[PATCH v10 2/3] mfd: add Gateworks System Controller core driver

From: Tim Harvey
Date: Fri May 15 2020 - 11:18:30 EST

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@xxxxxxxxxxxxx>
Acked-for-MFD-by: Lee Jones <lee.jones@xxxxxxxxxx>
---
v10:
- fix typo and gramatical errors in Kconfig and comment block
- drop unused i2c device-id table
- added Lee's ack in s-o-b

v9:
- rebase against 5.7-rc2
- cleanup gsc_powerdown() by using BIT(), put_unaligned_le32(), and avoid
unnecessary assignments
- rename GSC_CTRL_1 SLEEP related defines to simplify
- add better description and sub-module info to driver description
- whitespace changes per review
- remove unused irq_data pointer in ddata
- remove unnecesary i2c_set_clientdata
- use devm_i2c_new_dummy_device to avoid need of free's
- change regsiter definitions to enum
- export gsc_{read,write} instead of sharing them via ddata

v8:
- whitespace fixes
- describe sub-devices in Kconfig
- add error print for invalid command
- update copyright
- use devm_of_platform_populate
- use probe_new
- move hwmon's regmap init to hwmon

v7:
- remove irq from private data struct

v6:
- remove duplicate signature and fix commit log

v5:
- simplify powerdown function

v4:
- remove hwmon max reg check/define
- fix powerdown function

v3:
- rename gsc->gateworks-gsc
- remove uncecessary include for linux/mfd/core.h
- upercase I2C in comments
- remove i2c debug
- remove uncecessary comments
- don't use KBUILD_MODNAME for name
- remove unnecessary v1/v2/v3 tracking
- unregister hwmon i2c adapter on remove

v2:
- change license comment block style
- remove COMPILE_TEST (Randy)
- fixed whitespace issues
- replaced a printk with dev_err
---
MAINTAINERS | 8 ++
drivers/mfd/Kconfig | 15 +++
drivers/mfd/Makefile | 1 +
drivers/mfd/gateworks-gsc.c | 278 ++++++++++++++++++++++++++++++++++++++++++++
include/linux/mfd/gsc.h | 76 ++++++++++++
5 files changed, 378 insertions(+)
create mode 100644 drivers/mfd/gateworks-gsc.c
create mode 100644 include/linux/mfd/gsc.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 091ec22..c78a014 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7028,6 +7028,14 @@ F: kernel/futex.c
F: tools/perf/bench/futex*
F: tools/testing/selftests/futex/

+GATEWORKS SYSTEM CONTROLLER (GSC) DRIVER
+M: Tim Harvey <tharvey@xxxxxxxxxxxxx>
+M: Robert Jones <rjones@xxxxxxxxxxxxx>
+S: Maintained
+F: Documentation/devicetree/bindings/mfd/gateworks-gsc.yaml
+F: drivers/mfd/gateworks-gsc.c
+F: include/linux/mfd/gsc.h
+
GASKET DRIVER FRAMEWORK
M: Rob Springer <rspringer@xxxxxxxxxx>
M: Todd Poynor <toddpoynor@xxxxxxxxxx>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 0a59249..05448e7 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -407,6 +407,21 @@ config MFD_EXYNOS_LPASS
Select this option to enable support for Samsung Exynos Low Power
Audio Subsystem.

+config MFD_GATEWORKS_GSC
+ tristate "Gateworks System Controller"
+ depends on (I2C && OF)
+ select MFD_CORE
+ select REGMAP_I2C
+ select REGMAP_IRQ
+ help
+ Enable support for the Gateworks System Controller (GSC) found
+ on Gateworks Single Board Computers supporting system functions
+ such as push-button monitor, multiple ADC's for voltage and
+ temperature monitoring, fan controller and watchdog monitor.
+ This driver provides common support for accessing the device.
+ Additional drivers must be enabled in order to use the
+ functionality of the device.
+
config MFD_MC13XXX
tristate
depends on (SPI_MASTER || I2C)
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index f935d10..ed433ae 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_MFD_BCM590XX) += bcm590xx.o
obj-$(CONFIG_MFD_BD9571MWV) += bd9571mwv.o
obj-$(CONFIG_MFD_CROS_EC_DEV) += cros_ec_dev.o
obj-$(CONFIG_MFD_EXYNOS_LPASS) += exynos-lpass.o
+obj-$(CONFIG_MFD_GATEWORKS_GSC) += gateworks-gsc.o

obj-$(CONFIG_HTC_PASIC3) += htc-pasic3.o
obj-$(CONFIG_HTC_I2CPLD) += htc-i2cpld.o
diff --git a/drivers/mfd/gateworks-gsc.c b/drivers/mfd/gateworks-gsc.c
new file mode 100644
index 00000000..d43a4dd
--- /dev/null
+++ b/drivers/mfd/gateworks-gsc.c
@@ -0,0 +1,278 @@
+// 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, &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 = 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_FALLING, 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 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 = "gateworks-gsc",
+ .of_match_table = gsc_of_match,
+ },
+ .id_table = gsc_id_table,
+ .probe_new = gsc_probe,
+ .remove = gsc_remove,
+};
+module_i2c_driver(gsc_driver);
+
+MODULE_AUTHOR("Tim Harvey <tharvey@xxxxxxxxxxxxx>");
+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 00000000..6bd639c
--- /dev/null
+++ b/include/linux/mfd/gsc.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2020 Gateworks Corporation
+ */
+#ifndef __LINUX_MFD_GSC_H_
+#define __LINUX_MFD_GSC_H_
+
+#include <linux/regmap.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 */
+enum {
+ GSC_CTRL_0 = 0x00,
+ GSC_CTRL_1 = 0x01,
+ GSC_TIME = 0x02,
+ GSC_TIME_ADD = 0x06,
+ GSC_IRQ_STATUS = 0x0A,
+ GSC_IRQ_ENABLE = 0x0B,
+ GSC_FW_CRC = 0x0C,
+ GSC_FW_VER = 0x0E,
+ 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_SLEEP_ACTIVATE 1
+#define GSC_CTRL_1_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
+
+int gsc_read(void *context, unsigned int reg, unsigned int *val);
+int gsc_write(void *context, unsigned int reg, unsigned int val);
+
+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;
+
+ unsigned int fwver;
+ unsigned short fwcrc;
+};
+
+#endif /* __LINUX_MFD_GSC_H_ */
--
2.7.4