1 /* 2 * Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.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 as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 */ 10 11 #include <linux/clk-provider.h> 12 #include <linux/clkdev.h> 13 #include <linux/clk/at91_pmc.h> 14 #include <linux/of.h> 15 #include <linux/mfd/syscon.h> 16 #include <linux/regmap.h> 17 18 #include "pmc.h" 19 20 #define MASTER_PRES_MASK 0x7 21 #define MASTER_PRES_MAX MASTER_PRES_MASK 22 #define MASTER_DIV_SHIFT 8 23 #define MASTER_DIV_MASK 0x3 24 25 #define to_clk_master(hw) container_of(hw, struct clk_master, hw) 26 27 struct clk_master { 28 struct clk_hw hw; 29 struct regmap *regmap; 30 const struct clk_master_layout *layout; 31 const struct clk_master_characteristics *characteristics; 32 }; 33 34 static inline bool clk_master_ready(struct regmap *regmap) 35 { 36 unsigned int status; 37 38 regmap_read(regmap, AT91_PMC_SR, &status); 39 40 return status & AT91_PMC_MCKRDY ? 1 : 0; 41 } 42 43 static int clk_master_prepare(struct clk_hw *hw) 44 { 45 struct clk_master *master = to_clk_master(hw); 46 47 while (!clk_master_ready(master->regmap)) 48 cpu_relax(); 49 50 return 0; 51 } 52 53 static int clk_master_is_prepared(struct clk_hw *hw) 54 { 55 struct clk_master *master = to_clk_master(hw); 56 57 return clk_master_ready(master->regmap); 58 } 59 60 static unsigned long clk_master_recalc_rate(struct clk_hw *hw, 61 unsigned long parent_rate) 62 { 63 u8 pres; 64 u8 div; 65 unsigned long rate = parent_rate; 66 struct clk_master *master = to_clk_master(hw); 67 const struct clk_master_layout *layout = master->layout; 68 const struct clk_master_characteristics *characteristics = 69 master->characteristics; 70 unsigned int mckr; 71 72 regmap_read(master->regmap, AT91_PMC_MCKR, &mckr); 73 mckr &= layout->mask; 74 75 pres = (mckr >> layout->pres_shift) & MASTER_PRES_MASK; 76 div = (mckr >> MASTER_DIV_SHIFT) & MASTER_DIV_MASK; 77 78 if (characteristics->have_div3_pres && pres == MASTER_PRES_MAX) 79 rate /= 3; 80 else 81 rate >>= pres; 82 83 rate /= characteristics->divisors[div]; 84 85 if (rate < characteristics->output.min) 86 pr_warn("master clk is underclocked"); 87 else if (rate > characteristics->output.max) 88 pr_warn("master clk is overclocked"); 89 90 return rate; 91 } 92 93 static u8 clk_master_get_parent(struct clk_hw *hw) 94 { 95 struct clk_master *master = to_clk_master(hw); 96 unsigned int mckr; 97 98 regmap_read(master->regmap, AT91_PMC_MCKR, &mckr); 99 100 return mckr & AT91_PMC_CSS; 101 } 102 103 static const struct clk_ops master_ops = { 104 .prepare = clk_master_prepare, 105 .is_prepared = clk_master_is_prepared, 106 .recalc_rate = clk_master_recalc_rate, 107 .get_parent = clk_master_get_parent, 108 }; 109 110 struct clk_hw * __init 111 at91_clk_register_master(struct regmap *regmap, 112 const char *name, int num_parents, 113 const char **parent_names, 114 const struct clk_master_layout *layout, 115 const struct clk_master_characteristics *characteristics) 116 { 117 struct clk_master *master; 118 struct clk_init_data init; 119 struct clk_hw *hw; 120 int ret; 121 122 if (!name || !num_parents || !parent_names) 123 return ERR_PTR(-EINVAL); 124 125 master = kzalloc(sizeof(*master), GFP_KERNEL); 126 if (!master) 127 return ERR_PTR(-ENOMEM); 128 129 init.name = name; 130 init.ops = &master_ops; 131 init.parent_names = parent_names; 132 init.num_parents = num_parents; 133 init.flags = 0; 134 135 master->hw.init = &init; 136 master->layout = layout; 137 master->characteristics = characteristics; 138 master->regmap = regmap; 139 140 hw = &master->hw; 141 ret = clk_hw_register(NULL, &master->hw); 142 if (ret) { 143 kfree(master); 144 hw = ERR_PTR(ret); 145 } 146 147 return hw; 148 } 149 150 151 const struct clk_master_layout at91rm9200_master_layout = { 152 .mask = 0x31F, 153 .pres_shift = 2, 154 }; 155 156 const struct clk_master_layout at91sam9x5_master_layout = { 157 .mask = 0x373, 158 .pres_shift = 4, 159 }; 160