1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2015 Chen-Yu Tsai 4 * 5 * Chen-Yu Tsai <wens@csie.org> 6 * 7 * Allwinner A80 CPUS clock driver 8 * 9 */ 10 11 #include <linux/clk.h> 12 #include <linux/clk-provider.h> 13 #include <linux/io.h> 14 #include <linux/slab.h> 15 #include <linux/spinlock.h> 16 #include <linux/of.h> 17 #include <linux/of_address.h> 18 19 static DEFINE_SPINLOCK(sun9i_a80_cpus_lock); 20 21 /** 22 * sun9i_a80_cpus_clk_setup() - Setup function for a80 cpus composite clk 23 */ 24 25 #define SUN9I_CPUS_MAX_PARENTS 4 26 #define SUN9I_CPUS_MUX_PARENT_PLL4 3 27 #define SUN9I_CPUS_MUX_SHIFT 16 28 #define SUN9I_CPUS_MUX_MASK GENMASK(17, 16) 29 #define SUN9I_CPUS_MUX_GET_PARENT(reg) ((reg & SUN9I_CPUS_MUX_MASK) >> \ 30 SUN9I_CPUS_MUX_SHIFT) 31 32 #define SUN9I_CPUS_DIV_SHIFT 4 33 #define SUN9I_CPUS_DIV_MASK GENMASK(5, 4) 34 #define SUN9I_CPUS_DIV_GET(reg) ((reg & SUN9I_CPUS_DIV_MASK) >> \ 35 SUN9I_CPUS_DIV_SHIFT) 36 #define SUN9I_CPUS_DIV_SET(reg, div) ((reg & ~SUN9I_CPUS_DIV_MASK) | \ 37 (div << SUN9I_CPUS_DIV_SHIFT)) 38 #define SUN9I_CPUS_PLL4_DIV_SHIFT 8 39 #define SUN9I_CPUS_PLL4_DIV_MASK GENMASK(12, 8) 40 #define SUN9I_CPUS_PLL4_DIV_GET(reg) ((reg & SUN9I_CPUS_PLL4_DIV_MASK) >> \ 41 SUN9I_CPUS_PLL4_DIV_SHIFT) 42 #define SUN9I_CPUS_PLL4_DIV_SET(reg, div) ((reg & ~SUN9I_CPUS_PLL4_DIV_MASK) | \ 43 (div << SUN9I_CPUS_PLL4_DIV_SHIFT)) 44 45 struct sun9i_a80_cpus_clk { 46 struct clk_hw hw; 47 void __iomem *reg; 48 }; 49 50 #define to_sun9i_a80_cpus_clk(_hw) container_of(_hw, struct sun9i_a80_cpus_clk, hw) 51 52 static unsigned long sun9i_a80_cpus_clk_recalc_rate(struct clk_hw *hw, 53 unsigned long parent_rate) 54 { 55 struct sun9i_a80_cpus_clk *cpus = to_sun9i_a80_cpus_clk(hw); 56 unsigned long rate; 57 u32 reg; 58 59 /* Fetch the register value */ 60 reg = readl(cpus->reg); 61 62 /* apply pre-divider first if parent is pll4 */ 63 if (SUN9I_CPUS_MUX_GET_PARENT(reg) == SUN9I_CPUS_MUX_PARENT_PLL4) 64 parent_rate /= SUN9I_CPUS_PLL4_DIV_GET(reg) + 1; 65 66 /* clk divider */ 67 rate = parent_rate / (SUN9I_CPUS_DIV_GET(reg) + 1); 68 69 return rate; 70 } 71 72 static long sun9i_a80_cpus_clk_round(unsigned long rate, u8 *divp, u8 *pre_divp, 73 u8 parent, unsigned long parent_rate) 74 { 75 u8 div, pre_div = 1; 76 77 /* 78 * clock can only divide, so we will never be able to achieve 79 * frequencies higher than the parent frequency 80 */ 81 if (parent_rate && rate > parent_rate) 82 rate = parent_rate; 83 84 div = DIV_ROUND_UP(parent_rate, rate); 85 86 /* calculate pre-divider if parent is pll4 */ 87 if (parent == SUN9I_CPUS_MUX_PARENT_PLL4 && div > 4) { 88 /* pre-divider is 1 ~ 32 */ 89 if (div < 32) { 90 pre_div = div; 91 div = 1; 92 } else if (div < 64) { 93 pre_div = DIV_ROUND_UP(div, 2); 94 div = 2; 95 } else if (div < 96) { 96 pre_div = DIV_ROUND_UP(div, 3); 97 div = 3; 98 } else { 99 pre_div = DIV_ROUND_UP(div, 4); 100 div = 4; 101 } 102 } 103 104 /* we were asked to pass back divider values */ 105 if (divp) { 106 *divp = div - 1; 107 *pre_divp = pre_div - 1; 108 } 109 110 return parent_rate / pre_div / div; 111 } 112 113 static int sun9i_a80_cpus_clk_determine_rate(struct clk_hw *clk, 114 struct clk_rate_request *req) 115 { 116 struct clk_hw *parent, *best_parent = NULL; 117 int i, num_parents; 118 unsigned long parent_rate, best = 0, child_rate, best_child_rate = 0; 119 unsigned long rate = req->rate; 120 121 /* find the parent that can help provide the