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