1 /* 2 * Copyright (C) 2013 Emilio López <emilio@elopez.com.ar> 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 * Adjustable factor-based clock implementation 9 */ 10 11 #include <linux/clk-provider.h> 12 #include <linux/delay.h> 13 #include <linux/err.h> 14 #include <linux/io.h> 15 #include <linux/module.h> 16 #include <linux/of_address.h> 17 #include <linux/slab.h> 18 #include <linux/string.h> 19 20 #include "clk-factors.h" 21 22 /* 23 * DOC: basic adjustable factor-based clock 24 * 25 * Traits of this clock: 26 * prepare - clk_prepare only ensures that parents are prepared 27 * enable - clk_enable only ensures that parents are enabled 28 * rate - rate is adjustable. 29 * clk->rate = (parent->rate * N * (K + 1) >> P) / (M + 1) 30 * parent - fixed parent. No clk_set_parent support 31 */ 32 33 #define to_clk_factors(_hw) container_of(_hw, struct clk_factors, hw) 34 35 #define FACTORS_MAX_PARENTS 5 36 37 #define SETMASK(len, pos) (((1U << (len)) - 1) << (pos)) 38 #define CLRMASK(len, pos) (~(SETMASK(len, pos))) 39 #define FACTOR_GET(bit, len, reg) (((reg) & SETMASK(len, bit)) >> (bit)) 40 41 #define FACTOR_SET(bit, len, reg, val) \ 42 (((reg) & CLRMASK(len, bit)) | (val << (bit))) 43 44 static unsigned long clk_factors_recalc_rate(struct clk_hw *hw, 45 unsigned long parent_rate) 46 { 47 u8 n = 1, k = 0, p = 0, m = 0; 48 u32 reg; 49 unsigned long rate; 50 struct clk_factors *factors = to_clk_factors(hw); 51 struct clk_factors_config *config = factors->config; 52 53 /* Fetch the register value */ 54 reg = readl(factors->reg); 55 56 /* Get each individual factor if applicable */ 57 if (config->nwidth != SUNXI_FACTORS_NOT_APPLICABLE) 58 n = FACTOR_GET(config->nshift, config->nwidth, reg); 59 if (config->kwidth != SUNXI_FACTORS_NOT_APPLICABLE) 60 k = FACTOR_GET(config->kshift, config->kwidth, reg); 61 if (config->mwidth != SUNXI_FACTORS_NOT_APPLICABLE) 62 m = FACTOR_GET(config->mshift, config->mwidth, reg); 63 if (config->pwidth != SUNXI_FACTORS_NOT_APPLICABLE) 64 p = FACTOR_GET(config->pshift, config->pwidth, reg); 65 66 /* Calculate the rate */ 67 rate = (parent_rate * (n + config->n_start) * (k + 1) >> p) / (m + 1); 68 69 return rate; 70 } 71 72 static long clk_factors_round_rate(struct clk_hw *hw, unsigned long rate, 73 unsigned long *parent_rate) 74 { 75 struct clk_factors *factors = to_clk_factors(hw); 76 factors->get_factors((u32 *)&rate, (u32)*parent_rate, 77 NULL, NULL, NULL, NULL); 78 79 return rate; 80 } 81 82 static long clk_factors_determine_rate(struct clk_hw *hw, unsigned long rate, 83 unsigned long *best_parent_rate, 84 struct clk_hw **best_parent_p) 85 { 86 struct clk *clk = hw->clk, *parent, *best_parent = NULL; 87 int i, num_parents; 88 unsigned long parent_rate, best = 0, child_rate, best_child_rate = 0; 89 90 /* find the parent that can help provide the fastest rate <= rate */ 91 num_parents = __clk_get_num_parents(clk); 92 for (i = 0; i < num_parents; i++) { 93 parent = clk_get_parent_by_index(clk, i); 94 if (!parent) 95 continue; 96 if (__clk_get_flags(clk) & CLK_SET_RATE_PARENT) 97 parent_rate = __clk_round_rate(parent, rate); 98 else 99 parent_rate = __clk_get_rate(parent); 100 101 child_rate = clk_factors_round_rate(hw, rate, &parent_rate); 102 103 if (child_rate <= rate && child_rate > best_child_rate) { 104 best_parent = parent; 105 best = parent_rate; 106 best_child_rate = child_rate; 107 } 108 } 109 110 if (best_parent) 111 *best_parent_p = __clk_get_hw(best_parent); 112 *best_parent_rate = best; 113 114 return best_child_rate; 115 } 116 117 static int clk_factors_set_rate(struct