drivers/mfd/gateworks-gsc.c

   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 <linux/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 const 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, &reg))
 219                 return -EIO;
 220         gsc->fwver = reg;
 221
 222         regmap_read(gsc->regmap, GSC_FW_CRC, &reg);
 223         gsc->fwcrc = reg;
 224         regmap_read(gsc->regmap, GSC_FW_CRC + 1, &reg);
 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");