Mike Turquette | 9d9f78e | 2012-03-15 23:11:20 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com> |
| 3 | * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License version 2 as |
| 7 | * published by the Free Software Foundation. |
| 8 | * |
| 9 | * Gated clock implementation |
| 10 | */ |
| 11 | |
| 12 | #include <linux/clk-provider.h> |
| 13 | #include <linux/module.h> |
| 14 | #include <linux/slab.h> |
| 15 | #include <linux/io.h> |
| 16 | #include <linux/err.h> |
| 17 | #include <linux/string.h> |
| 18 | |
| 19 | /** |
| 20 | * DOC: basic gatable clock which can gate and ungate it's ouput |
| 21 | * |
| 22 | * Traits of this clock: |
| 23 | * prepare - clk_(un)prepare only ensures parent is (un)prepared |
| 24 | * enable - clk_enable and clk_disable are functional & control gating |
| 25 | * rate - inherits rate from parent. No clk_set_rate support |
| 26 | * parent - fixed parent. No clk_set_parent support |
| 27 | */ |
| 28 | |
| 29 | #define to_clk_gate(_hw) container_of(_hw, struct clk_gate, hw) |
| 30 | |
| 31 | static void clk_gate_set_bit(struct clk_gate *gate) |
| 32 | { |
| 33 | u32 reg; |
| 34 | unsigned long flags = 0; |
| 35 | |
| 36 | if (gate->lock) |
| 37 | spin_lock_irqsave(gate->lock, flags); |
| 38 | |
| 39 | reg = readl(gate->reg); |
| 40 | reg |= BIT(gate->bit_idx); |
| 41 | writel(reg, gate->reg); |
| 42 | |
| 43 | if (gate->lock) |
| 44 | spin_unlock_irqrestore(gate->lock, flags); |
| 45 | } |
| 46 | |
| 47 | static void clk_gate_clear_bit(struct clk_gate *gate) |
| 48 | { |
| 49 | u32 reg; |
| 50 | unsigned long flags = 0; |
| 51 | |
| 52 | if (gate->lock) |
| 53 | spin_lock_irqsave(gate->lock, flags); |
| 54 | |
| 55 | reg = readl(gate->reg); |
| 56 | reg &= ~BIT(gate->bit_idx); |
| 57 | writel(reg, gate->reg); |
| 58 | |
| 59 | if (gate->lock) |
| 60 | spin_unlock_irqrestore(gate->lock, flags); |
| 61 | } |
| 62 | |
| 63 | static int clk_gate_enable(struct clk_hw *hw) |
| 64 | { |
| 65 | struct clk_gate *gate = to_clk_gate(hw); |
| 66 | |
| 67 | if (gate->flags & CLK_GATE_SET_TO_DISABLE) |
| 68 | clk_gate_clear_bit(gate); |
| 69 | else |
| 70 | clk_gate_set_bit(gate); |
| 71 | |
| 72 | return 0; |
| 73 | } |
| 74 | EXPORT_SYMBOL_GPL(clk_gate_enable); |
| 75 | |
| 76 | static void clk_gate_disable(struct clk_hw *hw) |
| 77 | { |
| 78 | struct clk_gate *gate = to_clk_gate(hw); |
| 79 | |
| 80 | if (gate->flags & CLK_GATE_SET_TO_DISABLE) |
| 81 | clk_gate_set_bit(gate); |
| 82 | else |
| 83 | clk_gate_clear_bit(gate); |
| 84 | } |
| 85 | EXPORT_SYMBOL_GPL(clk_gate_disable); |
| 86 | |
| 87 | static int clk_gate_is_enabled(struct clk_hw *hw) |
| 88 | { |
| 89 | u32 reg; |
| 90 | struct clk_gate *gate = to_clk_gate(hw); |
| 91 | |
| 92 | reg = readl(gate->reg); |
| 93 | |
| 94 | /* if a set bit disables this clk, flip it before masking */ |
| 95 | if (gate->flags & CLK_GATE_SET_TO_DISABLE) |
| 96 | reg ^= BIT(gate->bit_idx); |
| 97 | |
| 98 | reg &= BIT(gate->bit_idx); |
| 99 | |
| 100 | return reg ? 1 : 0; |
| 101 | } |
| 102 | EXPORT_SYMBOL_GPL(clk_gate_is_enabled); |
| 103 | |
| 104 | struct clk_ops clk_gate_ops = { |
| 105 | .enable = clk_gate_enable, |
| 106 | .disable = clk_gate_disable, |
| 107 | .is_enabled = clk_gate_is_enabled, |
| 108 | }; |
| 109 | EXPORT_SYMBOL_GPL(clk_gate_ops); |
| 110 | |
| 111 | struct clk *clk_register_gate(struct device *dev, const char *name, |
| 112 | const char *parent_name, unsigned long flags, |
| 113 | void __iomem *reg, u8 bit_idx, |
| 114 | u8 clk_gate_flags, spinlock_t *lock) |
| 115 | { |
| 116 | struct clk_gate *gate; |
| 117 | struct clk *clk; |
| 118 | |
| 119 | gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL); |
| 120 | |
| 121 | if (!gate) { |
| 122 | pr_err("%s: could not allocate gated clk\n", __func__); |
| 123 | return NULL; |
| 124 | } |
| 125 | |
| 126 | /* struct clk_gate assignments */ |
| 127 | gate->reg = reg; |
| 128 | gate->bit_idx = bit_idx; |
| 129 | gate->flags = clk_gate_flags; |
| 130 | gate->lock = lock; |
| 131 | |
| 132 | if (parent_name) { |
| 133 | gate->parent[0] = kstrdup(parent_name, GFP_KERNEL); |
| 134 | if (!gate->parent[0]) |
| 135 | goto out; |
| 136 | } |
| 137 | |
| 138 | clk = clk_register(dev, name, |
| 139 | &clk_gate_ops, &gate->hw, |
| 140 | gate->parent, |
| 141 | (parent_name ? 1 : 0), |
| 142 | flags); |
| 143 | if (clk) |
| 144 | return clk; |
| 145 | out: |
| 146 | kfree(gate->parent[0]); |
| 147 | kfree(gate); |
| 148 | |
| 149 | return NULL; |
| 150 | } |