1/*
2 * max8973-regulator.c -- Maxim max8973
3 *
4 * Regulator driver for MAXIM 8973 DC-DC step-down switching regulator.
5 *
6 * Copyright (c) 2012, NVIDIA Corporation.
7 *
8 * Author: Laxman Dewangan <ldewangan@nvidia.com>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation version 2.
13 *
14 * This program is distributed "as is" WITHOUT ANY WARRANTY of any kind,
15 * whether express or implied; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
22 * 02111-1307, USA
23 */
24
25#include <linux/kernel.h>
26#include <linux/module.h>
27#include <linux/init.h>
28#include <linux/err.h>
29#include <linux/of.h>
30#include <linux/platform_device.h>
31#include <linux/regulator/driver.h>
32#include <linux/regulator/machine.h>
33#include <linux/regulator/max8973-regulator.h>
34#include <linux/regulator/of_regulator.h>
35#include <linux/gpio.h>
36#include <linux/i2c.h>
37#include <linux/slab.h>
38#include <linux/regmap.h>
39
40/* Register definitions */
41#define MAX8973_VOUT					0x0
42#define MAX8973_VOUT_DVS				0x1
43#define MAX8973_CONTROL1				0x2
44#define MAX8973_CONTROL2				0x3
45#define MAX8973_CHIPID1					0x4
46#define MAX8973_CHIPID2					0x5
47
48#define MAX8973_MAX_VOUT_REG				2
49
50/* MAX8973_VOUT */
51#define MAX8973_VOUT_ENABLE				BIT(7)
52#define MAX8973_VOUT_MASK				0x7F
53
54/* MAX8973_VOUT_DVS */
55#define MAX8973_DVS_VOUT_MASK				0x7F
56
57/* MAX8973_CONTROL1 */
58#define MAX8973_SNS_ENABLE				BIT(7)
59#define MAX8973_FPWM_EN_M				BIT(6)
60#define MAX8973_NFSR_ENABLE				BIT(5)
61#define MAX8973_AD_ENABLE				BIT(4)
62#define MAX8973_BIAS_ENABLE				BIT(3)
63#define MAX8973_FREQSHIFT_9PER				BIT(2)
64
65#define MAX8973_RAMP_12mV_PER_US			0x0
66#define MAX8973_RAMP_25mV_PER_US			0x1
67#define MAX8973_RAMP_50mV_PER_US			0x2
68#define MAX8973_RAMP_200mV_PER_US			0x3
69
70/* MAX8973_CONTROL2 */
71#define MAX8973_WDTMR_ENABLE				BIT(6)
72#define MAX8973_DISCH_ENBABLE				BIT(5)
73#define MAX8973_FT_ENABLE				BIT(4)
74
75#define MAX8973_CKKADV_TRIP_DISABLE			0xC
76#define MAX8973_CKKADV_TRIP_75mV_PER_US			0x0
77#define MAX8973_CKKADV_TRIP_150mV_PER_US		0x4
78#define MAX8973_CKKADV_TRIP_75mV_PER_US_HIST_DIS	0x8
79#define MAX8973_CONTROL_CLKADV_TRIP_MASK		0x00030000
80
81#define MAX8973_INDUCTOR_MIN_30_PER			0x0
82#define MAX8973_INDUCTOR_NOMINAL			0x1
83#define MAX8973_INDUCTOR_PLUS_30_PER			0x2
84#define MAX8973_INDUCTOR_PLUS_60_PER			0x3
85#define MAX8973_CONTROL_INDUCTOR_VALUE_MASK		0x00300000
86
87#define MAX8973_MIN_VOLATGE				606250
88#define MAX8973_MAX_VOLATGE				1400000
89#define MAX8973_VOLATGE_STEP				6250
90#define MAX8973_BUCK_N_VOLTAGE				0x80
91
92/* Maxim 8973 chip information */
93struct max8973_chip {
94	struct device *dev;
95	struct regulator_desc desc;
96	struct regmap *regmap;
97	bool enable_external_control;
98	int dvs_gpio;
99	int lru_index[MAX8973_MAX_VOUT_REG];
100	int curr_vout_val[MAX8973_MAX_VOUT_REG];
101	int curr_vout_reg;
102	int curr_gpio_val;
103	bool valid_dvs_gpio;
104	struct regulator_ops ops;
105};
106
107/*
108 * find_voltage_set_register: Find new voltage configuration register (VOUT).
