151 lines
3.7 KiB
C
151 lines
3.7 KiB
C
/*
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* Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
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* Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Gated clock implementation
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*/
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#include <linux/clk-provider.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/io.h>
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#include <linux/err.h>
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#include <linux/string.h>
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/**
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* DOC: basic gatable clock which can gate and ungate it's ouput
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*
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* Traits of this clock:
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* prepare - clk_(un)prepare only ensures parent is (un)prepared
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* enable - clk_enable and clk_disable are functional & control gating
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* rate - inherits rate from parent. No clk_set_rate support
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* parent - fixed parent. No clk_set_parent support
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*/
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#define to_clk_gate(_hw) container_of(_hw, struct clk_gate, hw)
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/*
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* It works on following logic:
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*
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* For enabling clock, enable = 1
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* set2dis = 1 -> clear bit -> set = 0
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* set2dis = 0 -> set bit -> set = 1
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*
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* For disabling clock, enable = 0
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* set2dis = 1 -> set bit -> set = 1
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* set2dis = 0 -> clear bit -> set = 0
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*
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* So, result is always: enable xor set2dis.
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*/
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static void clk_gate_endisable(struct clk_hw *hw, int enable)
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{
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struct clk_gate *gate = to_clk_gate(hw);
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int set = gate->flags & CLK_GATE_SET_TO_DISABLE ? 1 : 0;
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unsigned long flags = 0;
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u32 reg;
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set ^= enable;
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if (gate->lock)
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spin_lock_irqsave(gate->lock, flags);
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reg = readl(gate->reg);
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if (set)
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reg |= BIT(gate->bit_idx);
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else
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reg &= ~BIT(gate->bit_idx);
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writel(reg, gate->reg);
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if (gate->lock)
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spin_unlock_irqrestore(gate->lock, flags);
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}
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static int clk_gate_enable(struct clk_hw *hw)
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{
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clk_gate_endisable(hw, 1);
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return 0;
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}
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static void clk_gate_disable(struct clk_hw *hw)
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{
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clk_gate_endisable(hw, 0);
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}
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static int clk_gate_is_enabled(struct clk_hw *hw)
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{
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u32 reg;
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struct clk_gate *gate = to_clk_gate(hw);
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reg = readl(gate->reg);
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/* if a set bit disables this clk, flip it before masking */
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if (gate->flags & CLK_GATE_SET_TO_DISABLE)
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reg ^= BIT(gate->bit_idx);
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reg &= BIT(gate->bit_idx);
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return reg ? 1 : 0;
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}
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const struct clk_ops clk_gate_ops = {
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.enable = clk_gate_enable,
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.disable = clk_gate_disable,
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.is_enabled = clk_gate_is_enabled,
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};
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EXPORT_SYMBOL_GPL(clk_gate_ops);
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/**
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* clk_register_gate - register a gate clock with the clock framework
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* @dev: device that is registering this clock
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* @name: name of this clock
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* @parent_name: name of this clock's parent
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* @flags: framework-specific flags for this clock
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* @reg: register address to control gating of this clock
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* @bit_idx: which bit in the register controls gating of this clock
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* @clk_gate_flags: gate-specific flags for this clock
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* @lock: shared register lock for this clock
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*/
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struct clk *clk_register_gate(struct device *dev, const char *name,
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const char *parent_name, unsigned long flags,
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void __iomem *reg, u8 bit_idx,
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u8 clk_gate_flags, spinlock_t *lock)
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{
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struct clk_gate *gate;
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struct clk *clk;
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struct clk_init_data init;
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/* allocate the gate */
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gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL);
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if (!gate) {
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pr_err("%s: could not allocate gated clk\n", __func__);
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return ERR_PTR(-ENOMEM);
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}
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init.name = name;
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init.ops = &clk_gate_ops;
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init.flags = flags | CLK_IS_BASIC;
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init.parent_names = (parent_name ? &parent_name: NULL);
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init.num_parents = (parent_name ? 1 : 0);
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/* struct clk_gate assignments */
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gate->reg = reg;
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gate->bit_idx = bit_idx;
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gate->flags = clk_gate_flags;
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gate->lock = lock;
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gate->hw.init = &init;
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clk = clk_register(dev, &gate->hw);
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if (IS_ERR(clk))
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kfree(gate);
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return clk;
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}
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