1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * r8a7790 Common Clock Framework support
4 *
5 * Copyright (C) 2013 Renesas Solutions Corp.
6 *
7 * Contact: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
8 */
9
10 #include <linux/bitfield.h>
11 #include <linux/clk-provider.h>
12 #include <linux/init.h>
13 #include <linux/io.h>
14 #include <linux/kernel.h>
15 #include <linux/notifier.h>
16 #include <linux/of.h>
17 #include <linux/of_address.h>
18 #include <linux/pm.h>
19 #include <linux/slab.h>
20
21 #include "clk-div6.h"
22
23 #define CPG_DIV6_CKSTP BIT(8)
24 #define CPG_DIV6_DIV(d) ((d) & 0x3f)
25 #define CPG_DIV6_DIV_MASK 0x3f
26
27 /**
28 * struct div6_clock - CPG 6 bit divider clock
29 * @hw: handle between common and hardware-specific interfaces
30 * @reg: IO-remapped register
31 * @div: divisor value (1-64)
32 * @src_mask: Bitmask covering the register bits to select the parent clock
33 * @nb: Notifier block to save/restore clock state for system resume
34 * @parents: Array to map from valid parent clocks indices to hardware indices
35 */
36 struct div6_clock {
37 struct clk_hw hw;
38 void __iomem *reg;
39 unsigned int div;
40 u32 src_mask;
41 struct notifier_block nb;
42 u8 parents[];
43 };
44
45 #define to_div6_clock(_hw) container_of(_hw, struct div6_clock, hw)
46
cpg_div6_clock_enable(struct clk_hw * hw)47 static int cpg_div6_clock_enable(struct clk_hw *hw)
48 {
49 struct div6_clock *clock = to_div6_clock(hw);
50 u32 val;
51
52 val = (readl(clock->reg) & ~(CPG_DIV6_DIV_MASK | CPG_DIV6_CKSTP))
53 | CPG_DIV6_DIV(clock->div - 1);
54 writel(val, clock->reg);
55
56 return 0;
57 }
58
cpg_div6_clock_disable(struct clk_hw * hw)59 static void cpg_div6_clock_disable(struct clk_hw *hw)
60 {
61 struct div6_clock *clock = to_div6_clock(hw);
62 u32 val;
63
64 val = readl(clock->reg);
65 val |= CPG_DIV6_CKSTP;
66 /*
67 * DIV6 clocks require the divisor field to be non-zero when stopping
68 * the clock. However, some clocks (e.g. ZB on sh73a0) fail to be
69 * re-enabled later if the divisor field is changed when stopping the
70 * clock
71 */
72 if (!(val & CPG_DIV6_DIV_MASK))
73 val |= CPG_DIV6_DIV_MASK;
74 writel(val, clock->reg);
75 }
76
cpg_div6_clock_is_enabled(struct clk_hw * hw)77 static int cpg_div6_clock_is_enabled(struct clk_hw *hw)
78 {
79 struct div6_clock *clock = to_div6_clock(hw);
80
81 return !(readl(clock->reg) & CPG_DIV6_CKSTP);
82 }
83
cpg_div6_clock_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)84 static unsigned long cpg_div6_clock_recalc_rate(struct clk_hw *hw,
85 unsigned long parent_rate)
86 {
87 struct div6_clock *clock = to_div6_clock(hw);
88
89 return parent_rate / clock->div;
90 }
91
cpg_div6_clock_calc_div(unsigned long rate,unsigned long parent_rate)92 static unsigned int cpg_div6_clock_calc_div(unsigned long rate,
93 unsigned long parent_rate)
94 {
95 unsigned int div;
96
97 if (!rate)
98 rate = 1;
99
100 div = DIV_ROUND_CLOSEST(parent_rate, rate);
101 return clamp(div, 1U, 64U);
102 }
103
cpg_div6_clock_determine_rate(struct clk_hw * hw,struct clk_rate_request * req)104 static int cpg_div6_clock_determine_rate(struct clk_hw *hw,
105 struct clk_rate_request *req)
106 {
107 unsigned long prate, calc_rate, diff, best_rate, best_prate;
108 unsigned int num_parents = clk_hw_get_num_parents(hw);
109 struct clk_hw *parent, *best_parent = NULL;
110 unsigned int i, min_div, max_div, div;
111 unsigned long min_diff = ULONG_MAX;
112
113 for (i = 0; i < num_parents; i++) {
