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 <[email protected]> 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 const struct regmap_config regmap_config = { 100 .name = "ntxec", 101 .reg_bits = 8, 102 .val_bits = 16, 103 .cache_type = REGCACHE_NONE, 104 .val_format_endian = REGMAP_ENDIAN_BIG, 105 }; 106 107 static const struct mfd_cell ntxec_subdevices[] = { 108 { .name = "ntxec-rtc" }, 109 { .name = "ntxec-pwm" }, 110 }; 111 112 static int ntxec_probe(struct i2c_client *client) 113 { 114 struct ntxec *ec; 115 unsigned int version; 116 int res; 117 118 ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL); 119 if (!ec) 120 return -ENOMEM; 121 122 ec->dev = &client->dev; 123 124 ec->regmap = devm_regmap_init_i2c(client, ®map_config); 125 if (IS_ERR(ec->regmap)) { 126 dev_err(ec->dev, "Failed to set up regmap for device\n"); 127 return PTR_ERR(ec->regmap); 128 } 129 130 /* Determine the firmware version */ 131 res = regmap_read(ec->regmap, NTXEC_REG_VERSION, &version); 132 if (res < 0) { 133 dev_err(ec->dev, "Failed to read firmware version number\n"); 134 return res; 135 } 136 137 /* Bail out if we encounter an unknown firmware version */ 138 switch (version) { 139 case NTXEC_VERSION_KOBO_AURA: 140 break; 141 default: 142 dev_err(ec->dev, 143 "Netronix embedded controller version %04x is not supported.\n", 144 version); 145 return -ENODEV; 146 } 147 148 dev_info(ec->dev, 149 "Netronix embedded controller version %04x detected.\n", version); 150 151 if (of_device_is_system_power_controller(ec->dev->of_node)) { 152 /* 153 * Set the 'powerkeep' bit. This is necessary on some boards 154 * in order to keep the system running. 155 */ 156 res = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP, 157 NTXEC_POWERKEEP_VALUE); 158 if (res < 0) 159 return res; 160 161 if (poweroff_restart_client) 162 /* 163 * Another instance of the driver already took 164 * poweroff/restart duties. 165 */ 166 dev_err(ec->dev, "poweroff_restart_client already assigned\n"); 167 else 168 poweroff_restart_client = client; 169 170 if (pm_power_off) 171 /* Another driver already registered a poweroff handler. */ 172 dev_err(ec->dev, "pm_power_off already assigned\n"); 173 else 174 pm_power_off = ntxec_poweroff; 175 176 res = register_restart_handler(&ntxec_restart_handler); 177 if (res) 178 dev_err(ec->dev, 179 "Failed to register restart handler: %d\n", res); 180 } 181 182 i2c_set_clientdata(client, ec); 183 184 res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE, ntxec_subdevices, 185 ARRAY_SIZE(ntxec_subdevices), NULL, 0, NULL); 186 if (res) 187 dev_err(ec->dev, "Failed to add subdevices: %d\n", res); 188 189 return res; 190 } 191 192 static int ntxec_remove(struct i2c_client *client) 193 { 194 if (client == poweroff_restart_client) { 195 poweroff_restart_client = NULL; 196 pm_power_off = NULL; 197 unregister_restart_handler(&ntxec_restart_handler); 198 } 199 200 return 0; 201 } 202 203 static const struct of_device_id of_ntxec_match_table[] = { 204 { .compatible = "netronix,ntxec", }, 205 {} 206 }; 207 MODULE_DEVICE_TABLE(of, of_ntxec_match_table); 208 209 static struct i2c_driver ntxec_driver = { 210 .driver = { 211 .name = "ntxec", 212 .of_match_table = of_ntxec_match_table, 213 }, 214 .probe_new = ntxec_probe, 215 .remove = ntxec_remove, 216 }; 217 module_i2c_driver(ntxec_driver); 218 219 MODULE_AUTHOR("Jonathan Neuschäfer <[email protected]>"); 220 MODULE_DESCRIPTION("Core driver for Netronix EC"); 221 MODULE_LICENSE("GPL"); 222