1/*
2 * Copyright (c) 2013, The Linux Foundation. All rights reserved.
3 *
4 * This software is licensed under the terms of the GNU General Public
5 * License version 2, as published by the Free Software Foundation, and
6 * may be copied, distributed, and modified under those terms.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11 * GNU General Public License for more details.
12 */
13
14#include <linux/kernel.h>
15#include <linux/bitops.h>
16#include <linux/err.h>
17#include <linux/delay.h>
18#include <linux/export.h>
19#include <linux/clk-provider.h>
20#include <linux/regmap.h>
21
22#include "clk-branch.h"
23
24static bool clk_branch_in_hwcg_mode(const struct clk_branch *br)
25{
26	u32 val;
27
28	if (!br->hwcg_reg)
29		return 0;
30
31	regmap_read(br->clkr.regmap, br->hwcg_reg, &val);
32
33	return !!(val & BIT(br->hwcg_bit));
34}
35
36static bool clk_branch_check_halt(const struct clk_branch *br, bool enabling)
37{
38	bool invert = (br->halt_check == BRANCH_HALT_ENABLE);
39	u32 val;
40
41	regmap_read(br->clkr.regmap, br->halt_reg, &val);
42
43	val &= BIT(br->halt_bit);
44	if (invert)
45		val = !val;
46
47	return !!val == !enabling;
48}
49
50#define BRANCH_CLK_OFF			BIT(31)
51#define BRANCH_NOC_FSM_STATUS_SHIFT	28
52#define BRANCH_NOC_FSM_STATUS_MASK	0x7
53#define BRANCH_NOC_FSM_STATUS_ON	(0x2 << BRANCH_NOC_FSM_STATUS_SHIFT)
54
55static bool clk_branch2_check_halt(const struct clk_branch *br, bool enabling)
56{
57	u32 val;
58	u32 mask;
59
60	mask = BRANCH_NOC_FSM_STATUS_MASK << BRANCH_NOC_FSM_STATUS_SHIFT;
61	mask |= BRANCH_CLK_OFF;
62
63	regmap_read(br->clkr.regmap, br->halt_reg, &val);
64
65	if (enabling) {
66		val &= mask;
67		return (val & BRANCH_CLK_OFF) == 0 ||
68			val == BRANCH_NOC_FSM_STATUS_ON;
69	} else {
70		return val & BRANCH_CLK_OFF;
71	}
72}
73
74static int clk_branch_wait(const struct clk_branch *br, bool enabling,
75		bool (check_halt)(const struct clk_branch *, bool))
76{
77	bool voted = br->halt_check & BRANCH_VOTED;
78	const char *name = __clk_get_name(br->clkr.hw.clk);
79
80	/* Skip checking halt bit if the clock is in hardware gated mode */
81	if (clk_branch_in_hwcg_mode(br))
82		return 0;
83
84	if (br->halt_check == BRANCH_HALT_DELAY || (!enabling && voted)) {
85		udelay(10);
86	} else if (br->halt_check == BRANCH_HALT_ENABLE ||
87		   br->halt_check == BRANCH_HALT ||
88		   (enabling && voted)) {
89		int count = 200;
90
91		while (count-- > 0) {
92			if (check_halt(br, enabling))
93				return 0;
94			udelay(1);
95		}
96		WARN(1, "%s status stuck at 'o%s'", name,
97				enabling ? "ff" : "n");
98		return -EBUSY;
99	}
100	return 0;
101}
102
103static int clk_branch_toggle(struct clk_hw *hw, bool en,
104		bool (check_halt)(const struct clk_branch *, bool))
105{
106	struct clk_branch *br = to_clk_branch(hw);
107	int ret;
108
109	if (en) {
110		ret = clk_enable_regmap(hw);
111		if (ret)
112			return ret;
113	} else {
114		clk_disable_regmap(hw);
115	}
116
117	return clk_branch_wait(br, en, check_halt);
118}
119
120static int clk_branch_enable(struct clk_hw *hw)
121{
122	return clk_branch_toggle(hw, true, clk_branch_check_halt);
123}
124
125static void clk_branch_disable(struct clk_hw *hw)
126{
127	clk_branch_toggle(hw, false, clk_branch_check_halt);
128}
129
130const struct clk_ops clk_branch_ops = {
131	.enable = clk_branch_enable,
132	.disable = clk_branch_disable,
133	.is_enabled = clk_is_enabled_regmap,
134};
135EXPORT_SYMBOL_GPL(clk_branch_ops);
136
137static int clk_branch2_enable(struct clk_hw *hw)
138{
139	return clk_branch_toggle(hw, true, clk_branch2_check_halt);
140}
141
142static void clk_branch2_disable(struct clk_hw *hw)
143{
144	clk_branch_toggle(hw, false, clk_branch2_check_halt);
145}
146
147const struct clk_ops clk_branch2_ops = {
148	.enable = clk_branch2_enable,
149	.disable = clk_branch2_disable,
150	.is_enabled = clk_is_enabled_regmap,
151};
152EXPORT_SYMBOL_GPL(clk_branch2_ops);
153
154const struct clk_ops clk_branch_simple_ops = {
155	.enable = clk_enable_regmap,
156	.disable = clk_disable_regmap,
157	.is_enabled = clk_is_enabled_regmap,
158};
159EXPORT_SYMBOL_GPL(clk_branch_simple_ops);
160