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Diffstat (limited to '')
| -rw-r--r-- | drivers/mfd/gateworks-gsc.c | 275 |
1 files changed, 275 insertions, 0 deletions
diff --git a/drivers/mfd/gateworks-gsc.c b/drivers/mfd/gateworks-gsc.c new file mode 100644 index 000000000..9d7d870c4 --- /dev/null +++ b/drivers/mfd/gateworks-gsc.c @@ -0,0 +1,275 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * The Gateworks System Controller (GSC) is a multi-function + * device designed for use in Gateworks Single Board Computers. + * The control interface is I2C, with an interrupt. The device supports + * system functions such as push-button monitoring, multiple ADC's for + * voltage and temperature monitoring, fan controller and watchdog monitor. + * + * Copyright (C) 2020 Gateworks Corporation + */ + +#include <linux/device.h> +#include <linux/i2c.h> +#include <linux/interrupt.h> +#include <linux/mfd/gsc.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/of.h> +#include <linux/of_platform.h> +#include <linux/platform_device.h> +#include <linux/regmap.h> + +#include <asm/unaligned.h> + +/* + * The GSC suffers from an errata where occasionally during + * ADC cycles the chip can NAK I2C transactions. To ensure we have reliable + * register access we place retries around register access. + */ +#define I2C_RETRIES 3 + +int gsc_write(void *context, unsigned int reg, unsigned int val) +{ + struct i2c_client *client = context; + int retry, ret; + + for (retry = 0; retry < I2C_RETRIES; retry++) { + ret = i2c_smbus_write_byte_data(client, reg, val); + /* + * -EAGAIN returned when the i2c host controller is busy + * -EIO returned when i2c device is busy + */ + if (ret != -EAGAIN && ret != -EIO) + break; + } + + return 0; +} +EXPORT_SYMBOL_GPL(gsc_write); + +int gsc_read(void *context, unsigned int reg, unsigned int *val) +{ + struct i2c_client *client = context; + int retry, ret; + + for (retry = 0; retry < I2C_RETRIES; retry++) { + ret = i2c_smbus_read_byte_data(client, reg); + /* + * -EAGAIN returned when the i2c host controller is busy + * -EIO returned when i2c device is busy + */ + if (ret != -EAGAIN && ret != -EIO) + break; + } + *val = ret & 0xff; + + return 0; +} +EXPORT_SYMBOL_GPL(gsc_read); + +/* + * gsc_powerdown - API to use GSC to power down board for a specific time + * + * secs - number of seconds to remain powered off + */ +static int gsc_powerdown(struct gsc_dev *gsc, unsigned long secs) +{ + int ret; + unsigned char regs[4]; + + dev_info(&gsc->i2c->dev, "GSC powerdown for %ld seconds\n", + secs); + + put_unaligned_le32(secs, regs); + ret = regmap_bulk_write(gsc->regmap, GSC_TIME_ADD, regs, 4); + if (ret) + return ret; + + ret = regmap_update_bits(gsc->regmap, GSC_CTRL_1, + BIT(GSC_CTRL_1_SLEEP_ADD), + BIT(GSC_CTRL_1_SLEEP_ADD)); + if (ret) + return ret; + + ret = regmap_update_bits(gsc->regmap, GSC_CTRL_1, + BIT(GSC_CTRL_1_SLEEP_ACTIVATE) | + BIT(GSC_CTRL_1_SLEEP_ENABLE), + BIT(GSC_CTRL_1_SLEEP_ACTIVATE) | + BIT(GSC_CTRL_1_SLEEP_ENABLE)); + + + return ret; +} + +static ssize_t gsc_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct gsc_dev *gsc = dev_get_drvdata(dev); + const char *name = attr->attr.name; + int rz = 0; + + if (strcasecmp(name, "fw_version") == 0) + rz = sprintf(buf, "%d\n", gsc->fwver); + else if (strcasecmp(name, "fw_crc") == 0) + rz = sprintf(buf, "0x%04x\n", gsc->fwcrc); + else + dev_err(dev, "invalid command: '%s'\n", name); + + return rz; +} + +static ssize_t gsc_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct gsc_dev *gsc = dev_get_drvdata(dev); + const char *name = attr->attr.name; + long value; + + if (strcasecmp(name, "powerdown") == 0) { + if (kstrtol(buf, 0, &value) == 