1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Zynq UltraScale+ MPSoC Divider support
4 *
5 * Copyright (C) 2016-2019 Xilinx
6 *
7 * Adjustable divider clock implementation
8 */
9
10#include <linux/clk.h>
11#include <linux/clk-provider.h>
12#include <linux/slab.h>
13#include "clk-zynqmp.h"
14
15/*
16 * DOC: basic adjustable divider clock that cannot gate
17 *
18 * Traits of this clock:
19 * prepare - clk_prepare only ensures that parents are prepared
20 * enable - clk_enable only ensures that parents are enabled
21 * rate - rate is adjustable. clk->rate = ceiling(parent->rate / divisor)
22 * parent - fixed parent. No clk_set_parent support
23 */
24
25#define to_zynqmp_clk_divider(_hw) \
26 container_of(_hw, struct zynqmp_clk_divider, hw)
27
28#define CLK_FRAC BIT(13) /* has a fractional parent */
29#define CUSTOM_FLAG_CLK_FRAC BIT(0) /* has a fractional parent in custom type flag */
30
31/**
32 * struct zynqmp_clk_divider - adjustable divider clock
33 * @hw: handle between common and hardware-specific interfaces
34 * @flags: Hardware specific flags
35 * @is_frac: The divider is a fractional divider
36 * @clk_id: Id of clock
37 * @div_type: divisor type (TYPE_DIV1 or TYPE_DIV2)
38 * @max_div: maximum supported divisor (fetched from firmware)
39 */
40struct zynqmp_clk_divider {
41 struct clk_hw hw;
42 u8 flags;
43 bool is_frac;
44 u32 clk_id;
45 u32 div_type;
46 u16 max_div;
47};
48
49static inline int zynqmp_divider_get_val(unsigned long parent_rate,
50 unsigned long rate, u16 flags)
51{
52 int up, down;
53 unsigned long up_rate, down_rate;
54
55 if (flags & CLK_DIVIDER_POWER_OF_TWO) {
56 up = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
57 down = DIV_ROUND_DOWN_ULL((u64)parent_rate, rate);
58
59 up = __roundup_pow_of_two(n: up);
60 down = __rounddown_pow_of_two(n: down);
61
62 up_rate = DIV_ROUND_UP_ULL((u64)parent_rate, up);
63 down_rate = DIV_ROUND_UP_ULL((u64)parent_rate, down);
64
65 return (rate - up_rate) <= (down_rate - rate) ? up : down;
66
67 } else {
68 return DIV_ROUND_CLOSEST(parent_rate, rate);
69 }
70}
71
72/**
73 * zynqmp_clk_divider_recalc_rate() - Recalc rate of divider clock
74 * @hw: handle between common and hardware-specific interfaces
75 * @parent_rate: rate of parent clock
76 *
77 * Return: 0 on success else error+reason
78 */
79static unsigned long zynqmp_clk_divider_recalc_rate(struct clk_hw *hw,
80 unsigned long parent_rate)
81{
82 struct zynqmp_clk_divider *divider = to_zynqmp_clk_divider(hw);
83 const char *clk_name = clk_hw_get_name(hw);
84 u32 clk_id = divider->clk_id;
85 u32 div_type = divider->div_type;
86 u32 div, value;
87 int ret;
88
89 ret = zynqmp_pm_clock_getdivider(clock_id: clk_id, divider: &div);
90
91 if (ret)
92 pr_debug("%s() get divider failed for %s, ret = %d\n",
93 __func__, clk_name, ret);
94
95 if (div_type == TYPE_DIV1)
96 value = div & 0xFFFF;
97 else
98 value = div >> 16;
99
100 if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
101 value = 1 << value;
102
103 if (!value) {
104 WARN(!(divider->flags & CLK_DIVIDER_ALLOW_ZERO),
105 "%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
106 clk_name);
107 return parent_rate;
108 }
109
110 return DIV_ROUND_UP_ULL(parent_rate, value);
111}
112
113static void zynqmp_get_divider2_val(struct clk_hw *hw,
114 unsigned long rate,
115 struct zynqmp_clk_divider *divider,
116 u32 *bestdiv)
117{
118 int div1;
119 int div2;
120 long error = LONG_MAX;
121 unsigned long div1_prate;
122 struct clk_hw *div1_parent_hw;
123 struct zynqmp_clk_divider *pdivider;
124 struct clk_hw *div2_parent_hw = clk_hw_get_parent(hw);
125
126 if (!div2_parent_hw)
127 return;
128
129 pdivider = to_zynqmp_clk_divider(div2_parent_hw);
130 if (!pdivider)
131 return;
132
133 div1_parent_hw = clk_hw_get_parent(hw: div2_parent_hw);
134 if (!div1_parent_hw)
135 return;
136
137 div1_prate = clk_hw_get_rate(hw: div1_parent_hw);
138 *bestdiv = 1;
139 for (div1 = 1; div1 <= pdivider->max_div;) {
