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/*
* Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
* Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Gated clock implementation
*/
#include <linux/clk-provider.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/string.h>
/**
* DOC: basic gatable clock which can gate and ungate it's ouput
*
* Traits of this clock:
* prepare - clk_(un)prepare only ensures parent is (un)prepared
* enable - clk_enable and clk_disable are functional & control gating
* rate - inherits rate from parent. No clk_set_rate support
* parent - fixed parent. No clk_set_parent support
*/
#define to_clk_gate(_hw) container_of(_hw, struct clk_gate, hw)
static void clk_gate_set_bit(struct clk_gate *gate)
{
u32 reg;
unsigned long flags = 0;
if (gate->lock)
spin_lock_irqsave(gate->lock, flags);
reg = readl(gate->reg);
reg |= BIT(gate->bit_idx);
writel(reg, gate->reg);
if (gate->lock)
spin_unlock_irqrestore(gate->lock, flags);
}
static void clk_gate_clear_bit(struct clk_gate *gate)
{
u32 reg;
unsigned long flags = 0;
if (gate->lock)
spin_lock_irqsave(gate->lock, flags);
reg = readl(gate->reg);
reg &= ~BIT(gate->bit_idx);
writel(reg, gate->reg);
if (gate->lock)
spin_unlock_irqrestore(gate->lock, flags);
}
static int clk_gate_enable(struct clk_hw *hw)
{
struct clk_gate *gate = to_clk_gate(hw);
if (gate->flags & CLK_GATE_SET_TO_DISABLE)
clk_gate_clear_bit(gate);
else
clk_gate_set_bit(gate);
return 0;
}
static void clk_gate_disable(struct clk_hw *hw)
{
struct clk_gate *gate = to_clk_gate(hw);
if (gate->flags & CLK_GATE_SET_TO_DISABLE)
clk_gate_set_bit(gate);
else
clk_gate_clear_bit(gate);
}
static int clk_gate_is_enabled(struct clk_hw *hw)
{
u32 reg;
struct clk_gate *gate = to_clk_gate(hw);
reg = readl(gate->reg);
/* if a set bit disables this clk, flip it before masking */
if (gate->flags & CLK_GATE_SET_TO_DISABLE)
reg ^= BIT(gate->bit_idx);
reg &= BIT(gate->bit_idx);
return reg ? 1 : 0;
}
struct clk_ops clk_gate_ops = {
.enable = clk_gate_enable,
.disable = clk_gate_disable,
.is_enabled = clk_gate_is_enabled,
};
EXPORT_SYMBOL_GPL(clk_gate_ops);
struct clk *clk_register_gate(struct device *dev, const char *name,
const char *parent_name, unsigned long flags,
void __iomem *reg, u8 bit_idx,
u8 clk_gate_flags, spinlock_t *lock)
{
struct clk_gate *gate;
struct clk *clk;
gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL);
if (!gate) {
pr_err("%s: could not allocate gated clk\n", __func__);
return NULL;
}
/* struct clk_gate assignments */
gate->reg = reg;
gate->bit_idx = bit_idx;
gate->flags = clk_gate_flags;
gate->lock = lock;
if (parent_name) {
gate->parent[0] = kstrdup(parent_name, GFP_KERNEL);
if (!gate->parent[0])
goto out;
}
clk = clk_register(dev, name,
&clk_gate_ops, &gate->hw,
gate->parent,
(parent_name ? 1 : 0),
flags);
if (clk)
return clk;
out:
kfree(gate->parent[0]);
kfree(gate);
return NULL;
}
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