[RFC 2/4] mfd: add Gateworks System Controller core driver

Tim Harvey
2018-02-28T01:21:12Z

The Gateworks System Controller (GSC) is an I2C slave controller
implemented with an MSP430 micro-controller whose firmware embeds the
following features:
- I/O expander (16 GPIO's) using PCA955x protocol
- Real Time Clock using DS1672 protocol
- User EEPROM using AT24 protocol
- HWMON using custom protocol
- Interrupt controller with tamper detect, user pushbotton
- Watchdog controller capable of full board power-cycle
- Power Control capable of full board power-cycle

see http://trac.gateworks.com/wiki/gsc for more details

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
---
drivers/mfd/Kconfig | 10 ++
drivers/mfd/Makefile | 1 +
drivers/mfd/gsc.c | 330 ++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/mfd/gsc.h | 79 ++++++++++++
4 files changed, 420 insertions(+)
create mode 100644 drivers/mfd/gsc.c
create mode 100644 include/linux/mfd/gsc.h

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 1d20a80..16dd486 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -341,6 +341,16 @@ config MFD_EXYNOS_LPASS
Select this option to enable support for Samsung Exynos Low Power
Audio Subsystem.

+config MFD_GSC
+ tristate "Gateworks System Controller"
+ depends on (I2C && OF) || COMPILE_TEST
+ select MFD_CORE
+ select REGMAP_I2C
+ select REGMAP_IRQ
+ help
+ Enable support for the Gateworks System Controller found
+ on Gateworks Single Board Computers.
+
config MFD_MC13XXX
tristate
depends on (SPI_MASTER || I2C)
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index d9474ad..aede0bc 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_MFD_CROS_EC) += cros_ec_core.o
obj-$(CONFIG_MFD_CROS_EC_I2C) += cros_ec_i2c.o
obj-$(CONFIG_MFD_CROS_EC_SPI) += cros_ec_spi.o
obj-$(CONFIG_MFD_EXYNOS_LPASS) += exynos-lpass.o
+obj-$(CONFIG_MFD_GSC) += gsc.o

