1 /* 2 * Copyright (C) 2014 Free Electrons 3 * 4 * License Terms: GNU General Public License v2 5 * Author: Boris BREZILLON <boris.brezillon@free-electrons.com> 6 * 7 * Allwinner A31 AR100 clock driver 8 * 9 */ 10 11 #include <linux/clk-provider.h> 12 #include <linux/module.h> 13 #include <linux/of.h> 14 #include <linux/platform_device.h> 15 16 #define SUN6I_AR100_MAX_PARENTS 4 17 #define SUN6I_AR100_SHIFT_MASK 0x3 18 #define SUN6I_AR100_SHIFT_MAX SUN6I_AR100_SHIFT_MASK 19 #define SUN6I_AR100_SHIFT_SHIFT 4 20 #define SUN6I_AR100_DIV_MASK 0x1f 21 #define SUN6I_AR100_DIV_MAX (SUN6I_AR100_DIV_MASK + 1) 22 #define SUN6I_AR100_DIV_SHIFT 8 23 #define SUN6I_AR100_MUX_MASK 0x3 24 #define SUN6I_AR100_MUX_SHIFT 16 25 26 struct ar100_clk { 27 struct clk_hw hw; 28 void __iomem *reg; 29 }; 30 31 static inline struct ar100_clk *to_ar100_clk(struct clk_hw *hw) 32 { 33 return container_of(hw, struct ar100_clk, hw); 34 } 35 36 static unsigned long ar100_recalc_rate(struct clk_hw *hw, 37 unsigned long parent_rate) 38 { 39 struct ar100_clk *clk = to_ar100_clk(hw); 40 u32 val = readl(clk->reg); 41 int shift = (val >> SUN6I_AR100_SHIFT_SHIFT) & SUN6I_AR100_SHIFT_MASK; 42 int div = (val >> SUN6I_AR100_DIV_SHIFT) & SUN6I_AR100_DIV_MASK; 43 44 return (parent_rate >> shift) / (div + 1); 45 } 46 47 static int ar100_determine_rate(struct clk_hw *hw, 48 struct clk_rate_request *req) 49 { 50 int nparents = clk_hw_get_num_parents(hw); 51 long best_rate = -EINVAL; 52 int i; 53 54 req->best_parent_hw = NULL; 55 56 for (i = 0; i < nparents; i++) { 57 unsigned long parent_rate; 58 unsigned long tmp_rate; 59 struct clk_hw *parent; 60 unsigned long div; 61 int shift; 62 63 parent = clk_hw_get_parent_by_index(hw, i); 64 parent_rate = clk_hw_get_rate(parent); 65 div = DIV_ROUND_UP(parent_rate, req->rate); 66 67 /* 68 * The AR100 clk contains 2 divisors: 69 * - one power of 2 divisor 70 * - one regular divisor 71 * 72 * First check if we can safely shift (or divide by a power 73 * of 2) without losing precision on the requested rate. 74 */ 75 shift = ffs(div) - 1; 76 if (shift > SUN6I_AR100_SHIFT_MAX) 77 shift = SUN6I_AR100_SHIFT_MAX; 78 79 div >>= shift; 80 81 /* 82 * Then if the divisor is still bigger than what the HW 83 * actually supports, use a bigger shift (or power of 2 84 * divider) value and accept to lose some precision. 85 */ 86 while (div > SUN6I_AR100_DIV_MAX) { 87 shift++; 88 div >>= 1; 89 if (shift > SUN6I_AR100_SHIFT_MAX) 90 break; 91 } 92 93 /* 94 * If the shift value (or power of 2 divider) is bigger 95 * than what the HW actually support, skip this parent. 96 */ 97 if (shift > SUN6I_AR100_SHIFT_MAX) 98 continue; 99 100 tmp_rate = (parent_rate >> shift) / div; 101 if (!req->best_parent_hw || tmp_rate > best_rate) { 102 req->best_parent_hw = parent; 103 req->best_parent_rate = parent_rate; 104 best_rate = tmp_rate; 105 } 106 } 107 108 if (best_rate < 0) 109 return best_rate; 110 111 req->rate = best_rate; 112 113 return 0; 114 } 115 116 static int ar100_set_parent(struct clk_hw *hw, u8 index) 117 { 118 struct ar100_clk *clk = to_ar100_clk(hw); 119 u32 val = readl(clk->reg); 120 121 if (index >= SUN6I_AR100_MAX_PARENTS) 122 return -EINVAL; 