1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * The Netronix embedded controller is a microcontroller found in some 4 * e-book readers designed by the original design manufacturer Netronix, Inc. 5 * It contains RTC, battery monitoring, system power management, and PWM 6 * functionality. 7 * 8 * This driver implements register access, version detection, and system 9 * 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 <asm/unaligned.h> 25 26 #define NTXEC_REG_VERSION 0x00 27 #define NTXEC_REG_POWEROFF 0x50 28 #define NTXEC_REG_POWERKEEP 0x70 29 #define NTXEC_REG_RESET 0x90 30 31 #define NTXEC_POWEROFF_VALUE 0x0100 32 #define NTXEC_POWERKEEP_VALUE 0x0800 33 #define NTXEC_RESET_VALUE 0xff00 34 35 static struct i2c_client *poweroff_restart_client; 36 37 static 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 off 59 * has been observed to be about 2.5 to 3 seconds. Sleep long enough to 60 * safely avoid returning from the poweroff handler. 61 */ 62 msleep(5000); 63 } 64 65 static 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 sending 72 * it causes an I2C error. (The reset handler in the downstream driver 73 * 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 94 static struct notifier_block ntxec_restart_handler = { 95 .notifier_call = ntxec_restart, 96 .priority = 128, 97 }; 98 99 static 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 } 109 110 static 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. It 120 * is used to stack another regmap on top. 121 */ 122 static 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_read 129 }; 130 131 static 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 }; 138 139 static const struct mfd_cell ntxec_subdev[] = { 140 { .name = "ntxec-rtc" }, 141 { .name = "ntxec-pwm" }, 142 }; 143 144 static const struct mfd_cell ntxec_subdev_pwm[] = { 145 { .name = "ntxec-pwm" }, 146 }; 147 148 static 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 subdevs = ntxec_subdev; 179 n_subdevs = ARRAY_SIZE(ntxec_subdev); 180 break; 181 case NTXEC_VERSION_TOLINO_SHINE2: 182 subdevs = ntxec_subdev_pwm; 183 n_subdevs = ARRAY_SIZE(ntxec_subdev_pwm); 184 /* Another regmap stacked on top of the other */ 185 ec->regmap = devm_regmap_init(ec->dev, NULL, 186 ec->regmap, 187 ®map_config_noack); 188 if (IS_ERR(ec->regmap)) 189 return PTR_ERR(ec->regmap); 190 break; 191 default: 192 dev_err(ec->dev, 193 "Netronix embedded controller version %04x is not supported.\n", 194 version); 195 return -ENODEV; 196 } 197 198 dev_info(ec->dev, 199 "Netronix embedded controller version %04x detected.\n", version); 200 201 if (of_device_is_system_power_controller(ec->dev->of_node)) { 202 /* 203 * Set the 'powerkeep' bit. This is necessary on some boards 204 * in order to keep the system running. 205 */ 206 res = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP, 207 NTXEC_POWERKEEP_VALUE); 208 if (res < 0) 209 return res; 210 211 if (poweroff_restart_client) 212 /* 213 * Another instance of the driver already took 214 * poweroff/restart duties. 215 */ 216 dev_err(ec->dev, "poweroff_restart_client already assigned\n"); 217 else 218 poweroff_restart_client = client; 219 220 if (pm_power_off) 221 /* Another driver already registered a poweroff handler. */ 222 dev_err(ec->dev, "pm_power_off already assigned\n"); 223 else 224 pm_power_off = ntxec_poweroff; 225 226 res = register_restart_handler(&ntxec_restart_handler); 227 if (res) 228 dev_err(ec->dev, 229 "Failed to register restart handler: %d\n", res); 230 } 231 232 i2c_set_clientdata(client, ec); 233 234 res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE, 235 subdevs, n_subdevs, NULL, 0, NULL); 236 if (res) 237 dev_err(ec->dev, "Failed to add subdevices: %d\n", res); 238 239 return res; 240 } 241 242 static void ntxec_remove(struct i2c_client *client) 243 { 244 if (client == poweroff_restart_client) { 245 poweroff_restart_client = NULL; 246 pm_power_off = NULL; 247 unregister_restart_handler(&ntxec_restart_handler); 248 } 249 } 250 251 static const struct of_device_id of_ntxec_match_table[] = { 252 { .compatible = "netronix,ntxec", }, 253 {} 254 }; 255 MODULE_DEVICE_TABLE(of, of_ntxec_match_table); 256 257 static struct i2c_driver ntxec_driver = { 258 .driver = { 259 .name = "ntxec", 260 .of_match_table = of_ntxec_match_table, 261 }, 262 .probe_new = ntxec_probe, 263 .remove = ntxec_remove, 264 }; 265 module_i2c_driver(ntxec_driver); 266 267 MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>"); 268 MODULE_DESCRIPTION("Core driver for Netronix EC"); 269 MODULE_LICENSE("GPL"); 270