1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2015 Chen-Yu Tsai
4 *
5 * Chen-Yu Tsai <wens@csie.org>
6 *
7 * Allwinner A80 CPUS clock driver
8 *
9 */
10
11 #include <linux/clk.h>
12 #include <linux/clk-provider.h>
13 #include <linux/io.h>
14 #include <linux/slab.h>
15 #include <linux/spinlock.h>
16 #include <linux/of.h>
17 #include <linux/of_address.h>
18
19 static DEFINE_SPINLOCK(sun9i_a80_cpus_lock);
20
21
22 #define SUN9I_CPUS_MAX_PARENTS 4
23 #define SUN9I_CPUS_MUX_PARENT_PLL4 3
24 #define SUN9I_CPUS_MUX_SHIFT 16
25 #define SUN9I_CPUS_MUX_MASK GENMASK(17, 16)
26 #define SUN9I_CPUS_MUX_GET_PARENT(reg) ((reg & SUN9I_CPUS_MUX_MASK) >> \
27 SUN9I_CPUS_MUX_SHIFT)
28
29 #define SUN9I_CPUS_DIV_SHIFT 4
30 #define SUN9I_CPUS_DIV_MASK GENMASK(5, 4)
31 #define SUN9I_CPUS_DIV_GET(reg) ((reg & SUN9I_CPUS_DIV_MASK) >> \
32 SUN9I_CPUS_DIV_SHIFT)
33 #define SUN9I_CPUS_DIV_SET(reg, div) ((reg & ~SUN9I_CPUS_DIV_MASK) | \
34 (div << SUN9I_CPUS_DIV_SHIFT))
35 #define SUN9I_CPUS_PLL4_DIV_SHIFT 8
36 #define SUN9I_CPUS_PLL4_DIV_MASK GENMASK(12, 8)
37 #define SUN9I_CPUS_PLL4_DIV_GET(reg) ((reg & SUN9I_CPUS_PLL4_DIV_MASK) >> \
38 SUN9I_CPUS_PLL4_DIV_SHIFT)
39 #define SUN9I_CPUS_PLL4_DIV_SET(reg, div) ((reg & ~SUN9I_CPUS_PLL4_DIV_MASK) | \
40 (div << SUN9I_CPUS_PLL4_DIV_SHIFT))
41
42 struct sun9i_a80_cpus_clk {
43 struct clk_hw hw;
44 void __iomem *reg;
45 };
46
47 #define to_sun9i_a80_cpus_clk(_hw) container_of(_hw, struct sun9i_a80_cpus_clk, hw)
48
sun9i_a80_cpus_clk_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)49 static unsigned long sun9i_a80_cpus_clk_recalc_rate(struct clk_hw *hw,
50 unsigned long parent_rate)
51 {
52 struct sun9i_a80_cpus_clk *cpus = to_sun9i_a80_cpus_clk(hw);
53 unsigned long rate;
54 u32 reg;
55
56 /* Fetch the register value */
57 reg = readl(cpus->reg);
58
59 /* apply pre-divider first if parent is pll4 */
60 if (SUN9I_CPUS_MUX_GET_PARENT(reg) == SUN9I_CPUS_MUX_PARENT_PLL4)
61 parent_rate /= SUN9I_CPUS_PLL4_DIV_GET(reg) + 1;
62
63 /* clk divider */
64 rate = parent_rate / (SUN9I_CPUS_DIV_GET(reg) + 1);
65
66 return rate;
67 }
68
sun9i_a80_cpus_clk_round(unsigned long rate,u8 * divp,u8 * pre_divp,u8 parent,unsigned long parent_rate)69 static long sun9i_a80_cpus_clk_round(unsigned long rate, u8 *divp, u8 *pre_divp,
70 u8 parent, unsigned long parent_rate)
71 {
72 u8 div, pre_div = 1;
73
74 /*
75 * clock can only divide, so we will never be able to achieve
76 * frequencies higher than the parent frequency
77 */
78 if (parent_rate && rate > parent_rate)
79 rate = parent_rate;
80
81 div = DIV_ROUND_UP(parent_rate, rate);
82
83 /* calculate pre-divider if parent is pll4 */
84 if (parent == SUN9I_CPUS_MUX_PARENT_PLL4 && div > 4) {
85 /* pre-divider is 1 ~ 32 */
86 if (div < 32) {
87 pre_div = div;
88 div = 1;
89 } else if (div < 64) {
90 pre_div = DIV_ROUND_UP(div, 2);
91 div = 2;
92 } else if (div < 96) {
93 pre_div = DIV_ROUND_UP(div, 3);
94 div = 3;
95 } else {
96 pre_div = DIV_ROUND_UP(div, 4);
97 div = 4;
98 }
99 }
100
101 /* we were asked to pass back divider values */
102 if (divp) {
103 *divp = div - 1;
104 *pre_divp = pre_div - 1;
105 }
106
107 return parent_rate / pre_div / div;
108 }
109
sun9i_a80_cpus_clk_determine_rate(struct clk_hw * clk,struct clk_rate_request * req)110 static int sun9i_a80_cpus_clk_determine_rate(struct clk_hw *clk,
111 struct clk_rate_request *req)
112 {
113 struct clk_hw *parent, *best_parent = NULL;
114 int i, num_parents;
115 unsigned long parent_rate, best = 0, child_rate, best_child_rate = 0;
116 unsigned long rate = req->rate;
117
118 /* find the parent that can help provide the fastest rate <= rate */
119 num_parents = clk_hw_get_num_parents(clk);
