hwmon: (pmbus/ltc2978) Explicit driver for LTC2978

Provide explicit driver for LTC2978 to enable support for minimum and peak
attributes. Remove ltc2978 chip id from generic pmbus driver.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Reviewed-by: Robert Coulson <robert.coulson@ericsson.com>

4 files changed, 307 insertions, 2 deletions

diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index efaf340651a0..c4dcdca25555 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -20,7 +20,7 @@ config SENSORS_PMBUS
         help
           If you say yes here you get hardware monitoring support for generic
           PMBus devices, including but not limited to ADP4000, BMR450, BMR451,
-          BMR453, BMR454, LTC2978, NCP4200, and NCP4208.
+          BMR453, BMR454, NCP4200, and NCP4208.
 
           This driver can also be built as a module. If so, the module will
           be called pmbus.
@@ -46,6 +46,16 @@ config SENSORS_LM25066
           This driver can also be built as a module. If so, the module will
           be called lm25066.
 
+config SENSORS_LTC2978
+        tristate "Linear Technologies LTC2978"
+        default n
+        help
+          If you say yes here you get hardware monitoring support for Linear
+          Technology LTC2978.
+
+          This driver can also be built as a module. If so, the module will
+          be called ltc2978.
+
 config SENSORS_MAX16064
         tristate "Maxim MAX16064"
         default n
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index b9e4fb421f6c..789376c85dbb 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_PMBUS)		+= pmbus_core.o
 obj-$(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_MAX16064)  += max16064.o
 obj-$(CONFIG_SENSORS_MAX34440)  += max34440.o
 obj-$(CONFIG_SENSORS_MAX8688)   += max8688.o
diff --git a/drivers/hwmon/pmbus/ltc2978.c b/drivers/hwmon/pmbus/ltc2978.c
new file mode 100644
index 000000000000..02b2e49adb31
--- /dev/null
+++ b/drivers/hwmon/pmbus/ltc2978.c
@@ -0,0 +1,295 @@
+/*
+ * Hardware monitoring driver for LTC2978
+ *
+ * Copyright (c) 2011 Ericsson AB.
+ *
+ * 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, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include "pmbus.h"
+
+enum chips { ltc2978 };
+
+#define LTC2978_MFR_VOUT_PEAK           0xdd
+#define LTC2978_MFR_VIN_PEAK            0xde
+#define LTC2978_MFR_TEMPERATURE_PEAK    0xdf
+#define LTC2978_MFR_SPECIAL_ID          0xe7
+
+#define LTC2978_MFR_VOUT_MIN            0xfb
+#define LTC2978_MFR_VIN_MIN             0xfc
+#define LTC2978_MFR_TEMPERATURE_MIN     0xfd
+
+#define LTC2978_ID_REV1                 0x0121
+#define LTC2978_ID_REV2                 0x0122
+
+/*
+ * LTC2978 clears peak data whenever the CLEAR_FAULTS command is executed, which
+ * happens pretty much each time chip data is updated. Raw peak data therefore
+ * does not provide much value. To be able to provide useful peak data, keep an
+ * internal cache of measured peak data, which is only cleared if an explicit
+ * "clear peak" command is executed for the sensor in question.
+ */
+struct ltc2978_data {
+        enum chips id;
+        int vin_min, vin_max;
+        int temp_min, temp_max;
+        int vout_min[8], vout_max[8];
+        struct pmbus_driver_info info;
+};
+
+#define to_ltc2978_data(x)  container_of(x, struct ltc2978_data, info)
+
+static inline int lin11_to_val(int data)
+{
+        s16 e = ((s16)data) >> 11;
+        s32 m = (((s16)(data << 5)) >> 5);
+
+        /*
+         * mantissa is 10 bit + sign, exponent adds up to 15 bit.
+         * Add 6 bit to exponent for maximum accuracy (10 + 15 + 6 = 31).
+         */
+        e += 6;
+        return (e < 0 ? m >> -e : m << e);
+}
+
+static int ltc2978_read_word_data(struct i2c_client *client, int page, int reg)
+{
+        const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+        struct ltc2978_data *data = to_ltc2978_data(info);
+        int ret;
+
+        switch (reg) {
+        case PMBUS_VIRT_READ_VIN_MAX:
+                ret = pmbus_read_word_data(client, page, LTC2978_MFR_VIN_PEAK);
