1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Driver for Silicon Labs Si514 Programmable Oscillator
4 *
5 * Copyright (C) 2015 Topic Embedded Products
6 *
7 * Author: Mike Looijmans <mike.looijmans@topic.nl>
8 */
9
10#include <linux/clk-provider.h>
11#include <linux/delay.h>
12#include <linux/module.h>
13#include <linux/i2c.h>
14#include <linux/regmap.h>
15#include <linux/slab.h>
16
17/* I2C registers */
18#define SI514_REG_LP 0
19#define SI514_REG_M_FRAC1 5
20#define SI514_REG_M_FRAC2 6
21#define SI514_REG_M_FRAC3 7
22#define SI514_REG_M_INT_FRAC 8
23#define SI514_REG_M_INT 9
24#define SI514_REG_HS_DIV 10
25#define SI514_REG_LS_HS_DIV 11
26#define SI514_REG_OE_STATE 14
27#define SI514_REG_RESET 128
28#define SI514_REG_CONTROL 132
29
30/* Register values */
31#define SI514_RESET_RST BIT(7)
32
33#define SI514_CONTROL_FCAL BIT(0)
34#define SI514_CONTROL_OE BIT(2)
35
36#define SI514_MIN_FREQ 100000U
37#define SI514_MAX_FREQ 250000000U
38
39#define FXO 31980000U
40
41#define FVCO_MIN 2080000000U
42#define FVCO_MAX 2500000000U
43
44#define HS_DIV_MAX 1022
45
46struct clk_si514 {
47 struct clk_hw hw;
48 struct regmap *regmap;
49 struct i2c_client *i2c_client;
50};
51#define to_clk_si514(_hw) container_of(_hw, struct clk_si514, hw)
52
53/* Multiplier/divider settings */
54struct clk_si514_muldiv {
55 u32 m_frac; /* 29-bit Fractional part of multiplier M */
56 u8 m_int; /* Integer part of multiplier M, 65..78 */
57 u8 ls_div_bits; /* 2nd divider, as 2^x */
58 u16 hs_div; /* 1st divider, must be even and 10<=x<=1022 */
59};
60
61/* Enables or disables the output driver */
62static int si514_enable_output(struct clk_si514 *data, bool enable)
63{
64 return regmap_update_bits(map: data->regmap, SI514_REG_CONTROL,
65 SI514_CONTROL_OE, val: enable ? SI514_CONTROL_OE : 0);
66}
67
68static int si514_prepare(struct clk_hw *hw)
69{
70 struct clk_si514 *data = to_clk_si514(hw);
71
72 return si514_enable_output(data, enable: true);
73}
74
75static void si514_unprepare(struct clk_hw *hw)
76{
77 struct clk_si514 *data = to_clk_si514(hw);
78
79 si514_enable_output(data, enable: false);
80}
81
82static int si514_is_prepared(struct clk_hw *hw)
83{
84 struct clk_si514 *data = to_clk_si514(hw);
85 unsigned int val;
86 int err;
87
88 err = regmap_read(map: data->regmap, SI514_REG_CONTROL, val: &val);
89 if (err < 0)
90 return err;
91
92 return !!(val & SI514_CONTROL_OE);
93}
94
95/* Retrieve clock multiplier and dividers from hardware */
96static int si514_get_muldiv(struct clk_si514 *data,
97 struct clk_si514_muldiv *settings)
98{
99 int err;
100 u8 reg[7];
101
102 err = regmap_bulk_read(map: data->regmap, SI514_REG_M_FRAC1,
103 val: reg, ARRAY_SIZE(reg));
104 if (err)
105 return err;
106
107 settings->m_frac = reg[0] | reg[1] << 8 | reg[2] << 16 |
108 (reg[3] & 0x1F) << 24;
109 settings->m_int = (reg[4] & 0x3f) << 3 | reg[3] >> 5;
110 settings->ls_div_bits = (reg[6] >> 4) & 0x07;
111 settings->hs_div = (reg[6] & 0x03) << 8 | reg[5];
112 return 0;
113}
114
115static int si514_set_muldiv(struct clk_si514 *data,
116 struct clk_si514_muldiv *settings)
117{
118 u8 lp;
119 u8 reg[7];
120 int err;
121
122 /* Calculate LP1/LP2 according to table 13 in the datasheet */
123 /* 65.259980246 */
124 if (settings->m_int < 65 ||
125 (settings->m_int == 65 && settings->m_frac <= 139575831))
126 lp = 0x22;
127 /* 67.859763463 */
128 else if (settings->m_int < 67 ||
129 (settings->m_int == 67 && settings->m_frac <= 461581994))
130 lp = 0x23;
131 /* 72.937624981 */