123 124 val &= ~(SUN6I_AR100_MUX_MASK << SUN6I_AR100_MUX_SHIFT); 125 val |= (index << SUN6I_AR100_MUX_SHIFT); 126 writel(val, clk->reg); 127 128 return 0; 129 } 130 131 static u8 ar100_get_parent(struct clk_hw *hw) 132 { 133 struct ar100_clk *clk = to_ar100_clk(hw); 134 return (readl(clk->reg) >> SUN6I_AR100_MUX_SHIFT) & 135 SUN6I_AR100_MUX_MASK; 136 } 137 138 static int ar100_set_rate(struct clk_hw *hw, unsigned long rate, 139 unsigned long parent_rate) 140 { 141 unsigned long div = parent_rate / rate; 142 struct ar100_clk *clk = to_ar100_clk(hw); 143 u32 val = readl(clk->reg); 144 int shift; 145 146 if (parent_rate % rate) 147 return -EINVAL; 148 149 shift = ffs(div) - 1; 150 if (shift > SUN6I_AR100_SHIFT_MAX) 151 shift = SUN6I_AR100_SHIFT_MAX; 152 153 div >>= shift; 154 155 if (div > SUN6I_AR100_DIV_MAX) 156 return -EINVAL; 157 158 val &= ~((SUN6I_AR100_SHIFT_MASK << SUN6I_AR100_SHIFT_SHIFT) | 159 (SUN6I_AR100_DIV_MASK << SUN6I_AR100_DIV_SHIFT)); 160 val |= (shift << SUN6I_AR100_SHIFT_SHIFT) | 161 (div << SUN6I_AR100_DIV_SHIFT); 162 writel(val, clk->reg); 163 164 return 0; 165 } 166 167 static struct clk_ops ar100_ops = { 168 .recalc_rate = ar100_recalc_rate, 169 .determine_rate = ar100_determine_rate, 170 .set_parent = ar100_set_parent, 171 .get_parent = ar100_get_parent, 172 .set_rate = ar100_set_rate, 173 }; 174 175 static int sun6i_a31_ar100_clk_probe(struct platform_device *pdev) 176 { 177 const char *parents[SUN6I_AR100_MAX_PARENTS]; 178 struct device_node *np = pdev->dev.of_node; 179 const char *clk_name = np->name; 180 struct clk_init_data init; 181 struct ar100_clk *ar100; 182 struct resource *r; 183 struct clk *clk; 184 int nparents; 185 186 ar100 = devm_kzalloc(&pdev->dev, sizeof(*ar100), GFP_KERNEL); 187 if (!ar100) 188 return -ENOMEM; 189 190 r = platform_get_resource(pdev, IORESOURCE_MEM, 0); 191 ar100->reg = devm_ioremap_resource(&pdev->dev, r); 192 if (IS_ERR(ar100->reg)) 193 return PTR_ERR(ar100->reg); 194 195 nparents = of_clk_get_parent_count(np); 196 if (nparents > SUN6I_AR100_MAX_PARENTS) 197 nparents = SUN6I_AR100_MAX_PARENTS; 198 199 of_clk_parent_fill(np, parents, nparents); 200 201 of_property_read_string(np, "clock-output-names", &clk_name); 202 203 init.name = clk_name; 204 init.ops = &ar100_ops; 205 init.parent_names = parents; 206 init.num_parents = nparents; 207 init.flags = 0; 208 209 ar100->hw.init = &init; 210 211 clk = clk_register(&pdev->dev, &ar100->hw); 212 if (IS_ERR(clk)) 213 return PTR_ERR(clk); 214 215 return of_clk_add_provider(np, of_clk_src_simple_get, clk); 216 } 217 218 static const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = { 219 { .compatible = "allwinner,sun6i-a31-ar100-clk" }, 220 { /* sentinel */ } 221 }; 222 223 static struct platform_driver sun6i_a31_ar100_clk_driver = { 224 .driver = { 225 .name = "sun6i-a31-ar100-clk", 226 .of_match_table = sun6i_a31_ar100_clk_dt_ids, 227 }, 228 .probe = sun6i_a31_ar100_clk_probe, 229 }; 230 module_platform_driver(sun6i_a31_ar100_clk_driver); 231 232 MODULE_AUTHOR("Boris BREZILLON <boris.brezillon@free-electrons.com>"); 233 MODULE_DESCRIPTION("Allwinner A31 AR100 clock Driver"); 234 MODULE_LICENSE("GPL v2"); 235