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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * The Netronix embedded controller is a microcontroller found in some4 * e-book readers designed by the original design manufacturer Netronix, Inc.5 * It contains RTC, battery monitoring, system power management, and PWM6 * functionality.7 *8 * This driver implements register access, version detection, and system9 * power-off/reset.10 *11 * Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net>12 */13 14#include <linux/delay.h>15#include <linux/errno.h>16#include <linux/i2c.h>17#include <linux/mfd/core.h>18#include <linux/mfd/ntxec.h>19#include <linux/module.h>20#include <linux/pm.h>21#include <linux/reboot.h>22#include <linux/regmap.h>23#include <linux/types.h>24#include <linux/unaligned.h>25 26#define NTXEC_REG_VERSION 0x0027#define NTXEC_REG_POWEROFF 0x5028#define NTXEC_REG_POWERKEEP 0x7029#define NTXEC_REG_RESET 0x9030 31#define NTXEC_POWEROFF_VALUE 0x010032#define NTXEC_POWERKEEP_VALUE 0x080033#define NTXEC_RESET_VALUE 0xff0034 35static struct i2c_client *poweroff_restart_client;36 37static void ntxec_poweroff(void)38{39 int res;40 u8 buf[3] = { NTXEC_REG_POWEROFF };41 struct i2c_msg msgs[] = {42 {43 .addr = poweroff_restart_client->addr,44 .flags = 0,45 .len = sizeof(buf),46 .buf = buf,47 },48 };49 50 put_unaligned_be16(NTXEC_POWEROFF_VALUE, buf + 1);51 52 res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));53 if (res < 0)54 dev_warn(&poweroff_restart_client->dev,55 "Failed to power off (err = %d)\n", res);56 57 /*58 * The time from the register write until the host CPU is powered off59 * has been observed to be about 2.5 to 3 seconds. Sleep long enough to60 * safely avoid returning from the poweroff handler.61 */62 msleep(5000);63}64 65static int ntxec_restart(struct notifier_block *nb,66 unsigned long action, void *data)67{68 int res;69 u8 buf[3] = { NTXEC_REG_RESET };70 /*71 * NOTE: The lower half of the reset value is not sent, because sending72 * it causes an I2C error. (The reset handler in the downstream driver73 * does send the full two-byte value, but doesn't check the result).74 */75 struct i2c_msg msgs[] = {76 {77 .addr = poweroff_restart_client->addr,78 .flags = 0,79 .len = sizeof(buf) - 1,80 .buf = buf,81 },82 };83 84 put_unaligned_be16(NTXEC_RESET_VALUE, buf + 1);85 86 res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));87 if (res < 0)88 dev_warn(&poweroff_restart_client->dev,89 "Failed to restart (err = %d)\n", res);90 91 return NOTIFY_DONE;92}93 94static struct notifier_block ntxec_restart_handler = {95 .notifier_call = ntxec_restart,96 .priority = 128,97};98 99static int regmap_ignore_write(void *context,100 unsigned int reg, unsigned int val)101 102{103 struct regmap *regmap = context;104 105 regmap_write(regmap, reg, val);106 107 return 0;108}109 110static int regmap_wrap_read(void *context, unsigned int reg,111 unsigned int *val)112{113 struct regmap *regmap = context;114 115 return regmap_read(regmap, reg, val);116}117 118/*119 * Some firmware versions do not ack written data, add a wrapper. It120 * is used to stack another regmap on top.121 */122static const struct regmap_config regmap_config_noack = {123 .name = "ntxec_noack",124 .reg_bits = 8,125 .val_bits = 16,126 .cache_type = REGCACHE_NONE,127 .reg_write = regmap_ignore_write,128 .reg_read = regmap_wrap_read129};130 131static const struct regmap_config regmap_config = {132 .name = "ntxec",133 .reg_bits = 8,134 .val_bits = 16,135 .cache_type = REGCACHE_NONE,136 .val_format_endian = REGMAP_ENDIAN_BIG,137};138 