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

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Allwinner sun4i low res adc attached tablet keys driver
   4  *
   5  * Copyright (C) 2014 Hans de Goede <hdegoede@redhat.com>
   6  */
   7
   8 /*
   9  * Allwinnner sunxi SoCs have a lradc which is specifically designed to have
  10  * various (tablet) keys (ie home, back, search, etc). attached to it using
  11  * a resistor network. This driver is for the keys on such boards.
  12  *
  13  * There are 2 channels, currently this driver only supports channel 0 since
  14  * there are no boards known to use channel 1.
  15  */
  16
  17 #include <linux/clk.h>
  18 #include <linux/err.h>
  19 #include <linux/init.h>
  20 #include <linux/input.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/io.h>
  23 #include <linux/module.h>
  24 #include <linux/of.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/pm_wakeirq.h>
  27 #include <linux/property.h>
  28 #include <linux/regulator/consumer.h>
  29 #include <linux/reset.h>
  30 #include <linux/slab.h>
  31
  32 #define LRADC_CTRL              0x00
  33 #define LRADC_INTC              0x04
  34 #define LRADC_INTS              0x08
  35 #define LRADC_DATA0             0x0c
  36 #define LRADC_DATA1             0x10
  37
  38 /* LRADC_CTRL bits */
  39 #define FIRST_CONVERT_DLY(x)    ((x) << 24) /* 8 bits */
  40 #define CHAN_SELECT(x)          ((x) << 22) /* 2 bits */
  41 #define CONTINUE_TIME_SEL(x)    ((x) << 16) /* 4 bits */
  42 #define KEY_MODE_SEL(x)         ((x) << 12) /* 2 bits */
  43 #define LEVELA_B_CNT(x)         ((x) << 8)  /* 4 bits */
  44 #define HOLD_KEY_EN(x)          ((x) << 7)
  45 #define HOLD_EN(x)              ((x) << 6)
  46 #define LEVELB_VOL(x)           ((x) << 4)  /* 2 bits */
  47 #define SAMPLE_RATE(x)          ((x) << 2)  /* 2 bits */
  48 #define ENABLE(x)               ((x) << 0)
  49
  50 /* LRADC_INTC and LRADC_INTS bits */
  51 #define CHAN1_KEYUP_IRQ         BIT(12)
  52 #define CHAN1_ALRDY_HOLD_IRQ    BIT(11)
  53 #define CHAN1_HOLD_IRQ          BIT(10)
  54 #define CHAN1_KEYDOWN_IRQ       BIT(9)
  55 #define CHAN1_DATA_IRQ          BIT(8)
  56 #define CHAN0_KEYUP_IRQ         BIT(4)
  57 #define CHAN0_ALRDY_HOLD_IRQ    BIT(3)
  58 #define CHAN0_HOLD_IRQ          BIT(2)
  59 #define CHAN0_KEYDOWN_IRQ       BIT(1)
  60 #define CHAN0_DATA_IRQ          BIT(0)
  61
  62 /* struct lradc_variant - Describe sun4i-a10-lradc-keys hardware variant
  63  * @divisor_numerator:          The numerator of lradc Vref internally divisor
  64  * @divisor_denominator:        The denominator of lradc Vref internally divisor
  65  * @has_clock_reset:            If the binding requires a clock and reset
  66  */
  67 struct lradc_variant {
  68         u8 divisor_numerator;
  69         u8 divisor_denominator;
  70         bool has_clock_reset;
  71 };
  72
  73 static const struct lradc_variant lradc_variant_a10 = {
  74         .divisor_numerator = 2,
  75         .divisor_denominator = 3
  76 };
  77
  78 static const struct lradc_variant r_lradc_variant_a83t = {
  79         .divisor_numerator = 3,
  80         .divisor_denominator = 4
  81 };
  82
  83 static const struct lradc_variant lradc_variant_r329 = {
  84         .divisor_numerator = 3,
  85         .divisor_denominator = 4,
  86         .has_clock_reset = true,
  87 };
  88
  89 struct sun4i_lradc_keymap {
  90         u32 voltage;
  91         u32 keycode;
  92 };
  93
  94 struct sun4i_lradc_data {
  95         struct device *dev;
  96         struct input_dev *input;
  97         void __iomem *base;
  98         struct clk *clk;
  99         struct reset_control *reset;
 100         struct regulator *vref_supply;
 101         struct sun4i_lradc_keymap *chan0_map;
 102         const struct lradc_variant *variant;
 103         u32 chan0_map_count;
 104         u32 chan0_keycode;
 105         u32 vref;
 106 };
 107
 108 static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
 109 {
 110         struct sun4i_lradc_data *lradc = dev_id;
 111         u32 i, ints, val, voltage, diff, keycode = 0, closest = 0xffffffff;
 112
 113         ints  = readl(lradc->base + LRADC_INTS);
 114
 115         /*
 116          * lradc supports only one keypress at a time, release does not give
 117          * any info as to which key was released, so we cache the keycode.
