hwmon: (pmbus) Add client driver for LTC3815

LTC3815 is a Monolithic Synchronous DC/DC Step-Down Converter.

Cc: Michael Jones <mike@proclivis.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

4 files changed, 287 insertions, 0 deletions

diff --git a/Documentation/hwmon/ltc3815 b/Documentation/hwmon/ltc3815
new file mode 100644
index 000000000000..eb7db2d13587
--- /dev/null
+++ b/Documentation/hwmon/ltc3815
@@ -0,0 +1,61 @@
+Kernel driver ltc3815
+=====================
+
+Supported chips:
+  * Linear Technology LTC3815
+    Prefix: 'ltc3815'
+    Addresses scanned: -
+    Datasheet: http://www.linear.com/product/ltc3815
+
+Author: Guenter Roeck <linux@roeck-us.net>
+
+
+Description
+-----------
+
+LTC3815 is a Monolithic Synchronous DC/DC Step-Down Converter.
+
+
+Usage Notes
+-----------
+
+This driver does not probe for PMBus devices. You will have to instantiate
+devices explicitly.
+
+Example: the following commands will load the driver for an LTC3815
+at address 0x20 on I2C bus #1:
+
+# modprobe ltc3815
+# echo ltc3815 0x20 > /sys/bus/i2c/devices/i2c-1/new_device
+
+
+Sysfs attributes
+----------------
+
+in1_label               "vin"
+in1_input               Measured input voltage.
+in1_alarm               Input voltage alarm.
+in1_highest             Highest input voltage.
+in1_reset_history       Reset input voltage history.
+
+in2_label               "vout1".
+in2_input               Measured output voltage.
+in2_alarm               Output voltage alarm.
+in2_highest             Highest output voltage.
+in2_reset_history       Reset output voltage history.
+
+temp1_input             Measured chip temperature.
+temp1_alarm             Temperature alarm.
+temp1_highest           Highest measured temperature.
+temp1_reset_history     Reset temperature history.
+
+curr1_label             "iin".
+curr1_input             Measured input current.
+curr1_highest           Highest input current.
+curr1_reset_history     Reset input current history.
+
+curr2_label             "iout1".
+curr2_input             Measured output current.
+curr2_alarm             Output current alarm.
+curr2_highest           Highest output current.
+curr2_reset_history     Reset output current history.
diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index df6ebb2b8f0f..7e5cc3d025ef 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -65,6 +65,16 @@ config SENSORS_LTC2978_REGULATOR
           If you say yes here you get regulator support for Linear
           Technology LTC2974, LTC2977, LTC2978, LTC3880, LTC3883, and LTM4676.
 
