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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2024 Analog Devices Inc.
4 * Copyright (C) 2024 BayLibre, SAS
5 *
6 * Generic PWM trigger for SPI offload.
7 */
8
9#include <linux/device.h>
10#include <linux/err.h>
11#include <linux/math.h>
12#include <linux/module.h>
13#include <linux/platform_device.h>
14#include <linux/property.h>
15#include <linux/pwm.h>
16#include <linux/spi/offload/provider.h>
17#include <linux/spi/offload/types.h>
18#include <linux/time.h>
19#include <linux/types.h>
20
21struct spi_offload_trigger_pwm_state {
22 struct device *dev;
23 struct pwm_device *pwm;
24};
25
26static bool spi_offload_trigger_pwm_match(struct spi_offload_trigger *trigger,
27 enum spi_offload_trigger_type type,
28 u64 *args, u32 nargs)
29{
30 if (nargs)
31 return false;
32
33 return type == SPI_OFFLOAD_TRIGGER_PERIODIC;
34}
35
36static int spi_offload_trigger_pwm_validate(struct spi_offload_trigger *trigger,
37 struct spi_offload_trigger_config *config)
38{
39 struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
40 struct spi_offload_trigger_periodic *periodic = &config->periodic;
41 struct pwm_waveform wf = { };
42 int ret;
43
44 if (config->type != SPI_OFFLOAD_TRIGGER_PERIODIC)
45 return -EINVAL;
46
47 if (!periodic->frequency_hz)
48 return -EINVAL;
49
50 wf.period_length_ns = DIV_ROUND_UP_ULL(NSEC_PER_SEC, periodic->frequency_hz);
51 /* REVISIT: 50% duty-cycle for now - may add config parameter later */
52 wf.duty_length_ns = wf.period_length_ns / 2;
53 wf.duty_offset_ns = periodic->offset_ns;
54
55 ret = pwm_round_waveform_might_sleep(st->pwm, &wf);
56 if (ret < 0)
57 return ret;
58
59 periodic->frequency_hz = DIV_ROUND_UP_ULL(NSEC_PER_SEC, wf.period_length_ns);
60 periodic->offset_ns = wf.duty_offset_ns;
61
62 return 0;
63}
64
65static int spi_offload_trigger_pwm_enable(struct spi_offload_trigger *trigger,
66 struct spi_offload_trigger_config *config)
67{
68 struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
69 struct spi_offload_trigger_periodic *periodic = &config->periodic;
70 struct pwm_waveform wf = { };
71
72 if (config->type != SPI_OFFLOAD_TRIGGER_PERIODIC)
73 return -EINVAL;
74
75 if (!periodic->frequency_hz)
76 return -EINVAL;
77
78 wf.period_length_ns = DIV_ROUND_UP_ULL(NSEC_PER_SEC, periodic->frequency_hz);
79 /* REVISIT: 50% duty-cycle for now - may add config parameter later */
80 wf.duty_length_ns = wf.period_length_ns / 2;
81 wf.duty_offset_ns = periodic->offset_ns;
82
83 return pwm_set_waveform_might_sleep(st->pwm, &wf, false);
84}
85
86static void spi_offload_trigger_pwm_disable(struct spi_offload_trigger *trigger)
87{
88 struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
89 struct pwm_waveform wf;
90 int ret;
91
92 ret = pwm_get_waveform_might_sleep(st->pwm, &wf);
93 if (ret < 0) {
94 dev_err(st->dev, "failed to get waveform: %d\n", ret);
95 return;
96 }
97
98 wf.duty_length_ns = 0;
99
100 ret = pwm_set_waveform_might_sleep(st->pwm, &wf, false);
101 if (ret < 0)
102 dev_err(st->dev, "failed to disable PWM: %d\n", ret);
103}
104
105static const struct spi_offload_trigger_ops spi_offload_trigger_pwm_ops = {
106 .match = spi_offload_trigger_pwm_match,
107 .validate = spi_offload_trigger_pwm_validate,
108 .enable = spi_offload_trigger_pwm_enable,
109 .disable = spi_offload_trigger_pwm_disable,
110};
111
112static void spi_offload_trigger_pwm_release(void *data)
113{
114 pwm_disable(data);
115}
116
117static int spi_offload_trigger_pwm_probe(struct platform_device *pdev)
118{
119 struct device *dev = &pdev->dev;
120 struct spi_offload_trigger_info info = {
121 .fwnode = dev_fwnode(dev),
122 .ops = &spi_offload_trigger_pwm_ops,
123 };
124 struct spi_offload_trigger_pwm_state *st;
125 struct pwm_state state;
126 int ret;
127
128 st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
129 if (!st)
130 return -ENOMEM;
131
132 info.priv = st;
133 st->dev = dev;
134
135 st->pwm = devm_pwm_get(dev, NULL);
136 if (IS_ERR(st->pwm))
137 return dev_err_probe(dev, PTR_ERR(st->pwm), "failed to get PWM\n");
138
139 /* init with duty_cycle = 0, output enabled to ensure trigger off */
140 pwm_init_state(st->pwm, &state);
141 state.enabled = true;
142
143 ret = pwm_apply_might_sleep(st->pwm, &state);
144 if (ret < 0)
145 return dev_err_probe(dev, ret, "failed to apply PWM state\n");
146
147 ret = devm_add_action_or_reset(dev, spi_offload_trigger_pwm_release, st->pwm);
148 if (ret)
149 return ret;
150
151 return devm_spi_offload_trigger_register(dev, &info);
152}
153
154static const struct of_device_id spi_offload_trigger_pwm_of_match_table[] = {
155 { .compatible = "pwm-trigger" },
156 { }
157};
158MODULE_DEVICE_TABLE(of, spi_offload_trigger_pwm_of_match_table);
159
160static struct platform_driver spi_offload_trigger_pwm_driver = {
161 .driver = {
162 .name = "pwm-trigger",
163 .of_match_table = spi_offload_trigger_pwm_of_match_table,
164 },
165 .probe = spi_offload_trigger_pwm_probe,
166};
167module_platform_driver(spi_offload_trigger_pwm_driver);
168
169MODULE_AUTHOR("David Lechner <[email protected]>");
170MODULE_DESCRIPTION("Generic PWM trigger");
171MODULE_LICENSE("GPL");