[PATCHv0] hwmon: Add support for GMT G751 Temp. Sensor and Thermal Watchdog

From: Arnaud Ebalard
Date: Fri Nov 08 2013 - 18:33:16 EST


This patch adds support for GMT G751 Temperature Sensor and Thermal
Watchdog I2C chip. It has been tested via DT on a Netgear ReadyNAS
2120 (Marvell Armada XP based ARM device).

Signed-off-by: Arnaud Ebalard <arno@xxxxxxxxxxxx>
---
Documentation/devicetree/bindings/hwmon/g751.txt | 24 +
.../devicetree/bindings/vendor-prefixes.txt | 1 +
Documentation/hwmon/g751 | 44 ++
drivers/hwmon/Kconfig | 11 +
drivers/hwmon/Makefile | 1 +
drivers/hwmon/g751.c | 481 +++++++++++++++++++++
include/linux/platform_data/g751.h | 35 ++
7 files changed, 597 insertions(+)
create mode 100644 Documentation/devicetree/bindings/hwmon/g751.txt
create mode 100644 Documentation/hwmon/g751
create mode 100644 drivers/hwmon/g751.c
create mode 100644 include/linux/platform_data/g751.h

diff --git a/Documentation/devicetree/bindings/hwmon/g751.txt b/Documentation/devicetree/bindings/hwmon/g751.txt
new file mode 100644
index 0000000..ebec788
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/g751.txt
@@ -0,0 +1,24 @@
+GMT G751 Digital Temperature Sensor and Thermal Watchdog
+
+Required node properties:
+
+ - "compatible": must be either "gmt,g751"
+ - "reg": I2C bus address of the device
+
+Optional properties:
+
+ - "polarity": Over temperature Shutdown (OS) output polarity. Accepted values
+ are 0 and 1. 0 (the default) is used to make the output active
+ low. 1 makes the output active high.
+
+Additional information on operational parameters for the device is available
+in Documentation/hwmon/g751. A detailed datasheet for the device is available
+at http://natisbad.org/NAS4/refs/GMT_G751.pdf.
+
+Example g751 node:
+
+ g751: g751@4c {
+ compatible = "gmt,g751";
+ reg = <0x4c>;
+ polarity = <1>; /* OS output Active High */
+ };
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index 2956800..634c35f 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -28,6 +28,7 @@ est ESTeem Wireless Modems
fsl Freescale Semiconductor
GEFanuc GE Fanuc Intelligent Platforms Embedded Systems, Inc.
gef GE Fanuc Intelligent Platforms Embedded Systems, Inc.
+gmt Global Mixed-mode Technology Inc.
hisilicon Hisilicon Limited.
hp Hewlett Packard
ibm International Business Machines (IBM)
diff --git a/Documentation/hwmon/g751 b/Documentation/hwmon/g751
new file mode 100644
index 0000000..3508d53
--- /dev/null
+++ b/Documentation/hwmon/g751
@@ -0,0 +1,44 @@
+Kernel driver g751
+==================
+
+The GMT G751 is an I2C digital temperature sensor and thermal watchdog. For
+additional information, a detailed datasheet of the chip is available at
+http://natisbad.org/NAS4/refs/GMT_G751.pdf.
+
+sysfs bindings (found in a subdirectory of/sys/bus/i2c/drivers/g751/) are
+described below. They are available to the user to control the operation
+of the device. The main information provided by the device (temperature,
+via temp_input) is usually used by a userland daemon like fancontrol.
+
+Note that polarity of Over temperature Shutdown (OS) output is considered
+a hardware characteristics of the system and can be modified via devicetree
+bindings documented in Documentation/devicetree/bindings/hwmon/g751.txt or
+using a specific platform_data structure in board initialization file (see
+include/linux/platform_data/g751.h).
+
+temp_input: current temperature input value in millidegree Celsius. This
+ parameter is RO.
+
+thyst: defined Thyst value in millidegree Celsius. See 'mode' below for
+ details. Default value depends on G751 flavour (45000 for G751-1,
+ 75000 for G751-2). This parameter is RW.
+
+tos: defined Tos value in millidegree Celsius. See 'mode' below for details.
+ Default value depends on G751 flavour (50000 for G751-1, 80000 for
+ G751-2). This parameter is RW.
+
+fault_queue: number of faults necessary to detect before setting OS output.
