drivers/input/keyboard/sun4i-lradc-keys.c

   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         platform_set_drvdata(pdev, lradc);
 265         return 0;
 266 }
 267
 268 static const struct of_device_id sun4i_lradc_of_match[] = {
 269         { .compatible = "allwinner,sun4i-a10-lradc-keys", },
 270         { /* sentinel */ }
 271 };
 272 MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
 273
 274 static struct platform_driver sun4i_lradc_driver = {
 275         .driver = {
 276                 .name   = "sun4i-a10-lradc-keys",
 277                 .of_match_table = of_match_ptr(sun4i_lradc_of_match),
 278         },
 279         .probe  = sun4i_lradc_probe,
 280 };
 281
 282 module_platform_driver(sun4i_lradc_driver);
 283
 284 MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
 285 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
 286 MODULE_LICENSE("GPL");