+                if (ret >= 0) {
+                        if (lin11_to_val(ret) > lin11_to_val(data->vin_max))
+                                data->vin_max = ret;
+                        ret = data->vin_max;
+                }
+                break;
+        case PMBUS_VIRT_READ_VOUT_MAX:
+                ret = pmbus_read_word_data(client, page, LTC2978_MFR_VOUT_PEAK);
+                if (ret >= 0) {
+                        /*
+                         * VOUT is 16 bit unsigned with fixed exponent,
+                         * so we can compare it directly
+                         */
+                        if (ret > data->vout_max[page])
+                                data->vout_max[page] = ret;
+                        ret = data->vout_max[page];
+                }
+                break;
+        case PMBUS_VIRT_READ_TEMP_MAX:
+                ret = pmbus_read_word_data(client, page,
+                                           LTC2978_MFR_TEMPERATURE_PEAK);
+                if (ret >= 0) {
+                        if (lin11_to_val(ret) > lin11_to_val(data->temp_max))
+                                data->temp_max = ret;
+                        ret = data->temp_max;
+                }
+                break;
+        case PMBUS_VIRT_READ_VIN_MIN:
+                ret = pmbus_read_word_data(client, page, LTC2978_MFR_VIN_MIN);
+                if (ret >= 0) {
+                        if (lin11_to_val(ret) < lin11_to_val(data->vin_min))
+                                data->vin_min = ret;
+                        ret = data->vin_min;
+                }
+                break;
+        case PMBUS_VIRT_READ_VOUT_MIN:
+                ret = pmbus_read_word_data(client, page, LTC2978_MFR_VOUT_MIN);
+                if (ret >= 0) {
+                        /*
+                         * VOUT_MIN is known to not be supported on some lots
+                         * of LTC2978 revision 1, and will return the maximum
+                         * possible voltage if read. If VOUT_MAX is valid and
+                         * lower than the reading of VOUT_MIN, use it instead.
+                         */
+                        if (data->vout_max[page] && ret > data->vout_max[page])
+                                ret = data->vout_max[page];
+                        if (ret < data->vout_min[page])
+                                data->vout_min[page] = ret;
+                        ret = data->vout_min[page];
+                }
+                break;
+        case PMBUS_VIRT_READ_TEMP_MIN:
+                ret = pmbus_read_word_data(client, page,
+                                           LTC2978_MFR_TEMPERATURE_MIN);
+                if (ret >= 0) {
+                        if (lin11_to_val(ret)
+                            < lin11_to_val(data->temp_min))
+                                data->temp_min = ret;
+                        ret = data->temp_min;
+                }
+                break;
+        case PMBUS_VIRT_RESET_VOUT_HISTORY:
+        case PMBUS_VIRT_RESET_VIN_HISTORY:
+        case PMBUS_VIRT_RESET_TEMP_HISTORY:
+                ret = 0;
+                break;
+        default:
+                ret = -ENODATA;
+                break;
+        }
+        return ret;
+}
+
+static int ltc2978_write_word_data(struct i2c_client *client, int page,
+                                    int reg, u16 word)
+{
+        const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+        struct ltc2978_data *data = to_ltc2978_data(info);
+        int ret;
+
+        switch (reg) {
+        case PMBUS_VIRT_RESET_VOUT_HISTORY:
+                data->vout_min[page] = 0xffff;
+                data->vout_max[page] = 0;
+                ret = pmbus_write_byte(client, page, PMBUS_CLEAR_FAULTS);
+                break;
+        case PMBUS_VIRT_RESET_VIN_HISTORY:
+                data->vin_min = 0x7bff;
+                data->vin_max = 0;
+                ret = pmbus_write_byte(client, page, PMBUS_CLEAR_FAULTS);
+                break;
+        case PMBUS_VIRT_RESET_TEMP_HISTORY:
+                data->temp_min = 0x7bff;