120 for (i = 0; i < num_parents; i++) {
121 parent = clk_hw_get_parent_by_index(clk, i);
122 if (!parent)
123 continue;
124 if (clk_hw_get_flags(clk) & CLK_SET_RATE_PARENT)
125 parent_rate = clk_hw_round_rate(parent, rate);
126 else
127 parent_rate = clk_hw_get_rate(parent);
128
129 child_rate = sun9i_a80_cpus_clk_round(rate, NULL, NULL, i,
130 parent_rate);
131
132 if (child_rate <= rate && child_rate > best_child_rate) {
133 best_parent = parent;
134 best = parent_rate;
135 best_child_rate = child_rate;
136 }
137 }
138
139 if (!best_parent)
140 return -EINVAL;
141
142 req->best_parent_hw = best_parent;
143 req->best_parent_rate = best;
144 req->rate = best_child_rate;
145
146 return 0;
147 }
148
sun9i_a80_cpus_clk_set_rate(struct clk_hw * hw,unsigned long rate,unsigned long parent_rate)149 static int sun9i_a80_cpus_clk_set_rate(struct clk_hw *hw, unsigned long rate,
150 unsigned long parent_rate)
151 {
152 struct sun9i_a80_cpus_clk *cpus = to_sun9i_a80_cpus_clk(hw);
153 unsigned long flags;
154 u8 div, pre_div, parent;
155 u32 reg;
156
157 spin_lock_irqsave(&sun9i_a80_cpus_lock, flags);
158
159 reg = readl(cpus->reg);
160
161 /* need to know which parent is used to apply pre-divider */
162 parent = SUN9I_CPUS_MUX_GET_PARENT(reg);
163 sun9i_a80_cpus_clk_round(rate, &div, &pre_div, parent, parent_rate);
164
165 reg = SUN9I_CPUS_DIV_SET(reg, div);
166 reg = SUN9I_CPUS_PLL4_DIV_SET(reg, pre_div);
167 writel(reg, cpus->reg);
168
169 spin_unlock_irqrestore(&sun9i_a80_cpus_lock, flags);
170
171 return 0;
172 }
173
174 static const struct clk_ops sun9i_a80_cpus_clk_ops = {
175 .determine_rate = sun9i_a80_cpus_clk_determine_rate,
176 .recalc_rate = sun9i_a80_cpus_clk_recalc_rate,
177 .set_rate = sun9i_a80_cpus_clk_set_rate,
178 };
179
180 /**
181 * sun9i_a80_cpus_setup() - Setup function for a80 cpus composite clk
182 * @node: &struct device_node for the clock
183 */
sun9i_a80_cpus_setup(struct device_node * node)184 static void sun9i_a80_cpus_setup(struct device_node *node)
185 {
186 const char *clk_name = node->name;
187 const char *parents[SUN9I_CPUS_MAX_PARENTS];
188 struct resource res;
189 struct sun9i_a80_cpus_clk *cpus;
190 struct clk_mux *mux;
191 struct clk *clk;
192 int ret;
193
194 cpus = kzalloc(sizeof(*cpus), GFP_KERNEL);
195 if (!cpus)
196 return;
197
198 cpus->reg = of_io_request_and_map(node, 0, of_node_full_name(node));
199 if (IS_ERR(cpus->reg))
200 goto err_free_cpus;
201
202 of_property_read_string(node, "clock-output-names", &clk_name);
203
204 /* we have a mux, we will have >1 parents */
205 ret = of_clk_parent_fill(node, parents, SUN9I_CPUS_MAX_PARENTS);
206
207 mux = kzalloc(sizeof(*mux), GFP_KERNEL);
208 if (!mux)
209 goto err_unmap;
210
211 /* set up clock properties */
212 mux->reg = cpus->reg;
213 mux->shift = SUN9I_CPUS_MUX_SHIFT;
214 /* un-shifted mask is what mux_clk expects */
215 mux->mask = SUN9I_CPUS_MUX_MASK >> SUN9I_CPUS_MUX_SHIFT;
216 mux->lock = &sun9i_a80_cpus_lock;
217
218 clk = clk_register_composite(NULL, clk_name, parents, ret,
219 &mux->hw, &clk_mux_ops,
220 &cpus->hw, &sun9i_a80_cpus_clk_ops,
221 NULL, NULL, 0);
222 if (IS_ERR(clk))
223 goto err_free_mux;
224
225 ret = of_clk_add_provider(node, of_clk_src_simple_get, clk);
226 if (ret)
227 goto err_unregister;
228
229 return;
230
231 err_unregister:
232 clk_unregister(clk);
233 err_free_mux:
234 kfree(mux);
235 err_unmap:
236 iounmap(cpus->reg);
237 of_address_to_resource(node, 0, &res);
238 release_mem_region(res.start, resource_size(&res));
239 err_free_cpus:
240 kfree(cpus);
241 }
242 CLK_OF_DECLARE(sun9i_a80_cpus, "allwinner,sun9i-a80-cpus-clk",
243 sun9i_a80_cpus_setup);
244