1/*
2 * TI clock autoidle support
3 *
4 * Copyright (C) 2013 Texas Instruments, Inc.
5 *
6 * Tero Kristo <t-kristo@ti.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 *
12 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
13 * kind, whether express or implied; without even the implied warranty
14 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 */
17
18#include <linux/clk-provider.h>
19#include <linux/slab.h>
20#include <linux/io.h>
21#include <linux/of.h>
22#include <linux/of_address.h>
23#include <linux/clk/ti.h>
24
25#include "clock.h"
26
27struct clk_ti_autoidle {
28	struct clk_omap_reg	reg;
29	u8			shift;
30	u8			flags;
31	const char		*name;
32	struct list_head	node;
33};
34
35#define AUTOIDLE_LOW		0x1
36
37static LIST_HEAD(autoidle_clks);
38
39/*
40 * we have some non-atomic read/write
41 * operations behind it, so lets
42 * take one lock for handling autoidle
43 * of all clocks
44 */
45static DEFINE_SPINLOCK(autoidle_spinlock);
46
47static int _omap2_clk_deny_idle(struct clk_hw_omap *clk)
48{
49	if (clk->ops && clk->ops->deny_idle) {
50		unsigned long irqflags;
51
52		spin_lock_irqsave(&autoidle_spinlock, irqflags);
53		clk->autoidle_count++;
54		if (clk->autoidle_count == 1)
55			clk->ops->deny_idle(clk);
56
57		spin_unlock_irqrestore(&autoidle_spinlock, irqflags);
58	}
59	return 0;
60}
61
62static int _omap2_clk_allow_idle(struct clk_hw_omap *clk)
63{
64	if (clk->ops && clk->ops->allow_idle) {
65		unsigned long irqflags;
66
67		spin_lock_irqsave(&autoidle_spinlock, irqflags);
68		clk->autoidle_count--;
69		if (clk->autoidle_count == 0)
70			clk->ops->allow_idle(clk);
71
72		spin_unlock_irqrestore(&autoidle_spinlock, irqflags);
73	}
74	return 0;
75}
76
77/**
78 * omap2_clk_deny_idle - disable autoidle on an OMAP clock
79 * @clk: struct clk * to disable autoidle for
80 *
81 * Disable autoidle on an OMAP clock.
82 */
83int omap2_clk_deny_idle(struct clk *clk)
84{
85	struct clk_hw *hw;
86
87	if (!clk)
88		return -EINVAL;
89
90	hw = __clk_get_hw(clk);
91
92	if (omap2_clk_is_hw_omap(hw)) {
93		struct clk_hw_omap *c = to_clk_hw_omap(hw);
94
95		return _omap2_clk_deny_idle(c);
96	}
97
98	return -EINVAL;
99}
100
101/**
102 * omap2_clk_allow_idle - enable autoidle on an OMAP clock
103 * @clk: struct clk * to enable autoidle for
104 *
105 * Enable autoidle on an OMAP clock.
106 */
107int omap2_clk_allow_idle(struct clk *clk)
108{
109	struct clk_hw *hw;
110
111	if (!clk)
112		return -EINVAL;
113
114	hw = __clk_get_hw(clk);
115
116	if (omap2_clk_is_hw_omap(hw)) {
117		struct clk_hw_omap *c = to_clk_hw_omap(hw);
118
119		return _omap2_clk_allow_idle(c);
120	}
121
122	return -EINVAL;
123}
124
125static void _allow_autoidle(struct clk_ti_autoidle *clk)
126{
127	u32 val;
128
129	val = ti_clk_ll_ops->clk_readl(&clk->reg);
130
131	if (clk->flags & AUTOIDLE_LOW)
132		val &= ~(1 << clk->shift);
133	else
134		val |= (1 << clk->shift);
135
136	ti_clk_ll_ops->clk_writel(val, &clk->reg);
137}
138
139static void _deny_autoidle(struct clk_ti_autoidle *clk)
140{
141	u32 val;
142
143	val = ti_clk_ll_ops->clk_readl(&clk->reg);
144
145	if (clk->flags & AUTOIDLE_LOW)
146		val |= (1 << clk->shift);
147	else
148		val &= ~(1 << clk->shift);
149
150	ti_clk_ll_ops->clk_writel(val, &clk->reg);
151}
152
153/**
154 * _clk_generic_allow_autoidle_all - enable autoidle for all clocks
155 *
156 * Enables hardware autoidle for all registered DT clocks, which have
157 * the feature.
