1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Driver for Goodix touchscreens that use the i2c-hid protocol. 4 * 5 * Copyright 2020 Google LLC 6 */ 7 8 #include <linux/delay.h> 9 #include <linux/device.h> 10 #include <linux/gpio/consumer.h> 11 #include <linux/i2c.h> 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/of.h> 15 #include <linux/pm.h> 16 #include <linux/regulator/consumer.h> 17 18 #include "i2c-hid.h" 19 20 struct goodix_i2c_hid_timing_data { 21 unsigned int post_gpio_reset_delay_ms; 22 unsigned int post_power_delay_ms; 23 }; 24 25 struct i2c_hid_of_goodix { 26 struct i2chid_ops ops; 27 28 struct regulator *vdd; 29 struct notifier_block nb; 30 struct mutex regulator_mutex; 31 struct gpio_desc *reset_gpio; 32 const struct goodix_i2c_hid_timing_data *timings; 33 }; 34 35 static void goodix_i2c_hid_deassert_reset(struct i2c_hid_of_goodix *ihid_goodix, 36 bool regulator_just_turned_on) 37 { 38 if (regulator_just_turned_on && ihid_goodix->timings->post_power_delay_ms) 39 msleep(ihid_goodix->timings->post_power_delay_ms); 40 41 gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 0); 42 if (ihid_goodix->timings->post_gpio_reset_delay_ms) 43 msleep(ihid_goodix->timings->post_gpio_reset_delay_ms); 44 } 45 46 static int goodix_i2c_hid_power_up(struct i2chid_ops *ops) 47 { 48 struct i2c_hid_of_goodix *ihid_goodix = 49 container_of(ops, struct i2c_hid_of_goodix, ops); 50 51 return regulator_enable(ihid_goodix->vdd); 52 } 53 54 static void goodix_i2c_hid_power_down(struct i2chid_ops *ops) 55 { 56 struct i2c_hid_of_goodix *ihid_goodix = 57 container_of(ops, struct i2c_hid_of_goodix, ops); 58 59 regulator_disable(ihid_goodix->vdd); 60 } 61 62 static int ihid_goodix_vdd_notify(struct notifier_block *nb, 63 unsigned long event, 64 void *ignored) 65 { 66 struct i2c_hid_of_goodix *ihid_goodix = 67 container_of(nb, struct i2c_hid_of_goodix, nb); 68 int ret = NOTIFY_OK; 69 70 mutex_lock(&ihid_goodix->regulator_mutex); 71 72 switch (event) { 73 case REGULATOR_EVENT_PRE_DISABLE: 74 gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 1); 75 break; 76 77 case REGULATOR_EVENT_ENABLE: 78 goodix_i2c_hid_deassert_reset(ihid_goodix, true); 79 break; 80 81 case REGULATOR_EVENT_ABORT_DISABLE: 82 goodix_i2c_hid_deassert_reset(ihid_goodix, false); 83 break; 84 85 default: 86 ret = NOTIFY_DONE; 87 break; 88 } 89 90 mutex_unlock(&ihid_goodix->regulator_mutex); 91 92 return ret; 93 } 94 95 static int i2c_hid_of_goodix_probe(struct i2c_client *client, 96 const struct i2c_device_id *id) 97 { 98 struct i2c_hid_of_goodix *ihid_goodix; 99 int ret; 100 ihid_goodix = devm_kzalloc(&client->dev, sizeof(*ihid_goodix), 101 GFP_KERNEL); 102 if (!ihid_goodix) 103 return -ENOMEM; 104 105 mutex_init(&ihid_goodix->regulator_mutex); 106 107 ihid_goodix->ops.power_up = goodix_i2c_hid_power_up; 108 ihid_goodix->ops.power_down = goodix_i2c_hid_power_down; 109 110 /* Start out with reset asserted */ 111 ihid_goodix->reset_gpio = 112 devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_HIGH); 113 if (IS_ERR(ihid_goodix->reset_gpio)) 114 return PTR_ERR(ihid_goodix->reset_gpio); 115 116 ihid_goodix->vdd = devm_regulator_get(&client->dev, "vdd"); 117 if (IS_ERR(ihid_goodix->vdd)) 118 return PTR_ERR(ihid_goodix->vdd); 119 120 ihid_goodix->timings = device_get_match_data(&client->dev); 121 122 /* 123 * We need to control the "reset" line in lockstep with the regulator 124 * actually turning on an off instead of just when we make the request. 125 * This matters if the regulator is shared with another consumer. 126 * - If the regulator is off then we must assert reset. The reset 127 * line is active low and on some boards it could cause a current 128 * leak if left high. 129 * - If the regulator is on then we don't want reset asserted for very 130 * long. Holding the controller in reset apparently draws extra 131 * power. 132 */ 133 mutex_lock(&ihid_goodix->regulator_mutex); 134 ihid_goodix->nb.notifier_call = ihid_goodix_vdd_notify; 135 ret = devm_regulator_register_notifier(ihid_goodix->vdd, &ihid_goodix->nb); 136 if (ret) { 137 mutex_unlock(&ihid_goodix->regulator_mutex); 138 return dev_err_probe(&client->dev, ret, 139 "regulator notifier request failed\n"); 140 } 141 142 /* 143 * If someone else is holding the regulator on (or the regulator is 144 * an always-on one) we might never be told to deassert reset. Do it 145 * now. Here we'll assume that someone else might have _just 146 * barely_ turned the regulator on so we'll do the full 147 * "post_power_delay" just in case. 148 */ 149 if (ihid_goodix->reset_gpio && regulator_is_enabled(ihid_goodix->vdd)) 150 goodix_i2c_hid_deassert_reset(ihid_goodix, true); 151 mutex_unlock(&ihid_goodix->regulator_mutex); 152 153 return i2c_hid_core_probe(client, &ihid_goodix->ops, 0x0001); 154 } 155 156 static const struct goodix_i2c_hid_timing_data goodix_gt7375p_timing_data = { 157 .post_power_delay_ms = 10, 158 .post_gpio_reset_delay_ms = 180, 159 }; 160 161 static const struct of_device_id goodix_i2c_hid_of_match[] = { 162 { .compatible = "goodix,gt7375p", .data = &goodix_gt7375p_timing_data }, 163 { } 164 }; 165 MODULE_DEVICE_TABLE(of, goodix_i2c_hid_of_match); 166 167 static struct i2c_driver goodix_i2c_hid_ts_driver = { 168 .driver = { 169 .name = "i2c_hid_of_goodix", 170 .pm = &i2c_hid_core_pm, 171 .probe_type = PROBE_PREFER_ASYNCHRONOUS, 172 .of_match_table = of_match_ptr(goodix_i2c_hid_of_match), 173 }, 174 .probe = i2c_hid_of_goodix_probe, 175 .remove = i2c_hid_core_remove, 176 .shutdown = i2c_hid_core_shutdown, 177 }; 178 module_i2c_driver(goodix_i2c_hid_ts_driver); 179 180 MODULE_AUTHOR("Douglas Anderson <dianders@chromium.org>"); 181 MODULE_DESCRIPTION("Goodix i2c-hid touchscreen driver"); 182 MODULE_LICENSE("GPL v2"); 183