rtsx_pci-objs := rtsx_pcr.o rts5209.o rts5229.o rtl8411.o rts5227.o rts5249.o
obj-$(CONFIG_MFD_RTSX_PCI) += rtsx_pci.o
diff --git a/drivers/mfd/gsc.c b/drivers/mfd/gsc.c
new file mode 100644
index 0000000..2fe4174
--- /dev/null
+++ b/drivers/mfd/gsc.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Gateworks Corporation
+ *
+ * The Gateworks System Controller (GSC) is a family of a multi-function
+ * "Power Management and System Companion Device" chips originally designed for
+ * use in Gateworks Single Board Computers. The control interface is I2C,
+ * at 100kbps, with an interrupt.
+ *
+ */
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.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>
+
+/*
+ * 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
+
+static int gsc_regmap_regwrite(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;
+ }
+ if (ret < 0) {
+ dev_err(&client->dev, ">> 0x%02x %d\n", reg, ret);
+ return ret;
+ }
+ dev_dbg(&client->dev, ">> 0x%02x=0x%02x (%d)\n", reg, val, retry);
+
+ return 0;
+}
+
+static int gsc_regmap_regread(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;
+ }
+ if (ret < 0) {
+ dev_err(&client->dev, "<< 0x%02x %d\n", reg, ret);
+ return ret;
+ }
+
+ *val = ret & 0xff;
+ dev_dbg(&client->dev, "<< 0x%02x=0x%02x (%d)\n", reg, *val, retry);
+
+ return 0;
+}
+
+static struct regmap_bus regmap_gsc = {
+ .reg_write = gsc_regmap_regwrite,
+ .reg_read = gsc_regmap_regread,
+};
+
+/*
+ * 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);
+ regs[0] = secs & 0xff;
+ regs[1] = (secs >> 8) & 0xff;
+ regs[2] = (secs >> 16) & 0xff;
+ regs[3] = (secs >> 24) & 0xff;
+ ret = regmap_bulk_write(gsc->regmap, GSC_TIME_ADD, regs, 4);
+
+ return ret;
+}
+
+/*
+ * sysfs hooks
+ */
+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);
+
+ 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;
+ int ret;
+
+ if (strcasecmp(name, "powerdown") == 0) {
+ long value;
+
+ ret = kstrtol(buf, 0, &value);
+ if (ret == 0)
+ gsc_powerdown(gsc, value);
+ } else
+ printk(KERN_ERR "invalid name '%s\n", name);
+
+ return count;
+}
+
+
+/*
+ * Create a group of attributes so that we can create and destroy them all
+ * at once.
+ */
+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 i2c_device_id gsc_i2c_ids[] = {
+ { "gsc_v1", gsc_v1 },
+ { "gsc_v2", gsc_v2 },
+ { "gsc_v3", gsc_v3 },
+ { },
+};
+
+static const struct of_device_id gsc_of_match[] = {
+ { .compatible = "gw,gsc_v1", .data = (void *)gsc_v1 },
+ { .compatible = "gw,gsc_v2", .data = (void *)gsc_v2 },
+ { .compatible = "gw,gsc_v3", .data = (void *)gsc_v3 },
+ { }
+};
+
+static const struct regmap_config gsc_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .cache_type = REGCACHE_NONE,
+ .max_register = 0xf,
+};
+
+static const struct regmap_config gsc_regmap_hwmon_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .cache_type = REGCACHE_NONE,
+ .max_register = 0x37,
+};
+
+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 = KBUILD_MODNAME,
+ .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_of_probe(struct device_node *np, struct gsc_dev *gsc)
+{
+ const struct of_device_id *of_id;
+
+ if (!np)
+ return -ENODEV;
+
+ of_id = of_match_device(gsc_of_match, gsc->dev);
+ if (of_id)
+ gsc->type = (enum gsc_type)of_id->data;
+
+ return 0;
+}
+
+static int
+gsc_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ struct gsc_dev *gsc;
+ int ret;
+ unsigned int reg;
+
+ gsc = devm_kzalloc(dev, sizeof(*gsc), GFP_KERNEL);
+ if (!gsc)
+ return -ENOMEM;
+
+ gsc->dev = &client->dev;
+ gsc->i2c = client;
+ gsc->irq = client->irq;
+ i2c_set_clientdata(client, gsc);
+
+ gsc->regmap = devm_regmap_init(dev, &regmap_gsc, client,
+ &gsc_regmap_config);
+ if (IS_ERR(gsc->regmap))
+ return PTR_ERR(gsc->regmap);
+
+ ret = gsc_of_probe(dev->of_node, gsc);
+ if (reg < 0)
+ return ret;
+
+ if (regmap_read(gsc->regmap, GSC_FW_VER, &reg))