fastest rate <= rate */ 122 num_parents = clk_hw_get_num_parents(clk); 123 for (i = 0; i < num_parents; i++) { 124 parent = clk_hw_get_parent_by_index(clk, i); 125 if (!parent) 126 continue; 127 if (clk_hw_get_flags(clk) & CLK_SET_RATE_PARENT) 128 parent_rate = clk_hw_round_rate(parent, rate); 129 else 130 parent_rate = clk_hw_get_rate(parent); 131 132 child_rate = sun9i_a80_cpus_clk_round(rate, NULL, NULL, i, 133 parent_rate); 134 135 if (child_rate <= rate && child_rate > best_child_rate) { 136 best_parent = parent; 137 best = parent_rate; 138 best_child_rate = child_rate; 139 } 140 } 141 142 if (!best_parent) 143 return -EINVAL; 144 145 req->best_parent_hw = best_parent; 146 req->best_parent_rate = best; 147 req->rate = best_child_rate; 148 149 return 0; 150 } 151 152 static int sun9i_a80_cpus_clk_set_rate(struct clk_hw *hw, unsigned long rate, 153 unsigned long parent_rate) 154 { 155 struct sun9i_a80_cpus_clk *cpus = to_sun9i_a80_cpus_clk(hw); 156 unsigned long flags; 157 u8 div, pre_div, parent; 158 u32 reg; 159 160 spin_lock_irqsave(&sun9i_a80_cpus_lock, flags); 161 162 reg = readl(cpus->reg); 163 164 /* need to know which parent is used to apply pre-divider */ 165 parent = SUN9I_CPUS_MUX_GET_PARENT(reg); 166 sun9i_a80_cpus_clk_round(rate, &div, &pre_div, parent, parent_rate); 167 168 reg = SUN9I_CPUS_DIV_SET(reg, div); 169 reg = SUN9I_CPUS_PLL4_DIV_SET(reg, pre_div); 170 writel(reg, cpus->reg); 171 172 spin_unlock_irqrestore(&sun9i_a80_cpus_lock, flags); 173 174 return 0; 175 } 176 177 static const struct clk_ops sun9i_a80_cpus_clk_ops = { 178 .determine_rate = sun9i_a80_cpus_clk_determine_rate, 179 .recalc_rate = sun9i_a80_cpus_clk_recalc_rate, 180 .set_rate = sun9i_a80_cpus_clk_set_rate, 181 }; 182 183 static void sun9i_a80_cpus_setup(struct device_node *node) 184 { 185 const char *clk_name = node->name; 186 const char *parents[SUN9I_CPUS_MAX_PARENTS]; 187 struct resource res; 188 struct sun9i_a80_cpus_clk *cpus; 189 struct clk_mux *mux; 190 struct clk *clk; 191 int ret; 192 193 cpus = kzalloc(sizeof(*cpus), GFP_KERNEL); 194 if (!cpus) 195 return; 196 197 cpus->reg = of_io_request_and_map(node, 0, of_node_full_name(node)); 198 if (IS_ERR(cpus->reg)) 199 goto err_free_cpus; 200 201 of_property_read_string(node, "clock-output-names", &clk_name); 202 203 /* we have a mux, we will have >1 parents */ 204 ret = of_clk_parent_fill(node, parents, SUN9I_CPUS_MAX_PARENTS); 205 206 mux = kzalloc(sizeof(*mux), GFP_KERNEL); 207 if (!mux) 208 goto err_unmap; 209 210 /* set up clock properties */ 211 mux->reg = cpus->reg; 212 mux->shift = SUN9I_CPUS_MUX_SHIFT; 213 /* un-shifted mask is what mux_clk expects */ 214 mux->mask = SUN9I_CPUS_MUX_MASK >> SUN9I_CPUS_MUX_SHIFT; 215 mux->lock = &sun9i_a80_cpus_lock; 216 217 clk = clk_register_composite(NULL, clk_name, parents, ret, 218 &mux->hw, &clk_mux_ops, 219 &cpus->hw, &sun9i_a80_cpus_clk_ops, 220 NULL, NULL, 0); 221 if (IS_ERR(clk)) 222 goto err_free_mux; 223 224 ret = of_clk_add_provider(node, of_clk_src_simple_get, clk); 225 if (ret) 226 goto err_unregister; 227 228 return; 229 230 err_unregister: 231 clk_unregister(clk); 232 err_free_mux: 233 kfree(mux); 234 err_unmap: 235 iounmap(cpus->reg); 236 of_address_to_resource(node, 0, &res); 237 release_mem_region(res.start, resource_size(&res)); 238 err_free_cpus: 239 kfree(cpus); 240 } 241 CLK_OF_DECLARE(sun9i_a80_cpus, "allwinner,sun9i-a80-cpus-clk", 242 sun9i_a80_cpus_setup); 243