+ This can be used to avoid false tripping due to noise. Valid values
+ are 1 (default), 2, 4 and 6. This parameter is RW.
+
+mode: used to toggle between comparatore mode (0, default mode) and interrupt
+ mode (1). In comparator mode, the OS output behaves like a thermostat
+ and becomes active when temperature exceeds Tos limit. It then leaves
+ the active state when the temperature drops again below Thyst. In
+ interrupt mode, exceeding Tos also makes OS output active in which case
+ it will remain active until reading any register. It can then be activated
+ again only after temperature goes below Thyst. This parameter is RW.
+
+shutdown: when set to 1 (0 being the default), the G751 goes to low power
+ shutdown mode. Placing G751 in shutdown mode also has the effect of
+ resetting the OS output. This parameter is RW.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index b3ab9d4..524d1d7 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -451,6 +451,17 @@ config SENSORS_FSCHMD
This driver can also be built as a module. If so, the module
will be called fschmd.

+config SENSORS_G751
+ tristate "GMT G751"
+ depends on I2C
+ help
+ If you say yes here you get support for Global Mixed-mode
+ Technology Inc G751 Digital Temperature Sensor and Thermal
+ Watchdog.
+
+ This driver can also be built as a module. If so, the module
+ will be called g751.
+
config SENSORS_G760A
tristate "GMT G760A"
depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index ec7cde0..5c8bfc6 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_SENSORS_F71882FG) += f71882fg.o
obj-$(CONFIG_SENSORS_F75375S) += f75375s.o
obj-$(CONFIG_SENSORS_FAM15H_POWER) += fam15h_power.o
obj-$(CONFIG_SENSORS_FSCHMD) += fschmd.o
+obj-$(CONFIG_SENSORS_G751) += g751.o
obj-$(CONFIG_SENSORS_G760A) += g760a.o
obj-$(CONFIG_SENSORS_G762) += g762.o
obj-$(CONFIG_SENSORS_GL518SM) += gl518sm.o
diff --git a/drivers/hwmon/g751.c b/drivers/hwmon/g751.c
new file mode 100644
index 0000000..9c85c41
--- /dev/null
+++ b/drivers/hwmon/g751.c
@@ -0,0 +1,481 @@
+/*
+ * g751 - Driver for the Global Mixed-mode Technology Inc. G751 digital
+ * temperature sensor and thermal watchdog chip.
+ *
+ * Copyright (C) 2013, Arnaud EBALARD <arno@xxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation.
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_data/g751.h>
+
+#define DRVNAME "g751"
+
+static const struct i2c_device_id g751_id[] = {
+ { "g751", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, g751_id);
+
+/* Four data registers can be addressed via a pointer register */
+enum g751_data_reg {
+ G751_REG_TEMP = 0x00, /* 16-bit reg */
+ G751_REG_CONF = 0x01, /* 8-bit reg */
+ G751_REG_THYST = 0x02, /* 16-bit reg */
+ G751_REG_TOS = 0x03, /* 16-bit reg */
+};
+
+/* Provide size of given register */
+#define G751_DATA_REG_LEN(reg) (((reg) == G751_REG_CONF) ? 1 : 2)
+
+/* Configuration register bits: shifts and masks */
+#define G751_CONF_FQUEUE_SHIFT 3
+#define G751_CONF_FQUEUE_MASK 0x03
+#define G751_CONF_POLARITY_SHIFT 2
+#define G751_CONF_POLARITY_MASK 0x02
+#define G751_CONF_MODE_SHIFT 1
+#define G751_CONF_MODE_MASK 0x01
+#define G751_CONF_SHUTDOWN_SHIFT 0
+#define G751_CONF_SHUTDOWN_MASK 0x01
+
+/* Temperature conversion helpers from/to register value */
+static inline void temp_from_reg(int32_t *temp, u8 *regval)
+{
+ int8_t *buf = (int8_t *)(regval);
+ *temp = (buf[0]*1000 + ((buf[1] & 0x80) ? 500 : 0));
+}
+
+static inline void temp_to_reg(u8 *regval, int32_t temp)
+{
+ regval[0] = (temp < 0 && temp/1000 == 0) ? 0xff : temp/1000;
+ regval[1] = ((temp/500) & 0x1) ? 0x80 : 0x00;
+}
+
+struct g751_data {
+ struct i2c_client *client;
+ struct device *hwmon_dev;
+ struct mutex lock;
+};
+
+/*
+ * Read content of 'reg' register and put result in 'val' buffer if
+ * everything went ok; 0 is returned in that case. A negative value
+ * is returned on error, in which case 'val' is not updated.