+ return -EIO;
+ gsc->fwver = reg;
+ regmap_read(gsc->regmap, GSC_FW_CRC, &reg);
+ gsc->fwcrc = reg;
+ regmap_read(gsc->regmap, GSC_FW_CRC + 1, &reg);
+ gsc->fwcrc |= reg << 8;
+
+ gsc->i2c_hwmon = i2c_new_dummy(client->adapter, GSC_HWMON);
+ if (!gsc->i2c_hwmon) {
+ dev_err(dev, "Failed to allocate I2C device for HWMON\n");
+ return -ENODEV;
+ }
+ i2c_set_clientdata(gsc->i2c_hwmon, gsc);
+
+ gsc->regmap_hwmon = devm_regmap_init(dev, &regmap_gsc, gsc->i2c_hwmon,
+ &gsc_regmap_hwmon_config);
+ if (IS_ERR(gsc->regmap_hwmon)) {
+ ret = PTR_ERR(gsc->regmap_hwmon);
+ dev_err(dev, "failed to allocate register map: %d\n", ret);
+ goto err_regmap;
+ }
+
+ ret = devm_regmap_add_irq_chip(dev, gsc->regmap, gsc->irq,
+ IRQF_ONESHOT | IRQF_SHARED |
+ IRQF_TRIGGER_FALLING, 0,
+ &gsc_irq_chip, &gsc->irq_chip_data);
+ if (ret)
+ goto err_regmap;
+
+ dev_info(dev, "Gateworks System Controller v%d: fw v%02d 0x%04x\n",
+ gsc->type, gsc->fwver, gsc->fwcrc);
+
+ /* sysfs hooks */
+ ret = sysfs_create_group(&dev->kobj, &attr_group);
+ if (ret)
+ dev_err(dev, "failed to create sysfs attrs\n");
+
+ ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
+ if (ret)
+ goto err_sysfs;
+
+ return 0;
+
+err_sysfs:
+ sysfs_remove_group(&dev->kobj, &attr_group);
+err_regmap:
+ i2c_unregister_device(gsc->i2c_hwmon);
+
+ return ret;
+}
+
+static int gsc_remove(struct i2c_client *client)
+{
+ sysfs_remove_group(&client->dev.kobj, &attr_group);
+
+ return 0;
+}
+
+static struct i2c_driver gsc_driver = {
+ .driver = {
+ .name = KBUILD_MODNAME,
+ .of_match_table = of_match_ptr(gsc_of_match),
+ },
+ .probe = gsc_probe,
+ .remove = gsc_remove,
+ .id_table = gsc_i2c_ids,
+};
+
+module_i2c_driver(gsc_driver);
+
+MODULE_AUTHOR("Tim Harvey <tharvey@gateworks.com>");
+MODULE_DESCRIPTION("I2C Core interface for GSC");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/mfd/gsc.h b/include/linux/mfd/gsc.h
new file mode 100644
index 0000000..2a55e0d
--- /dev/null
+++ b/include/linux/mfd/gsc.h
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Gateworks Corporation
+ */
+#ifndef __LINUX_MFD_GSC_H_
+#define __LINUX_MFD_GSC_H_
+
+/* Device Addresses */
+#define GSC_MISC 0x20
+#define GSC_UPDATE 0x21
+#define GSC_GPIO 0x23
+#define GSC_HWMON 0x29
+#define GSC_EEPROM0 0x50
+#define GSC_EEPROM1 0x51
+#define GSC_EEPROM2 0x52
+#define GSC_EEPROM3 0x53
+#define GSC_RTC 0x68
+
+/* Register offsets */
+#define GSC_CTRL_0 0x00
+#define GSC_CTRL_1 0x01
+#define GSC_TIME 0x02
+#define GSC_TIME_ADD 0x06
+#define GSC_IRQ_STATUS 0x0A
+#define GSC_IRQ_ENABLE 0x0B
+#define GSC_FW_CRC 0x0C
+#define GSC_FW_VER 0x0E
+#define GSC_WP 0x0F
+
+/* Bit definitions */
+#define GSC_CTRL_0_PB_HARD_RESET 0
+#define GSC_CTRL_0_PB_CLEAR_SECURE_KEY 1
+#define GSC_CTRL_0_PB_SOFT_POWER_DOWN 2
+#define GSC_CTRL_0_PB_BOOT_ALTERNATE 3
+#define GSC_CTRL_0_PERFORM_CRC 4
+#define GSC_CTRL_0_TAMPER_DETECT 5
+#define GSC_CTRL_0_SWITCH_HOLD 6
+
+#define GSC_CTRL_1_SLEEP_ENABLE 0
+#define GSC_CTRL_1_ACTIVATE_SLEEP 1
+#define GSC_CTRL_1_LATCH_SLEEP_ADD 2
+#define GSC_CTRL_1_SLEEP_NOWAKEPB 3
+#define GSC_CTRL_1_WDT_TIME 4
+#define GSC_CTRL_1_WDT_ENABLE 5
+#define GSC_CTRL_1_SWITCH_BOOT_ENABLE 6
+#define GSC_CTRL_1_SWITCH_BOOT_CLEAR 7
+
+#define GSC_IRQ_PB 0
+#define GSC_IRQ_KEY_ERASED 1
+#define GSC_IRQ_EEPROM_WP 2
+#define GSC_IRQ_RESV 3
+#define GSC_IRQ_GPIO 4
+#define GSC_IRQ_TAMPER 5
+#define GSC_IRQ_WDT_TIMEOUT 6
+#define GSC_IRQ_SWITCH_HOLD 7
+
+enum gsc_type {
+ gsc_v1 = 1,
+ gsc_v2 = 2,
+ gsc_v3 = 3,
+};
+
+struct gsc_dev {
+ struct device *dev;
+
+ struct i2c_client *i2c; /* 0x20: interrupt controller, WDT */
+ struct i2c_client *i2c_hwmon; /* 0x29: hwmon, fan controller */
+
+ struct regmap *regmap;
+ struct regmap *regmap_hwmon;
+ struct regmap_irq_chip_data *irq_chip_data;
+
+ int irq;
+ enum gsc_type type;
+ unsigned int fwver;
+ unsigned short fwcrc;
+};
+
+#endif /* __LINUX_MFD_GSC_H_ */
--
2.7.4