diff options
Diffstat (limited to 'drivers/clk/clk-multiplier.c')
| -rw-r--r-- | drivers/clk/clk-multiplier.c | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/drivers/clk/clk-multiplier.c b/drivers/clk/clk-multiplier.c new file mode 100644 index 000000000..e507aa958 --- /dev/null +++ b/drivers/clk/clk-multiplier.c @@ -0,0 +1,156 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2015 Maxime Ripard <maxime.ripard@free-electrons.com> + */ + +#include <linux/bitops.h> +#include <linux/clk-provider.h> +#include <linux/err.h> +#include <linux/export.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/of.h> +#include <linux/slab.h> + +static inline u32 clk_mult_readl(struct clk_multiplier *mult) +{ + if (mult->flags & CLK_MULTIPLIER_BIG_ENDIAN) + return ioread32be(mult->reg); + + return readl(mult->reg); +} + +static inline void clk_mult_writel(struct clk_multiplier *mult, u32 val) +{ + if (mult->flags & CLK_MULTIPLIER_BIG_ENDIAN) + iowrite32be(val, mult->reg); + else + writel(val, mult->reg); +} + +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_mult_readl(mult) >> 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) +{ + struct clk_multiplier *mult = to_clk_multiplier(hw); + unsigned long orig_parent_rate = *best_parent_rate; + unsigned long parent_rate, current_rate, best_rate = ~0; + unsigned int i, bestmult = 0; + unsigned int maxmult = (1 << width) - 1; + + if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) { + bestmult = rate / orig_parent_rate; + + /* Make sure we don't end up with a 0 multiplier */ + if ((bestmult == 0) && + !(mult->flags & CLK_MULTIPLIER_ZERO_BYPASS)) + bestmult = 1; + + /* Make sure we don't overflow the multiplier */ + if (bestmult > maxmult) + bestmult = maxmult; + + return bestmult; + } + + for (i = 1; i < maxmult; 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_mult_readl(mult); + val &= ~GENMASK(mult->width + mult->shift - 1, mult->shift); + val |= factor << mult->shift; + clk_mult_writel(mult, val); + + 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); |