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1// SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0-or-later2/*3 * ENE KB3930 Embedded Controller Driver4 *5 * Copyright (C) 2020 Lubomir Rintel6 */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. */17enum {18 EC_DATA_IN = 0x00,19 EC_RAM_OUT = 0x80,20 EC_RAM_IN = 0x81,21};22 23/* EC RAM registers. */24enum {25 EC_MODEL = 0x30,26 EC_VERSION_MAJ = 0x31,27 EC_VERSION_MIN = 0x32,28};29 30struct kb3930 {31 struct i2c_client *client;32 struct regmap *ram_regmap;33 struct gpio_descs *off_gpios;34};35 36static struct kb3930 *kb3930_power_off;37 38#define EC_GPIO_WAVE 039#define EC_GPIO_OFF_MODE 140 41#define EC_OFF_MODE_REBOOT 042#define EC_OFF_MODE_POWER 143 44static 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 a51 * shutdown request to the EC. Once the EC detects it, it will52 * proceed to turn the power off or reset the board depending on53 * 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 63static 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 70static void kb3930_pm_power_off(void)71{72 kb3930_off(kb3930_power_off, EC_OFF_MODE_POWER);73}74 75static struct notifier_block kb3930_restart_nb = {76 .notifier_call = kb3930_restart,77};78 79static const struct mfd_cell ariel_ec_cells[] = {80 { .name = "dell-wyse-ariel-led", },81 { .name = "dell-wyse-ariel-power", },82};83 84static 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 93static 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 111static 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 122static 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 180static void 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 192static const struct of_device_id kb3930_dt_ids[] = {193 { .compatible = "ene,kb3930" },194 { }195};196MODULE_DEVICE_TABLE(of, kb3930_dt_ids);197 198static struct i2c_driver kb3930_driver = {199 .probe = kb3930_probe,200 .remove = kb3930_remove,201 .driver = {202 .name = "ene-kb3930",203 .of_match_table = kb3930_dt_ids,204 },205};206module_i2c_driver(kb3930_driver);207 208MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");209MODULE_DESCRIPTION("ENE KB3930 Embedded Controller Driver");210MODULE_LICENSE("Dual BSD/GPL");211