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#include "clk.h"
 19
 20/**
 21 * DOC: basic gatable clock which can gate and ungate it's ouput
 22 *
 23 * Traits of this clock:
 24 * prepare - clk_(un)prepare only ensures parent is (un)prepared
 25 * enable - clk_enable and clk_disable are functional & control gating
 26 * rate - inherits rate from parent.  No clk_set_rate support
 27 * parent - fixed parent.  No clk_set_parent support
 28 */
 29
 30struct clk_gate2 {
 31	struct clk_hw hw;
 32	void __iomem	*reg;
 33	u8		bit_idx;
 34	u8		cgr_val;
 35	u8		flags;
 36	spinlock_t	*lock;
 37	unsigned int	*share_count;
 38};
 39
 40#define to_clk_gate2(_hw) container_of(_hw, struct clk_gate2, hw)
 41
 42static int clk_gate2_enable(struct clk_hw *hw)
 43{
 44	struct clk_gate2 *gate = to_clk_gate2(hw);
 45	u32 reg;
 46	unsigned long flags = 0;
 47
 48	spin_lock_irqsave(gate->lock, flags);
 49
 50	if (gate->share_count && (*gate->share_count)++ > 0)
 51		goto out;
 52
 53	reg = readl(gate->reg);
 54	reg &= ~(3 << gate->bit_idx);
 55	reg |= gate->cgr_val << gate->bit_idx;
 56	writel(reg, gate->reg);
 57
 58out:
 59	spin_unlock_irqrestore(gate->lock, flags);
 60
 61	return 0;
 62}
 63
 64static void clk_gate2_disable(struct clk_hw *hw)
 65{
 66	struct clk_gate2 *gate = to_clk_gate2(hw);
 67	u32 reg;
 68	unsigned long flags = 0;
 69
 70	spin_lock_irqsave(gate->lock, flags);
 71
 72	if (gate->share_count) {
 73		if (WARN_ON(*gate->share_count == 0))
 74			goto out;
 75		else if (--(*gate->share_count) > 0)
 76			goto out;
 77	}
 78
 79	reg = readl(gate->reg);
 80	reg &= ~(3 << gate->bit_idx);
 81	writel(reg, gate->reg);
 82
 83out:
 84	spin_unlock_irqrestore(gate->lock, flags);
 85}
 86
 87static int clk_gate2_reg_is_enabled(void __iomem *reg, u8 bit_idx)
 88{
 89	u32 val = readl(reg);
 90
 91	if (((val >> bit_idx) & 1) == 1)
 92		return 1;
 93
 94	return 0;
 95}
 96
 97static int clk_gate2_is_enabled(struct clk_hw *hw)
 98{
 99	struct clk_gate2 *gate = to_clk_gate2(hw);
100
101	return clk_gate2_reg_is_enabled(gate->reg, gate->bit_idx);
102}
103
104static void clk_gate2_disable_unused(struct clk_hw *hw)
105{
106	struct clk_gate2 *gate = to_clk_gate2(hw);
107	unsigned long flags = 0;
108	u32 reg;
109
110	spin_lock_irqsave(gate->lock, flags);
111
112	if (!gate->share_count || *gate->share_count == 0) {
113		reg = readl(gate->reg);
114		reg &= ~(3 << gate->bit_idx);
115		writel(reg, gate->reg);
116	}
117
118	spin_unlock_irqrestore(gate->lock, flags);
119}
120
121static struct clk_ops clk_gate2_ops = {
122	.enable = clk_gate2_enable,
123	.disable = clk_gate2_disable,
124	.disable_unused = clk_gate2_disable_unused,
125	.is_enabled = clk_gate2_is_enabled,
126};
127
128struct clk *clk_register_gate2(struct device *dev, const char *name,
129		const char *parent_name, unsigned long flags,
130		void __iomem *reg, u8 bit_idx, u8 cgr_val,
131		u8 clk_gate2_flags, spinlock_t *lock,
132		unsigned int *share_count)
133{
134	struct clk_gate2 *gate;
135	struct clk *clk;
136	struct clk_init_data init;
137
138	gate = kzalloc(sizeof(struct clk_gate2), GFP_KERNEL);
139	if (!gate)
140		return ERR_PTR(-ENOMEM);
141
142	/* struct clk_gate2 assignments */
143	gate->reg = reg;
144	gate->bit_idx = bit_idx;
145	gate->cgr_val = cgr_val;
146	gate->flags = clk_gate2_flags;
147	gate->lock = lock;
148	gate->share_count = share_count;
149
150	init.name = name;
151	init.ops = &clk_gate2_ops;
152	init.flags = flags;
153	init.parent_names = parent_name ? &parent_name : NULL;
154	init.num_parents = parent_name ? 1 : 0;
155
156	gate->hw.init = &init;
157
158	clk = clk_register(dev, &gate->hw);
159	if (IS_ERR(clk))
160		kfree(gate);
161
162	return clk;
163}