1 /*
2  * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or modify it
5  * under the terms and conditions of the GNU General Public License,
6  * version 2, as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope it will be useful, but WITHOUT
9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
11  * more details.
12  *
13  * You should have received a copy of the GNU General Public License
14  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
15  */
16 
17 #include <linux/clk.h>
18 #include <linux/clk-provider.h>
19 #include <linux/slab.h>
20 #include <linux/io.h>
21 #include <linux/delay.h>
22 #include <linux/err.h>
23 #include <linux/tegra-soc.h>
24 
25 #include "clk.h"
26 
27 static DEFINE_SPINLOCK(periph_ref_lock);
28 
29 /* Macros to assist peripheral gate clock */
30 #define read_enb(gate) \
31 	readl_relaxed(gate->clk_base + (gate->regs->enb_reg))
32 #define write_enb_set(val, gate) \
33 	writel_relaxed(val, gate->clk_base + (gate->regs->enb_set_reg))
34 #define write_enb_clr(val, gate) \
35 	writel_relaxed(val, gate->clk_base + (gate->regs->enb_clr_reg))
36 
37 #define read_rst(gate) \
38 	readl_relaxed(gate->clk_base + (gate->regs->rst_reg))
39 #define write_rst_set(val, gate) \
40 	writel_relaxed(val, gate->clk_base + (gate->regs->rst_set_reg))
41 #define write_rst_clr(val, gate) \
42 	writel_relaxed(val, gate->clk_base + (gate->regs->rst_clr_reg))
43 
44 #define periph_clk_to_bit(periph) (1 << (gate->clk_num % 32))
45 
46 /* Peripheral gate clock ops */
47 static int clk_periph_is_enabled(struct clk_hw *hw)
48 {
49 	struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
50 	int state = 1;
51 
52 	if (!(read_enb(gate) & periph_clk_to_bit(gate)))
53 		state = 0;
54 
55 	if (!(gate->flags & TEGRA_PERIPH_NO_RESET))
56 		if (read_rst(gate) & periph_clk_to_bit(gate))
57 			state = 0;
58 
59 	return state;
60 }
61 
62 static int clk_periph_enable(struct clk_hw *hw)
63 {
64 	struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
65 	unsigned long flags = 0;
66 
67 	spin_lock_irqsave(&periph_ref_lock, flags);
68 
69 	gate->enable_refcnt[gate->clk_num]++;
70 	if (gate->enable_refcnt[gate->clk_num] > 1) {
71 		spin_unlock_irqrestore(&periph_ref_lock, flags);
72 		return 0;
73 	}
74 
75 	write_enb_set(periph_clk_to_bit(gate), gate);
76 	udelay(2);
77 
78 	if (!(gate->flags & TEGRA_PERIPH_NO_RESET) &&
79 	    !(gate->flags & TEGRA_PERIPH_MANUAL_RESET)) {
80 		if (read_rst(gate) & periph_clk_to_bit(gate)) {
81 			udelay(5); /* reset propogation delay */
82 			write_rst_clr(periph_clk_to_bit(gate), gate);
83 		}
84 	}
85 
86 	spin_unlock_irqrestore(&periph_ref_lock, flags);
87 
88 	return 0;
89 }
90 
91 static void clk_periph_disable(struct clk_hw *hw)
92 {
93 	struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
94 	unsigned long flags = 0;
95 
96 	spin_lock_irqsave(&periph_ref_lock, flags);
97 
98 	gate->enable_refcnt[gate->clk_num]--;
99 	if (gate->enable_refcnt[gate->clk_num] > 0) {
100 		spin_unlock_irqrestore(&periph_ref_lock, flags);
101 		return;
102 	}
103 
104 	/*
105 	 * If peripheral is in the APB bus then read the APB bus to
106 	 * flush the write operation in apb bus. This will avoid the
107 	 * peripheral access after disabling clock
108 	 */
109 	if (gate->flags & TEGRA_PERIPH_ON_APB)
110 		tegra_read_chipid();
111 
112 	write_enb_clr(periph_clk_to_bit(gate), gate);
113 
114 	spin_unlock_irqrestore(&periph_ref_lock, flags);
115 }
116 
117 void tegra_periph_reset(struct tegra_clk_periph_gate *gate, bool assert)
118 {
119 	if (gate->flags & TEGRA_PERIPH_NO_RESET)
120 		return;
121 
122 	if (assert) {
123 		/*
124 		 * If peripheral is in the APB bus then read the APB bus to
125 		 * flush the write operation in apb bus. This will avoid the
126 		 * peripheral access after disabling clock
127 		 */
128 		if (gate->flags & TEGRA_PERIPH_ON_APB)
129 			tegra_read_chipid();
130 
131 		write_rst_set(periph_clk_to_bit(gate), gate);
132 	} else {
133 		write_rst_clr(periph_clk_to_bit(gate), gate);
134 	}
135 }
136 
137 const struct clk_ops tegra_clk_periph_gate_ops = {
138 	.is_enabled = clk_periph_is_enabled,
139 	.enable = clk_periph_enable,
140 	.disable = clk_periph_disable,
141 };
142 
143 struct clk *tegra_clk_register_periph_gate(const char *name,
144 		const char *parent_name, u8 gate_flags, void __iomem *clk_base,
145 		unsigned long flags, int clk_num,
146 		struct tegra_clk_periph_regs *pregs, int *enable_refcnt)
147 {
148 	struct tegra_clk_periph_gate *gate;
149 	struct clk *clk;
150 	struct clk_init_data init;
151 
152 	gate = kzalloc(sizeof(*gate), GFP_KERNEL);
153 	if (!gate) {
154 		pr_err("%s: could not allocate periph gate clk\n", __func__);
155 		return ERR_PTR(-ENOMEM);
156 	}
157 
158 	init.name = name;
159 	init.flags = flags;
160 	init.parent_names = parent_name ? &parent_name : NULL;
161 	init.num_parents = parent_name ? 1 : 0;
162 	init.ops = &tegra_clk_periph_gate_ops;
163 
164 	gate->magic = TEGRA_CLK_PERIPH_GATE_MAGIC;
165 	gate->clk_base = clk_base;
166 	gate->clk_num = clk_num;
167 	gate->flags = gate_flags;
168 	gate->enable_refcnt = enable_refcnt;
169 	gate->regs = pregs;
170 
171 	/* Data in .init is copied by clk_register(), so stack variable OK */
172 	gate->hw.init = &init;
173 
174 	clk = clk_register(NULL, &gate->hw);
175 	if (IS_ERR(clk))
176 		kfree(gate);
177 
178 	return clk;
179 }
180