+ */
+static int g751_reg_read(struct device *dev, u8 reg, u8 *val)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ u8 buf[2] = { reg , 0 };
+ struct i2c_msg msgs[2] = {
+ {
+ .addr = client->addr,
+ .flags = client->flags,
+ .len = sizeof(u8),
+ .buf = buf
+ },
+ {
+ .addr = client->addr,
+ .flags = client->flags | I2C_M_RD,
+ .len = G751_DATA_REG_LEN(reg),
+ .buf = buf
+ }
+ };
+ int ret;
+
+ BUG_ON(reg > 3);
+
+ ret = i2c_transfer(client->adapter, msgs, 2);
+ if (ret < 0) {
+ dev_err(&client->dev, "%s: register read failed\n", __func__);
+ return ret;
+ }
+ memcpy(val, buf, G751_DATA_REG_LEN(reg));
+
+ return 0;
+}
+
+/*
+ * Write content of given 'val' buffer to 'reg' register. 0 is returned
+ * on success. A negative value is returned on error.
+ */
+static int g751_reg_write(struct device *dev, u8 reg, u8 *val)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ u8 buf[3] = { reg, 0, 0 };
+ struct i2c_msg msgs[1] = {
+ {
+ .addr = client->addr,
+ .flags = client->flags,
+ .len = G751_DATA_REG_LEN(reg) + 1,
+ .buf = buf
+ }
+ };
+ int ret;
+
+ BUG_ON(reg > 3 || reg == 0); /* temp reg (0) is read-only */
+
+ memcpy(&buf[1], val, G751_DATA_REG_LEN(reg));
+ ret = i2c_transfer(client->adapter, msgs, 1);
+ if (ret < 0) {
+ dev_err(&client->dev, "%s: register write failed\n", __func__);
+ return ret;
+ }
+
+ return 0;
+}
+
+/* Generic helper to extract some specific bits of conf register */
+static int conf_reg_bits_get(struct device *dev, u8 *val,
+ u8 bitshift, u8 bitmask)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct g751_data *data = i2c_get_clientdata(client);
+ u8 regval;
+ int ret;
+
+ mutex_lock(&data->lock);
+ ret = g751_reg_read(dev, G751_REG_CONF, &regval);
+ mutex_unlock(&data->lock);
+ if (ret < 0)
+ return ret;
+
+ *val = (regval >> bitshift) & bitmask;
+
+ return 0;
+}
+
+/* Generic helper to set some specific bits of conf register */
+static int conf_reg_bits_set(struct device *dev, u8 val,
+ u8 bitshift, u8 bitmask)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct g751_data *data = i2c_get_clientdata(client);
+ u8 regval;
+ int ret;
+
+ mutex_lock(&data->lock);
+ ret = g751_reg_read(dev, G751_REG_CONF, &regval);
+ if (ret < 0)
+ goto out;
+
+ regval &= ~(bitmask << bitshift);
+ regval |= val << bitshift;
+
+ ret = g751_reg_write(dev, G751_REG_CONF, &regval);
+ out:
+ mutex_unlock(&data->lock);
+
+ return ret;
+}
+
+/*
+ * sysfs
+ */
+
+#define show_temp(value, reg) \
+static ssize_t show_##value(struct device *dev, struct device_attribute *da, \
+ char *buf) \
+{ \
+ u8 regval[2]; \
+ int32_t temp; \
+ int ret; \
+ \
+ ret = g751_reg_read(dev, reg, regval); \
+ if (ret < 0) \
+ return ret; \
+ temp_from_reg(&temp, regval); \
+ \
+ return sprintf(buf, "%d\n", temp); \
+}
+
+show_temp(temp_input, G751_REG_TEMP);
+show_temp(temp_hyst, G751_REG_THYST);
+show_temp(temp_os, G751_REG_TOS);
+
+#define set_temp(value, reg) \
+static ssize_t set_##value(struct device *dev, struct device_attribute *da, \
+ const char *buf, size_t count) \
+{ \
+ u8 regval[2]; \
+ int32_t temp; \
+ int ret; \
+ \
+ ret = kstrtos32(buf, 10, &temp); \
+ if (ret) \
+ return ret; \
+ temp_to_reg(regval, temp); \
+ \
+ ret = g751_reg_write(dev, reg, regval); \
+ if (ret < 0) \
+ return ret; \
+ \
+ return count; \
+}
+
+set_temp(temp_hyst, G751_REG_THYST);
+set_temp(temp_os, G751_REG_TOS);
+
+/*
+ * Read and write functions for fault_queue sysfs file. Get and set
+ * fault_queue length (either 1 (default), 2, 4 or 6).
