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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Azoteq IQS620A PWM Generator
4 *
5 * Copyright (C) 2019 Jeff LaBundy <jeff@labundy.com>
6 *
7 * Limitations:
8 * - The period is fixed to 1 ms and is generated continuously despite changes
9 * to the duty cycle or enable/disable state.
10 * - Changes to the duty cycle or enable/disable state take effect immediately
11 * and may result in a glitch during the period in which the change is made.
12 * - The device cannot generate a 0% duty cycle. For duty cycles below 1 / 256
13 * ms, the output is disabled and relies upon an external pull-down resistor
14 * to hold the GPIO3/LTX pin low.
15 */
16
17#include <linux/device.h>
18#include <linux/kernel.h>
19#include <linux/mfd/iqs62x.h>
20#include <linux/module.h>
21#include <linux/mutex.h>
22#include <linux/notifier.h>
23#include <linux/platform_device.h>
24#include <linux/pwm.h>
25#include <linux/regmap.h>
26#include <linux/slab.h>
27
28#define IQS620_PWR_SETTINGS 0xd2
29#define IQS620_PWR_SETTINGS_PWM_OUT BIT(7)
30
31#define IQS620_PWM_DUTY_CYCLE 0xd8
32
33#define IQS620_PWM_PERIOD_NS 1000000
34
35struct iqs620_pwm_private {
36 struct iqs62x_core *iqs62x;
37 struct pwm_chip chip;
38 struct notifier_block notifier;
39 struct mutex lock;
40 unsigned int duty_scale;
41};
42
43static int iqs620_pwm_init(struct iqs620_pwm_private *iqs620_pwm,
44 unsigned int duty_scale)
45{
46 struct iqs62x_core *iqs62x = iqs620_pwm->iqs62x;
47 int ret;
48
49 if (!duty_scale)
50 return regmap_clear_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
51 IQS620_PWR_SETTINGS_PWM_OUT);
52
53 ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
54 duty_scale - 1);
55 if (ret)
56 return ret;
57
58 return regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
59 IQS620_PWR_SETTINGS_PWM_OUT, 0xff);
60}
61
62static int iqs620_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
63 const struct pwm_state *state)
64{
65 struct iqs620_pwm_private *iqs620_pwm;
66 unsigned int duty_cycle;
67 unsigned int duty_scale;
68 int ret;
69
70 if (state->polarity != PWM_POLARITY_NORMAL)
71 return -EINVAL;
72
73 if (state->period < IQS620_PWM_PERIOD_NS)
74 return -EINVAL;
75
76 iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
77
78 /*
79 * The duty cycle generated by the device is calculated as follows:
80 *
81 * duty_cycle = (IQS620_PWM_DUTY_CYCLE + 1) / 256 * 1 ms
82 *
83 * ...where IQS620_PWM_DUTY_CYCLE is a register value between 0 and 255
84 * (inclusive). Therefore the lowest duty cycle the device can generate
85 * while the output is enabled is 1 / 256 ms.
86 *
87 * For lower duty cycles (e.g. 0), the PWM output is simply disabled to
88 * allow an external pull-down resistor to hold the GPIO3/LTX pin low.
89 */
90 duty_cycle = min_t(u64, state->duty_cycle, IQS620_PWM_PERIOD_NS);
91 duty_scale = duty_cycle * 256 / IQS620_PWM_PERIOD_NS;
92
93 if (!state->enabled)
94 duty_scale = 0;
95
96 mutex_lock(&iqs620_pwm->lock);
97
98 ret = iqs620_pwm_init(iqs620_pwm, duty_scale);
99 if (!ret)
100 iqs620_pwm->duty_scale = duty_scale;
101
102 mutex_unlock(&iqs620_pwm->lock);
103
104 return ret;
105}
106
107static int iqs620_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
108 struct pwm_state *state)
109{
110 struct iqs620_pwm_private *iqs620_pwm;
111
112 iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
113
114 mutex_lock(&iqs620_pwm->lock);
115
116 /*
117 * Since the device cannot generate a 0% duty cycle, requests to do so
118 * cause subsequent calls to iqs620_pwm_get_state to report the output
119 * as disabled. This is not ideal, but is the best compromise based on
120 * the capabilities of the device.