+config SENSORS_LTC3815
+        tristate "Linear Technologies LTC3815"
+        default n
+        help
+          If you say yes here you get hardware monitoring support for Linear
+          Technology LTC3815.
+
+          This driver can also be built as a module. If so, the module will
+          be called ltc3815.
+
 config SENSORS_MAX16064
         tristate "Maxim MAX16064"
         default n
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index bce046d37f02..562132054aaf 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_SENSORS_PMBUS)	+= pmbus.o
 obj-$(CONFIG_SENSORS_ADM1275)   += adm1275.o
 obj-$(CONFIG_SENSORS_LM25066)   += lm25066.o
 obj-$(CONFIG_SENSORS_LTC2978)   += ltc2978.o
+obj-$(CONFIG_SENSORS_LTC3815)   += ltc3815.o
 obj-$(CONFIG_SENSORS_MAX16064)  += max16064.o
 obj-$(CONFIG_SENSORS_MAX20751)  += max20751.o
 obj-$(CONFIG_SENSORS_MAX34440)  += max34440.o
diff --git a/drivers/hwmon/pmbus/ltc3815.c b/drivers/hwmon/pmbus/ltc3815.c
new file mode 100644
index 000000000000..bb32e6276622
--- /dev/null
+++ b/drivers/hwmon/pmbus/ltc3815.c
@@ -0,0 +1,215 @@
+/*
+ * Hardware monitoring driver for LTC3815
+ *
+ * Copyright (c) 2015 Linear Technology
+ * Copyright (c) 2015 Guenter Roeck
+ *
+ * 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/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include "pmbus.h"
+
+#define LTC3815_MFR_IOUT_PEAK   0xd7
+#define LTC3815_MFR_VOUT_PEAK   0xdd
+#define LTC3815_MFR_VIN_PEAK    0xde
+#define LTC3815_MFR_TEMP_PEAK   0xdf
+#define LTC3815_MFR_IIN_PEAK    0xe1
+#define LTC3815_MFR_SPECIAL_ID  0xe7
+
+#define LTC3815_ID              0x8000
+#define LTC3815_ID_MASK         0xff00
+
+static int ltc3815_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+        int ret;
+
+        switch (reg) {
+        case PMBUS_VOUT_MODE:
+                /*
+                 * The chip returns 0x3e, suggesting VID mode with manufacturer
+                 * specific VID codes. Since the output voltage is reported
+                 * with a LSB of 0.5mV, override and report direct mode with
+                 * appropriate coefficients.
+                 */
+                ret = 0x40;
+                break;
+        default:
+                ret = -ENODATA;
+                break;
+        }
+        return ret;
+}
+
+static int ltc3815_write_byte(struct i2c_client *client, int page, u8 reg)
+{
+        int ret;
+
+        switch (reg) {
+        case PMBUS_CLEAR_FAULTS:
+                /*
+                 * LTC3815 does not support the CLEAR_FAULTS command.
+                 * Emulate it by clearing the status register.
+                 */
+                ret = pmbus_read_word_data(client, 0, PMBUS_STATUS_WORD);
+                if (ret > 0) {
+                        pmbus_write_word_data(client, 0, PMBUS_STATUS_WORD,
+                                              ret);
+                        ret = 0;
+                }
+                break;
+        default:
+                ret = -ENODATA;
+                break;
+        }
+        return ret;
+}
+
+static int ltc3815_read_word_data(struct i2c_client *client, int page, int reg)
+{
+        int ret;
+
+        switch (reg) {
+        case PMBUS_VIRT_READ_VIN_MAX:
+                ret = pmbus_read_word_data(client, page, LTC3815_MFR_VIN_PEAK);
+                break;
+        case PMBUS_VIRT_READ_VOUT_MAX:
+                ret = pmbus_read_word_data(client, page, LTC3815_MFR_VOUT_PEAK);
+                break;
+        case PMBUS_VIRT_READ_TEMP_MAX:
+                ret = pmbus_read_word_data(client, page, LTC3815_MFR_TEMP_PEAK);
+                break;
+        case PMBUS_VIRT_READ_IOUT_MAX:
+                ret = pmbus_read_word_data(client, page, LTC3815_MFR_IOUT_PEAK);
+                break;
+        case PMBUS_VIRT_READ_IIN_MAX:
+                ret = pmbus_read_word_data(client, page, LTC3815_MFR_IIN_PEAK);
+                break;