+ */
+static ssize_t show_fqueue(struct device *dev, struct device_attribute *da,
+ char *buf)
+{
+ u8 regval;
+ int ret;
+
+ ret = conf_reg_bits_get(dev, &regval, G751_CONF_FQUEUE_SHIFT,
+ G751_CONF_FQUEUE_MASK);
+ if (ret < 0)
+ return ret;
+
+ return sprintf(buf, "%d\n", regval ? regval * 2 : 1);
+}
+
+static ssize_t set_fqueue(struct device *dev,
+ struct device_attribute *da,
+ const char *buf, size_t count)
+{
+ int ret;
+ u8 val;
+
+ if (kstrtou8(buf, 10, &val))
+ return -EINVAL;
+
+ switch (val) {
+ case 1:
+ val = 0;
+ break;
+ case 2:
+ case 4:
+ case 6:
+ val /= 2;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ ret = conf_reg_bits_set(dev, val, G751_CONF_FQUEUE_SHIFT,
+ G751_CONF_FQUEUE_MASK);
+
+ return ret < 0 ? ret : count;
+}
+
+/*
+ * Read and write functions for mode sysfs file. Get and set mode (0 for
+ * comparator mode and 1 for interrupt mode).
+ */
+static ssize_t show_mode(struct device *dev, struct device_attribute *da,
+ char *buf)
+{
+ u8 regval;
+ int ret;
+
+ ret = conf_reg_bits_get(dev, &regval, G751_CONF_MODE_SHIFT,
+ G751_CONF_MODE_MASK);
+ if (ret < 0)
+ return ret;
+
+ return sprintf(buf, "%d\n", regval);
+}
+
+static ssize_t set_mode(struct device *dev,
+ struct device_attribute *da,
+ const char *buf, size_t count)
+{
+ int ret;
+ u8 val;
+
+ if (kstrtou8(buf, 10, &val) || val > 1)
+ return -EINVAL;
+
+ ret = conf_reg_bits_set(dev, val, G751_CONF_MODE_SHIFT,
+ G751_CONF_MODE_MASK);
+
+ return ret < 0 ? ret : count;
+}
+
+/*
+ * Read and write functions for shutdown sysfs file. Get and set low power
+ * shutdown mode (1 for low power shutdown mode).
+ */
+static ssize_t show_shutdown(struct device *dev,
+ struct device_attribute *da, char *buf)
+{
+ u8 regval;
+ int ret;
+
+ ret = conf_reg_bits_get(dev, &regval, G751_CONF_MODE_SHIFT,
+ G751_CONF_MODE_MASK);
+ if (ret < 0)
+ return ret;
+
+ return sprintf(buf, "%d\n", regval);
+}
+
+static ssize_t set_shutdown(struct device *dev,
+ struct device_attribute *da,
+ const char *buf, size_t count)
+{
+ int ret;
+ u8 val;
+
+ if (kstrtou8(buf, 10, &val) || val > 1)
+ return -EINVAL;
+
+ ret = conf_reg_bits_set(dev, val, G751_CONF_SHUTDOWN_SHIFT,
+ G751_CONF_SHUTDOWN_MASK);
+
+ return ret < 0 ? ret : count;
+}
+
+#ifdef CONFIG_OF
+static struct of_device_id g751_dt_match[] = {
+ { .compatible = "gmt,g751" },
+ { },
+};
+
+static void g751_of_import_polarity(struct i2c_client *client, int *pol)
+{
+ const __be32 *prop;
+ int len;
+
+ prop = of_get_property(client->dev.of_node, "polarity", &len);
+ if (!prop || len != sizeof(u32))
+ return;
+
+ *pol = !!be32_to_cpu(prop[0]);
+}
+#else
+static void g751_of_import_polarity(struct i2c_client *client, int *pol) {}
+#endif
+
+static DEVICE_ATTR(temp_input, S_IRUGO, show_temp_input, NULL);
+static DEVICE_ATTR(thyst, S_IRUGO|S_IWUSR, show_temp_hyst, set_temp_hyst);
+static DEVICE_ATTR(tos, S_IRUGO|S_IWUSR, show_temp_os, set_temp_os);
+static DEVICE_ATTR(fault_queue, S_IRUGO|S_IWUSR, show_fqueue, set_fqueue);
+static DEVICE_ATTR(mode, S_IRUGO|S_IWUSR, show_mode, set_mode);
+static DEVICE_ATTR(shutdown, S_IRUGO|S_IWUSR, show_shutdown, set_shutdown);
+