140 for (div2 = 1; div2 <= divider->max_div;) {
141 long new_error = ((div1_prate / div1) / div2) - rate;
142
143 if (abs(new_error) < abs(error)) {
144 *bestdiv = div2;
145 error = new_error;
146 }
147 if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
148 div2 = div2 << 1;
149 else
150 div2++;
151 }
152 if (pdivider->flags & CLK_DIVIDER_POWER_OF_TWO)
153 div1 = div1 << 1;
154 else
155 div1++;
156 }
157}
158
159/**
160 * zynqmp_clk_divider_round_rate() - Round rate of divider clock
161 * @hw: handle between common and hardware-specific interfaces
162 * @rate: rate of clock to be set
163 * @prate: rate of parent clock
164 *
165 * Return: 0 on success else error+reason
166 */
167static long zynqmp_clk_divider_round_rate(struct clk_hw *hw,
168 unsigned long rate,
169 unsigned long *prate)
170{
171 struct zynqmp_clk_divider *divider = to_zynqmp_clk_divider(hw);
172 const char *clk_name = clk_hw_get_name(hw);
173 u32 clk_id = divider->clk_id;
174 u32 div_type = divider->div_type;
175 u32 bestdiv;
176 int ret;
177
178 /* if read only, just return current value */
179 if (divider->flags & CLK_DIVIDER_READ_ONLY) {
180 ret = zynqmp_pm_clock_getdivider(clock_id: clk_id, divider: &bestdiv);
181
182 if (ret)
183 pr_debug("%s() get divider failed for %s, ret = %d\n",
184 __func__, clk_name, ret);
185 if (div_type == TYPE_DIV1)
186 bestdiv = bestdiv & 0xFFFF;
187 else
188 bestdiv = bestdiv >> 16;
189
190 if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
191 bestdiv = 1 << bestdiv;
192
193 return DIV_ROUND_UP_ULL((u64)*prate, bestdiv);
194 }
195
196 bestdiv = zynqmp_divider_get_val(parent_rate: *prate, rate, flags: divider->flags);
197
198 /*
199 * In case of two divisors, compute best divider values and return
200 * divider2 value based on compute value. div1 will be automatically
201 * set to optimum based on required total divider value.
202 */
203 if (div_type == TYPE_DIV2 &&
204 (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
205 zynqmp_get_divider2_val(hw, rate, divider, bestdiv: &bestdiv);
206 }
207
208 if ((clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) && divider->is_frac)
209 bestdiv = rate % *prate ? 1 : bestdiv;
210
211 bestdiv = min_t(u32, bestdiv, divider->max_div);
212 *prate = rate * bestdiv;
213
214 return rate;
215}
216
217/**
218 * zynqmp_clk_divider_set_rate() - Set rate of divider clock
219 * @hw: handle between common and hardware-specific interfaces
220 * @rate: rate of clock to be set
221 * @parent_rate: rate of parent clock
222 *
223 * Return: 0 on success else error+reason
224 */
225static int zynqmp_clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
226 unsigned long parent_rate)
227{
228 struct zynqmp_clk_divider *divider = to_zynqmp_clk_divider(hw);
229 const char *clk_name = clk_hw_get_name(hw);
230 u32 clk_id = divider->clk_id;
231 u32 div_type = divider->div_type;
232 u32 value, div;
233 int ret;
234
235 value = zynqmp_divider_get_val(parent_rate, rate, flags: divider->flags);
236 if (div_type == TYPE_DIV1) {
237 div = value & 0xFFFF;
238 div |= 0xffff << 16;
239 } else {
240 div = 0xffff;
241 div |= value << 16;
242 }
243
244 if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
245 div = __ffs(div);
246
247 ret = zynqmp_pm_clock_setdivider(clock_id: clk_id, divider: div);
248
249 if (ret)
250 pr_debug("%s() set divider failed for %s, ret = %d\n",
251 __func__, clk_name, ret);
252
253 return ret;
254}
255
256static const struct clk_ops zynqmp_clk_divider_ops = {
257 .recalc_rate = zynqmp_clk_divider_recalc_rate,
258 .round_rate = zynqmp_clk_divider_round_rate,
259 .set_rate = zynqmp_clk_divider_set_rate,
260};
261
262static const struct clk_ops zynqmp_clk_divider_ro_ops = {
263 .recalc_rate = zynqmp_clk_divider_recalc_rate,
264 .round_rate = zynqmp_clk_divider_round_rate,
265};
266
267/**
268 * zynqmp_clk_get_max_divisor() - Get maximum supported divisor from firmware.