114 parent = clk_hw_get_parent_by_index(hw, i);
115 if (!parent)
116 continue;
117
118 prate = clk_hw_get_rate(parent);
119 if (!prate)
120 continue;
121
122 min_div = max(DIV_ROUND_UP(prate, req->max_rate), 1UL);
123 max_div = req->min_rate ? min(prate / req->min_rate, 64UL) : 64;
124 if (max_div < min_div)
125 continue;
126
127 div = cpg_div6_clock_calc_div(req->rate, prate);
128 div = clamp(div, min_div, max_div);
129 calc_rate = prate / div;
130 diff = calc_rate > req->rate ? calc_rate - req->rate
131 : req->rate - calc_rate;
132 if (diff < min_diff) {
133 best_rate = calc_rate;
134 best_parent = parent;
135 best_prate = prate;
136 min_diff = diff;
137 }
138 }
139
140 if (!best_parent)
141 return -EINVAL;
142
143 req->best_parent_rate = best_prate;
144 req->best_parent_hw = best_parent;
145 req->rate = best_rate;
146 return 0;
147 }
148
cpg_div6_clock_set_rate(struct clk_hw * hw,unsigned long rate,unsigned long parent_rate)149 static int cpg_div6_clock_set_rate(struct clk_hw *hw, unsigned long rate,
150 unsigned long parent_rate)
151 {
152 struct div6_clock *clock = to_div6_clock(hw);
153 unsigned int div = cpg_div6_clock_calc_div(rate, parent_rate);
154 u32 val;
155
156 clock->div = div;
157
158 val = readl(clock->reg) & ~CPG_DIV6_DIV_MASK;
159 /* Only program the new divisor if the clock isn't stopped. */
160 if (!(val & CPG_DIV6_CKSTP))
161 writel(val | CPG_DIV6_DIV(clock->div - 1), clock->reg);
162
163 return 0;
164 }
165
cpg_div6_clock_get_parent(struct clk_hw * hw)166 static u8 cpg_div6_clock_get_parent(struct clk_hw *hw)
167 {
168 struct div6_clock *clock = to_div6_clock(hw);
169 unsigned int i;
170 u8 hw_index;
171
172 if (clock->src_mask == 0)
173 return 0;
174
175 hw_index = field_get(clock->src_mask, readl(clock->reg));
176 for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
177 if (clock->parents[i] == hw_index)
178 return i;
179 }
180
181 pr_err("%s: %s DIV6 clock set to invalid parent %u\n",
182 __func__, clk_hw_get_name(hw), hw_index);
183 return 0;
184 }
185
cpg_div6_clock_set_parent(struct clk_hw * hw,u8 index)186 static int cpg_div6_clock_set_parent(struct clk_hw *hw, u8 index)
187 {
188 struct div6_clock *clock = to_div6_clock(hw);
189 u32 src;
190
191 if (index >= clk_hw_get_num_parents(hw))
192 return -EINVAL;
193
194 src = field_prep(clock->src_mask, clock->parents[index]);
195 writel((readl(clock->reg) & ~clock->src_mask) | src, clock->reg);
196 return 0;
197 }
198
199 static const struct clk_ops cpg_div6_clock_ops = {
200 .enable = cpg_div6_clock_enable,
201 .disable = cpg_div6_clock_disable,
202 .is_enabled = cpg_div6_clock_is_enabled,
203 .get_parent = cpg_div6_clock_get_parent,
204 .set_parent = cpg_div6_clock_set_parent,
205 .recalc_rate = cpg_div6_clock_recalc_rate,
206 .determine_rate = cpg_div6_clock_determine_rate,
207 .set_rate = cpg_div6_clock_set_rate,
208 };
209
cpg_div6_clock_notifier_call(struct notifier_block * nb,unsigned long action,void * data)210 static int cpg_div6_clock_notifier_call(struct notifier_block *nb,
211 unsigned long action, void *data)
212 {
213 struct div6_clock *clock = container_of(nb, struct div6_clock, nb);
214
215 switch (action) {
216 case PM_EVENT_RESUME:
217 /*
218 * TODO: This does not yet support DIV6 clocks with multiple
219 * parents, as the parent selection bits are not restored.
220 * Fortunately so far such DIV6 clocks are found only on
221 * R/SH-Mobile SoCs, while the resume functionality is only
222 * needed on R-Car Gen3.
