drivers/mfd/ene-kb3930.c

   1 // SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0-or-later
   2 /*
   3  * ENE KB3930 Embedded Controller Driver
   4  *
   5  * Copyright (C) 2020 Lubomir Rintel
   6  */
   7
   8 #include <linux/delay.h>
   9 #include <linux/gpio/consumer.h>
  10 #include <linux/i2c.h>
  11 #include <linux/mfd/core.h>
  12 #include <linux/module.h>
  13 #include <linux/reboot.h>
  14 #include <linux/regmap.h>
  15
  16 /* I2C registers that are multiplexing access to the EC RAM. */
  17 enum {
  18         EC_DATA_IN      = 0x00,
  19         EC_RAM_OUT      = 0x80,
  20         EC_RAM_IN       = 0x81,
  21 };
  22
  23 /* EC RAM registers. */
  24 enum {
  25         EC_MODEL        = 0x30,
  26         EC_VERSION_MAJ  = 0x31,
  27         EC_VERSION_MIN  = 0x32,
  28 };
  29
  30 struct kb3930 {
  31         struct i2c_client *client;
  32         struct regmap *ram_regmap;
  33         struct gpio_descs *off_gpios;
  34 };
  35
  36 struct kb3930 *kb3930_power_off;
  37
  38 #define EC_GPIO_WAVE            0
  39 #define EC_GPIO_OFF_MODE        1
  40
  41 #define EC_OFF_MODE_REBOOT      0
  42 #define EC_OFF_MODE_POWER       1
  43
  44 static void kb3930_off(struct kb3930 *ddata, int off_mode)
  45 {
  46         gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_OFF_MODE],
  47                                off_mode);
  48
  49         /*
  50          * This creates a 10 Hz wave on EC_GPIO_WAVE that signals a
  51          * shutdown request to the EC. Once the EC detects it, it will
  52          * proceed to turn the power off or reset the board depending on
  53          * the value of EC_GPIO_OFF_MODE.
  54          */
  55         while (1) {
  56                 mdelay(50);
  57                 gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_WAVE], 0);
  58                 mdelay(50);
  59                 gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_WAVE], 1);
  60         }
  61 }
  62
  63 static int kb3930_restart(struct notifier_block *this,
  64                           unsigned long mode, void *cmd)
  65 {
  66         kb3930_off(kb3930_power_off, EC_OFF_MODE_REBOOT);
  67         return NOTIFY_DONE;
  68 }
  69
  70 static void kb3930_pm_power_off(void)
  71 {
  72         kb3930_off(kb3930_power_off, EC_OFF_MODE_POWER);
  73 }
  74
  75 static struct notifier_block kb3930_restart_nb = {
  76         .notifier_call = kb3930_restart,
  77 };
  78
  79 static const struct mfd_cell ariel_ec_cells[] = {
  80         { .name = "dell-wyse-ariel-led", },
  81         { .name = "dell-wyse-ariel-power", },
  82 };
  83
  84 static int kb3930_ec_ram_reg_write(void *context, unsigned int reg,
  85                                    unsigned int val)
  86 {
  87         struct kb3930 *ddata = context;
  88
  89         return i2c_smbus_write_word_data(ddata->client, EC_RAM_OUT,
  90                                          (val << 8) | reg);
  91 }
  92
  93 static int kb3930_ec_ram_reg_read(void *context, unsigned int reg,
  94                                   unsigned int *val)
  95 {
  96         struct kb3930 *ddata = context;
  97         int ret;
  98
  99         ret = i2c_smbus_write_word_data(ddata->client, EC_RAM_IN, reg);
 100         if (ret < 0)
 101                 return ret;
 102
 103         ret = i2c_smbus_read_word_data(ddata->client, EC_DATA_IN);
 104         if (ret < 0)
 105                 return ret;
 106
 107         *val = ret >> 8;
 108         return 0;
 109 }
 110
 111 static const struct regmap_config kb3930_ram_regmap_config = {
 112         .name = "ec_ram",
 113         .reg_bits = 8,
 114         .val_bits = 8,
 115         .reg_stride = 1,
 116         .max_register = 0xff,
 117         .reg_write = kb3930_ec_ram_reg_write,
 118         .reg_read = kb3930_ec_ram_reg_read,
 119         .fast_io = false,
 120 };
 121
 122 static int kb3930_probe(struct i2c_client *client)
 123 {
 124         struct device *dev = &client->dev;
 125         struct device_node *np = dev->of_node;
 126         struct kb3930 *ddata;
 127         unsigned int model;
 128         int ret;
 129
 130         ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
 131         if (!ddata)
 132                 return -ENOMEM;
 133
 134         kb3930_power_off = ddata;
 135         ddata->client = client;
 136         i2c_set_clientdata(client, ddata);
 137
 138         ddata->ram_regmap = devm_regmap_init(dev, NULL, ddata,
 139                                              &kb3930_ram_regmap_config);
 140         if (IS_ERR(ddata->ram_regmap))
 141                 return PTR_ERR(ddata->ram_regmap);
 142
 143         ret = regmap_read(ddata->ram_regmap, EC_MODEL, &model);
 144         if (ret < 0)
 145                 return ret;
 146
 147         /* Currently we only support the cells present on Dell Ariel model. */
 148         if (model != 'J') {
 149                 dev_err(dev, "unknown board model: %02x\n", model);
 150                 return -ENODEV;
 151         }
 152
 153         ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO,
 154                                    ariel_ec_cells,
 155                                    ARRAY_SIZE(ariel_ec_cells),
 156                                    NULL, 0, NULL);
 157         if (ret)
 158                 return ret;
 159
 160         if (of_property_read_bool(np, "system-power-controller")) {
 161                 ddata->off_gpios =
 162                         devm_gpiod_get_array_optional(dev, "off", GPIOD_IN);
 163                 if (IS_ERR(ddata->off_gpios))
 164                         return PTR_ERR(ddata->off_gpios);
 165                 if (ddata->off_gpios->ndescs < 2) {
 166                         dev_err(dev, "invalid off-gpios property\n");
 167                         return -EINVAL;
 168                 }
 169         }
 170
 171         if (ddata->off_gpios) {
 172                 register_restart_handler(&kb3930_restart_nb);
 173                 if (!pm_power_off)
 174                         pm_power_off = kb3930_pm_power_off;
 175         }
 176
 177         return 0;
 178 }
 179
 180 static int kb3930_remove(struct i2c_client *client)
 181 {
 182         struct kb3930 *ddata = i2c_get_clientdata(client);
 183
 184         if (ddata->off_gpios) {
 185                 if (pm_power_off == kb3930_pm_power_off)
 186                         pm_power_off = NULL;
 187                 unregister_restart_handler(&kb3930_restart_nb);
 188         }
 189         kb3930_power_off = NULL;
 190
 191         return 0;
 192 }
 193
 194 static const struct of_device_id kb3930_dt_ids[] = {
 195         { .compatible = "ene,kb3930" },
 196         { }
 197 };
 198 MODULE_DEVICE_TABLE(of, kb3930_dt_ids);
 199
 200 static struct i2c_driver kb3930_driver = {
 201         .probe_new = kb3930_probe,
 202         .remove = kb3930_remove,
 203         .driver = {
 204                 .name = "ene-kb3930",
 205                 .of_match_table = kb3930_dt_ids,
 206         },
 207 };
 208 module_i2c_driver(kb3930_driver);
 209
 210 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 211 MODULE_DESCRIPTION("ENE KB3930 Embedded Controller Driver");
 212 MODULE_LICENSE("Dual BSD/GPL");