 118          */
 119
 120         if (ints & CHAN0_KEYUP_IRQ) {
 121                 input_report_key(lradc->input, lradc->chan0_keycode, 0);
 122                 lradc->chan0_keycode = 0;
 123         }
 124
 125         if ((ints & CHAN0_KEYDOWN_IRQ) && lradc->chan0_keycode == 0) {
 126                 val = readl(lradc->base + LRADC_DATA0) & 0x3f;
 127                 voltage = val * lradc->vref / 63;
 128
 129                 for (i = 0; i < lradc->chan0_map_count; i++) {
 130                         diff = abs(lradc->chan0_map[i].voltage - voltage);
 131                         if (diff < closest) {
 132                                 closest = diff;
 133                                 keycode = lradc->chan0_map[i].keycode;
 134                         }
 135                 }
 136
 137                 lradc->chan0_keycode = keycode;
 138                 input_report_key(lradc->input, lradc->chan0_keycode, 1);
 139         }
 140
 141         input_sync(lradc->input);
 142
 143         writel(ints, lradc->base + LRADC_INTS);
 144
 145         return IRQ_HANDLED;
 146 }
 147
 148 static int sun4i_lradc_open(struct input_dev *dev)
 149 {
 150         struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
 151         int error;
 152
 153         error = regulator_enable(lradc->vref_supply);
 154         if (error)
 155                 return error;
 156
 157         error = reset_control_deassert(lradc->reset);
 158         if (error)
 159                 goto err_disable_reg;
 160
 161         error = clk_prepare_enable(lradc->clk);
 162         if (error)
 163                 goto err_assert_reset;
 164
 165         lradc->vref = regulator_get_voltage(lradc->vref_supply) *
 166                       lradc->variant->divisor_numerator /
 167                       lradc->variant->divisor_denominator;
 168         /*
 169          * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to
 170          * stabilize on press, wait (1 + 1) * 4 ms for key release
 171          */
 172         writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
 173                 SAMPLE_RATE(0) | ENABLE(1), lradc->base + LRADC_CTRL);
 174
 175         writel(CHAN0_KEYUP_IRQ | CHAN0_KEYDOWN_IRQ, lradc->base + LRADC_INTC);
 176
 177         return 0;
 178
 179 err_assert_reset:
 180         reset_control_assert(lradc->reset);
 181 err_disable_reg:
 182         regulator_disable(lradc->vref_supply);
 183
 184         return error;
 185 }
 186
 187 static void sun4i_lradc_close(struct input_dev *dev)
 188 {
 189         struct sun4i_lradc_data *lradc = input_get_drvdata(dev);
 190
 191         /* Disable lradc, leave other settings unchanged */
 192         writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
 193                 SAMPLE_RATE(2), lradc->base + LRADC_CTRL);
 194         writel(0, lradc->base + LRADC_INTC);
 195
 196         clk_disable_unprepare(lradc->clk);
 197         reset_control_assert(lradc->reset);
 198         regulator_disable(lradc->vref_supply);
 199 }
 200
 201 static int sun4i_lradc_load_dt_keymap(struct device *dev,
 202                                       struct sun4i_lradc_data *lradc)
 203 {
 204         struct device_node *np;
 205         int i;
 206         int error;
 207
 208         np = dev->of_node;
 209         if (!np)
 210                 return -EINVAL;
 211
 212         lradc->chan0_map_count = of_get_child_count(np);
 213         if (lradc->chan0_map_count == 0) {
 214                 dev_err(dev, "keymap is missing in device tree\n");
 215                 return -EINVAL;
 216         }
 217
 218         lradc->chan0_map = devm_kmalloc_array(dev, lradc->chan0_map_count,
 219                                               sizeof(struct sun4i_lradc_keymap),
 220                                               GFP_KERNEL);
 221         if (!lradc->chan0_map)
 222                 return -ENOMEM;
 223
 224         i = 0;
 225         for_each_child_of_node_scoped(np, pp) {
 226                 struct sun4i_lradc_keymap *map = &lradc->chan0_map[i];
 227                 u32 channel;
 228
 229                 error = of_property_read_u32(pp, "channel", &channel);
 230                 if (error || channel != 0) {
 231                         dev_err(dev, "%pOFn: Inval channel prop\n", pp);
 232                         return -EINVAL;
 233                 }
 234
 235                 error = of_property_read_u32(pp, "voltage", &map->voltage);
 236                 if (error) {
 237                         dev_err(dev, "%pOFn: Inval voltage prop\n", pp);
 238                         return -EINVAL;
