aboutsummaryrefslogtreecommitdiff
path: root/drivers/clk/clk-si514.c
blob: 09b6718956bd2184a219703a32b7738a84489253 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
/*
 * Driver for Silicon Labs Si514 Programmable Oscillator
 *
 * Copyright (C) 2015 Topic Embedded Products
 *
 * Author: Mike Looijmans <mike.looijmans@topic.nl>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/regmap.h>
#include <linux/slab.h>

/* I2C registers */
#define SI514_REG_LP		0
#define SI514_REG_M_FRAC1	5
#define SI514_REG_M_FRAC2	6
#define SI514_REG_M_FRAC3	7
#define SI514_REG_M_INT_FRAC	8
#define SI514_REG_M_INT		9
#define SI514_REG_HS_DIV	10
#define SI514_REG_LS_HS_DIV	11
#define SI514_REG_OE_STATE	14
#define SI514_REG_RESET		128
#define SI514_REG_CONTROL	132

/* Register values */
#define SI514_RESET_RST		BIT(7)

#define SI514_CONTROL_FCAL	BIT(0)
#define SI514_CONTROL_OE	BIT(2)

#define SI514_MIN_FREQ	    100000U
#define SI514_MAX_FREQ	 250000000U

#define FXO		  31980000U

#define FVCO_MIN	2080000000U
#define FVCO_MAX	2500000000U

#define HS_DIV_MAX	1022

struct clk_si514 {
	struct clk_hw hw;
	struct regmap *regmap;
	struct i2c_client *i2c_client;
};
#define to_clk_si514(_hw)	container_of(_hw, struct clk_si514, hw)

/* Multiplier/divider settings */
struct clk_si514_muldiv {
	u32 m_frac;  /* 29-bit Fractional part of multiplier M */
	u8 m_int; /* Integer part of multiplier M, 65..78 */
	u8 ls_div_bits; /* 2nd divider, as 2^x */
	u16 hs_div; /* 1st divider, must be even and 10<=x<=1022 */
};

/* Enables or disables the output driver */
static int si514_enable_output(struct clk_si514 *data, bool enable)
{
	return regmap_update_bits(data->regmap, SI514_REG_CONTROL,
		SI514_CONTROL_OE, enable ? SI514_CONTROL_OE : 0);
}

/* Retrieve clock multiplier and dividers from hardware */
static int si514_get_muldiv(struct clk_si514 *data,
	struct clk_si514_muldiv *settings)
{
	int err;
	u8 reg[7];

	err = regmap_bulk_read(data->regmap, SI514_REG_M_FRAC1,
			reg, ARRAY_SIZE(reg));
	if (err)
		return err;

	settings->m_frac = reg[0] | reg[1] << 8 | reg[2] << 16 |
			   (reg[3] & 0x1F) << 24;
	settings->m_int = (reg[4] & 0x3f) << 3 | reg[3] >> 5;
	settings->ls_div_bits = (reg[6] >> 4) & 0x07;
	settings->hs_div = (reg[6] & 0x03) << 8 | reg[5];
	return 0;
}

static int si514_set_muldiv(struct clk_si514 *data,
	struct clk_si514_muldiv *settings)
{
	u8 lp;
	u8 reg[7];
	int err;

	/* Calculate LP1/LP2 according to table 13 in the datasheet */
	/* 65.259980246 */
	if (settings->m_int < 65 ||
		(settings->m_int == 65 && settings->m_frac <= 139575831))
		lp = 0x22;
	/* 67.859763463 */
	else if (settings->m_int < 67 ||
		(settings->m_int == 67 && settings->m_frac <= 461581994))
		lp = 0x23;
	/* 72.937624981 */
	else if (settings->m_int < 72 ||
		(settings->m_int == 72 && settings->m_frac <= 503383578))
		lp = 0x33;
	/* 75.843265046 */
	else if (settings->m_int < 75 ||
		(settings->m_int == 75 && settings->m_frac <= 452724474))
		lp = 0x34;
	else
		lp = 0x44;

	err = regmap_write(data->regmap, SI514_REG_LP, lp);
	if (err < 0)
		return err;

	reg[0] = settings->m_frac;
	reg[1] = settings->m_frac >> 8;
	reg[2] = settings->m_frac >> 16;
	reg[3] = settings->m_frac >> 24 | settings->m_int << 5;
	reg[4] = settings->m_int >> 3;
	reg[5] = settings->hs_div;
	reg[6] = (settings->hs_div >> 8) | (settings->ls_div_bits << 4);

	err = regmap_bulk_write(data->regmap, SI514_REG_HS_DIV, reg + 5, 2);
	if (err < 0)
		return err;
	/*
	 * Writing to SI514_REG_M_INT_FRAC triggers the clock change, so that
	 * must be written last
	 */
	return regmap_bulk_write(data->regmap, SI514_REG_M_FRAC1, reg, 5);
}

/* Calculate divider settings for a given frequency */
static int si514_calc_muldiv(struct clk_si514_muldiv *settings,
	unsigned long frequency)
{
	u64 m;
	u32 ls_freq;
	u32 tmp;
	u8 res;

	if ((frequency < SI514_MIN_FREQ) || (frequency > SI514_MAX_FREQ))
		return -EINVAL;

	/* Determine the minimum value of LS_DIV and resulting target freq. */
	ls_freq = frequency;
	if (frequency >= (FVCO_MIN / HS_DIV_MAX))
		settings->ls_div_bits = 0;
	else {
		res = 1;
		tmp = 2 * HS_DIV_MAX;
		while (tmp <= (HS_DIV_MAX * 32)) {
			if ((frequency * tmp) >= FVCO_MIN)
				break;
			++res;
			tmp <<= 1;
		}
		settings->ls_div_bits = res;
		ls_freq = frequency << res;
	}