121 */
122 state->enabled = iqs620_pwm->duty_scale > 0;
123 state->duty_cycle = DIV_ROUND_UP(iqs620_pwm->duty_scale *
124 IQS620_PWM_PERIOD_NS, 256);
125
126 mutex_unlock(&iqs620_pwm->lock);
127
128 state->period = IQS620_PWM_PERIOD_NS;
129
130 return 0;
131}
132
133static int iqs620_pwm_notifier(struct notifier_block *notifier,
134 unsigned long event_flags, void *context)
135{
136 struct iqs620_pwm_private *iqs620_pwm;
137 int ret;
138
139 if (!(event_flags & BIT(IQS62X_EVENT_SYS_RESET)))
140 return NOTIFY_DONE;
141
142 iqs620_pwm = container_of(notifier, struct iqs620_pwm_private,
143 notifier);
144
145 mutex_lock(&iqs620_pwm->lock);
146
147 /*
148 * The parent MFD driver already prints an error message in the event
149 * of a device reset, so nothing else is printed here unless there is
150 * an additional failure.
151 */
152 ret = iqs620_pwm_init(iqs620_pwm, iqs620_pwm->duty_scale);
153
154 mutex_unlock(&iqs620_pwm->lock);
155
156 if (ret) {
157 dev_err(iqs620_pwm->chip.dev,
158 "Failed to re-initialize device: %d\n", ret);
159 return NOTIFY_BAD;
160 }
161
162 return NOTIFY_OK;
163}
164
165static const struct pwm_ops iqs620_pwm_ops = {
166 .apply = iqs620_pwm_apply,
167 .get_state = iqs620_pwm_get_state,
168 .owner = THIS_MODULE,
169};
170
171static void iqs620_pwm_notifier_unregister(void *context)
172{
173 struct iqs620_pwm_private *iqs620_pwm = context;
174 int ret;
175
176 ret = blocking_notifier_chain_unregister(&iqs620_pwm->iqs62x->nh,
177 &iqs620_pwm->notifier);
178 if (ret)
179 dev_err(iqs620_pwm->chip.dev,
180 "Failed to unregister notifier: %d\n", ret);
181}
182
183static int iqs620_pwm_probe(struct platform_device *pdev)
184{
185 struct iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent);
186 struct iqs620_pwm_private *iqs620_pwm;
187 unsigned int val;
188 int ret;
189
190 iqs620_pwm = devm_kzalloc(&pdev->dev, sizeof(*iqs620_pwm), GFP_KERNEL);
191 if (!iqs620_pwm)
192 return -ENOMEM;
193
194 iqs620_pwm->iqs62x = iqs62x;
195
196 ret = regmap_read(iqs62x->regmap, IQS620_PWR_SETTINGS, &val);
197 if (ret)
198 return ret;
199
200 if (val & IQS620_PWR_SETTINGS_PWM_OUT) {
201 ret = regmap_read(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE, &val);
202 if (ret)
203 return ret;
204
205 iqs620_pwm->duty_scale = val + 1;
206 }
207
208 iqs620_pwm->chip.dev = &pdev->dev;
209 iqs620_pwm->chip.ops = &iqs620_pwm_ops;
210 iqs620_pwm->chip.npwm = 1;
211
212 mutex_init(&iqs620_pwm->lock);
213
214 iqs620_pwm->notifier.notifier_call = iqs620_pwm_notifier;
215 ret = blocking_notifier_chain_register(&iqs620_pwm->iqs62x->nh,
216 &iqs620_pwm->notifier);
217 if (ret) {
218 dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret);
219 return ret;
220 }
221
222 ret = devm_add_action_or_reset(&pdev->dev,
223 iqs620_pwm_notifier_unregister,
224 iqs620_pwm);
225 if (ret)
226 return ret;
227
228 ret = devm_pwmchip_add(&pdev->dev, &iqs620_pwm->chip);
229 if (ret)
230 dev_err(&pdev->dev, "Failed to add device: %d\n", ret);
231
232 return ret;
233}
234
235static struct platform_driver iqs620_pwm_platform_driver = {
236 .driver = {
237 .name = "iqs620a-pwm",
238 },
239 .probe = iqs620_pwm_probe,
240};
241module_platform_driver(iqs620_pwm_platform_driver);
242
243MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
244MODULE_DESCRIPTION("Azoteq IQS620A PWM Generator");
245MODULE_LICENSE("GPL");
246MODULE_ALIAS("platform:iqs620a-pwm");
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Azoteq IQS620A PWM Generator
4 *
5 * Copyright (C) 2019 Jeff LaBundy <jeff@labundy.com>
6 *
7 * Limitations:
8 * - The period is fixed to 1 ms and is generated continuously despite changes
9 * to the duty cycle or enable/disable state.
10 * - Changes to the duty cycle or enable/disable state take effect immediately
11 * and may result in a glitch during the period in which the change is made.