109 * The finding of the new VOUT register will be based on the LRU mechanism.
110 * Each VOUT register will have different voltage configured . This
111 * Function will look if any of the VOUT register have requested voltage set
112 * or not.
113 *     - If it is already there then it will make that register as most
114 *       recently used and return as found so that caller need not to set
115 *       the VOUT register but need to set the proper gpios to select this
116 *       VOUT register.
117 *     - If requested voltage is not found then it will use the least
118 *       recently mechanism to get new VOUT register for new configuration
119 *       and will return not_found so that caller need to set new VOUT
120 *       register and then gpios (both).
121 */
122static bool find_voltage_set_register(struct max8973_chip *tps,
123		int req_vsel, int *vout_reg, int *gpio_val)
124{
125	int i;
126	bool found = false;
127	int new_vout_reg = tps->lru_index[MAX8973_MAX_VOUT_REG - 1];
128	int found_index = MAX8973_MAX_VOUT_REG - 1;
129
130	for (i = 0; i < MAX8973_MAX_VOUT_REG; ++i) {
131		if (tps->curr_vout_val[tps->lru_index[i]] == req_vsel) {
132			new_vout_reg = tps->lru_index[i];
133			found_index = i;
134			found = true;
135			goto update_lru_index;
136		}
137	}
138
139update_lru_index:
140	for (i = found_index; i > 0; i--)
141		tps->lru_index[i] = tps->lru_index[i - 1];
142
143	tps->lru_index[0] = new_vout_reg;
144	*gpio_val = new_vout_reg;
145	*vout_reg = MAX8973_VOUT + new_vout_reg;
146	return found;
147}
148
149static int max8973_dcdc_get_voltage_sel(struct regulator_dev *rdev)
150{
151	struct max8973_chip *max = rdev_get_drvdata(rdev);
152	unsigned int data;
153	int ret;
154
155	ret = regmap_read(max->regmap, max->curr_vout_reg, &data);
156	if (ret < 0) {
157		dev_err(max->dev, "register %d read failed, err = %d\n",
158			max->curr_vout_reg, ret);
159		return ret;
160	}
161	return data & MAX8973_VOUT_MASK;
162}
163
164static int max8973_dcdc_set_voltage_sel(struct regulator_dev *rdev,
165	     unsigned vsel)
166{
167	struct max8973_chip *max = rdev_get_drvdata(rdev);
168	int ret;
169	bool found = false;
170	int vout_reg = max->curr_vout_reg;
171	int gpio_val = max->curr_gpio_val;
172
173	/*
174	 * If gpios are available to select the VOUT register then least
175	 * recently used register for new configuration.
