1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * The Gateworks System Controller (GSC) is a multi-function 4 * device designed for use in Gateworks Single Board Computers. 5 * The control interface is I2C, with an interrupt. The device supports 6 * system functions such as push-button monitoring, multiple ADC's for 7 * voltage and temperature monitoring, fan controller and watchdog monitor. 8 * 9 * Copyright (C) 2020 Gateworks Corporation 10 */ 11 12 #include <linux/device.h> 13 #include <linux/i2c.h> 14 #include <linux/interrupt.h> 15 #include <linux/mfd/gsc.h> 16 #include <linux/module.h> 17 #include <linux/mutex.h> 18 #include <linux/of.h> 19 #include <linux/of_platform.h> 20 #include <linux/platform_device.h> 21 #include <linux/regmap.h> 22 23 #include <asm/unaligned.h> 24 25 /* 26 * The GSC suffers from an errata where occasionally during 27 * ADC cycles the chip can NAK I2C transactions. To ensure we have reliable 28 * register access we place retries around register access. 29 */ 30 #define I2C_RETRIES 3 31 32 int gsc_write(void *context, unsigned int reg, unsigned int val) 33 { 34 struct i2c_client *client = context; 35 int retry, ret; 36 37 for (retry = 0; retry < I2C_RETRIES; retry++) { 38 ret = i2c_smbus_write_byte_data(client, reg, val); 39 /* 40 * -EAGAIN returned when the i2c host controller is busy 41 * -EIO returned when i2c device is busy 42 */ 43 if (ret != -EAGAIN && ret != -EIO) 44 break; 45 } 46 47 return 0; 48 } 49 EXPORT_SYMBOL_GPL(gsc_write); 50 51 int gsc_read(void *context, unsigned int reg, unsigned int *val) 52 { 53 struct i2c_client *client = context; 54 int retry, ret; 55 56 for (retry = 0; retry < I2C_RETRIES; retry++) { 57 ret = i2c_smbus_read_byte_data(client, reg); 58 /* 59 * -EAGAIN returned when the i2c host controller is busy 60 * -EIO returned when i2c device is busy 61 */ 62 if (ret != -EAGAIN && ret != -EIO) 63 break; 64 } 65 *val = ret & 0xff; 66 67 return 0; 68 } 69 EXPORT_SYMBOL_GPL(gsc_read); 70 71 /* 72 * gsc_powerdown - API to use GSC to power down board for a specific time 73 * 74 * secs - number of seconds to remain powered off 75 */ 76 static int gsc_powerdown(struct gsc_dev *gsc, unsigned long secs) 77 { 78 int ret; 79 unsigned char regs[4]; 80 81 dev_info(&gsc->i2c->dev, "GSC powerdown for %ld seconds\n", 82 secs); 83 84 put_unaligned_le32(secs, regs); 85 ret = regmap_bulk_write(gsc->regmap, GSC_TIME_ADD, regs, 4); 86 if (ret) 87 return ret; 88 89 ret = regmap_update_bits(gsc->regmap, GSC_CTRL_1, 90 BIT(GSC_CTRL_1_SLEEP_ADD), 91 BIT(GSC_CTRL_1_SLEEP_ADD)); 92 if (ret) 93 return ret; 94 95 ret = regmap_update_bits(gsc->regmap, GSC_CTRL_1, 96 BIT(GSC_CTRL_1_SLEEP_ACTIVATE) | 97 BIT(GSC_CTRL_1_SLEEP_ENABLE), 98 BIT(GSC_CTRL_1_SLEEP_ACTIVATE) | 99 BIT(GSC_CTRL_1_SLEEP_ENABLE)); 100 101 102 return ret; 103 } 104 105 static ssize_t gsc_show(struct device *dev, struct device_attribute *attr, 106 char *buf) 107 { 108 struct gsc_dev *gsc = dev_get_drvdata(dev); 109 const char *name = attr->attr.name; 110 int rz = 0; 111 112 if (strcasecmp(name, "fw_version") == 0) 113 rz = sprintf(buf, "%d\n", gsc->fwver); 114 else if (strcasecmp(name, "fw_crc") == 0) 115 rz = sprintf(buf, "0x%04x\n", gsc->fwcrc); 116 else 117 dev_err(dev, "invalid command: '%s'\n", name); 118 119 return rz; 120 } 121 122 static ssize_t gsc_store(struct device *dev, struct device_attribute *attr, 123 const char *buf, size_t count) 124 { 125 struct gsc_dev *gsc = dev_get_drvdata(dev); 126 const char *name = attr->attr.name; 127 long value; 128 129 if (strcasecmp(name, "powerdown") == 0) { 130 if (kstrtol(buf, 0, &value) == 0) 131 gsc_powerdown(gsc, value); 132 } else { 133 dev_err(dev, "invalid command: '%s\n", name); 134 } 135 136 return count; 137 } 138 139 static struct device_attribute attr_fwver = 140 __ATTR(fw_version, 