269 * @clk_id: Id of clock
270 * @type: Divider type
271 *
272 * Return: Maximum divisor of a clock if query data is successful
273 * U16_MAX in case of query data is not success
274 */
275static u32 zynqmp_clk_get_max_divisor(u32 clk_id, u32 type)
276{
277 struct zynqmp_pm_query_data qdata = {0};
278 u32 ret_payload[PAYLOAD_ARG_CNT];
279 int ret;
280
281 qdata.qid = PM_QID_CLOCK_GET_MAX_DIVISOR;
282 qdata.arg1 = clk_id;
283 qdata.arg2 = type;
284 ret = zynqmp_pm_query_data(qdata, out: ret_payload);
285 /*
286 * To maintain backward compatibility return maximum possible value
287 * (0xFFFF) if query for max divisor is not successful.
288 */
289 if (ret)
290 return U16_MAX;
291
292 return ret_payload[1];
293}
294
295static inline unsigned long zynqmp_clk_map_divider_ccf_flags(
296 const u32 zynqmp_type_flag)
297{
298 unsigned long ccf_flag = 0;
299
300 if (zynqmp_type_flag & ZYNQMP_CLK_DIVIDER_ONE_BASED)
301 ccf_flag |= CLK_DIVIDER_ONE_BASED;
302 if (zynqmp_type_flag & ZYNQMP_CLK_DIVIDER_POWER_OF_TWO)
303 ccf_flag |= CLK_DIVIDER_POWER_OF_TWO;
304 if (zynqmp_type_flag & ZYNQMP_CLK_DIVIDER_ALLOW_ZERO)
305 ccf_flag |= CLK_DIVIDER_ALLOW_ZERO;
306 if (zynqmp_type_flag & ZYNQMP_CLK_DIVIDER_POWER_OF_TWO)
307 ccf_flag |= CLK_DIVIDER_HIWORD_MASK;
308 if (zynqmp_type_flag & ZYNQMP_CLK_DIVIDER_ROUND_CLOSEST)
309 ccf_flag |= CLK_DIVIDER_ROUND_CLOSEST;
310 if (zynqmp_type_flag & ZYNQMP_CLK_DIVIDER_READ_ONLY)
311 ccf_flag |= CLK_DIVIDER_READ_ONLY;
312 if (zynqmp_type_flag & ZYNQMP_CLK_DIVIDER_MAX_AT_ZERO)
313 ccf_flag |= CLK_DIVIDER_MAX_AT_ZERO;
314
315 return ccf_flag;
316}
317
318/**
319 * zynqmp_clk_register_divider() - Register a divider clock
320 * @name: Name of this clock
321 * @clk_id: Id of clock
322 * @parents: Name of this clock's parents
323 * @num_parents: Number of parents
324 * @nodes: Clock topology node
325 *
326 * Return: clock hardware to registered clock divider
327 */
328struct clk_hw *zynqmp_clk_register_divider(const char *name,
329 u32 clk_id,
330 const char * const *parents,
331 u8 num_parents,
332 const struct clock_topology *nodes)
333{
334 struct zynqmp_clk_divider *div;
335 struct clk_hw *hw;
336 struct clk_init_data init;
337 int ret;
338
339 /* allocate the divider */
340 div = kzalloc(size: sizeof(*div), GFP_KERNEL);
341 if (!div)
342 return ERR_PTR(error: -ENOMEM);
343
344 init.name = name;
345 if (nodes->type_flag & CLK_DIVIDER_READ_ONLY)
346 init.ops = &zynqmp_clk_divider_ro_ops;
347 else
348 init.ops = &zynqmp_clk_divider_ops;
349
350 init.flags = zynqmp_clk_map_common_ccf_flags(zynqmp_flag: nodes->flag);
351
352 init.parent_names = parents;
353 init.num_parents = 1;
354
355 /* struct clk_divider assignments */
356 div->is_frac = !!((nodes->flag & CLK_FRAC) |
357 (nodes->custom_type_flag & CUSTOM_FLAG_CLK_FRAC));
358 div->flags = zynqmp_clk_map_divider_ccf_flags(zynqmp_type_flag: nodes->type_flag);
359 div->hw.init = &init;
360 div->clk_id = clk_id;
361 div->div_type = nodes->type;
362
363 /*
364 * To achieve best possible rate, maximum limit of divider is required
365 * while computation.
366 */
367 div->max_div = zynqmp_clk_get_max_divisor(clk_id, type: nodes->type);
368
369 hw = &div->hw;
370 ret = clk_hw_register(NULL, hw);
371 if (ret) {
372 kfree(objp: div);
373 hw = ERR_PTR(error: ret);
374 }
375
376 return hw;
377}
378

source code of linux/drivers/clk/zynqmp/divider.c