->hw); + if (IS_ERR(clk)) + kfree(mult); + + return clk; +} +EXPORT_SYMBOL_GPL(clk_register_multiplier); + +void clk_unregister_multiplier(struct clk *clk) +{ + struct clk_multiplier *mult; + struct clk_hw *hw; + + hw = __clk_get_hw(clk); + if (!hw) + return; + + mult = to_clk_multiplier(hw); + + clk_unregister(clk); + kfree(mult); +} +EXPORT_SYMBOL_GPL(clk_unregister_multiplier); |