0) + gsc_powerdown(gsc, value); + } else { + dev_err(dev, "invalid command: '%s\n", name); + } + + return count; +} + +static struct device_attribute attr_fwver = + __ATTR(fw_version, 0440, gsc_show, NULL); +static struct device_attribute attr_fwcrc = + __ATTR(fw_crc, 0440, gsc_show, NULL); +static struct device_attribute attr_pwrdown = + __ATTR(powerdown, 0220, NULL, gsc_store); + +static struct attribute *gsc_attrs[] = { + &attr_fwver.attr, + &attr_fwcrc.attr, + &attr_pwrdown.attr, + NULL, +}; + +static struct attribute_group attr_group = { + .attrs = gsc_attrs, +}; + +static const struct of_device_id gsc_of_match[] = { + { .compatible = "gw,gsc", }, + { } +}; +MODULE_DEVICE_TABLE(of, gsc_of_match); + +static struct regmap_bus gsc_regmap_bus = { + .reg_read = gsc_read, + .reg_write = gsc_write, +}; + +static const struct regmap_config gsc_regmap_config = { + .reg_bits = 8, + .val_bits = 8, + .cache_type = REGCACHE_NONE, + .max_register = GSC_WP, +}; + +static const struct regmap_irq gsc_irqs[] = { + REGMAP_IRQ_REG(GSC_IRQ_PB, 0, BIT(GSC_IRQ_PB)), + REGMAP_IRQ_REG(GSC_IRQ_KEY_ERASED, 0, BIT(GSC_IRQ_KEY_ERASED)), + REGMAP_IRQ_REG(GSC_IRQ_EEPROM_WP, 0, BIT(GSC_IRQ_EEPROM_WP)), + REGMAP_IRQ_REG(GSC_IRQ_RESV, 0, BIT(GSC_IRQ_RESV)), + REGMAP_IRQ_REG(GSC_IRQ_GPIO, 0, BIT(GSC_IRQ_GPIO)), + REGMAP_IRQ_REG(GSC_IRQ_TAMPER, 0, BIT(GSC_IRQ_TAMPER)), + REGMAP_IRQ_REG(GSC_IRQ_WDT_TIMEOUT, 0, BIT(GSC_IRQ_WDT_TIMEOUT)), + REGMAP_IRQ_REG(GSC_IRQ_SWITCH_HOLD, 0, BIT(GSC_IRQ_SWITCH_HOLD)), +}; + +static const struct regmap_irq_chip gsc_irq_chip = { + .name = "gateworks-gsc", + .irqs = gsc_irqs, + .num_irqs = ARRAY_SIZE(gsc_irqs), + .num_regs = 1, + .status_base = GSC_IRQ_STATUS, + .mask_base = GSC_IRQ_ENABLE, + .mask_invert = true, + .ack_base = GSC_IRQ_STATUS, + .ack_invert = true, +}; + +static int gsc_probe(struct i2c_client *client) +{ + struct device *dev = &client->dev; + struct gsc_dev *gsc; + struct regmap_irq_chip_data *irq_data; + int ret; + unsigned int reg; + + gsc = devm_kzalloc(dev, sizeof(*gsc), GFP_KERNEL); + if (!gsc) + return -ENOMEM; + + gsc->dev = &client->dev; + gsc->i2c = client; + i2c_set_clientdata(client, gsc); + + gsc->regmap = devm_regmap_init(dev, &gsc_regmap_bus, client, + &gsc_regmap_config); + if (IS_ERR(gsc->regmap)) + return PTR_ERR(gsc->regmap); + + if (regmap_read(gsc->regmap, GSC_FW_VER, ®)) + return -EIO; + gsc->fwver = reg; + + regmap_read(gsc->regmap, GSC_FW_CRC, ®); + gsc->fwcrc = reg; + regmap_read(gsc->regmap, GSC_FW_CRC + 1, ®); + gsc->fwcrc |= reg << 8; + + gsc->i2c_hwmon = devm_i2c_new_dummy_device(dev, client->adapter, + GSC_HWMON); + if (IS_ERR(gsc->i2c_hwmon)) { + dev_err(dev, "Failed to allocate I2C device for HWMON\n"); + return PTR_ERR(gsc->i2c_hwmon); + } + + ret = devm_regmap_add_irq_chip(dev, gsc->regmap, client->irq, + IRQF_ONESHOT | IRQF_SHARED | + IRQF_TRIGGER_LOW, 0, + &gsc_irq_chip, &irq_data); + if (ret) + return ret; + + dev_info(dev, "Gateworks System Controller v%d: fw 0x%04x\n", + gsc->fwver, gsc->fwcrc); + + ret = sysfs_create_group(&dev->kobj, &attr_group); + if (ret) + dev_err(dev, "failed to create sysfs attrs\n"); + + ret = devm_of_platform_populate(dev); + if (ret) { + sysfs_remove_group(&dev->kobj, &attr_group); + return ret; + } + + return 0; +} + +static void gsc_remove(struct i2c_client *client) +{ + sysfs_remove_group(&client->dev.kobj, &attr_group); +} + +static struct i2c_driver gsc_driver = { + .driver = { + .name = "gateworks-gsc", + .of_match_table = gsc_of_match, + }, + .probe_new = gsc_probe, + .remove = gsc_remove, +}; +module_i2c_driver(gsc_driver); + +MODULE_AUTHOR("Tim Harvey <tharvey@gateworks.com>"); +MODULE_DESCRIPTION("I2C Core interface for GSC"); +MODULE_LICENSE("GPL v2"); |