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| 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 | + .mask_base = GSC_IRQ_ENABLE, |
| 193 | + .mask_invert = true, |
| 194 | + .ack_base = GSC_IRQ_STATUS, |
| 195 | + .ack_invert = true, |
| 196 | +}; |
| 197 | + |
| 198 | +static int gsc_probe(struct i2c_client *client) |
| 199 | +{ |
| 200 | + struct device *dev = &client->dev; |
| 201 | + struct gsc_dev *gsc; |
| 202 | + struct regmap_irq_chip_data *irq_data; |
| 203 | + int ret; |
| 204 | + unsigned int reg; |
| 205 | + |
| 206 | + gsc = devm_kzalloc(dev, sizeof(*gsc), GFP_KERNEL); |
| 207 | + if (!gsc) |
| 208 | + return -ENOMEM; |
| 209 | + |
| 210 | + gsc->dev = &client->dev; |
| 211 | + gsc->i2c = client; |
| 212 | + i2c_set_clientdata(client, gsc); |
| 213 | + |
| 214 | + gsc->regmap = devm_regmap_init(dev, &gsc_regmap_bus, client, |
| 215 | + &gsc_regmap_config); |
| 216 | + if (IS_ERR(gsc->regmap)) |
| 217 | + return PTR_ERR(gsc->regmap); |
| 218 | + |
| 219 | + if (regmap_read(gsc->regmap, GSC_FW_VER, ®)) |
| 220 | + return -EIO; |
| 221 | + gsc->fwver = reg; |
| 222 | + |
| 223 | + regmap_read(gsc->regmap, GSC_FW_CRC, ®); |
| 224 | + gsc->fwcrc = reg; |
| 225 | + regmap_read(gsc->regmap, GSC_FW_CRC + 1, ®); |
| 226 | + gsc->fwcrc |= reg << 8; |
| 227 | + |
| 228 | + gsc->i2c_hwmon = devm_i2c_new_dummy_device(dev, client->adapter, |
| 229 | + GSC_HWMON); |
| 230 | + if (IS_ERR(gsc->i2c_hwmon)) { |
| 231 | + dev_err(dev, "Failed to allocate I2C device for HWMON\n"); |
| 232 | + return PTR_ERR(gsc->i2c_hwmon); |
| 233 | + } |
| 234 | + |
| 235 | + ret = devm_regmap_add_irq_chip(dev, gsc->regmap, client->irq, |
| 236 | + IRQF_ONESHOT | IRQF_SHARED | |
| 237 | + IRQF_TRIGGER_FALLING, 0, |
| 238 | + &gsc_irq_chip, &irq_data); |
| 239 | + if (ret) |
| 240 | + return ret; |
| 241 | + |
| 242 | + dev_info(dev, "Gateworks System Controller v%d: fw 0x%04x\n", |
| 243 | + gsc->fwver, gsc->fwcrc); |
| 244 | + |
| 245 | + ret = sysfs_create_group(&dev->kobj, &attr_group); |
| 246 | + if (ret) |
| 247 | + dev_err(dev, "failed to create sysfs attrs\n"); |
| 248 | + |
| 249 | + ret = devm_of_platform_populate(dev); |
| 250 | + if (ret) { |
| 251 | + sysfs_remove_group(&dev->kobj, &attr_group); |
| 252 | + return ret; |
| 253 | + } |
| 254 | + |
| 255 | + return 0; |
| 256 | +} |
| 257 | + |
| 258 | +static int gsc_remove(struct i2c_client *client) |
| 259 | +{ |
| 260 | + sysfs_remove_group(&client->dev.kobj, &attr_group); |
| 261 | + |
| 262 | + return 0; |
| 263 | +} |
| 264 | + |
| 265 | +static struct i2c_driver gsc_driver = { |
| 266 | + .driver = { |
| 267 | + .name = "gateworks-gsc", |
| 268 | + .of_match_table = gsc_of_match, |
| 269 | + }, |
| 270 | + .probe_new = gsc_probe, |
| 271 | + .remove = gsc_remove, |
| 272 | +}; |
| 273 | +module_i2c_driver(gsc_driver); |
| 274 | + |
| 275 | +MODULE_AUTHOR( "Tim Harvey <[email protected]>"); |
| 276 | +MODULE_DESCRIPTION("I2C Core interface for GSC"); |
| 277 | +MODULE_LICENSE("GPL v2"); |
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