176	 */
177	if (max->valid_dvs_gpio)
178		found = find_voltage_set_register(max, vsel,
179					&vout_reg, &gpio_val);
180
181	if (!found) {
182		ret = regmap_update_bits(max->regmap, vout_reg,
183					MAX8973_VOUT_MASK, vsel);
184		if (ret < 0) {
185			dev_err(max->dev, "register %d update failed, err %d\n",
186				 vout_reg, ret);
187			return ret;
188		}
189		max->curr_vout_reg = vout_reg;
190		max->curr_vout_val[gpio_val] = vsel;
191	}
192
193	/* Select proper VOUT register vio gpios */
194	if (max->valid_dvs_gpio) {
195		gpio_set_value_cansleep(max->dvs_gpio, gpio_val & 0x1);
196		max->curr_gpio_val = gpio_val;
197	}
198	return 0;
199}
200
201static int max8973_dcdc_set_mode(struct regulator_dev *rdev, unsigned int mode)
202{
203	struct max8973_chip *max = rdev_get_drvdata(rdev);
204	int ret;
205	int pwm;
206
207	/* Enable force PWM mode in FAST mode only. */
208	switch (mode) {
209	case REGULATOR_MODE_FAST:
210		pwm = MAX8973_FPWM_EN_M;
211		break;
212
213	case REGULATOR_MODE_NORMAL:
214		pwm = 0;
215		break;
216
217	default:
218		return -EINVAL;
219	}
220
221	ret = regmap_update_bits(max->regmap, MAX8973_CONTROL1,
222				MAX8973_FPWM_EN_M, pwm);
223	if (ret < 0)
224		dev_err(max->dev, "register %d update failed, err %d\n",
225				MAX8973_CONTROL1, ret);
226	return ret;
227}
228
229static unsigned int max8973_dcdc_get_mode(struct regulator_dev *rdev)
230{
231	struct max8973_chip *max = rdev_get_drvdata(rdev);
232	unsigned int data;
233	int ret;
234
235	ret = regmap_read(max->regmap, MAX8973_CONTROL1, &data);
236	if (ret < 0) {
237		dev_err(max->dev, "register %d read failed, err %d\n",
238				MAX8973_CONTROL1, ret);
239		return ret;
240	}
241	return (data & MAX8973_FPWM_EN_M) ?
242		REGULATOR_MODE_FAST : REGULATOR_MODE_NORMAL;
243}
244
245static const struct regulator_ops max8973_dcdc_ops = {
246	.get_voltage_sel	= max8973_dcdc_get_voltage_sel,
247	.set_voltage_sel	= max8973_dcdc_set_voltage_sel,
248	.list_voltage		= regulator_list_voltage_linear,
249	.set_mode		= max8973_dcdc_set_mode,
250	.get_mode		= max8973_dcdc_get_mode,
251};
252
253static int max8973_init_dcdc(struct max8973_chip *max,
254			     struct max8973_regulator_platform_data *pdata)
255{
256	int ret;
257	uint8_t	control1 = 0;
258	uint8_t control2 = 0;
259
260	if (pdata->control_flags & MAX8973_CONTROL_REMOTE_SENSE_ENABLE)
261		control1 |= MAX8973_SNS_ENABLE;
262
263	if (!(pdata->control_flags & MAX8973_CONTROL_FALLING_SLEW_RATE_ENABLE))
264		control1 |= MAX8973_NFSR_ENABLE;
265
266	if (pdata->control_flags & MAX8973_CONTROL_OUTPUT_ACTIVE_DISCH_ENABLE)
267		control1 |= MAX8973_AD_ENABLE;
268
269	if (pdata->control_flags & MAX8973_CONTROL_BIAS_ENABLE)
270		control1 |= MAX8973_BIAS_ENABLE;
271
272	if (pdata->control_flags & MAX8973_CONTROL_FREQ_SHIFT_9PER_ENABLE)
273		control1 |= MAX8973_FREQSHIFT_9PER;
274
275	/* Set ramp delay */
276	if (pdata->reg_init_data &&
277			pdata->reg_init_data->constraints.ramp_delay) {
278		if (pdata->reg_init_data->constraints.ramp_delay < 25000)
279			control1 |= MAX8973_RAMP_12mV_PER_US;
280		else if (pdata->reg_init_data->constraints.ramp_delay < 50000)
281			control1 |= MAX8973_RAMP_25mV_PER_US;
282		else if (pdata->reg_init_data->constraints.ramp_delay < 200000)
283			control1 |= MAX8973_RAMP_50mV_PER_US;