12 * - The device cannot generate a 0% duty cycle. For duty cycles below 1 / 256
13 * ms, the output is disabled and relies upon an external pull-down resistor
14 * to hold the GPIO3/LTX pin low.
15 */
16
17#include <linux/device.h>
18#include <linux/kernel.h>
19#include <linux/mfd/iqs62x.h>
20#include <linux/module.h>
21#include <linux/mutex.h>
22#include <linux/notifier.h>
23#include <linux/platform_device.h>
24#include <linux/pwm.h>
25#include <linux/regmap.h>
26#include <linux/slab.h>
27
28#define IQS620_PWR_SETTINGS 0xd2
29#define IQS620_PWR_SETTINGS_PWM_OUT BIT(7)
30
31#define IQS620_PWM_DUTY_CYCLE 0xd8
32
33#define IQS620_PWM_PERIOD_NS 1000000
34
35struct iqs620_pwm_private {
36 struct iqs62x_core *iqs62x;
37 struct pwm_chip chip;
38 struct notifier_block notifier;
39 struct mutex lock;
40 bool out_en;
41 u8 duty_val;
42};
43
44static int iqs620_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
45 const struct pwm_state *state)
46{
47 struct iqs620_pwm_private *iqs620_pwm;
48 struct iqs62x_core *iqs62x;
49 u64 duty_scale;
50 int ret;
51
52 if (state->polarity != PWM_POLARITY_NORMAL)
53 return -ENOTSUPP;
54
55 if (state->period < IQS620_PWM_PERIOD_NS)
56 return -EINVAL;
57
58 iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
59 iqs62x = iqs620_pwm->iqs62x;
60
61 /*
62 * The duty cycle generated by the device is calculated as follows:
63 *
64 * duty_cycle = (IQS620_PWM_DUTY_CYCLE + 1) / 256 * 1 ms
65 *
66 * ...where IQS620_PWM_DUTY_CYCLE is a register value between 0 and 255
67 * (inclusive). Therefore the lowest duty cycle the device can generate
68 * while the output is enabled is 1 / 256 ms.
69 *
70 * For lower duty cycles (e.g. 0), the PWM output is simply disabled to
71 * allow an external pull-down resistor to hold the GPIO3/LTX pin low.
72 */
73 duty_scale = div_u64(state->duty_cycle * 256, IQS620_PWM_PERIOD_NS);
74
75 mutex_lock(&iqs620_pwm->lock);
76
77 if (!state->enabled || !duty_scale) {
78 ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
79 IQS620_PWR_SETTINGS_PWM_OUT, 0);
80 if (ret)
81 goto err_mutex;
82 }
83
84 if (duty_scale) {
85 u8 duty_val = min_t(u64, duty_scale - 1, 0xff);
86
87 ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
88 duty_val);
89 if (ret)
90 goto err_mutex;
91
92 iqs620_pwm->duty_val = duty_val;
93 }
94
95 if (state->enabled && duty_scale) {
96 ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
97 IQS620_PWR_SETTINGS_PWM_OUT, 0xff);
98 if (ret)
99 goto err_mutex;
100 }
101
102 iqs620_pwm->out_en = state->enabled;
103
104err_mutex:
105 mutex_unlock(&iqs620_pwm->lock);
106
107 return ret;
108}
109
110static void iqs620_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
111 struct pwm_state *state)
112{
113 struct iqs620_pwm_private *iqs620_pwm;
114
115 iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
116
117 mutex_lock(&iqs620_pwm->lock);
118
119 /*
120 * Since the device cannot generate a 0% duty cycle, requests to do so
121 * cause subsequent calls to iqs620_pwm_get_state to report the output
122 * as disabled with duty cycle equal to that which was in use prior to
123 * the request. This is not ideal, but is the best compromise based on
124 * the capabilities of the device.
125 */
126 state->enabled = iqs620_pwm->out_en;
127 state->duty_cycle = DIV_ROUND_UP((iqs620_pwm->duty_val + 1) *
128 IQS620_PWM_PERIOD_NS, 256);
129
130 mutex_unlock(&iqs620_pwm->lock);
131
132 state->period = IQS620_PWM_PERIOD_NS;
133}
134
135static int iqs620_pwm_notifier(struct notifier_block *notifier,
136 unsigned long event_flags, void *context)
137{
138 struct iqs620_pwm_private *iqs620_pwm;
139 struct iqs62x_core *iqs62x;
140 int ret;
141
142 if (!(event_flags & BIT(IQS62X_EVENT_SYS_RESET)))
143 return NOTIFY_DONE;
144
145 iqs620_pwm = container_of(notifier, struct iqs620_pwm_private,
146 notifier);
147 iqs62x = iqs620_pwm->iqs62x;
148
149 mutex_lock(&iqs620_pwm->lock);
150
151 /*
152 * The parent MFD driver already prints an error message in the event
153 * of a device reset, so nothing else is printed here unless there is
154 * an additional failure.