+/* Driver data */
+static struct attribute *g751_attributes[] = {
+ &dev_attr_temp_input.attr,
+ &dev_attr_thyst.attr,
+ &dev_attr_tos.attr,
+ &dev_attr_fault_queue.attr,
+ &dev_attr_mode.attr,
+ &dev_attr_shutdown.attr,
+ NULL
+};
+
+static const struct attribute_group g751_group = {
+ .name = "g751",
+ .attrs = g751_attributes,
+};
+
+static int g751_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+ struct g751_platform_data *pdata;
+ struct g751_data *data;
+ int polarity = -1;
+ int ret;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+ return -ENODEV;
+
+ data = devm_kzalloc(&client->dev, sizeof(struct g751_data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ i2c_set_clientdata(client, data);
+ data->client = client;
+ mutex_init(&data->lock);
+
+ /* Change polarity if requested either via platform data or OF */
+ pdata = dev_get_platdata(&client->dev);
+ if (pdata)
+ polarity = !!pdata->polarity;
+ else
+ g751_of_import_polarity(client, &polarity);
+
+ if (polarity != -1) {
+ dev_dbg(&client->dev, "found polarity (%d)\n", polarity);
+
+ ret = conf_reg_bits_set(&client->dev, polarity,
+ G751_CONF_POLARITY_SHIFT,
+ G751_CONF_POLARITY_MASK);
+ if (ret)
+ dev_err(&client->dev, "unable to set polarity (%d)\n",
+ polarity);
+ }
+
+ /* Register sysfs hooks */
+ ret = sysfs_create_group(&client->dev.kobj, &g751_group);
+ if (ret)
+ goto out;
+
+ data->hwmon_dev = hwmon_device_register(&client->dev);
+ if (IS_ERR(data->hwmon_dev)) {
+ ret = PTR_ERR(data->hwmon_dev);
+ goto sysfs_clean;
+ }
+
+ return 0;
+
+ sysfs_clean:
+ sysfs_remove_group(&client->dev.kobj, &g751_group);
+
+ out:
+ return ret;
+}
+
+static int g751_remove(struct i2c_client *client)
+{
+ struct g751_data *data = i2c_get_clientdata(client);
+
+ hwmon_device_unregister(data->hwmon_dev);
+ sysfs_remove_group(&client->dev.kobj, &g751_group);
+
+ return 0;
+}
+
+static struct i2c_driver g751_driver = {
+ .driver = {
+ .name = DRVNAME,
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(g751_dt_match),
+ },
+ .probe = g751_probe,
+ .remove = g751_remove,
+ .id_table = g751_id,
+};
+
+module_i2c_driver(g751_driver);
+
+MODULE_AUTHOR("Arnaud EBALARD <arno@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("GMT G751 driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/platform_data/g751.h b/include/linux/platform_data/g751.h
new file mode 100644
index 0000000..fec0415
--- /dev/null
+++ b/include/linux/platform_data/g751.h
@@ -0,0 +1,35 @@
+/*
+ * Platform data structure for g751 temperature sensor and thermal
+ * watchdog driver
+ *
+ * Copyright (C) 2013, Arnaud EBALARD <arno@xxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation.
+ */
+#ifndef __LINUX_PLATFORM_DATA_G751_H__
+#define __LINUX_PLATFORM_DATA_G751_H__
+
+/*
+ * Following structure can be used to set g751 driver platform
+ * specific data during board init, i.e. over temperature (OS)
+ * output polarity: 0 for active low (the default), 1 for active
+ * high).
+ */
+
+struct g751_platform_data {
+ u8 polarity;
+};
+
+#endif /* __LINUX_PLATFORM_DATA_G751_H__ */
--
1.8.4.rc3

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