1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
4 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
5 * Copyright 2019 NXP
6 *
7 * Gated clock implementation
8 */
9
10 #include <common.h>
11 #include <asm/io.h>
12 #include <malloc.h>
13 #include <clk-uclass.h>
14 #include <dm/device.h>
15 #include <linux/clk-provider.h>
16 #include <clk.h>
17 #include "clk.h"
18
19 #define UBOOT_DM_CLK_GATE "clk_gate"
20
21 /**
22 * DOC: basic gatable clock which can gate and ungate it's output
23 *
24 * Traits of this clock:
25 * prepare - clk_(un)prepare only ensures parent is (un)prepared
26 * enable - clk_enable and clk_disable are functional & control gating
27 * rate - inherits rate from parent. No clk_set_rate support
28 * parent - fixed parent. No clk_set_parent support
29 */
30
31 /*
32 * It works on following logic:
33 *
34 * For enabling clock, enable = 1
35 * set2dis = 1 -> clear bit -> set = 0
36 * set2dis = 0 -> set bit -> set = 1
37 *
38 * For disabling clock, enable = 0
39 * set2dis = 1 -> set bit -> set = 1
40 * set2dis = 0 -> clear bit -> set = 0
41 *
42 * So, result is always: enable xor set2dis.
43 */
clk_gate_endisable(struct clk * clk,int enable)44 static void clk_gate_endisable(struct clk *clk, int enable)
45 {
46 struct clk_gate *gate = to_clk_gate(clk_dev_binded(clk) ?
47 dev_get_clk_ptr(clk->dev) : clk);
48 int set = gate->flags & CLK_GATE_SET_TO_DISABLE ? 1 : 0;
49 u32 reg;
50
51 set ^= enable;
52
53 if (gate->flags & CLK_GATE_HIWORD_MASK) {
54 reg = BIT(gate->bit_idx + 16);
55 if (set)
56 reg |= BIT(gate->bit_idx);
57 } else {
58 #if CONFIG_IS_ENABLED(SANDBOX_CLK_CCF)
59 reg = gate->io_gate_val;
60 #else
61 reg = readl(gate->reg);
62 #endif
63
64 if (set)
65 reg |= BIT(gate->bit_idx);
66 else
67 reg &= ~BIT(gate->bit_idx);
68 }
69
70 writel(reg, gate->reg);
71 }
72
clk_gate_enable(struct clk * clk)73 static int clk_gate_enable(struct clk *clk)
74 {
75 clk_gate_endisable(clk, 1);
76
77 return 0;
78 }
79
clk_gate_disable(struct clk * clk)80 static int clk_gate_disable(struct clk *clk)
81 {
82 clk_gate_endisable(clk, 0);
83
84 return 0;
85 }
86
clk_gate_is_enabled(struct clk * clk)87 int clk_gate_is_enabled(struct clk *clk)
88 {
89 struct clk_gate *gate = to_clk_gate(clk_dev_binded(clk) ?
90 dev_get_clk_ptr(clk->dev) : clk);
91 u32 reg;
92
93 #if CONFIG_IS_ENABLED(SANDBOX_CLK_CCF)
94 reg = gate->io_gate_val;
95 #else
96 reg = readl(gate->reg);
97 #endif
98
99 /* if a set bit disables this clk, flip it before masking */
100 if (gate->flags & CLK_GATE_SET_TO_DISABLE)
101 reg ^= BIT(gate->bit_idx);
102
103 reg &= BIT(gate->bit_idx);
104
105 return reg ? 1 : 0;
106 }
107
108 const struct clk_ops clk_gate_ops = {
109 .enable = clk_gate_enable,
110 .disable = clk_gate_disable,
111 .get_rate = clk_generic_get_rate,
112 };
113
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)114 struct clk *clk_register_gate(struct device *dev, const char *name,
115 const char *parent_name, unsigned long flags,
116 void __iomem *reg, u8 bit_idx,
117 u8 clk_gate_flags, spinlock_t *lock)
118 {
119 struct clk_gate *gate;
120 struct clk *clk;
121 int ret;
122
123 if (clk_gate_flags & CLK_GATE_HIWORD_MASK) {
124 if (bit_idx > 15) {
125 pr_err("gate bit exceeds LOWORD field\n");
126 return ERR_PTR(-EINVAL);
127 }
128 }
129
130 /* allocate the gate */
131 gate = kzalloc(sizeof(*gate), GFP_KERNEL);
132 if (!gate)
133 return ERR_PTR(-ENOMEM);
134
135 /* struct clk_gate assignments */
136 gate->reg = reg;
137 gate->bit_idx = bit_idx;
138 gate->flags = clk_gate_flags;
139 #if CONFIG_IS_ENABLED(SANDBOX_CLK_CCF)
140 gate->io_gate_val = *(u32 *)reg;
141 #endif
142
143 clk = &gate->clk;
144
145 ret = clk_register(clk, UBOOT_DM_CLK_GATE, name, parent_name);
146 if (ret) {
147 kfree(gate);
148 return ERR_PTR(ret);
149 }
150
151 return clk;
152 }
153
154 U_BOOT_DRIVER(clk_gate) = {
155 .name = UBOOT_DM_CLK_GATE,
156 .id = UCLASS_CLK,
157 .ops = &clk_gate_ops,
158 .flags = DM_FLAG_PRE_RELOC,
159 };
160