132 else if (settings->m_int < 72 ||
133 (settings->m_int == 72 && settings->m_frac <= 503383578))
134 lp = 0x33;
135 /* 75.843265046 */
136 else if (settings->m_int < 75 ||
137 (settings->m_int == 75 && settings->m_frac <= 452724474))
138 lp = 0x34;
139 else
140 lp = 0x44;
141
142 err = regmap_write(map: data->regmap, SI514_REG_LP, val: lp);
143 if (err < 0)
144 return err;
145
146 reg[0] = settings->m_frac;
147 reg[1] = settings->m_frac >> 8;
148 reg[2] = settings->m_frac >> 16;
149 reg[3] = settings->m_frac >> 24 | settings->m_int << 5;
150 reg[4] = settings->m_int >> 3;
151 reg[5] = settings->hs_div;
152 reg[6] = (settings->hs_div >> 8) | (settings->ls_div_bits << 4);
153
154 err = regmap_bulk_write(map: data->regmap, SI514_REG_HS_DIV, val: reg + 5, val_count: 2);
155 if (err < 0)
156 return err;
157 /*
158 * Writing to SI514_REG_M_INT_FRAC triggers the clock change, so that
159 * must be written last
160 */
161 return regmap_bulk_write(map: data->regmap, SI514_REG_M_FRAC1, val: reg, val_count: 5);
162}
163
164/* Calculate divider settings for a given frequency */
165static int si514_calc_muldiv(struct clk_si514_muldiv *settings,
166 unsigned long frequency)
167{
168 u64 m;
169 u32 ls_freq;
170 u32 tmp;
171 u8 res;
172
173 if ((frequency < SI514_MIN_FREQ) || (frequency > SI514_MAX_FREQ))
174 return -EINVAL;
175
176 /* Determine the minimum value of LS_DIV and resulting target freq. */
177 ls_freq = frequency;
178 if (frequency >= (FVCO_MIN / HS_DIV_MAX))
179 settings->ls_div_bits = 0;
180 else {
181 res = 1;
182 tmp = 2 * HS_DIV_MAX;
183 while (tmp <= (HS_DIV_MAX * 32)) {
184 if ((frequency * tmp) >= FVCO_MIN)
185 break;
186 ++res;
187 tmp <<= 1;
188 }
189 settings->ls_div_bits = res;
190 ls_freq = frequency << res;
191 }
192
193 /* Determine minimum HS_DIV, round up to even number */
194 settings->hs_div = DIV_ROUND_UP(FVCO_MIN >> 1, ls_freq) << 1;
195
196 /* M = LS_DIV x HS_DIV x frequency / F_XO (in fixed-point) */
197 m = ((u64)(ls_freq * settings->hs_div) << 29) + (FXO / 2);
198 do_div(m, FXO);
199 settings->m_frac = (u32)m & (BIT(29) - 1);
200 settings->m_int = (u32)(m >> 29);
201
202 return 0;
203}
204
205/* Calculate resulting frequency given the register settings */
206static unsigned long si514_calc_rate(struct clk_si514_muldiv *settings)
207{
208 u64 m = settings->m_frac | ((u64)settings->m_int << 29);
209 u32 d = settings->hs_div * BIT(settings->ls_div_bits);
210
211 return ((u32)(((m * FXO) + (FXO / 2)) >> 29)) / d;
212}
213
214static unsigned long si514_recalc_rate(struct clk_hw *hw,
215 unsigned long parent_rate)
216{
217 struct clk_si514 *data = to_clk_si514(hw);
218 struct clk_si514_muldiv settings;
219 int err;
220
221 err = si514_get_muldiv(data, settings: &settings);
222 if (err) {
223 dev_err(&data->i2c_client->dev, "unable to retrieve settings\n");
224 return 0;
225 }
226
227 return si514_calc_rate(settings: &settings);
228}
229
230static int si514_determine_rate(struct clk_hw *hw,
231 struct clk_rate_request *req)
232{
233 struct clk_si514_muldiv settings;
234 int err;
235
236 if (!req->rate) {
237 req->rate = 0;
238
239 return 0;
240 }
241
242 err = si514_calc_muldiv(settings: &settings, frequency: req->rate);
243 if (err) {
244 req->rate = err;
245
246 return 0;
247 }
248
249 req->rate = si514_calc_rate(settings: &settings);
250
251 return 0;
252}
253
254/*
255 * Update output frequency for big frequency changes (> 1000 ppm).
256 * The chip supports <1000ppm changes "on the fly", we haven't implemented
257 * that here.
