drivers/regulator/rpi-panel-attiny-regulator.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2020 Marek Vasut <marex@denx.de>
   4  *
   5  * Based on rpi_touchscreen.c by Eric Anholt <eric@anholt.net>
   6  */
   7
   8 #include <linux/backlight.h>
   9 #include <linux/err.h>
  10 #include <linux/gpio/driver.h>
  11 #include <linux/i2c.h>
  12 #include <linux/init.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/module.h>
  15 #include <linux/regmap.h>
  16 #include <linux/regulator/driver.h>
  17 #include <linux/regulator/machine.h>
  18 #include <linux/regulator/of_regulator.h>
  19 #include <linux/slab.h>
  20
  21 /* I2C registers of the Atmel microcontroller. */
  22 #define REG_ID          0x80
  23 #define REG_PORTA       0x81
  24 #define REG_PORTB       0x82
  25 #define REG_PORTC       0x83
  26 #define REG_POWERON     0x85
  27 #define REG_PWM         0x86
  28 #define REG_ADDR_L      0x8c
  29 #define REG_ADDR_H      0x8d
  30 #define REG_WRITE_DATA_H        0x90
  31 #define REG_WRITE_DATA_L        0x91
  32
  33 #define PA_LCD_DITHB            BIT(0)
  34 #define PA_LCD_MODE             BIT(1)
  35 #define PA_LCD_LR               BIT(2)
  36 #define PA_LCD_UD               BIT(3)
  37
  38 #define PB_BRIDGE_PWRDNX_N      BIT(0)
  39 #define PB_LCD_VCC_N            BIT(1)
  40 #define PB_LCD_MAIN             BIT(7)
  41
  42 #define PC_LED_EN               BIT(0)
  43 #define PC_RST_TP_N             BIT(1)
  44 #define PC_RST_LCD_N            BIT(2)
  45 #define PC_RST_BRIDGE_N         BIT(3)
  46
  47 enum gpio_signals {
  48         RST_BRIDGE_N,   /* TC358762 bridge reset */
  49         RST_TP_N,       /* Touch controller reset */
  50         NUM_GPIO
  51 };
  52
  53 struct gpio_signal_mappings {
  54         unsigned int reg;
  55         unsigned int mask;
  56 };
  57
  58 static const struct gpio_signal_mappings mappings[NUM_GPIO] = {
  59         [RST_BRIDGE_N] = { REG_PORTC, PC_RST_BRIDGE_N | PC_RST_LCD_N  },
  60         [RST_TP_N] = { REG_PORTC, PC_RST_TP_N },
  61 };
  62
  63 struct attiny_lcd {
  64         /* lock to serialise overall accesses to the Atmel */
  65         struct mutex    lock;
  66         struct regmap   *regmap;
  67         bool gpio_states[NUM_GPIO];
  68         u8 port_states[3];
  69
  70         struct gpio_chip gc;
  71 };
  72
  73 static const struct regmap_config attiny_regmap_config = {
  74         .reg_bits = 8,
  75         .val_bits = 8,
  76         .disable_locking = 1,
  77         .max_register = REG_WRITE_DATA_L,
  78         .cache_type = REGCACHE_MAPLE,
  79 };
  80
  81 static int attiny_set_port_state(struct attiny_lcd *state, int reg, u8 val)
  82 {
  83         state->port_states[reg - REG_PORTA] = val;
  84         return regmap_write(state->regmap, reg, val);
  85 };
  86
  87 static u8 attiny_get_port_state(struct attiny_lcd *state, int reg)
  88 {
  89         return state->port_states[reg - REG_PORTA];
  90 };
  91
  92 static int attiny_lcd_power_enable(struct regulator_dev *rdev)
  93 {
  94         struct attiny_lcd *state = rdev_get_drvdata(rdev);
  95
  96         mutex_lock(&state->lock);
  97
  98         /* Ensure bridge, and tp stay in reset */
  99         attiny_set_port_state(state, REG_PORTC, 0);
 100         usleep_range(5000, 10000);
 101
 102         /* Default to the same orientation as the closed source
 103          * firmware used for the panel.  Runtime rotation
 104          * configuration will be supported using VC4's plane
 105          * orientation bits.
