Maxime Ripard | f2e0a53 | 2015-05-19 22:19:33 +0200 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2015 Maxime Ripard <maxime.ripard@free-electrons.com> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 as |
| 6 | * published by the Free Software Foundation. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/bitops.h> |
| 10 | #include <linux/clk-provider.h> |
| 11 | #include <linux/err.h> |
| 12 | #include <linux/export.h> |
| 13 | #include <linux/kernel.h> |
| 14 | #include <linux/of.h> |
| 15 | #include <linux/slab.h> |
| 16 | |
| 17 | #define to_clk_multiplier(_hw) container_of(_hw, struct clk_multiplier, hw) |
| 18 | |
| 19 | static unsigned long __get_mult(struct clk_multiplier *mult, |
| 20 | unsigned long rate, |
| 21 | unsigned long parent_rate) |
| 22 | { |
| 23 | if (mult->flags & CLK_MULTIPLIER_ROUND_CLOSEST) |
| 24 | return DIV_ROUND_CLOSEST(rate, parent_rate); |
| 25 | |
| 26 | return rate / parent_rate; |
| 27 | } |
| 28 | |
| 29 | static unsigned long clk_multiplier_recalc_rate(struct clk_hw *hw, |
| 30 | unsigned long parent_rate) |
| 31 | { |
| 32 | struct clk_multiplier *mult = to_clk_multiplier(hw); |
| 33 | unsigned long val; |
| 34 | |
| 35 | val = clk_readl(mult->reg) >> mult->shift; |
| 36 | val &= GENMASK(mult->width - 1, 0); |
| 37 | |
| 38 | if (!val && mult->flags & CLK_MULTIPLIER_ZERO_BYPASS) |
| 39 | val = 1; |
| 40 | |
| 41 | return parent_rate * val; |
| 42 | } |
| 43 | |
| 44 | static bool __is_best_rate(unsigned long rate, unsigned long new, |
| 45 | unsigned long best, unsigned long flags) |
| 46 | { |
| 47 | if (flags & CLK_MULTIPLIER_ROUND_CLOSEST) |
| 48 | return abs(rate - new) < abs(rate - best); |
| 49 | |
| 50 | return new >= rate && new < best; |
| 51 | } |
| 52 | |
| 53 | static unsigned long __bestmult(struct clk_hw *hw, unsigned long rate, |
| 54 | unsigned long *best_parent_rate, |
| 55 | u8 width, unsigned long flags) |
| 56 | { |
| 57 | unsigned long orig_parent_rate = *best_parent_rate; |
| 58 | unsigned long parent_rate, current_rate, best_rate = ~0; |
| 59 | unsigned int i, bestmult = 0; |
| 60 | |
| 61 | if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) |
| 62 | return rate / *best_parent_rate; |
| 63 | |
| 64 | for (i = 1; i < ((1 << width) - 1); i++) { |
| 65 | if (rate == orig_parent_rate * i) { |
| 66 | /* |
| 67 | * This is the best case for us if we have a |
| 68 | * perfect match without changing the parent |
| 69 | * rate. |
| 70 | */ |
| 71 | *best_parent_rate = orig_parent_rate; |
| 72 | return i; |
| 73 | } |
| 74 | |
| 75 | parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw), |
| 76 | rate / i); |
| 77 | current_rate = parent_rate * i; |
| 78 | |
| 79 | if (__is_best_rate(rate, current_rate, best_rate, flags)) { |
| 80 | bestmult = i; |
| 81 | best_rate = current_rate; |
| 82 | *best_parent_rate = parent_rate; |
| 83 | } |
| 84 | } |
| 85 | |
| 86 | return bestmult; |
| 87 | } |
| 88 | |
| 89 | static long clk_multiplier_round_rate(struct clk_hw *hw, unsigned long rate, |
| 90 | unsigned long *parent_rate) |
| 91 | { |
| 92 | struct clk_multiplier *mult = to_clk_multiplier(hw); |
| 93 | unsigned long factor = __bestmult(hw, rate, parent_rate, |
| 94 | mult->width, mult->flags); |
| 95 | |
| 96 | return *parent_rate * factor; |
| 97 | } |
| 98 | |
| 99 | static int clk_multiplier_set_rate(struct clk_hw *hw, unsigned long rate, |
| 100 | unsigned long parent_rate) |
| 101 | { |
| 102 | struct clk_multiplier *mult = to_clk_multiplier(hw); |
| 103 | unsigned long factor = __get_mult(mult, rate, parent_rate); |
| 104 | unsigned long flags = 0; |
| 105 | unsigned long val; |
| 106 | |
| 107 | if (mult->lock) |
| 108 | spin_lock_irqsave(mult->lock, flags); |
| 109 | else |
| 110 | __acquire(mult->lock); |
| 111 | |
| 112 | val = clk_readl(mult->reg); |
| 113 | val &= ~GENMASK(mult->width + mult->shift - 1, mult->shift); |
| 114 | val |= factor << mult->shift; |
| 115 | clk_writel(val, mult->reg); |
| 116 | |
| 117 | if (mult->lock) |
| 118 | spin_unlock_irqrestore(mult->lock, flags); |
| 119 | else |
| 120 | __release(mult->lock); |
| 121 | |
| 122 | return 0; |
| 123 | } |
| 124 | |
| 125 | const struct clk_ops clk_multiplier_ops = { |
| 126 | .recalc_rate = clk_multiplier_recalc_rate, |
| 127 | .round_rate = clk_multiplier_round_rate, |
| 128 | .set_rate = clk_multiplier_set_rate, |
| 129 | }; |
| 130 | EXPORT_SYMBOL_GPL(clk_multiplier_ops); |