284		else
285			control1 |= MAX8973_RAMP_200mV_PER_US;
286	} else {
287		control1 |= MAX8973_RAMP_12mV_PER_US;
288		max->desc.ramp_delay = 12500;
289	}
290
291	if (!(pdata->control_flags & MAX8973_CONTROL_PULL_DOWN_ENABLE))
292		control2 |= MAX8973_DISCH_ENBABLE;
293
294	/*  Clock advance trip configuration */
295	switch (pdata->control_flags & MAX8973_CONTROL_CLKADV_TRIP_MASK) {
296	case MAX8973_CONTROL_CLKADV_TRIP_DISABLED:
297		control2 |= MAX8973_CKKADV_TRIP_DISABLE;
298		break;
299
300	case MAX8973_CONTROL_CLKADV_TRIP_75mV_PER_US:
301		control2 |= MAX8973_CKKADV_TRIP_75mV_PER_US;
302		break;
303
304	case MAX8973_CONTROL_CLKADV_TRIP_150mV_PER_US:
305		control2 |= MAX8973_CKKADV_TRIP_150mV_PER_US;
306		break;
307
308	case MAX8973_CONTROL_CLKADV_TRIP_75mV_PER_US_HIST_DIS:
309		control2 |= MAX8973_CKKADV_TRIP_75mV_PER_US_HIST_DIS;
310		break;
311	}
312
313	/* Configure inductor value */
314	switch (pdata->control_flags & MAX8973_CONTROL_INDUCTOR_VALUE_MASK) {
315	case MAX8973_CONTROL_INDUCTOR_VALUE_NOMINAL:
316		control2 |= MAX8973_INDUCTOR_NOMINAL;
317		break;
318
319	case MAX8973_CONTROL_INDUCTOR_VALUE_MINUS_30_PER:
320		control2 |= MAX8973_INDUCTOR_MIN_30_PER;
321		break;
322
323	case MAX8973_CONTROL_INDUCTOR_VALUE_PLUS_30_PER:
324		control2 |= MAX8973_INDUCTOR_PLUS_30_PER;
325		break;
326
327	case MAX8973_CONTROL_INDUCTOR_VALUE_PLUS_60_PER:
328		control2 |= MAX8973_INDUCTOR_PLUS_60_PER;
329		break;
330	}
331
332	ret = regmap_write(max->regmap, MAX8973_CONTROL1, control1);
333	if (ret < 0) {
334		dev_err(max->dev, "register %d write failed, err = %d",
335				MAX8973_CONTROL1, ret);
336		return ret;
337	}
338
339	ret = regmap_write(max->regmap, MAX8973_CONTROL2, control2);
340	if (ret < 0) {
341		dev_err(max->dev, "register %d write failed, err = %d",
342				MAX8973_CONTROL2, ret);
343		return ret;
344	}
345
346	/* If external control is enabled then disable EN bit */
347	if (max->enable_external_control) {
348		ret = regmap_update_bits(max->regmap, MAX8973_VOUT,
349						MAX8973_VOUT_ENABLE, 0);
350		if (ret < 0)
351			dev_err(max->dev, "register %d update failed, err = %d",
352				MAX8973_VOUT, ret);
353	}
354	return ret;
355}
356
357static const struct regmap_config max8973_regmap_config = {
358	.reg_bits		= 8,
359	.val_bits		= 8,
360	.max_register		= MAX8973_CHIPID2,
361	.cache_type		= REGCACHE_RBTREE,
362};
363
364static int max8973_probe(struct i2c_client *client,
365			 const struct i2c_device_id *id)
366{
367	struct max8973_regulator_platform_data *pdata;
368	struct regulator_config config = { };
369	struct regulator_dev *rdev;
370	struct max8973_chip *max;
371	int ret;
372
373	pdata = dev_get_platdata(&client->dev);
374
375	if (!pdata && !client->dev.of_node) {
376		dev_err(&client->dev, "No Platform data");
377		return -EIO;
378	}
379
380	max = devm_kzalloc(&client->dev, sizeof(*max), GFP_KERNEL);
381	if (!max)
382		return -ENOMEM;
383
384	max->regmap = devm_regmap_init_i2c(client, &max8973_regmap_config);
385	if (IS_ERR(max->regmap)) {
386		ret = PTR_ERR(max->regmap);
387		dev_err(&client->dev, "regmap init failed, err %d\n", ret);
388		return ret;
389	}
390
391	i2c_set_clientdata(client, max);
392	max->ops = max8973_dcdc_ops;
393	max->dev = &client->dev;
394	max->desc.name = id->name;