 106          */
 107         attiny_set_port_state(state, REG_PORTA, PA_LCD_LR);
 108         usleep_range(5000, 10000);
 109         /* Main regulator on, and power to the panel (LCD_VCC_N) */
 110         attiny_set_port_state(state, REG_PORTB, PB_LCD_MAIN);
 111         usleep_range(5000, 10000);
 112         /* Bring controllers out of reset */
 113         attiny_set_port_state(state, REG_PORTC, PC_LED_EN);
 114
 115         msleep(80);
 116
 117         mutex_unlock(&state->lock);
 118
 119         return 0;
 120 }
 121
 122 static int attiny_lcd_power_disable(struct regulator_dev *rdev)
 123 {
 124         struct attiny_lcd *state = rdev_get_drvdata(rdev);
 125
 126         mutex_lock(&state->lock);
 127
 128         regmap_write(rdev->regmap, REG_PWM, 0);
 129         usleep_range(5000, 10000);
 130
 131         attiny_set_port_state(state, REG_PORTA, 0);
 132         usleep_range(5000, 10000);
 133         attiny_set_port_state(state, REG_PORTB, PB_LCD_VCC_N);
 134         usleep_range(5000, 10000);
 135         attiny_set_port_state(state, REG_PORTC, 0);
 136         msleep(30);
 137
 138         mutex_unlock(&state->lock);
 139
 140         return 0;
 141 }
 142
 143 static int attiny_lcd_power_is_enabled(struct regulator_dev *rdev)
 144 {
 145         struct attiny_lcd *state = rdev_get_drvdata(rdev);
 146         unsigned int data;
 147         int ret, i;
 148
 149         mutex_lock(&state->lock);
 150
 151         for (i = 0; i < 10; i++) {
 152                 ret = regmap_read(rdev->regmap, REG_PORTC, &data);
 153                 if (!ret)
 154                         break;
 155                 usleep_range(10000, 12000);
 156         }
 157
 158         mutex_unlock(&state->lock);
 159
 160         if (ret < 0)
 161                 return ret;
 162
 163         return data & PC_RST_BRIDGE_N;
 164 }
 165
 166 static const struct regulator_init_data attiny_regulator_default = {
 167         .constraints = {
 168                 .valid_ops_mask = REGULATOR_CHANGE_STATUS,
 169         },
 170 };
 171
 172 static const struct regulator_ops attiny_regulator_ops = {
 173         .enable = attiny_lcd_power_enable,
 174         .disable = attiny_lcd_power_disable,
 175         .is_enabled = attiny_lcd_power_is_enabled,
 176 };
 177
 178 static const struct regulator_desc attiny_regulator = {
 179         .name   = "tc358762-power",
 180         .ops    = &attiny_regulator_ops,
 181         .type   = REGULATOR_VOLTAGE,
 182         .owner  = THIS_MODULE,
 183 };
 184
 185 static int attiny_update_status(struct backlight_device *bl)
 186 {
 187         struct attiny_lcd *state = bl_get_data(bl);
 188         struct regmap *regmap = state->regmap;
 189         int brightness = backlight_get_brightness(bl);
 190         int ret, i;
 191
 192         mutex_lock(&state->lock);
 193
 194         for (i = 0; i < 10; i++) {
 195                 ret = regmap_write(regmap, REG_PWM, brightness);
 196                 if (!ret)
 197                         break;
 198         }
 199
 200         mutex_unlock(&state->lock);
 201
 202         return ret;
 203 }
 204
 205 static const struct backlight_ops attiny_bl = {
 206         .update_status  = attiny_update_status,
 207 };
 208
 209 static int attiny_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
 210 {
 211         return GPIO_LINE_DIRECTION_OUT;
 212 }
 213
 214 static void attiny_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
 215 {
 216         struct attiny_lcd *state = gpiochip_get_data(gc);
 217         u8 last_val;
 218
 219         if (off >= NUM_GPIO)
 220                 return;
 221
 222         mutex_lock(&state->lock);
 223
 224         last_val = attiny_get_port_state(state, mappings[off].reg);
 225         if (val)
 226                 last_val |= mappings[off].mask;
 227         else
 228                 last_val &= ~mappings[off].mask;
 229
 230         attiny_set_port_state(state, mappings[off].reg, last_val);
 231
 232         if (off == RST_BRIDGE_N && val) {
 233                 usleep_range(5000, 8000);
 234                 regmap_write(state->regmap, REG_ADDR_H, 0x04);
 235                 usleep_range(5000, 8000);
 236                 regmap_write(state->regmap, REG_ADDR_L, 0x7c);
 237                 usleep_range(5000, 8000);
 238                 regmap_write(state->regmap, REG_WRITE_DATA_H, 0x00);
 239                 usleep_range(5000, 8000);
 240                 regmap_write(state->regmap, REG_WRITE_DATA_L, 0x00);
 241
 242                 msleep(100);
 243         }
 244
 245         mutex_unlock(&state->lock);
 246 }
 247
 248 static int attiny_i2c_read(struct i2c_client *client, u8 reg, unsigned int *buf)
 249 {
 250         struct i2c_msg msgs[1];
 251         u8 addr_buf[1] = { reg };
 252         u8 data_buf[1] = { 0, };
 253         int ret;
 254
 255         /* Write register address */
 256         msgs[0].addr = client->addr;
 257         msgs[0].flags = 0;
 258         msgs[0].len = ARRAY_SIZE(addr_buf);
 259         msgs[0].buf = addr_buf;
 260