 239                 }
 240
 241                 error = of_property_read_u32(pp, "linux,code", &map->keycode);
 242                 if (error) {
 243                         dev_err(dev, "%pOFn: Inval linux,code prop\n", pp);
 244                         return -EINVAL;
 245                 }
 246
 247                 i++;
 248         }
 249
 250         return 0;
 251 }
 252
 253 static int sun4i_lradc_probe(struct platform_device *pdev)
 254 {
 255         struct sun4i_lradc_data *lradc;
 256         struct device *dev = &pdev->dev;
 257         int error, i, irq;
 258
 259         lradc = devm_kzalloc(dev, sizeof(struct sun4i_lradc_data), GFP_KERNEL);
 260         if (!lradc)
 261                 return -ENOMEM;
 262
 263         error = sun4i_lradc_load_dt_keymap(dev, lradc);
 264         if (error)
 265                 return error;
 266
 267         lradc->variant = of_device_get_match_data(&pdev->dev);
 268         if (!lradc->variant) {
 269                 dev_err(&pdev->dev, "Missing sun4i-a10-lradc-keys variant\n");
 270                 return -EINVAL;
 271         }
 272
 273         if (lradc->variant->has_clock_reset) {
 274                 lradc->clk = devm_clk_get(dev, NULL);
 275                 if (IS_ERR(lradc->clk))
 276                         return PTR_ERR(lradc->clk);
 277
 278                 lradc->reset = devm_reset_control_get_exclusive(dev, NULL);
 279                 if (IS_ERR(lradc->reset))
 280                         return PTR_ERR(lradc->reset);
 281         }
 282
 283         lradc->vref_supply = devm_regulator_get(dev, "vref");
 284         if (IS_ERR(lradc->vref_supply))
 285                 return PTR_ERR(lradc->vref_supply);
 286
 287         lradc->dev = dev;
 288         lradc->input = devm_input_allocate_device(dev);
 289         if (!lradc->input)
 290                 return -ENOMEM;
 291
 292         lradc->input->name = pdev->name;
 293         lradc->input->phys = "sun4i_lradc/input0";
 294         lradc->input->open = sun4i_lradc_open;
 295         lradc->input->close = sun4i_lradc_close;
 296         lradc->input->id.bustype = BUS_HOST;
 297         lradc->input->id.vendor = 0x0001;
 298         lradc->input->id.product = 0x0001;
 299         lradc->input->id.version = 0x0100;
 300
 301         __set_bit(EV_KEY, lradc->input->evbit);
 302         for (i = 0; i < lradc->chan0_map_count; i++)
 303                 __set_bit(lradc->chan0_map[i].keycode, lradc->input->keybit);
 304
 305         input_set_drvdata(lradc->input, lradc);
 306
 307         lradc->base = devm_platform_ioremap_resource(pdev, 0);
 308         if (IS_ERR(lradc->base))
 309                 return PTR_ERR(lradc->base);
 310
 311         irq = platform_get_irq(pdev, 0);
 312         if (irq < 0)
 313                 return irq;
 314
 315         error = devm_request_irq(dev, irq, sun4i_lradc_irq, 0,
 316                                  "sun4i-a10-lradc-keys", lradc);
 317         if (error)
 318                 return error;
 319
 320         error = input_register_device(lradc->input);
 321         if (error)
 322                 return error;
 323
 324         if (device_property_read_bool(dev, "wakeup-source")) {
 325                 error = dev_pm_set_wake_irq(dev, irq);
 326                 if (error)
 327                         dev_warn(dev,
 328                                  "Failed to set IRQ %d as a wake IRQ: %d\n",
 329                                  irq, error);
 330                 else
 331                         device_set_wakeup_capable(dev, true);
 332         }
 333
 334         return 0;
 335 }
 336
 337 static const struct of_device_id sun4i_lradc_of_match[] = {
 338         { .compatible = "allwinner,sun4i-a10-lradc-keys",
 339                 .data = &lradc_variant_a10 },
 340         { .compatible = "allwinner,sun8i-a83t-r-lradc",
 341                 .data = &r_lradc_variant_a83t },
 342         { .compatible = "allwinner,sun50i-r329-lradc",
 343                 .data = &lradc_variant_r329 },
 344         { /* sentinel */ }
 345 };
 346 MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
 347
 348 static struct platform_driver sun4i_lradc_driver = {
 349         .driver = {
 350                 .name   = "sun4i-a10-lradc-keys",
 351                 .of_match_table = of_match_ptr(sun4i_lradc_of_match),
 352         },
 353         .probe  = sun4i_lradc_probe,
 354 };
 355
 356 module_platform_driver(sun4i_lradc_driver);
 357
 358 MODULE_DESCRIPTION("Allwinner sun4i low res adc attached tablet keys driver");
 359 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
 360 MODULE_LICENSE("GPL");