395	max->desc.id = 0;
396	max->desc.ops = &max->ops;
397	max->desc.type = REGULATOR_VOLTAGE;
398	max->desc.owner = THIS_MODULE;
399	max->desc.min_uV = MAX8973_MIN_VOLATGE;
400	max->desc.uV_step = MAX8973_VOLATGE_STEP;
401	max->desc.n_voltages = MAX8973_BUCK_N_VOLTAGE;
402
403	if (!pdata || !pdata->enable_ext_control) {
404		max->desc.enable_reg = MAX8973_VOUT;
405		max->desc.enable_mask = MAX8973_VOUT_ENABLE;
406		max->ops.enable = regulator_enable_regmap;
407		max->ops.disable = regulator_disable_regmap;
408		max->ops.is_enabled = regulator_is_enabled_regmap;
409	}
410
411	if (pdata) {
412		max->dvs_gpio = pdata->dvs_gpio;
413		max->enable_external_control = pdata->enable_ext_control;
414		max->curr_gpio_val = pdata->dvs_def_state;
415		max->curr_vout_reg = MAX8973_VOUT + pdata->dvs_def_state;
416	} else {
417		max->dvs_gpio = -EINVAL;
418		max->curr_vout_reg = MAX8973_VOUT;
419	}
420
421	max->lru_index[0] = max->curr_vout_reg;
422
423	if (gpio_is_valid(max->dvs_gpio)) {
424		int gpio_flags;
425		int i;
426
427		gpio_flags = (pdata->dvs_def_state) ?
428				GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
429		ret = devm_gpio_request_one(&client->dev, max->dvs_gpio,
430				gpio_flags, "max8973-dvs");
431		if (ret) {
432			dev_err(&client->dev,
433				"gpio_request for gpio %d failed, err = %d\n",
434				max->dvs_gpio, ret);
435			return ret;
436		}
437		max->valid_dvs_gpio = true;
438
439		/*
440		 * Initialize the lru index with vout_reg id
441		 * The index 0 will be most recently used and
442		 * set with the max->curr_vout_reg */
443		for (i = 0; i < MAX8973_MAX_VOUT_REG; ++i)
444			max->lru_index[i] = i;
445		max->lru_index[0] = max->curr_vout_reg;
446		max->lru_index[max->curr_vout_reg] = 0;
447	} else {
448		max->valid_dvs_gpio = false;
449	}
450
451	if (pdata) {
452		ret = max8973_init_dcdc(max, pdata);
453		if (ret < 0) {
454			dev_err(max->dev, "Max8973 Init failed, err = %d\n", ret);
455			return ret;
456		}
457	}
458
459	config.dev = &client->dev;
460	config.init_data = pdata ? pdata->reg_init_data :
461		of_get_regulator_init_data(&client->dev, client->dev.of_node);
462	config.driver_data = max;
463	config.of_node = client->dev.of_node;
464	config.regmap = max->regmap;
465
466	/* Register the regulators */
467	rdev = devm_regulator_register(&client->dev, &max->desc, &config);
468	if (IS_ERR(rdev)) {
469		ret = PTR_ERR(rdev);
470		dev_err(max->dev, "regulator register failed, err %d\n", ret);
471		return ret;
472	}
473
474	return 0;
475}
476
477static const struct i2c_device_id max8973_id[] = {
478	{.name = "max8973",},
479	{},
480};
481
482MODULE_DEVICE_TABLE(i2c, max8973_id);
483
484static struct i2c_driver max8973_i2c_driver = {
485	.driver = {
486		.name = "max8973",
487		.owner = THIS_MODULE,
488	},
489	.probe = max8973_probe,
490	.id_table = max8973_id,
491};
492
493static int __init max8973_init(void)
494{
495	return i2c_add_driver(&max8973_i2c_driver);
496}
497subsys_initcall(max8973_init);
498
499static void __exit max8973_cleanup(void)
500{
501	i2c_del_driver(&max8973_i2c_driver);
502}
503module_exit(max8973_cleanup);
504
505MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
506MODULE_DESCRIPTION("MAX8973 voltage regulator driver");
507MODULE_LICENSE("GPL v2");
508