[PATCH 1/2] pmbus: added tps544c20 driver with trimming support

[Romain Porte <romain.porte@nokia.com>]

Trimming is a manufacturer-specific command provided by TPS544C20.
Since there is no generic interface for trimming yet this patch
proposes a new driver with dedicated sysfs entries for trimming
support for the component, according to its datasheet. This
allows users to access the VREF_TRIM and STORE_USER_ALL commands.
---
 drivers/hwmon/pmbus/Kconfig     |  10 +++
 drivers/hwmon/pmbus/Makefile    |   1 +
 drivers/hwmon/pmbus/tps544c20.c | 164 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 175 insertions(+)
 create mode 100644 drivers/hwmon/pmbus/tps544c20.c

diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index 40019325b517..6f46e17d2004 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -153,6 +153,16 @@ config SENSORS_TPS53679
 	  This driver can also be built as a module. If so, the module will
 	  be called tps53679.
 
+config SENSORS_TPS544C20
+	tristate "TI TPS544C20"
+	default n
+	help
+	  If you say yes here you get hardware monitoring support for TI
+	  TPS544C20 with trimming support.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called tps544c20.
+
 config SENSORS_UCD9000
 	tristate "TI UCD90120, UCD90124, UCD90160, UCD9090, UCD90910"
 	default n
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 459a6be3390e..5b8e0a37551a 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_SENSORS_MAX34440)	+= max34440.o
 obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
 obj-$(CONFIG_SENSORS_TPS40422)	+= tps40422.o
 obj-$(CONFIG_SENSORS_TPS53679)	+= tps53679.o
+obj-$(CONFIG_SENSORS_TPS544C20)	+= tps544c20.o
 obj-$(CONFIG_SENSORS_UCD9000)	+= ucd9000.o
 obj-$(CONFIG_SENSORS_UCD9200)	+= ucd9200.o
 obj-$(CONFIG_SENSORS_ZL6100)	+= zl6100.o
diff --git a/drivers/hwmon/pmbus/tps544c20.c b/drivers/hwmon/pmbus/tps544c20.c
new file mode 100644
index 000000000000..241c030fc216
--- /dev/null
+++ b/drivers/hwmon/pmbus/tps544c20.c
@@ -0,0 +1,164 @@
+/*
+ * Hardware monitoring driver for TI TPS544C20 with trim support
+ *
+ * Copyright (c) 2017 Nokia Solutions and Networks.
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include "pmbus.h"
+
+#define VREF_TRIM_ADDR      0xD4
+#define STORE_USER_ALL_ADDR 0x15
+
+static struct pmbus_driver_info tps544c20_info = {
+	.pages = 1,
+	.format[PSC_VOLTAGE_IN] = linear,
+	.format[PSC_VOLTAGE_OUT] = linear,
+	.format[PSC_TEMPERATURE] = linear,
+	.func[0] = PMBUS_HAVE_VOUT | PMBUS_HAVE_TEMP2
+	    | PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_STATUS_TEMP
+	    | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT,
+};
+
+static ssize_t show_vref_trim(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	int ret;
+	struct i2c_client *client = to_i2c_client(dev);
+
+	ret = pmbus_read_word_data(client, 0, VREF_TRIM_ADDR);
+	if (ret < 0) {
+		dev_err(dev, "error reading vref_trim (%d)\n", ret);
+		return ret;
+	}
+
+	ret = snprintf(buf, PAGE_SIZE, "%d\n", (int16_t) ret);
+	return ret;
+}
+
+static ssize_t store_vref_trim(struct device *dev,
+			       struct device_attribute *attr, const char *buf,
+			       size_t count)
+{
+	int ret;
+	int value;
+	struct i2c_client *client = to_i2c_client(dev);
+
+	ret = sscanf(buf, "%d", &value);
+	if (ret != 1) {
+		dev_err(dev, "bad value, please write integer\n");
+		return -EINVAL;
+	}
+
+	ret = pmbus_write_word_data(client, 0, VREF_TRIM_ADDR, (int16_t) value);
+	if (ret < 0) {
+		dev_err(dev, "error writing vref_trim\n");
+		return ret;
+	}
+
+	/* Delay of at least 15 us/mV of change (0.067 mV/us), lets wait 10ms */
+	msleep(10);
+
+	return count;
+}
+
+static ssize_t set_store_user_all(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	int ret;
+	int read_value;
+	struct i2c_client *client = to_i2c_client(dev);
+
+	ret = sscanf(buf, "%d", &read_value);
+	if (ret != 1 || read_value != 1) {
+		dev_err(dev, "bad value, write 1 to store. abort\n");
+		return -EINVAL;
+	}
+
+	ret = pmbus_write_byte(client, 0, STORE_USER_ALL_ADDR);
+	if (ret < 0) {
+		dev_err(dev, "error writing store_user_all\n");
+		return ret;
+	}
+
+	return count;
+}
+
+DEVICE_ATTR(vref_trim, S_IWUSR | S_IRUGO, show_vref_trim, store_vref_trim);
+DEVICE_ATTR(store_user_all, S_IWUSR, NULL, set_store_user_all);
+
+static struct attribute *tps544c20_attributes[] = {
+	&dev_attr_vref_trim.attr,
+	&dev_attr_store_user_all.attr,
+	NULL
+};
+
+static const struct attribute_group tps544c20_group = {
+	.attrs = tps544c20_attributes,
+};
+
+static int tps544c20_probe(struct i2c_client *client,
+			   const struct i2c_device_id *id)
+{
+	int ret;
+
+	ret = pmbus_do_probe(client, id, &tps544c20_info);
+	if (ret < 0) {
+		pr_err("error during pmbus probe\n");
+		return ret;
+	}
+
+	ret = sysfs_create_group(&client->dev.kobj, &tps544c20_group);
+	if (ret < 0) {
+		pr_err("error creating sysfs\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int tps544c20_remove(struct i2c_client *client)
+{
+	sysfs_remove_group(&client->dev.kobj, &tps544c20_group);
+
+	return pmbus_do_remove(client);
+}
+
+static const struct i2c_device_id tps544c20_id[] = {
+	{"tps544c20", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, tps544c20_id);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver tps544c20_driver = {
+	.driver = {
+		   .name = "tps544c20",
+		   },
+	.probe = tps544c20_probe,
+	.remove = tps544c20_remove,
+	.id_table = tps544c20_id,
+};
+
+module_i2c_driver(tps544c20_driver);
+
+MODULE_AUTHOR("Romain Porte <romain.porte@nokia.com>");
+MODULE_DESCRIPTION("PMBus driver for TI TPS544C20 with trim support");
+MODULE_LICENSE("GPL");
-- 
2.11.0