tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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/mod_devicetable.h>
13#include <linux/module.h>
14#include <linux/platform_device.h>
15#include <linux/property.h>
16#include <linux/pwm.h>
17#include <linux/spi/offload/provider.h>
18#include <linux/spi/offload/types.h>
19#include <linux/time.h>
20#include <linux/types.h>
21
22struct spi_offload_trigger_pwm_state {
23 struct device *dev;
24 struct pwm_device *pwm;
25};
26
27static bool spi_offload_trigger_pwm_match(struct spi_offload_trigger *trigger,
28 enum spi_offload_trigger_type type,
29 u64 *args, u32 nargs)
30{
31 if (nargs)
32 return false;
33
34 return type == SPI_OFFLOAD_TRIGGER_PERIODIC;
35}
36
37static int spi_offload_trigger_pwm_validate(struct spi_offload_trigger *trigger,
38 struct spi_offload_trigger_config *config)
39{
40 struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
41 struct spi_offload_trigger_periodic *periodic = &config->periodic;
42 struct pwm_waveform wf = { };
43 int ret;
44
45 if (config->type != SPI_OFFLOAD_TRIGGER_PERIODIC)
46 return -EINVAL;
47
48 if (!periodic->frequency_hz)
49 return -EINVAL;
50
51 wf.period_length_ns = DIV_ROUND_UP_ULL(NSEC_PER_SEC, periodic->frequency_hz);
52 /* REVISIT: 50% duty-cycle for now - may add config parameter later */
53 wf.duty_length_ns = wf.period_length_ns / 2;
54 wf.duty_offset_ns = periodic->offset_ns;
55
56 ret = pwm_round_waveform_might_sleep(st->pwm, &wf);
57 if (ret < 0)
58 return ret;
59
60 periodic->frequency_hz = DIV_ROUND_UP_ULL(NSEC_PER_SEC, wf.period_length_ns);
61 periodic->offset_ns = wf.duty_offset_ns;
62
63 return 0;
64}
65
66static int spi_offload_trigger_pwm_enable(struct spi_offload_trigger *trigger,
67 struct spi_offload_trigger_config *config)
68{
69 struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
70 struct spi_offload_trigger_periodic *periodic = &config->periodic;
71 struct pwm_waveform wf = { };
72
73 if (config->type != SPI_OFFLOAD_TRIGGER_PERIODIC)
74 return -EINVAL;
75
76 if (!periodic->frequency_hz)
77 return -EINVAL;
78
79 wf.period_length_ns = DIV_ROUND_UP_ULL(NSEC_PER_SEC, periodic->frequency_hz);
80 /* REVISIT: 50% duty-cycle for now - may add config parameter later */
81 wf.duty_length_ns = wf.period_length_ns / 2;
82 wf.duty_offset_ns = periodic->offset_ns;
83
84 return pwm_set_waveform_might_sleep(st->pwm, &wf, false);
85}
86
87static void spi_offload_trigger_pwm_disable(struct spi_offload_trigger *trigger)
88{
89 struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
90 struct pwm_waveform wf;
91 int ret;
92
93 ret = pwm_get_waveform_might_sleep(st->pwm, &wf);
94 if (ret < 0) {
95 dev_err(st->dev, "failed to get waveform: %d\n", ret);
96 return;
97 }
98
99 wf.duty_length_ns = 0;
100
101 ret = pwm_set_waveform_might_sleep(st->pwm, &wf, false);
102 if (ret < 0)
103 dev_err(st->dev, "failed to disable PWM: %d\n", ret);
104}
105
106static const struct spi_offload_trigger_ops spi_offload_trigger_pwm_ops = {
107 .match = spi_offload_trigger_pwm_match,
108 .validate = spi_offload_trigger_pwm_validate,
109 .enable = spi_offload_trigger_pwm_enable,
110 .disable = spi_offload_trigger_pwm_disable,
111};
112
113static void spi_offload_trigger_pwm_release(void *data)
114{
115 pwm_disable(data);
116}
117
118static int spi_offload_trigger_pwm_probe(struct platform_device *pdev)
119{
120 struct device *dev = &pdev->dev;
121 struct spi_offload_trigger_info info = {
122 .fwnode = dev_fwnode(dev),
123 .ops = &spi_offload_trigger_pwm_ops,
124 };
125 struct spi_offload_trigger_pwm_state *st;
126 struct pwm_state state;
127 int ret;
128
129 st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
130 if (!st)
131 return -ENOMEM;
132
133 info.priv = st;
134 st->dev = dev;
135
136 st->pwm = devm_pwm_get(dev, NULL);
137 if (IS_ERR(st->pwm))
138 return dev_err_probe(dev, PTR_ERR(st->pwm), "failed to get PWM\n");
139
140 /* init with duty_cycle = 0, output enabled to ensure trigger off */
141 pwm_init_state(st->pwm, &state);
142 state.enabled = true;
143
144 ret = pwm_apply_might_sleep(st->pwm, &state);
145 if (ret < 0)
146 return dev_err_probe(dev, ret, "failed to apply PWM state\n");
147
148 ret = devm_add_action_or_reset(dev, spi_offload_trigger_pwm_release, st->pwm);
149 if (ret)
150 return ret;
151
152 return devm_spi_offload_trigger_register(dev, &info);
153}
154
155static const struct of_device_id spi_offload_trigger_pwm_of_match_table[] = {
156 { .compatible = "pwm-trigger" },
157 { }
158};
159MODULE_DEVICE_TABLE(of, spi_offload_trigger_pwm_of_match_table);
160
161static struct platform_driver spi_offload_trigger_pwm_driver = {
162 .driver = {
163 .name = "pwm-trigger",
164 .of_match_table = spi_offload_trigger_pwm_of_match_table,
165 },
166 .probe = spi_offload_trigger_pwm_probe,
167};
168module_platform_driver(spi_offload_trigger_pwm_driver);
169
170MODULE_AUTHOR("David Lechner <dlechner@baylibre.com>");
171MODULE_DESCRIPTION("Generic PWM trigger");
172MODULE_LICENSE("GPL");