158 */
159static void _clk_generic_allow_autoidle_all(void)
160{
161	struct clk_ti_autoidle *c;
162
163	list_for_each_entry(c, &autoidle_clks, node)
164		_allow_autoidle(c);
165}
166
167/**
168 * _clk_generic_deny_autoidle_all - disable autoidle for all clocks
169 *
170 * Disables hardware autoidle for all registered DT clocks, which have
171 * the feature.
172 */
173static void _clk_generic_deny_autoidle_all(void)
174{
175	struct clk_ti_autoidle *c;
176
177	list_for_each_entry(c, &autoidle_clks, node)
178		_deny_autoidle(c);
179}
180
181/**
182 * of_ti_clk_autoidle_setup - sets up hardware autoidle for a clock
183 * @node: pointer to the clock device node
184 *
185 * Checks if a clock has hardware autoidle support or not (check
186 * for presence of 'ti,autoidle-shift' property in the device tree
187 * node) and sets up the hardware autoidle feature for the clock
188 * if available. If autoidle is available, the clock is also added
189 * to the autoidle list for later processing. Returns 0 on success,
190 * negative error value on failure.
191 */
192int __init of_ti_clk_autoidle_setup(struct device_node *node)
193{
194	u32 shift;
195	struct clk_ti_autoidle *clk;
196	int ret;
197
198	/* Check if this clock has autoidle support or not */
199	if (of_property_read_u32(node, "ti,autoidle-shift", &shift))
200		return 0;
201
202	clk = kzalloc(sizeof(*clk), GFP_KERNEL);
203
204	if (!clk)
205		return -ENOMEM;
206
207	clk->shift = shift;
208	clk->name = ti_dt_clk_name(node);
209	ret = ti_clk_get_reg_addr(node, 0, &clk->reg);
210	if (ret) {
211		kfree(clk);
212		return ret;
213	}
214
215	if (of_property_read_bool(node, "ti,invert-autoidle-bit"))
216		clk->flags |= AUTOIDLE_LOW;
217
218	list_add(&clk->node, &autoidle_clks);
219
220	return 0;
221}
222
223/**
224 * omap2_clk_enable_autoidle_all - enable autoidle on all OMAP clocks that
225 * support it
226 *
227 * Enable clock autoidle on all OMAP clocks that have allow_idle
228 * function pointers associated with them.  This function is intended
229 * to be temporary until support for this is added to the common clock
230 * code.  Returns 0.
231 */
232int omap2_clk_enable_autoidle_all(void)
233{
234	int ret;
235
236	ret = omap2_clk_for_each(_omap2_clk_allow_idle);
237	if (ret)
238		return ret;
239
240	_clk_generic_allow_autoidle_all();
241
242	return 0;
243}
244
245/**
246 * omap2_clk_disable_autoidle_all - disable autoidle on all OMAP clocks that
247 * support it
248 *
249 * Disable clock autoidle on all OMAP clocks that have allow_idle
250 * function pointers associated with them.  This function is intended
251 * to be temporary until support for this is added to the common clock
252 * code.  Returns 0.
253 */
254int omap2_clk_disable_autoidle_all(void)
255{
256	int ret;
257
258	ret = omap2_clk_for_each(_omap2_clk_deny_idle);
259	if (ret)
260		return ret;
261
262	_clk_generic_deny_autoidle_all();
263
264	return 0;
265}
266