0440, gsc_show, NULL); 141 static struct device_attribute attr_fwcrc = 142 __ATTR(fw_crc, 0440, gsc_show, NULL); 143 static struct device_attribute attr_pwrdown = 144 __ATTR(powerdown, 0220, NULL, gsc_store); 145 146 static struct attribute *gsc_attrs[] = { 147 &attr_fwver.attr, 148 &attr_fwcrc.attr, 149 &attr_pwrdown.attr, 150 NULL, 151 }; 152 153 static struct attribute_group attr_group = { 154 .attrs = gsc_attrs, 155 }; 156 157 static const struct of_device_id gsc_of_match[] = { 158 { .compatible = "gw,gsc", }, 159 { } 160 }; 161 MODULE_DEVICE_TABLE(of, gsc_of_match); 162 163 static struct regmap_bus gsc_regmap_bus = { 164 .reg_read = gsc_read, 165 .reg_write = gsc_write, 166 }; 167 168 static const struct regmap_config gsc_regmap_config = { 169 .reg_bits = 8, 170 .val_bits = 8, 171 .cache_type = REGCACHE_NONE, 172 .max_register = GSC_WP, 173 }; 174 175 static const struct regmap_irq gsc_irqs[] = { 176 REGMAP_IRQ_REG(GSC_IRQ_PB, 0, BIT(GSC_IRQ_PB)), 177 REGMAP_IRQ_REG(GSC_IRQ_KEY_ERASED, 0, BIT(GSC_IRQ_KEY_ERASED)), 178 REGMAP_IRQ_REG(GSC_IRQ_EEPROM_WP, 0, BIT(GSC_IRQ_EEPROM_WP)), 179 REGMAP_IRQ_REG(GSC_IRQ_RESV, 0, BIT(GSC_IRQ_RESV)), 180 REGMAP_IRQ_REG(GSC_IRQ_GPIO, 0, BIT(GSC_IRQ_GPIO)), 181 REGMAP_IRQ_REG(GSC_IRQ_TAMPER, 0, BIT(GSC_IRQ_TAMPER)), 182 REGMAP_IRQ_REG(GSC_IRQ_WDT_TIMEOUT, 0, BIT(GSC_IRQ_WDT_TIMEOUT)), 183 REGMAP_IRQ_REG(GSC_IRQ_SWITCH_HOLD, 0, BIT(GSC_IRQ_SWITCH_HOLD)), 184 }; 185 186 static const struct regmap_irq_chip gsc_irq_chip = { 187 .name = "gateworks-gsc", 188 .irqs = gsc_irqs, 189 .num_irqs = ARRAY_SIZE(gsc_irqs), 190 .num_regs = 1, 191 .status_base = GSC_IRQ_STATUS, 192 .unmask_base = GSC_IRQ_ENABLE, 193 .ack_base = GSC_IRQ_STATUS, 194 .ack_invert = true, 195 }; 196 197 static int gsc_probe(struct i2c_client *client) 198 { 199 struct device *dev = &client->dev; 200 struct gsc_dev *gsc; 201 struct regmap_irq_chip_data *irq_data; 202 int ret; 203 unsigned int reg; 204 205 gsc = devm_kzalloc(dev, sizeof(*gsc), GFP_KERNEL); 206 if (!gsc) 207 return -ENOMEM; 208 209 gsc->dev = &client->dev; 210 gsc->i2c = client; 211 i2c_set_clientdata(client, gsc); 212 213 gsc->regmap = devm_regmap_init(dev, &gsc_regmap_bus, client, 214 &gsc_regmap_config); 215 if (IS_ERR(gsc->regmap)) 216 return PTR_ERR(gsc->regmap); 217 218 if (regmap_read(gsc->regmap, GSC_FW_VER, ®)) 219 return -EIO; 220 gsc->fwver = reg; 221 222 regmap_read(gsc->regmap, GSC_FW_CRC, ®); 223 gsc->fwcrc = reg; 224 regmap_read(gsc->regmap, GSC_FW_CRC + 1, ®); 225 gsc->fwcrc |= reg << 8; 226 227 gsc->i2c_hwmon = devm_i2c_new_dummy_device(dev, client->adapter, 228 GSC_HWMON); 229 if (IS_ERR(gsc->i2c_hwmon)) { 230 dev_err(dev, "Failed to allocate I2C device for HWMON\n"); 231 return PTR_ERR(gsc->i2c_hwmon); 232 } 233 234 ret = devm_regmap_add_irq_chip(dev, gsc->regmap, client->irq, 235 IRQF_ONESHOT | IRQF_SHARED | 236 IRQF_TRIGGER_LOW, 0, 237 &gsc_irq_chip, &irq_data); 238 if (ret) 239 return ret; 240 241 dev_info(dev, "Gateworks System Controller v%d: fw 0x%04x\n", 242 gsc->fwver, gsc->fwcrc); 243 244 ret = sysfs_create_group(&dev->kobj, &attr_group); 245 if (ret) 246 dev_err(dev, "failed to create sysfs attrs\n"); 247 248 ret = devm_of_platform_populate(dev); 249 if (ret) { 250 sysfs_remove_group(&dev->kobj, &attr_group); 251 return ret; 252 } 253 254 return 0; 255 } 256 257 static void gsc_remove(struct i2c_client *client) 258 { 259 sysfs_remove_group(&client->dev.kobj, &attr_group); 260 } 261 262 static struct i2c_driver gsc_driver = { 263 .driver = { 264 .name = "gateworks-gsc", 265 .of_match_table = gsc_of_match, 266 }, 267 .probe = gsc_probe, 268 .remove = gsc_remove, 269 }; 270 module_i2c_driver(gsc_driver); 271 272 MODULE_AUTHOR("Tim Harvey <tharvey@gateworks.com>"); 273 MODULE_DESCRIPTION("I2C Core interface for GSC"); 274 MODULE_LICENSE("GPL v2"); 275