1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2017 BayLibre, SAS 4 * Author: Neil Armstrong <narmstrong@baylibre.com> 5 * Author: Jerome Brunet <jbrunet@baylibre.com> 6 */ 7 8 /* 9 * The AO Domain embeds a dual/divider to generate a more precise 10 * 32,768KHz clock for low-power suspend mode and CEC. 11 * ______ ______ 12 * | | | | 13 * | Div1 |-| Cnt1 | 14 * /|______| |______|\ 15 * -| ______ ______ X--> Out 16 * \| | | |/ 17 * | Div2 |-| Cnt2 | 18 * |______| |______| 19 * 20 * The dividing can be switched to single or dual, with a counter 21 * for each divider to set when the switching is done. 22 */ 23 24 #include <linux/clk-provider.h> 25 #include <linux/module.h> 26 27 #include "clk-regmap.h" 28 #include "clk-dualdiv.h" 29 30 static inline struct meson_clk_dualdiv_data * 31 meson_clk_dualdiv_data(struct clk_regmap *clk) 32 { 33 return (struct meson_clk_dualdiv_data *)clk->data; 34 } 35 36 static unsigned long 37 __dualdiv_param_to_rate(unsigned long parent_rate, 38 const struct meson_clk_dualdiv_param *p) 39 { 40 if (!p->dual) 41 return DIV_ROUND_CLOSEST(parent_rate, p->n1); 42 43 return DIV_ROUND_CLOSEST(parent_rate * (p->m1 + p->m2), 44 p->n1 * p->m1 + p->n2 * p->m2); 45 } 46 47 static unsigned long meson_clk_dualdiv_recalc_rate(struct clk_hw *hw, 48 unsigned long parent_rate) 49 { 50 struct clk_regmap *clk = to_clk_regmap(hw); 51 struct meson_clk_dualdiv_data *dualdiv = meson_clk_dualdiv_data(clk); 52 struct meson_clk_dualdiv_param setting; 53 54 setting.dual = meson_parm_read(clk->map, &dualdiv->dual); 55 setting.n1 = meson_parm_read(clk->map, &dualdiv->n1) + 1; 56 setting.m1 = meson_parm_read(clk->map, &dualdiv->m1) + 1; 57 setting.n2 = meson_parm_read(clk->map, &dualdiv->n2) + 1; 58 setting.m2 = meson_parm_read(clk->map, &dualdiv->m2) + 1; 59 60 return __dualdiv_param_to_rate(parent_rate, &setting); 61 } 62 63 static const struct meson_clk_dualdiv_param * 64 __dualdiv_get_setting(unsigned long rate, unsigned long parent_rate, 65 struct meson_clk_dualdiv_data *dualdiv) 66 { 67 const struct meson_clk_dualdiv_param *table = dualdiv->table; 68 unsigned long best = 0, now = 0; 69 unsigned int i, best_i = 0; 70 71 if (!table) 72 return NULL; 73 74 for (i = 0; table[i].n1; i++) { 75 now = __dualdiv_param_to_rate(parent_rate, &table[i]); 76 77 /* If we get an exact match, don't bother any further */ 78 if (now == rate) { 79 return &table[i]; 80 } else if (abs(now - rate) < abs(best - rate)) { 81 best = now; 82 best_i = i; 83 } 84 } 85 86 return (struct meson_clk_dualdiv_param *)&table[best_i]; 87 } 88 89 static int meson_clk_dualdiv_determine_rate(struct clk_hw *hw, 90 struct clk_rate_request *req) 91 { 92 struct clk_regmap *clk = to_clk_regmap(hw); 93 struct meson_clk_dualdiv_data *dualdiv = meson_clk_dualdiv_data(clk); 94 const struct meson_clk_dualdiv_param *setting; 95 96 setting = __dualdiv_get_setting(req->rate, req->best_parent_rate, 97 dualdiv); 98 if (setting) 99 req->rate = __dualdiv_param_to_rate(req->best_parent_rate, 100 setting); 101 else 102 req->rate = meson_clk_dualdiv_recalc_rate(hw, 103 req->best_parent_rate); 104 105 return 0; 106 } 107 108 static int meson_clk_dualdiv_set_rate(struct clk_hw *hw, unsigned long rate, 109 unsigned long parent_rate) 110 { 111 struct clk_regmap *clk = to_clk_regmap(hw); 112 struct meson_clk_dualdiv_data *dualdiv = meson_clk_dualdiv_data(clk); 113 const struct meson_clk_dualdiv_param *setting = 114 __dualdiv_get_setting(rate, parent_rate, dualdiv); 115 116 if (!setting) 117 return -EINVAL; 118 119 meson_parm_write(clk->map, &dualdiv->dual, setting->dual); 120 meson_parm_write(clk->map, &dualdiv->n1, setting->n1 - 1); 121 meson_parm_write(clk->map, &dualdiv->m1, setting->m1 - 1); 122 meson_parm_write(clk->map, &dualdiv->n2, setting->n2 - 1); 123 meson_parm_write(clk->map, &dualdiv->m2, setting->m2 - 1); 124 125 return 0; 126 } 127 128 const struct clk_ops meson_clk_dualdiv_ops = { 129 .recalc_rate = meson_clk_dualdiv_recalc_rate, 130 .determine_rate = meson_clk_dualdiv_determine_rate, 131 .set_rate = meson_clk_dualdiv_set_rate, 132 }; 133 EXPORT_SYMBOL_GPL(meson_clk_dualdiv_ops); 134 135 const struct clk_ops meson_clk_dualdiv_ro_ops = { 136 .recalc_rate = meson_clk_dualdiv_recalc_rate, 137 }; 138 EXPORT_SYMBOL_GPL(meson_clk_dualdiv_ro_ops); 139 140 MODULE_DESCRIPTION("Amlogic dual divider driver"); 141 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>"); 142 MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>"); 143 MODULE_LICENSE("GPL v2"); 144