+                data->temp_max = 0x7fff;
+                ret = pmbus_write_byte(client, page, PMBUS_CLEAR_FAULTS);
+                break;
+        default:
+                ret = -ENODATA;
+                break;
+        }
+        return ret;
+}
+
+static const struct i2c_device_id ltc2978_id[] = {
+        {"ltc2978", ltc2978},
+        {}
+};
+MODULE_DEVICE_TABLE(i2c, ltc2978_id);
+
+static int ltc2978_probe(struct i2c_client *client,
+                         const struct i2c_device_id *id)
+{
+        int chip_id, ret, i;
+        struct ltc2978_data *data;
+        struct pmbus_driver_info *info;
+
+        if (!i2c_check_functionality(client->adapter,
+                                     I2C_FUNC_SMBUS_READ_WORD_DATA))
+                return -ENODEV;
+
+        data = kzalloc(sizeof(struct ltc2978_data), GFP_KERNEL);
+        if (!data)
+                return -ENOMEM;
+
+        chip_id = i2c_smbus_read_word_data(client, LTC2978_MFR_SPECIAL_ID);
+        if (chip_id < 0) {
+                ret = chip_id;
+                goto err_mem;
+        }
+
+        if (chip_id == LTC2978_ID_REV1 || chip_id == LTC2978_ID_REV2) {
+                data->id = ltc2978;
+        } else {
+                dev_err(&client->dev, "Unsupported chip ID 0x%x\n", chip_id);
+                ret = -ENODEV;
+                goto err_mem;
+        }
+        if (data->id != id->driver_data)
+                dev_warn(&client->dev,
+                         "Device mismatch: Configured %s, detected %s\n",
+                         id->name,
+                         ltc2978_id[data->id].name);
+
+        info = &data->info;
+        info->read_word_data = ltc2978_read_word_data;
+        info->write_word_data = ltc2978_write_word_data;
+
+        data->vout_min[0] = 0xffff;
+        data->vin_min = 0x7bff;
+        data->temp_min = 0x7bff;
+        data->temp_max = 0x7fff;
+
+        switch (id->driver_data) {
+        case ltc2978:
+                info->pages = 8;
+                info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_STATUS_INPUT
+                  | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
+                  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
+                for (i = 1; i < 8; i++) {
+                        info->func[i] = PMBUS_HAVE_VOUT
+                          | PMBUS_HAVE_STATUS_VOUT;
+                        data->vout_min[i] = 0xffff;
+                }
+                break;
+        default:
+                ret = -ENODEV;
+                goto err_mem;
+        }
+
+        ret = pmbus_do_probe(client, id, info);
+        if (ret)
+                goto err_mem;
+        return 0;
+
+err_mem:
+        kfree(data);
+        return ret;
+}
+
+static int ltc2978_remove(struct i2c_client *client)
+{
+        const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+        const struct ltc2978_data *data = to_ltc2978_data(info);
+
+        pmbus_do_remove(client);
+        kfree(data);
+        return 0;
+}
+
+/* This is the driver that will be inserted */
+static struct i2c_driver ltc2978_driver = {
+        .driver = {
+                   .name = "ltc2978",
+                   },
+        .probe = ltc2978_probe,
+        .remove = ltc2978_remove,
+        .id_table = ltc2978_id,
+};
+
+static int __init ltc2978_init(void)
+{
+        return i2c_add_driver(&ltc2978_driver);
+}
+
+static void __exit ltc2978_exit(void)
+{
+        i2c_del_driver(&ltc2978_driver);
+}
+
+MODULE_AUTHOR("Guenter Roeck");
+MODULE_DESCRIPTION("PMBus driver for LTC2978");
+MODULE_LICENSE("GPL");
+module_init(ltc2978_init);
+module_exit(ltc2978_exit);
diff --git a/drivers/hwmon/pmbus/pmbus.c b/drivers/hwmon/pmbus/pmbus.c
index 1dfba4477498..ef5cc1eda0f6 100644
--- a/drivers/hwmon/pmbus/pmbus.c
+++ b/drivers/hwmon/pmbus/pmbus.c
@@ -204,7 +204,6 @@ static const struct i2c_device_id pmbus_id[] = {
         {"bmr451", 1},
         {"bmr453", 1},
         {"bmr454", 1},
-        {"ltc2978", 8},
         {"ncp4200", 1},
         {"ncp4208", 1},
         {"pmbus", 0},