258 */
259static int si514_set_rate(struct clk_hw *hw, unsigned long rate,
260 unsigned long parent_rate)
261{
262 struct clk_si514 *data = to_clk_si514(hw);
263 struct clk_si514_muldiv settings;
264 unsigned int old_oe_state;
265 int err;
266
267 err = si514_calc_muldiv(settings: &settings, frequency: rate);
268 if (err)
269 return err;
270
271 err = regmap_read(map: data->regmap, SI514_REG_CONTROL, val: &old_oe_state);
272 if (err)
273 return err;
274
275 si514_enable_output(data, enable: false);
276
277 err = si514_set_muldiv(data, settings: &settings);
278 if (err < 0)
279 return err; /* Undefined state now, best to leave disabled */
280
281 /* Trigger calibration */
282 err = regmap_write(map: data->regmap, SI514_REG_CONTROL, SI514_CONTROL_FCAL);
283 if (err < 0)
284 return err;
285
286 /* Applying a new frequency can take up to 10ms */
287 usleep_range(min: 10000, max: 12000);
288
289 if (old_oe_state & SI514_CONTROL_OE)
290 si514_enable_output(data, enable: true);
291
292 return err;
293}
294
295static const struct clk_ops si514_clk_ops = {
296 .prepare = si514_prepare,
297 .unprepare = si514_unprepare,
298 .is_prepared = si514_is_prepared,
299 .recalc_rate = si514_recalc_rate,
300 .determine_rate = si514_determine_rate,
301 .set_rate = si514_set_rate,
302};
303
304static bool si514_regmap_is_volatile(struct device *dev, unsigned int reg)
305{
306 switch (reg) {
307 case SI514_REG_CONTROL:
308 case SI514_REG_RESET:
309 return true;
310 default:
311 return false;
312 }
313}
314
315static bool si514_regmap_is_writeable(struct device *dev, unsigned int reg)
316{
317 switch (reg) {
318 case SI514_REG_LP:
319 case SI514_REG_M_FRAC1 ... SI514_REG_LS_HS_DIV:
320 case SI514_REG_OE_STATE:
321 case SI514_REG_RESET:
322 case SI514_REG_CONTROL:
323 return true;
324 default:
325 return false;
326 }
327}
328
329static const struct regmap_config si514_regmap_config = {
330 .reg_bits = 8,
331 .val_bits = 8,
332 .cache_type = REGCACHE_MAPLE,
333 .max_register = SI514_REG_CONTROL,
334 .writeable_reg = si514_regmap_is_writeable,
335 .volatile_reg = si514_regmap_is_volatile,
336};
337
338static int si514_probe(struct i2c_client *client)
339{
340 struct clk_si514 *data;
341 struct clk_init_data init;
342 int err;
343
344 data = devm_kzalloc(dev: &client->dev, size: sizeof(*data), GFP_KERNEL);
345 if (!data)
346 return -ENOMEM;
347
348 init.ops = &si514_clk_ops;
349 init.flags = 0;
350 init.num_parents = 0;
351 data->hw.init = &init;
352 data->i2c_client = client;
353
354 if (of_property_read_string(np: client->dev.of_node, propname: "clock-output-names",
355 out_string: &init.name))
356 init.name = client->dev.of_node->name;
357
358 data->regmap = devm_regmap_init_i2c(client, &si514_regmap_config);
359 if (IS_ERR(ptr: data->regmap)) {
360 dev_err(&client->dev, "failed to allocate register map\n");
361 return PTR_ERR(ptr: data->regmap);
362 }
363
364 i2c_set_clientdata(client, data);
365
366 err = devm_clk_hw_register(dev: &client->dev, hw: &data->hw);
367 if (err) {
368 dev_err(&client->dev, "clock registration failed\n");
369 return err;
370 }
371 err = devm_of_clk_add_hw_provider(dev: &client->dev, get: of_clk_hw_simple_get,
372 data: &data->hw);
373 if (err) {
374 dev_err(&client->dev, "unable to add clk provider\n");
375 return err;
376 }
377
378 return 0;
379}
380
381static const struct i2c_device_id si514_id[] = {
382 { "si514" },
383 { }
384};
385MODULE_DEVICE_TABLE(i2c, si514_id);
386
387static const struct of_device_id clk_si514_of_match[] = {
388 { .compatible = "silabs,si514" },
389 { },
390};
391MODULE_DEVICE_TABLE(of, clk_si514_of_match);
392
393static struct i2c_driver si514_driver = {
394 .driver = {
395 .name = "si514",
396 .of_match_table = clk_si514_of_match,
397 },
398 .probe = si514_probe,
399 .id_table = si514_id,
400};
401module_i2c_driver(si514_driver);
402
403MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
404MODULE_DESCRIPTION("Si514 driver");
405MODULE_LICENSE("GPL");
406

source code of linux/drivers/clk/clk-si514.c