clk_hw *hw, unsigned long rate, 118 unsigned long parent_rate) 119 { 120 u8 n = 0, k = 0, m = 0, p = 0; 121 u32 reg; 122 struct clk_factors *factors = to_clk_factors(hw); 123 struct clk_factors_config *config = factors->config; 124 unsigned long flags = 0; 125 126 factors->get_factors((u32 *)&rate, (u32)parent_rate, &n, &k, &m, &p); 127 128 if (factors->lock) 129 spin_lock_irqsave(factors->lock, flags); 130 131 /* Fetch the register value */ 132 reg = readl(factors->reg); 133 134 /* Set up the new factors - macros do not do anything if width is 0 */ 135 reg = FACTOR_SET(config->nshift, config->nwidth, reg, n); 136 reg = FACTOR_SET(config->kshift, config->kwidth, reg, k); 137 reg = FACTOR_SET(config->mshift, config->mwidth, reg, m); 138 reg = FACTOR_SET(config->pshift, config->pwidth, reg, p); 139 140 /* Apply them now */ 141 writel(reg, factors->reg); 142 143 /* delay 500us so pll stabilizes */ 144 __delay((rate >> 20) * 500 / 2); 145 146 if (factors->lock) 147 spin_unlock_irqrestore(factors->lock, flags); 148 149 return 0; 150 } 151 152 static const struct clk_ops clk_factors_ops = { 153 .determine_rate = clk_factors_determine_rate, 154 .recalc_rate = clk_factors_recalc_rate, 155 .round_rate = clk_factors_round_rate, 156 .set_rate = clk_factors_set_rate, 157 }; 158 159 struct clk * __init sunxi_factors_register(struct device_node *node, 160 const struct factors_data *data, 161 spinlock_t *lock) 162 { 163 struct clk *clk; 164 struct clk_factors *factors; 165 struct clk_gate *gate = NULL; 166 struct clk_mux *mux = NULL; 167 struct clk_hw *gate_hw = NULL; 168 struct clk_hw *mux_hw = NULL; 169 const char *clk_name = node->name; 170 const char *parents[FACTORS_MAX_PARENTS]; 171 void __iomem *reg; 172 int i = 0; 173 174 reg = of_iomap(node, 0); 175 176 /* if we have a mux, we will have >1 parents */ 177 while (i < FACTORS_MAX_PARENTS && 178 (parents[i] = of_clk_get_parent_name(node, i)) != NULL) 179 i++; 180 181 /* 182 * some factor clocks, such as pll5 and pll6, may have multiple 183 * outputs, and have their name designated in factors_data 184 */ 185 if (data->name) 186 clk_name = data->name; 187 else 188 of_property_read_string(node, "clock-output-names", &clk_name); 189 190 factors = kzalloc(sizeof(struct clk_factors), GFP_KERNEL); 191 if (!factors) 192 return NULL; 193 194 /* set up factors properties */ 195 factors->reg = reg; 196 factors->config = data->table; 197 factors->get_factors = data->getter; 198 factors->lock = lock; 199 200 /* Add a gate if this factor clock can be gated */ 201 if (data->enable) { 202 gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL); 203 if (!gate) { 204 kfree(factors); 205 return NULL; 206 } 207 208 /* set up gate properties */ 209 gate->reg = reg; 210 gate->bit_idx = data->enable; 211 gate->lock = factors->lock; 212 gate_hw = &gate->hw; 213 } 214 215 /* Add a mux if this factor clock can be muxed */ 216 if (data->mux) { 217 mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL); 218 if (!mux) { 219 kfree(factors); 220 kfree(gate); 221 return NULL; 222 } 223 224 /* set up gate properties */ 225 mux->reg = reg; 226 mux->shift = data->mux; 227 mux->mask = data->muxmask; 228 mux->lock = factors->lock; 229 mux_hw = &mux->hw; 230 } 231 232 clk = clk_register_composite(NULL, clk_name, 233 parents, i, 234 mux_hw, &clk_mux_ops, 235 &factors->hw, &clk_factors_ops, 236 gate_hw, &clk_gate_ops, 0); 237 238 if (!IS_ERR(clk)) { 239 of_clk_add_provider(node, of_clk_src_simple_get, clk); 240 clk_register_clkdev(clk, clk_name, NULL); 241 } 242 243 return clk; 244 } 245