155 */
156 ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
157 iqs620_pwm->duty_val);
158 if (ret)
159 goto err_mutex;
160
161 ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
162 IQS620_PWR_SETTINGS_PWM_OUT,
163 iqs620_pwm->out_en ? 0xff : 0);
164
165err_mutex:
166 mutex_unlock(&iqs620_pwm->lock);
167
168 if (ret) {
169 dev_err(iqs620_pwm->chip.dev,
170 "Failed to re-initialize device: %d\n", ret);
171 return NOTIFY_BAD;
172 }
173
174 return NOTIFY_OK;
175}
176
177static const struct pwm_ops iqs620_pwm_ops = {
178 .apply = iqs620_pwm_apply,
179 .get_state = iqs620_pwm_get_state,
180 .owner = THIS_MODULE,
181};
182
183static void iqs620_pwm_notifier_unregister(void *context)
184{
185 struct iqs620_pwm_private *iqs620_pwm = context;
186 int ret;
187
188 ret = blocking_notifier_chain_unregister(&iqs620_pwm->iqs62x->nh,
189 &iqs620_pwm->notifier);
190 if (ret)
191 dev_err(iqs620_pwm->chip.dev,
192 "Failed to unregister notifier: %d\n", ret);
193}
194
195static int iqs620_pwm_probe(struct platform_device *pdev)
196{
197 struct iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent);
198 struct iqs620_pwm_private *iqs620_pwm;
199 unsigned int val;
200 int ret;
201
202 iqs620_pwm = devm_kzalloc(&pdev->dev, sizeof(*iqs620_pwm), GFP_KERNEL);
203 if (!iqs620_pwm)
204 return -ENOMEM;
205
206 platform_set_drvdata(pdev, iqs620_pwm);
207 iqs620_pwm->iqs62x = iqs62x;
208
209 ret = regmap_read(iqs62x->regmap, IQS620_PWR_SETTINGS, &val);
210 if (ret)
211 return ret;
212 iqs620_pwm->out_en = val & IQS620_PWR_SETTINGS_PWM_OUT;
213
214 ret = regmap_read(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE, &val);
215 if (ret)
216 return ret;
217 iqs620_pwm->duty_val = val;
218
219 iqs620_pwm->chip.dev = &pdev->dev;
220 iqs620_pwm->chip.ops = &iqs620_pwm_ops;
221 iqs620_pwm->chip.base = -1;
222 iqs620_pwm->chip.npwm = 1;
223
224 mutex_init(&iqs620_pwm->lock);
225
226 iqs620_pwm->notifier.notifier_call = iqs620_pwm_notifier;
227 ret = blocking_notifier_chain_register(&iqs620_pwm->iqs62x->nh,
228 &iqs620_pwm->notifier);
229 if (ret) {
230 dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret);
231 return ret;
232 }
233
234 ret = devm_add_action_or_reset(&pdev->dev,
235 iqs620_pwm_notifier_unregister,
236 iqs620_pwm);
237 if (ret)
238 return ret;
239
240 ret = pwmchip_add(&iqs620_pwm->chip);
241 if (ret)
242 dev_err(&pdev->dev, "Failed to add device: %d\n", ret);
243
244 return ret;
245}
246
247static int iqs620_pwm_remove(struct platform_device *pdev)
248{
249 struct iqs620_pwm_private *iqs620_pwm = platform_get_drvdata(pdev);
250 int ret;
251
252 ret = pwmchip_remove(&iqs620_pwm->chip);
253 if (ret)
254 dev_err(&pdev->dev, "Failed to remove device: %d\n", ret);
255
256 return ret;
257}
258
259static struct platform_driver iqs620_pwm_platform_driver = {
260 .driver = {
261 .name = "iqs620a-pwm",
262 },
263 .probe = iqs620_pwm_probe,
264 .remove = iqs620_pwm_remove,
265};
266module_platform_driver(iqs620_pwm_platform_driver);
267
268MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
269MODULE_DESCRIPTION("Azoteq IQS620A PWM Generator");
270MODULE_LICENSE("GPL");
271MODULE_ALIAS("platform:iqs620a-pwm");