	/* Determine minimum HS_DIV, round up to even number */
	settings->hs_div = DIV_ROUND_UP(FVCO_MIN >> 1, ls_freq) << 1;

	/* M = LS_DIV x HS_DIV x frequency / F_XO (in fixed-point) */
	m = ((u64)(ls_freq * settings->hs_div) << 29) + (FXO / 2);
	do_div(m, FXO);
	settings->m_frac = (u32)m & (BIT(29) - 1);
	settings->m_int = (u32)(m >> 29);

	return 0;
}

/* Calculate resulting frequency given the register settings */
static unsigned long si514_calc_rate(struct clk_si514_muldiv *settings)
{
	u64 m = settings->m_frac | ((u64)settings->m_int << 29);
	u32 d = settings->hs_div * BIT(settings->ls_div_bits);

	return ((u32)(((m * FXO) + (FXO / 2)) >> 29)) / d;
}

static unsigned long si514_recalc_rate(struct clk_hw *hw,
		unsigned long parent_rate)
{
	struct clk_si514 *data = to_clk_si514(hw);
	struct clk_si514_muldiv settings;
	int err;

	err = si514_get_muldiv(data, &settings);
	if (err) {
		dev_err(&data->i2c_client->dev, "unable to retrieve settings\n");
		return 0;
	}

	return si514_calc_rate(&settings);
}

static long si514_round_rate(struct clk_hw *hw, unsigned long rate,
		unsigned long *parent_rate)
{
	struct clk_si514_muldiv settings;
	int err;

	if (!rate)
		return 0;

	err = si514_calc_muldiv(&settings, rate);
	if (err)
		return err;

	return si514_calc_rate(&settings);
}

/*
 * Update output frequency for big frequency changes (> 1000 ppm).
 * The chip supports <1000ppm changes "on the fly", we haven't implemented
 * that here.
 */
static int si514_set_rate(struct clk_hw *hw, unsigned long rate,
		unsigned long parent_rate)
{
	struct clk_si514 *data = to_clk_si514(hw);
	struct clk_si514_muldiv settings;
	int err;

	err = si514_calc_muldiv(&settings, rate);
	if (err)
		return err;

	si514_enable_output(data, false);

	err = si514_set_muldiv(data, &settings);
	if (err < 0)
		return err; /* Undefined state now, best to leave disabled */

	/* Trigger calibration */
	err = regmap_write(data->regmap, SI514_REG_CONTROL, SI514_CONTROL_FCAL);
	if (err < 0)
		return err;

	/* Applying a new frequency can take up to 10ms */
	usleep_range(10000, 12000);

	si514_enable_output(data, true);

	return err;
}

static const struct clk_ops si514_clk_ops = {
	.recalc_rate = si514_recalc_rate,
	.round_rate = si514_round_rate,
	.set_rate = si514_set_rate,
};

static bool si514_regmap_is_volatile(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case SI514_REG_CONTROL:
	case SI514_REG_RESET:
		return true;
	default:
		return false;
	}
}

static bool si514_regmap_is_writeable(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case SI514_REG_LP:
	case SI514_REG_M_FRAC1 ... SI514_REG_LS_HS_DIV:
	case SI514_REG_OE_STATE:
	case SI514_REG_RESET:
	case SI514_REG_CONTROL:
		return true;
	default:
		return false;
	}
}

static const struct regmap_config si514_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.cache_type = REGCACHE_RBTREE,
	.max_register = SI514_REG_CONTROL,
	.writeable_reg = si514_regmap_is_writeable,
	.volatile_reg = si514_regmap_is_volatile,
};

static int si514_probe(struct i2c_client *client,
		const struct i2c_device_id *id)
{
	struct clk_si514 *data;
	struct clk_init_data init;
	int err;

	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	init.ops = &si514_clk_ops;
	init.flags = 0;
	init.num_parents = 0;
	data->hw.init = &init;
	data->i2c_client = client;

	if (of_property_read_string(client->dev.of_node, "clock-output-names",
			&init.name))
		init.name = client->dev.of_node->name;

	data->regmap = devm_regmap_init_i2c(client, &si514_regmap_config);
	if (IS_ERR(data->regmap)) {
		dev_err(&client->dev, "failed to allocate register map\n");
		return PTR_ERR(data->regmap);
	}

	i2c_set_clientdata(client, data);

	err = devm_clk_hw_register(&client->dev, &data->hw);
	if (err) {
		dev_err(&client->dev, "clock registration failed\n");
		return err;
	}
	err = of_clk_add_hw_provider(client->dev.of_node, of_clk_hw_simple_get,
				     &data->hw);
	if (err) {
		dev_err(&client->dev, "unable to add clk provider\n");
		return err;
	}

	return 0;
}

static int si514_remove(struct i2c_client *client)
{
	of_clk_del_provider(client->dev.of_node);
	return 0;
}

static const struct i2c_device_id si514_id[] = {
	{ "si514", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, si514_id);

static const struct of_device_id clk_si514_of_match[] = {
	{ .compatible = "silabs,si514" },
	{ },
};
MODULE_DEVICE_TABLE(of, clk_si514_of_match);

static struct i2c_driver si514_driver = {
	.driver = {
		.name = "si514",
		.of_match_table = clk_si514_of_match,
	},
	.probe		= si514_probe,
	.remove		= si514_remove,
	.id_table	= si514_id,
};
module_i2c_driver(si514_driver);

MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
MODULE_DESCRIPTION("Si514 driver");
MODULE_LICENSE("GPL");