1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com> 4 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org> 5 * 6 * Gated clock implementation 7 */ 8 9 #include <linux/clk-provider.h> 10 #include <linux/module.h> 11 #include <linux/slab.h> 12 #include <linux/io.h> 13 #include <linux/err.h> 14 #include <linux/string.h> 15 16 /** 17 * DOC: basic gatable clock which can gate and ungate it's ouput 18 * 19 * Traits of this clock: 20 * prepare - clk_(un)prepare only ensures parent is (un)prepared 21 * enable - clk_enable and clk_disable are functional & control gating 22 * rate - inherits rate from parent. No clk_set_rate support 23 * parent - fixed parent. No clk_set_parent support 24 */ 25 26 static inline u32 clk_gate_readl(struct clk_gate *gate) 27 { 28 if (gate->flags & CLK_GATE_BIG_ENDIAN) 29 return ioread32be(gate->reg); 30 31 return readl(gate->reg); 32 } 33 34 static inline void clk_gate_writel(struct clk_gate *gate, u32 val) 35 { 36 if (gate->flags & CLK_GATE_BIG_ENDIAN) 37 iowrite32be(val, gate->reg); 38 else 39 writel(val, gate->reg); 40 } 41 42 /* 43 * It works on following logic: 44 * 45 * For enabling clock, enable = 1 46 * set2dis = 1 -> clear bit -> set = 0 47 * set2dis = 0 -> set bit -> set = 1 48 * 49 * For disabling clock, enable = 0 50 * set2dis = 1 -> set bit -> set = 1 51 * set2dis = 0 -> clear bit -> set = 0 52 * 53 * So, result is always: enable xor set2dis. 54 */ 55 static void clk_gate_endisable(struct clk_hw *hw, int enable) 56 { 57 struct clk_gate *gate = to_clk_gate(hw); 58 int set = gate->flags & CLK_GATE_SET_TO_DISABLE ? 1 : 0; 59 unsigned long flags; 60 u32 reg; 61 62 set ^= enable; 63 64 if (gate->lock) 65 spin_lock_irqsave(gate->lock, flags); 66 else 67 __acquire(gate->lock); 68 69 if (gate->flags & CLK_GATE_HIWORD_MASK) { 70 reg = BIT(gate->bit_idx + 16); 71 if (set) 72 reg |= BIT(gate->bit_idx); 73 } else { 74 reg = clk_gate_readl(gate); 75 76 if (set) 77 reg |= BIT(gate->bit_idx); 78 else 79 reg &= ~BIT(gate->bit_idx); 80 } 81 82 clk_gate_writel(gate, reg); 83 84 if (gate->lock) 85 spin_unlock_irqrestore(gate->lock, flags); 86 else 87 __release(gate->lock); 88 } 89 90 static int clk_gate_enable(struct clk_hw *hw) 91 { 92 clk_gate_endisable(hw, 1); 93 94 return 0; 95 } 96 97 static void clk_gate_disable(struct clk_hw *hw) 98 { 99 clk_gate_endisable(hw, 0); 100 } 101 102 int clk_gate_is_enabled(struct clk_hw *hw) 103 { 104 u32 reg; 105 struct clk_gate *gate = to_clk_gate(hw); 106 107 reg = clk_gate_readl(gate); 108 109 /* if a set bit disables this clk, flip it before masking */ 110 if (gate->flags & CLK_GATE_SET_TO_DISABLE) 111 reg ^= BIT(gate->bit_idx); 112 113 reg &= BIT(gate->bit_idx); 114 115 return reg ? 1 : 0; 116 } 117 EXPORT_SYMBOL_GPL(clk_gate_is_enabled); 118 119 const struct clk_ops clk_gate_ops = { 120 .enable = clk_gate_enable, 121 .disable = clk_gate_disable, 122 .is_enabled = clk_gate_is_enabled, 123 }; 124 EXPORT_SYMBOL_GPL(clk_gate_ops); 125 126 struct clk_hw *__clk_hw_register_gate(struct device *dev, 127 struct device_node *np, const char *name, 128 const char *parent_name, const struct clk_hw *parent_hw, 129 const struct clk_parent_data *parent_data, 130 unsigned long flags, 131 void __iomem *reg, u8 bit_idx, 132 u8 clk_gate_flags, spinlock_t *lock) 133 { 134 struct clk_gate *gate; 135 struct clk_hw *hw; 136 struct clk_init_data init = {}; 137 int ret = -EINVAL; 138 139 if (clk_gate_flags & CLK_GATE_HIWORD_MASK) { 140 if (bit_idx > 15) { 141 pr_err("gate bit exceeds LOWORD field\n"); 142 return ERR_PTR(-EINVAL); 143 } 144 } 145 146 /* allocate the gate */ 147 gate = kzalloc(sizeof(*gate), GFP_KERNEL); 148 if (!gate) 149 return ERR_PTR(-ENOMEM); 150 151 init.name = name; 152 init.ops = &clk_gate_ops; 153 init.flags = flags; 154 init.parent_names = parent_name ? &parent_name : NULL; 155 init.parent_hws = parent_hw ? &parent_hw : NULL; 156 init.parent_data = parent_data; 157 if (parent_name || parent_hw || parent_data) 158 init.num_parents = 1; 159 else 160 init.num_parents = 0; 161 162 /* struct clk_gate assignments */ 163 gate->reg = reg; 164 gate->bit_idx = bit_idx; 165 gate->flags = clk_gate_flags; 166 gate->lock = lock; 167 gate->hw.init = &init; 168 169 hw = &gate->hw; 170 if (dev || !np) 171 ret = clk_hw_register(dev, hw); 172 else if (np) 173 ret = of_clk_hw_register(np, hw); 174 if (ret) { 175 kfree(gate); 176 hw = ERR_PTR(ret); 177 } 178 179 return hw; 180 181 } 182 EXPORT_SYMBOL_GPL(__clk_hw_register_gate); 183 184 struct clk *clk_register_gate(struct device *dev, const char *name, 185 const char *parent_name, unsigned long flags, 186 void __iomem *reg, u8 bit_idx, 187 u8 clk_gate_flags, spinlock_t *lock) 188 { 189 struct clk_hw *hw; 190 191 hw = clk_hw_register_gate(dev, name, parent_name, flags, reg, 192 bit_idx, clk_gate_flags, lock); 193 if (IS_ERR(hw)) 194 return ERR_CAST(hw); 195 return hw->clk; 196 } 197 EXPORT_SYMBOL_GPL(clk_register_gate); 198 199 void clk_unregister_gate(struct clk *clk) 200 { 201 struct clk_gate *gate; 202 struct clk_hw *hw; 203 204 hw = __clk_get_hw(clk); 205 if (!hw) 206 return; 207 208 gate = to_clk_gate(hw); 209 210 clk_unregister(clk); 211 kfree(gate); 212 } 213 EXPORT_SYMBOL_GPL(clk_unregister_gate); 214 215 void clk_hw_unregister_gate(struct clk_hw *hw) 216 { 217 struct clk_gate *gate; 218 219 gate = to_clk_gate(hw); 220 221 clk_hw_unregister(hw); 222 kfree(gate); 223 } 224 EXPORT_SYMBOL_GPL(clk_hw_unregister_gate); 225