 261         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 262         if (ret != ARRAY_SIZE(msgs))
 263                 return -EIO;
 264
 265         usleep_range(5000, 10000);
 266
 267         /* Read data from register */
 268         msgs[0].addr = client->addr;
 269         msgs[0].flags = I2C_M_RD;
 270         msgs[0].len = 1;
 271         msgs[0].buf = data_buf;
 272
 273         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 274         if (ret != ARRAY_SIZE(msgs))
 275                 return -EIO;
 276
 277         *buf = data_buf[0];
 278         return 0;
 279 }
 280
 281 /*
 282  * I2C driver interface functions
 283  */
 284 static int attiny_i2c_probe(struct i2c_client *i2c)
 285 {
 286         struct backlight_properties props = { };
 287         struct regulator_config config = { };
 288         struct backlight_device *bl;
 289         struct regulator_dev *rdev;
 290         struct attiny_lcd *state;
 291         struct regmap *regmap;
 292         unsigned int data;
 293         int ret;
 294
 295         state = devm_kzalloc(&i2c->dev, sizeof(*state), GFP_KERNEL);
 296         if (!state)
 297                 return -ENOMEM;
 298
 299         mutex_init(&state->lock);
 300         i2c_set_clientdata(i2c, state);
 301
 302         regmap = devm_regmap_init_i2c(i2c, &attiny_regmap_config);
 303         if (IS_ERR(regmap)) {
 304                 ret = PTR_ERR(regmap);
 305                 dev_err(&i2c->dev, "Failed to allocate register map: %d\n",
 306                         ret);
 307                 goto error;
 308         }
 309
 310         ret = attiny_i2c_read(i2c, REG_ID, &data);
 311         if (ret < 0) {
 312                 dev_err(&i2c->dev, "Failed to read REG_ID reg: %d\n", ret);
 313                 goto error;
 314         }
 315
 316         switch (data) {
 317         case 0xde: /* ver 1 */
 318         case 0xc3: /* ver 2 */
 319                 break;
 320         default:
 321                 dev_err(&i2c->dev, "Unknown Atmel firmware revision: 0x%02x\n", data);
 322                 ret = -ENODEV;
 323                 goto error;
 324         }
 325
 326         regmap_write(regmap, REG_POWERON, 0);
 327         msleep(30);
 328         regmap_write(regmap, REG_PWM, 0);
 329
 330         config.dev = &i2c->dev;
 331         config.regmap = regmap;
 332         config.of_node = i2c->dev.of_node;
 333         config.init_data = &attiny_regulator_default;
 334         config.driver_data = state;
 335
 336         rdev = devm_regulator_register(&i2c->dev, &attiny_regulator, &config);
 337         if (IS_ERR(rdev)) {
 338                 dev_err(&i2c->dev, "Failed to register ATTINY regulator\n");
 339                 ret = PTR_ERR(rdev);
 340                 goto error;
 341         }
 342
 343         props.type = BACKLIGHT_RAW;
 344         props.max_brightness = 0xff;
 345
 346         state->regmap = regmap;
 347
 348         bl = devm_backlight_device_register(&i2c->dev, dev_name(&i2c->dev),
 349                                             &i2c->dev, state, &attiny_bl,
 350                                             &props);
 351         if (IS_ERR(bl)) {
 352                 ret = PTR_ERR(bl);
 353                 goto error;
 354         }
 355
 356         bl->props.brightness = 0xff;
 357
 358         state->gc.parent = &i2c->dev;
 359         state->gc.label = i2c->name;
 360         state->gc.owner = THIS_MODULE;
 361         state->gc.base = -1;
 362         state->gc.ngpio = NUM_GPIO;
 363
 364         state->gc.set = attiny_gpio_set;
 365         state->gc.get_direction = attiny_gpio_get_direction;
 366         state->gc.can_sleep = true;
 367
 368         ret = devm_gpiochip_add_data(&i2c->dev, &state->gc, state);
 369         if (ret) {
 370                 dev_err(&i2c->dev, "Failed to create gpiochip: %d\n", ret);
 371                 goto error;
 372         }
 373
 374         return 0;
 375
 376 error:
 377         mutex_destroy(&state->lock);
 378
 379         return ret;
 380 }
 381
 382 static void attiny_i2c_remove(struct i2c_client *client)
 383 {
 384         struct attiny_lcd *state = i2c_get_clientdata(client);
 385
 386         mutex_destroy(&state->lock);
 387 }
 388
 389 static const struct of_device_id attiny_dt_ids[] = {
 390         { .compatible = "raspberrypi,7inch-touchscreen-panel-regulator" },
 391         {},
 392 };
 393 MODULE_DEVICE_TABLE(of, attiny_dt_ids);
 394
 395 static struct i2c_driver attiny_regulator_driver = {
 396         .driver = {
 397                 .name = "rpi_touchscreen_attiny",
 398                 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
 399                 .of_match_table = attiny_dt_ids,
 400         },
 401         .probe = attiny_i2c_probe,
 402         .remove = attiny_i2c_remove,
 403 };
 404
 405 module_i2c_driver(attiny_regulator_driver);
 406
 407 MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
 408 MODULE_DESCRIPTION("Regulator device driver for Raspberry Pi 7-inch touchscreen");
 409 MODULE_LICENSE("GPL v2");