drivers/clk/clk-gate.c

   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 uninitialized_var(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 /**
 127  * clk_hw_register_gate - register a gate clock with the clock framework
 128  * @dev: device that is registering this clock
 129  * @name: name of this clock
 130  * @parent_name: name of this clock's parent
 131  * @flags: framework-specific flags for this clock
 132  * @reg: register address to control gating of this clock
 133  * @bit_idx: which bit in the register controls gating of this clock
 134  * @clk_gate_flags: gate-specific flags for this clock
 135  * @lock: shared register lock for this clock
 136  */
 137 struct clk_hw *clk_hw_register_gate(struct device *dev, const char *name,
 138                 const char *parent_name, unsigned long flags,
 139                 void __iomem *reg, u8 bit_idx,
 140                 u8 clk_gate_flags, spinlock_t *lock)
 141 {
 142         struct clk_gate *gate;
 143         struct clk_hw *hw;
 144         struct clk_init_data init = {};
 145         int ret;
 146
 147         if (clk_gate_flags & CLK_GATE_HIWORD_MASK) {
 148                 if (bit_idx > 15) {
 149                         pr_err("gate bit exceeds LOWORD field\n");
 150                         return ERR_PTR(-EINVAL);
 151                 }
 152         }
 153
 154         /* allocate the gate */
 155         gate = kzalloc(sizeof(*gate), GFP_KERNEL);
 156         if (!gate)
 157                 return ERR_PTR(-ENOMEM);
 158
 159         init.name = name;
 160         init.ops = &clk_gate_ops;
 161         init.flags = flags;
 162         init.parent_names = parent_name ? &parent_name : NULL;
 163         init.num_parents = parent_name ? 1 : 0;
 164
 165         /* struct clk_gate assignments */
 166         gate->reg = reg;
 167         gate->bit_idx = bit_idx;
 168         gate->flags = clk_gate_flags;
 169         gate->lock = lock;
 170         gate->hw.init = &init;
 171
 172         hw = &gate->hw;
 173         ret = clk_hw_register(dev, hw);
 174         if (ret) {
 175                 kfree(gate);
 176                 hw = ERR_PTR(ret);
 177         }
 178
 179         return hw;
 180 }
 181 EXPORT_SYMBOL_GPL(clk_hw_register_gate);
 182
 183 struct clk *clk_register_gate(struct device *dev, const char *name,
 184                 const char *parent_name, unsigned long flags,
 185                 void __iomem *reg, u8 bit_idx,
 186                 u8 clk_gate_flags, spinlock_t *lock)
 187 {
 188         struct clk_hw *hw;
 189
 190         hw = clk_hw_register_gate(dev, name, parent_name, flags, reg,
 191                                   bit_idx, clk_gate_flags, lock);
 192         if (IS_ERR(hw))
 193                 return ERR_CAST(hw);
 194         return hw->clk;
 195 }
 196 EXPORT_SYMBOL_GPL(clk_register_gate);
 197
 198 void clk_unregister_gate(struct clk *clk)
 199 {
 200         struct clk_gate *gate;
 201         struct clk_hw *hw;
 202
 203         hw = __clk_get_hw(clk);
 204         if (!hw)
 205                 return;
 206
 207         gate = to_clk_gate(hw);
 208
 209         clk_unregister(clk);
 210         kfree(gate);
 211 }
 212 EXPORT_SYMBOL_GPL(clk_unregister_gate);
 213
 214 void clk_hw_unregister_gate(struct clk_hw *hw)
 215 {
 216         struct clk_gate *gate;
 217
 218         gate = to_clk_gate(hw);
 219
 220         clk_hw_unregister(hw);
 221         kfree(gate);
 222 }
 223 EXPORT_SYMBOL_GPL(clk_hw_unregister_gate);