xref: /openbmc/linux/drivers/clk/versatile/clk-icst.c (revision 21278aea)
1 /*
2  * Driver for the ICST307 VCO clock found in the ARM Reference designs.
3  * We wrap the custom interface from <asm/hardware/icst.h> into the generic
4  * clock framework.
5  *
6  * Copyright (C) 2012 Linus Walleij
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  * TODO: when all ARM reference designs are migrated to generic clocks, the
13  * ICST clock code from the ARM tree should probably be merged into this
14  * file.
15  */
16 #include <linux/clk.h>
17 #include <linux/clkdev.h>
18 #include <linux/err.h>
19 #include <linux/clk-provider.h>
20 #include <linux/io.h>
21 
22 #include "clk-icst.h"
23 
24 /**
25  * struct clk_icst - ICST VCO clock wrapper
26  * @hw: corresponding clock hardware entry
27  * @vcoreg: VCO register address
28  * @lockreg: VCO lock register address
29  * @params: parameters for this ICST instance
30  * @rate: current rate
31  */
32 struct clk_icst {
33 	struct clk_hw hw;
34 	void __iomem *vcoreg;
35 	void __iomem *lockreg;
36 	struct icst_params *params;
37 	unsigned long rate;
38 };
39 
40 #define to_icst(_hw) container_of(_hw, struct clk_icst, hw)
41 
42 /**
43  * vco_get() - get ICST VCO settings from a certain register
44  * @vcoreg: register containing the VCO settings
45  */
46 static struct icst_vco vco_get(void __iomem *vcoreg)
47 {
48 	u32 val;
49 	struct icst_vco vco;
50 
51 	val = readl(vcoreg);
52 	vco.v = val & 0x1ff;
53 	vco.r = (val >> 9) & 0x7f;
54 	vco.s = (val >> 16) & 03;
55 	return vco;
56 }
57 
58 /**
59  * vco_set() - commit changes to an ICST VCO
60  * @locreg: register to poke to unlock the VCO for writing
61  * @vcoreg: register containing the VCO settings
62  * @vco: ICST VCO parameters to commit
63  */
64 static void vco_set(void __iomem *lockreg,
65 			void __iomem *vcoreg,
66 			struct icst_vco vco)
67 {
68 	u32 val;
69 
70 	val = readl(vcoreg) & ~0x7ffff;
71 	val |= vco.v | (vco.r << 9) | (vco.s << 16);
72 
73 	/* This magic unlocks the VCO so it can be controlled */
74 	writel(0xa05f, lockreg);
75 	writel(val, vcoreg);
76 	/* This locks the VCO again */
77 	writel(0, lockreg);
78 }
79 
80 
81 static unsigned long icst_recalc_rate(struct clk_hw *hw,
82 				      unsigned long parent_rate)
83 {
84 	struct clk_icst *icst = to_icst(hw);
85 	struct icst_vco vco;
86 
87 	if (parent_rate)
88 		icst->params->ref = parent_rate;
89 	vco = vco_get(icst->vcoreg);
90 	icst->rate = icst_hz(icst->params, vco);
91 	return icst->rate;
92 }
93 
94 static long icst_round_rate(struct clk_hw *hw, unsigned long rate,
95 			    unsigned long *prate)
96 {
97 	struct clk_icst *icst = to_icst(hw);
98 	struct icst_vco vco;
99 
100 	vco = icst_hz_to_vco(icst->params, rate);
101 	return icst_hz(icst->params, vco);
102 }
103 
104 static int icst_set_rate(struct clk_hw *hw, unsigned long rate,
105 			 unsigned long parent_rate)
106 {
107 	struct clk_icst *icst = to_icst(hw);
108 	struct icst_vco vco;
109 
110 	if (parent_rate)
111 		icst->params->ref = parent_rate;
112 	vco = icst_hz_to_vco(icst->params, rate);
113 	icst->rate = icst_hz(icst->params, vco);
114 	vco_set(icst->lockreg, icst->vcoreg, vco);
115 	return 0;
116 }
117 
118 static const struct clk_ops icst_ops = {
119 	.recalc_rate = icst_recalc_rate,
120 	.round_rate = icst_round_rate,
121 	.set_rate = icst_set_rate,
122 };
123 
124 struct clk *icst_clk_register(struct device *dev,
125 			const struct clk_icst_desc *desc,
126 			const char *name,
127 			const char *parent_name,
128 			void __iomem *base)
129 {
130 	struct clk *clk;
131 	struct clk_icst *icst;
132 	struct clk_init_data init;
133 	struct icst_params *pclone;
134 
135 	icst = kzalloc(sizeof(struct clk_icst), GFP_KERNEL);
136 	if (!icst) {
137 		pr_err("could not allocate ICST clock!\n");
138 		return ERR_PTR(-ENOMEM);
139 	}
140 
141 	pclone = kmemdup(desc->params, sizeof(*pclone), GFP_KERNEL);
142 	if (!pclone) {
143 		kfree(icst);
144 		pr_err("could not clone ICST params\n");
145 		return ERR_PTR(-ENOMEM);
146 	}
147 
148 	init.name = name;
149 	init.ops = &icst_ops;
150 	init.flags = CLK_IS_ROOT;
151 	init.parent_names = (parent_name ? &parent_name : NULL);
152 	init.num_parents = (parent_name ? 1 : 0);
153 	icst->hw.init = &init;
154 	icst->params = pclone;
155 	icst->vcoreg = base + desc->vco_offset;
156 	icst->lockreg = base + desc->lock_offset;
157 
158 	clk = clk_register(dev, &icst->hw);
159 	if (IS_ERR(clk))
160 		kfree(icst);
161 
162 	return clk;
163 }
164 EXPORT_SYMBOL_GPL(icst_clk_register);
165