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 22 struct spi_offload_trigger_pwm_state { 23 struct device *dev; 24 struct pwm_device *pwm; 25 }; 26 27 static 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 37 static 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 66 static 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 87 static 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 } 105 106 static 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 }; 112 113 static void spi_offload_trigger_pwm_release(void *data) 114 { 115 pwm_disable(data); 116 } 117 118 static 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 } 154 155 static const struct of_device_id spi_offload_trigger_pwm_of_match_table[] = { 156 { .compatible = "pwm-trigger" }, 157 { } 158 }; 159 MODULE_DEVICE_TABLE(of, spi_offload_trigger_pwm_of_match_table); 160 161 static 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 }; 168 module_platform_driver(spi_offload_trigger_pwm_driver); 169 170 MODULE_AUTHOR("David Lechner <dlechner@baylibre.com>"); 171 MODULE_DESCRIPTION("Generic PWM trigger"); 172 MODULE_LICENSE("GPL"); 173