139static const struct mfd_cell ntxec_subdev[] = {140 { .name = "ntxec-rtc" },141 { .name = "ntxec-pwm" },142};143 144static const struct mfd_cell ntxec_subdev_pwm[] = {145 { .name = "ntxec-pwm" },146};147 148static int ntxec_probe(struct i2c_client *client)149{150 struct ntxec *ec;151 unsigned int version;152 int res;153 const struct mfd_cell *subdevs;154 size_t n_subdevs;155 156 ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL);157 if (!ec)158 return -ENOMEM;159 160 ec->dev = &client->dev;161 162 ec->regmap = devm_regmap_init_i2c(client, ®map_config);163 if (IS_ERR(ec->regmap)) {164 dev_err(ec->dev, "Failed to set up regmap for device\n");165 return PTR_ERR(ec->regmap);166 }167 168 /* Determine the firmware version */169 res = regmap_read(ec->regmap, NTXEC_REG_VERSION, &version);170 if (res < 0) {171 dev_err(ec->dev, "Failed to read firmware version number\n");172 return res;173 }174 175 /* Bail out if we encounter an unknown firmware version */176 switch (version) {177 case NTXEC_VERSION_KOBO_AURA:178 case NTXEC_VERSION_TOLINO_VISION:179 subdevs = ntxec_subdev;180 n_subdevs = ARRAY_SIZE(ntxec_subdev);181 break;182 case NTXEC_VERSION_TOLINO_SHINE2:183 subdevs = ntxec_subdev_pwm;184 n_subdevs = ARRAY_SIZE(ntxec_subdev_pwm);185 /* Another regmap stacked on top of the other */186 ec->regmap = devm_regmap_init(ec->dev, NULL,187 ec->regmap,188 ®map_config_noack);189 if (IS_ERR(ec->regmap))190 return PTR_ERR(ec->regmap);191 break;192 default:193 dev_err(ec->dev,194 "Netronix embedded controller version %04x is not supported.\n",195 version);196 return -ENODEV;197 }198 199 dev_info(ec->dev,200 "Netronix embedded controller version %04x detected.\n", version);201 202 if (of_device_is_system_power_controller(ec->dev->of_node)) {203 /*204 * Set the 'powerkeep' bit. This is necessary on some boards205 * in order to keep the system running.206 */207 res = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP,208 NTXEC_POWERKEEP_VALUE);209 if (res < 0)210 return res;211 212 if (poweroff_restart_client)213 /*214 * Another instance of the driver already took215 * poweroff/restart duties.216 */217 dev_err(ec->dev, "poweroff_restart_client already assigned\n");218 else219 poweroff_restart_client = client;220 221 if (pm_power_off)222 /* Another driver already registered a poweroff handler. */223 dev_err(ec->dev, "pm_power_off already assigned\n");224 else225 pm_power_off = ntxec_poweroff;226 227 res = register_restart_handler(&ntxec_restart_handler);228 if (res)229 dev_err(ec->dev,230 "Failed to register restart handler: %d\n", res);231 }232 233 i2c_set_clientdata(client, ec);234 235 res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE,236 subdevs, n_subdevs, NULL, 0, NULL);237 if (res)238 dev_err(ec->dev, "Failed to add subdevices: %d\n", res);239 240 return res;241}242 243static void ntxec_remove(struct i2c_client *client)244{245 if (client == poweroff_restart_client) {246 poweroff_restart_client = NULL;247 pm_power_off = NULL;248 unregister_restart_handler(&ntxec_restart_handler);249 }250}251 252static const struct of_device_id of_ntxec_match_table[] = {253 { .compatible = "netronix,ntxec", },254 {}255};256MODULE_DEVICE_TABLE(of, of_ntxec_match_table);257 258static struct i2c_driver ntxec_driver = {259 .driver = {260 .name = "ntxec",261 .of_match_table = of_ntxec_match_table,262 },263 .probe = ntxec_probe,264 .remove = ntxec_remove,265};266module_i2c_driver(ntxec_driver);267 268MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>");269MODULE_DESCRIPTION("Core driver for Netronix EC");270MODULE_LICENSE("GPL");271