+        case PMBUS_VIRT_RESET_VOUT_HISTORY:
+        case PMBUS_VIRT_RESET_VIN_HISTORY:
+        case PMBUS_VIRT_RESET_TEMP_HISTORY:
+        case PMBUS_VIRT_RESET_IOUT_HISTORY:
+        case PMBUS_VIRT_RESET_IIN_HISTORY:
+                ret = 0;
+                break;
+        default:
+                ret = -ENODATA;
+                break;
+        }
+        return ret;
+}
+
+static int ltc3815_write_word_data(struct i2c_client *client, int page,
+                                   int reg, u16 word)
+{
+        int ret;
+
+        switch (reg) {
+        case PMBUS_VIRT_RESET_IIN_HISTORY:
+                ret = pmbus_write_word_data(client, page,
+                                            LTC3815_MFR_IIN_PEAK, 0);
+                break;
+        case PMBUS_VIRT_RESET_IOUT_HISTORY:
+                ret = pmbus_write_word_data(client, page,
+                                            LTC3815_MFR_IOUT_PEAK, 0);
+                break;
+        case PMBUS_VIRT_RESET_VOUT_HISTORY:
+                ret = pmbus_write_word_data(client, page,
+                                            LTC3815_MFR_VOUT_PEAK, 0);
+                break;
+        case PMBUS_VIRT_RESET_VIN_HISTORY:
+                ret = pmbus_write_word_data(client, page,
+                                            LTC3815_MFR_VIN_PEAK, 0);
+                break;
+        case PMBUS_VIRT_RESET_TEMP_HISTORY:
+                ret = pmbus_write_word_data(client, page,
+                                            LTC3815_MFR_TEMP_PEAK, 0);
+                break;
+        default:
+                ret = -ENODATA;
+                break;
+        }
+        return ret;
+}
+
+static const struct i2c_device_id ltc3815_id[] = {
+        {"ltc3815", 0},
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, ltc3815_id);
+
+static struct pmbus_driver_info ltc3815_info = {
+        .pages = 1,
+        .format[PSC_VOLTAGE_IN] = direct,
+        .format[PSC_VOLTAGE_OUT] = direct,
+        .format[PSC_CURRENT_IN] = direct,
+        .format[PSC_CURRENT_OUT] = direct,
+        .format[PSC_TEMPERATURE] = direct,
+        .m[PSC_VOLTAGE_IN] = 250,
+        .b[PSC_VOLTAGE_IN] = 0,
+        .R[PSC_VOLTAGE_IN] = 0,
+        .m[PSC_VOLTAGE_OUT] = 2,
+        .b[PSC_VOLTAGE_OUT] = 0,
+        .R[PSC_VOLTAGE_OUT] = 3,
+        .m[PSC_CURRENT_IN] = 1,
+        .b[PSC_CURRENT_IN] = 0,
+        .R[PSC_CURRENT_IN] = 2,
+        .m[PSC_CURRENT_OUT] = 1,
+        .b[PSC_CURRENT_OUT] = 0,
+        .R[PSC_CURRENT_OUT] = 2,
+        .m[PSC_TEMPERATURE] = 1,
+        .b[PSC_TEMPERATURE] = 0,
+        .R[PSC_TEMPERATURE] = 0,
+        .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN | PMBUS_HAVE_VOUT |
+                PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,
+        .read_byte_data = ltc3815_read_byte_data,
+        .read_word_data = ltc3815_read_word_data,
+        .write_byte = ltc3815_write_byte,
+        .write_word_data = ltc3815_write_word_data,
+};
+
+static int ltc3815_probe(struct i2c_client *client,
+                         const struct i2c_device_id *id)
+{
+        int chip_id;
+
+        if (!i2c_check_functionality(client->adapter,
+                                     I2C_FUNC_SMBUS_READ_WORD_DATA))
+                return -ENODEV;
+
+        chip_id = i2c_smbus_read_word_data(client, LTC3815_MFR_SPECIAL_ID);
+        if (chip_id < 0)
+                return chip_id;
+        if ((chip_id & LTC3815_ID_MASK) != LTC3815_ID)
+                return -ENODEV;
+
+        return pmbus_do_probe(client, id, &ltc3815_info);
+}
+
+static struct i2c_driver ltc3815_driver = {
+        .driver = {
+                   .name = "ltc3815",
+                   },
+        .probe = ltc3815_probe,
+        .remove = pmbus_do_remove,
+        .id_table = ltc3815_id,
+};
+
+module_i2c_driver(ltc3815_driver);
+
+MODULE_AUTHOR("Guenter Roeck");
+MODULE_DESCRIPTION("PMBus driver for LTC3815");
+MODULE_LICENSE("GPL");