1 /* 2 * Allwinner sun4i low res adc attached tablet keys driver 3 * 4 * Copyright (C) 2014 Hans de Goede <hdegoede@redhat.com> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 */ 16 17 /* 18 * Allwinnner sunxi SoCs have a lradc which is specifically designed to have 19 * various (tablet) keys (ie home, back, search, etc). attached to it using 20 * a resistor network. This driver is for the keys on such boards. 21 * 22 * There are 2 channels, currently this driver only supports channel 0 since 23 * there are no boards known to use channel 1. 24 */ 25 26 #include <linux/err.h> 27 #include <linux/init.h> 28 #include <linux/input.h> 29 #include <linux/interrupt.h> 30 #include <linux/io.h> 31 #include <linux/module.h> 32 #include <linux/of_platform.h> 33 #include <linux/platform_device.h> 34 #include <linux/regulator/consumer.h> 35 #include <linux/slab.h> 36 37 #define LRADC_CTRL 0x00 38 #define LRADC_INTC 0x04 39 #define LRADC_INTS 0x08 40 #define LRADC_DATA0 0x0c 41 #define LRADC_DATA1 0x10 42 43 /* LRADC_CTRL bits */ 44 #define FIRST_CONVERT_DLY(x) ((x) << 24) /* 8 bits */ 45 #define CHAN_SELECT(x) ((x) << 22) /* 2 bits */ 46 #define CONTINUE_TIME_SEL(x) ((x) << 16) /* 4 bits */ 47 #define KEY_MODE_SEL(x) ((x) << 12) /* 2 bits */ 48 #define LEVELA_B_CNT(x) ((x) << 8) /* 4 bits */ 49 #define HOLD_EN(x) ((x) << 6) 50 #define LEVELB_VOL(x) ((x) << 4) /* 2 bits */ 51 #define SAMPLE_RATE(x) ((x) << 2) /* 2 bits */ 52 #define ENABLE(x) ((x) << 0) 53 54 /* LRADC_INTC and LRADC_INTS bits */ 55 #define CHAN1_KEYUP_IRQ BIT(12) 56 #define CHAN1_ALRDY_HOLD_IRQ BIT(11) 57 #define CHAN1_HOLD_IRQ BIT(10) 58 #define CHAN1_KEYDOWN_IRQ BIT(9) 59 #define CHAN1_DATA_IRQ BIT(8) 60 #define CHAN0_KEYUP_IRQ BIT(4) 61 #define CHAN0_ALRDY_HOLD_IRQ BIT(3) 62 #define CHAN0_HOLD_IRQ BIT(2) 63 #define CHAN0_KEYDOWN_IRQ BIT(1) 64 #define CHAN0_DATA_IRQ BIT(0) 65 66 struct sun4i_lradc_keymap { 67 u32 voltage; 68 u32 keycode; 69 }; 70 71 struct sun4i_lradc_data { 72 struct device *dev; 73 struct input_dev *input; 74 void __iomem *base; 75 struct regulator *vref_supply; 76 struct sun4i_lradc_keymap *chan0_map; 77 u32 chan0_map_count; 78 u32 chan0_keycode; 79 u32 vref; 80 }; 81 82 static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id) 83 { 84 struct sun4i_lradc_data *lradc = dev_id; 85 u32 i, ints, val, voltage, diff, keycode = 0, closest = 0xffffffff; 86 87 ints = readl(lradc->base + LRADC_INTS); 88 89 /* 90 * lradc supports only one keypress at a time, release does not give 91 * any info as to which key was released, so we cache the keycode. 92 */ 93 94 if (ints & CHAN0_KEYUP_IRQ) { 95 input_report_key(lradc->input, lradc->chan0_keycode, 0); 96 lradc->chan0_keycode = 0; 97 } 98 99 if ((ints & CHAN0_KEYDOWN_IRQ) && lradc->chan0_keycode == 0) { 100 val = readl(lradc->base + LRADC_DATA0) & 0x3f; 101 voltage = val * lradc->vref / 63; 102 103 for (i = 0; i < lradc->chan0_map_count; i++) { 104 diff = abs(lradc->chan0_map[i].voltage - voltage); 105 if (diff < closest) { 106 closest = diff; 107 keycode = lradc->chan0_map[i].keycode; 108 } 109 } 110 111 lradc->chan0_keycode = keycode; 112 input_report_key(lradc->input, lradc->chan0_keycode, 1); 113 } 114 115 input_sync(lradc->input); 116 117 writel(ints, lradc->base + LRADC_INTS); 118 119 return IRQ_HANDLED; 120 } 121 122 static int sun4i_lradc_open(struct input_dev *dev) 123 { 124 struct sun4i_lradc_data *lradc = input_get_drvdata(dev); 125 int error; 126 127 error = regulator_enable(lradc->vref_supply); 128 if (error) 129 return error; 130 131 /* lradc Vref internally is divided by 2/3 */ 132 lradc->vref = regulator_get_voltage(lradc->vref_supply) * 2 / 3; 133 134 /* 135 * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to 136 * stabilize on press, wait (1 + 1) * 4 ms for key release 137 */ 138 writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) | 139 SAMPLE_RATE(0) | ENABLE(1), lradc->base + LRADC_CTRL); 140 141 writel(CHAN0_KEYUP_IRQ | CHAN0_KEYDOWN_IRQ, lradc->base + LRADC_INTC); 142 143 return 0; 144 } 145 146 static void sun4i_lradc_close(struct input_dev *dev) 147 { 148 struct sun4i_lradc_data *lradc = input_get_drvdata(dev); 149 150 /* Disable lradc, leave other settings unchanged */ 151 writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) | 152 SAMPLE_RATE(2), lradc->base + LRADC_CTRL); 153 writel(0, lradc->base + LRADC_INTC); 154 155 regulator_disable(lradc->vref_supply); 156 } 157 158 static int sun4i_lradc_load_dt_keymap(struct device *dev, 159 struct sun4i_lradc_data *lradc) 160 { 161 struct device_node *np, *pp; 162 int i; 163 int error; 164 165 np = dev->of_node; 166 if (!np) 167 return -EINVAL; 168 169 lradc->chan0_map_count = of_get_child_count(np); 170 if (lradc->chan0_map_count == 0) { 171 dev_err(dev, "keymap is missing in device tree\n"); 172 return -EINVAL; 173 } 174 175 lradc->chan0_map = devm_kmalloc_array(dev, lradc->chan0_map_count, 176 sizeof(struct sun4i_lradc_keymap), 177 GFP_KERNEL); 178 if (!lradc->chan0_map) 179 return -ENOMEM; 180 181 i = 0; 182 for_each_child_of_node(np, pp) { 183 struct sun4i_lradc_keymap *map = &lradc->chan0_map[i]; 184 u32 channel; 185 186 error = of_property_read_u32(pp, "channel", &channel); 187 if (error || channel != 0) { 188 dev_err(dev, "%s: Inval channel prop\n", pp->name); 189 return -EINVAL; 190 } 191 192 error = of_property_read_u32(pp, "voltage", &map->voltage); 193 if (error) { 194 dev_err(dev, "%s: Inval voltage prop\n", pp->name); 195 return -EINVAL; 196 } 197 198 error = of_property_read_u32(pp, "linux,code", &map->keycode); 199 if (error) { 200 dev_err(dev, "%s: Inval linux,code prop\n", pp->name); 201 return -EINVAL; 202 } 203 204 i++; 205 } 206 207 return 0; 208 } 209 210 static int sun4i_lradc_probe(struct platform_device *pdev) 211 { 212 struct sun4i_lradc_data *lradc; 213 struct device *dev = &pdev->dev; 214 int i; 215 int error; 216 217 lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL); 218 if (!lradc) 219 return -ENOMEM; 220 221 error = sun4i_lradc_load_dt_keymap(dev, lradc); 222 if (error) 223 return error; 224 225 lradc->vref_supply = devm_regulator_get(dev, "vref"); 226 if (IS_ERR(lradc->vref_supply)) 227 return PTR_ERR(lradc->vref_supply); 228 229 lradc->dev = dev; 230 lradc->input = devm_input_allocate_device(dev); 231 if (!lradc->input) 232 return -ENOMEM; 233 234 lradc->input->name = pdev->name; 235 lradc->input->phys = "sun4i_lradc/input0"; 236 lradc->input->open = sun4i_lradc_open; 237 lradc->input->close = sun4i_lradc_close; 238 lradc->input->id.bustype = BUS_HOST; 239 lradc->input->id.vendor = 0x0001; 240 lradc->input->id.product = 0x0001; 241 lradc->input->id.version = 0x0100; 242 243 __set_bit(EV_KEY, lradc->input->evbit); 244 for (i = 0; i < lradc->chan0_map_count; i++) 245 __set_bit(lradc->chan0_map[i].keycode, lradc->input->keybit); 246 247 input_set_drvdata(lradc->input, lradc); 248 249 lradc->base = devm_ioremap_resource(dev, 250 platform_get_resource(pdev, IORESOURCE_MEM, 0)); 251 if (IS_ERR(lradc->base)) 252 return PTR_ERR(lradc->base); 253 254 error = devm_request_irq(dev, platform_get_irq(pdev, 0), 255 sun4i_lradc_irq, 0, 256 "sun4i-a10-lradc-keys", lradc); 257 if (error) 258 return error; 259 260 error = input_register_device(lradc->input); 261 if (error) 262 return error; 263 264 return 0; 265 } 266 267 static const struct of_device_id sun4i_lradc_of_match[] = { 268 { .compatible = "allwinner,sun4i-a10-lradc-keys", }, 269 { /* sentinel */ } 270 }; 271 MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match); 272 273 static struct platform_driver sun4i_lradc_driver = { 274 .driver = { 275 .name = "sun4i-a10-lradc-keys", 276 .of_match_table = of_match_ptr(sun4i_lradc_of_match), 277 }, 278 .probe = sun4i_lradc_probe, 279 }; 280 281 module_platform_driver(sun4i_lradc_driver); 282 283 MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver"); 284 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>"); 285 MODULE_LICENSE("GPL"); 286