223 */
224 if (__clk_get_enable_count(clock->hw.clk))
225 cpg_div6_clock_enable(&clock->hw);
226 else
227 cpg_div6_clock_disable(&clock->hw);
228 return NOTIFY_OK;
229 }
230
231 return NOTIFY_DONE;
232 }
233
234 /**
235 * cpg_div6_register - Register a DIV6 clock
236 * @name: Name of the DIV6 clock
237 * @num_parents: Number of parent clocks of the DIV6 clock (1, 4, or 8)
238 * @parent_names: Array containing the names of the parent clocks
239 * @reg: Mapped register used to control the DIV6 clock
240 * @notifiers: Optional notifier chain to save/restore state for system resume
241 */
cpg_div6_register(const char * name,unsigned int num_parents,const char ** parent_names,void __iomem * reg,struct raw_notifier_head * notifiers)242 struct clk * __init cpg_div6_register(const char *name,
243 unsigned int num_parents,
244 const char **parent_names,
245 void __iomem *reg,
246 struct raw_notifier_head *notifiers)
247 {
248 unsigned int valid_parents;
249 struct clk_init_data init = {};
250 struct div6_clock *clock;
251 struct clk *clk;
252 unsigned int i;
253
254 clock = kzalloc(struct_size(clock, parents, num_parents), GFP_KERNEL);
255 if (!clock)
256 return ERR_PTR(-ENOMEM);
257
258 clock->reg = reg;
259
260 /*
261 * Read the divisor. Disabling the clock overwrites the divisor, so we
262 * need to cache its value for the enable operation.
263 */
264 clock->div = (readl(clock->reg) & CPG_DIV6_DIV_MASK) + 1;
265
266 switch (num_parents) {
267 case 1:
268 /* fixed parent clock */
269 clock->src_mask = 0;
270 break;
271 case 4:
272 /* clock with EXSRC bits 6-7 */
273 clock->src_mask = GENMASK(7, 6);
274 break;
275 case 8:
276 /* VCLK with EXSRC bits 12-14 */
277 clock->src_mask = GENMASK(14, 12);
278 break;
279 default:
280 pr_err("%s: invalid number of parents for DIV6 clock %s\n",
281 __func__, name);
282 clk = ERR_PTR(-EINVAL);
283 goto free_clock;
284 }
285
286 /* Filter out invalid parents */
287 for (i = 0, valid_parents = 0; i < num_parents; i++) {
288 if (parent_names[i]) {
289 parent_names[valid_parents] = parent_names[i];
290 clock->parents[valid_parents] = i;
291 valid_parents++;
292 }
293 }
294
295 /* Register the clock. */
296 init.name = name;
297 init.ops = &cpg_div6_clock_ops;
298 init.parent_names = parent_names;
299 init.num_parents = valid_parents;
300
301 clock->hw.init = &init;
302
303 clk = clk_register(NULL, &clock->hw);
304 if (IS_ERR(clk))
305 goto free_clock;
306
307 if (notifiers) {
308 clock->nb.notifier_call = cpg_div6_clock_notifier_call;
309 raw_notifier_chain_register(notifiers, &clock->nb);
310 }
311
312 return clk;
313
314 free_clock:
315 kfree(clock);
316 return clk;
317 }
318
cpg_div6_clock_init(struct device_node * np)319 static void __init cpg_div6_clock_init(struct device_node *np)
320 {
321 unsigned int num_parents;
322 const char **parent_names;
323 const char *clk_name = np->name;
324 void __iomem *reg;
325 struct clk *clk;
326 unsigned int i;
327
328 num_parents = of_clk_get_parent_count(np);
329 if (num_parents < 1) {
330 pr_err("%s: no parent found for %pOFn DIV6 clock\n",
331 __func__, np);
332 return;
333 }
334
335 parent_names = kmalloc_array(num_parents, sizeof(*parent_names),
336 GFP_KERNEL);
337 if (!parent_names)
338 return;
339
340 reg = of_iomap(np, 0);
341 if (reg == NULL) {
342 pr_err("%s: failed to map %pOFn DIV6 clock register\n",
343 __func__, np);
344 goto error;
345 }
346
347 /* Parse the DT properties. */
348 of_property_read_string(np, "clock-output-names", &clk_name);
349
350 for (i = 0; i < num_parents; i++)
351 parent_names[i] = of_clk_get_parent_name(np, i);
352
353 clk = cpg_div6_register(clk_name, num_parents, parent_names, reg, NULL);
354 if (IS_ERR(clk)) {
355 pr_err("%s: failed to register %pOFn DIV6 clock (%ld)\n",
356 __func__, np, PTR_ERR(clk));
357 goto error;
358 }
359
360 of_clk_add_provider(np, of_clk_src_simple_get, clk);
361
362 kfree(parent_names);
363 return;
364
365 error:
366 if (reg)
367 iounmap(reg);
368 kfree(parent_names);
369 }
370 CLK_OF_DECLARE(cpg_div6_clk, "renesas,cpg-div6-clock", cpg_div6_clock_init);
371