hwmon: (ltc2978) Add polling for chips requiring it

Some of the LTC chips supported by this driver have to be polled
to ensure that they are ready to accept commands.

Signed-off-by: Michael Jones <mike@proclivis.com>
[Guenter Roeck: simplifications and formatting changes]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/pmbus/ltc2978.c b/drivers/hwmon/pmbus/ltc2978.c
index 60fe8f9839d3efda4690b37e717bf5a4f116fd56..f1c69c9de8498a6a9b03fcce181f099beec9ba6a 100644 (file)
--- a/drivers/hwmon/pmbus/ltc2978.c
+++ b/drivers/hwmon/pmbus/ltc2978.c
@@ -3,6 +3,7 @@
  *
  * Copyright (c) 2011 Ericsson AB.
  * Copyright (c) 2013, 2014, 2015 Guenter Roeck
+ * Copyright (c) 2015 Linear Technology
  *
  * 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
@@ -15,6 +16,8 @@
  * GNU General Public License for more details.
  */
 
+#include <linux/delay.h>
+#include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
@@ -32,6 +35,7 @@ enum chips { ltc2974, ltc2975, ltc2977, ltc2978, ltc2980, ltc3880, ltc3882,
 #define LTC2978_MFR_VIN_PEAK           0xde
 #define LTC2978_MFR_TEMPERATURE_PEAK   0xdf
 #define LTC2978_MFR_SPECIAL_ID         0xe7    /* Undocumented on LTC3882 */
+#define LTC2978_MFR_COMMON             0xef
 
 /* LTC2974, LTC2975, LCT2977, LTC2980, LTC2978, and LTM2987 */
 #define LTC2978_MFR_VOUT_MIN           0xfb
@@ -82,6 +86,11 @@ enum chips { ltc2974, ltc2975, ltc2977, ltc2978, ltc2980, ltc3880, ltc3882,
 #define LTC3880_NUM_PAGES              2
 #define LTC3883_NUM_PAGES              1
 
+#define LTC_POLL_TIMEOUT               100     /* in milli-seconds */
+
+#define LTC_NOT_BUSY                   BIT(5)
+#define LTC_NOT_PENDING                        BIT(4)
+
 /*
  * 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
@@ -105,8 +114,81 @@ struct ltc2978_data {
 #define to_ltc2978_data(x)  container_of(x, struct ltc2978_data, info)
 
 #define FEAT_CLEAR_PEAKS       BIT(0)
+#define FEAT_NEEDS_POLLING     BIT(1)
 
 #define has_clear_peaks(d)     ((d)->features & FEAT_CLEAR_PEAKS)
+#define needs_polling(d)       ((d)->features & FEAT_NEEDS_POLLING)
+
+static int ltc_wait_ready(struct i2c_client *client)
+{
+       unsigned long timeout = jiffies + msecs_to_jiffies(LTC_POLL_TIMEOUT);
+       const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+       struct ltc2978_data *data = to_ltc2978_data(info);
+       int status;
+       u8 mask;
+
+       if (!needs_polling(data))
+               return 0;
+
+       /*
+        * LTC3883 does not support LTC_NOT_PENDING, even though
+        * the datasheet claims that it does.
+        */
+       mask = LTC_NOT_BUSY;
+       if (data->id != ltc3883)
+               mask |= LTC_NOT_PENDING;
+
+       do {
+               status = pmbus_read_byte_data(client, 0, LTC2978_MFR_COMMON);
+               if (status == -EBADMSG || status == -ENXIO) {
+                       /* PEC error or NACK: chip may be busy, try again */
+                       usleep_range(50, 100);
+                       continue;
+               }
+               if (status < 0)
+                       return status;
+
+               if ((status & mask) == mask)
+                       return 0;
+
+               usleep_range(50, 100);
+       } while (time_before(jiffies, timeout));
+
+       return -ETIMEDOUT;
+}
+
+static int ltc_read_word_data(struct i2c_client *client, int page, int reg)
+{
+       int ret;
+
+       ret = ltc_wait_ready(client);
+       if (ret < 0)
+               return ret;
+
+       return pmbus_read_word_data(client, page, reg);
+}
+
+static int ltc_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+       int ret;
+
+       ret = ltc_wait_ready(client);
+       if (ret < 0)
+               return ret;
+
+       return pmbus_read_byte_data(client, page, reg);
+}
+
+static int ltc_write_byte(struct i2c_client *client, int page, u8 byte)
+{
+       int ret;
+
+       ret = ltc_wait_ready(client);
+       if (ret < 0)
+               return ret;
+
+       return pmbus_write_byte(client, page, byte);
+}
 
 static inline int lin11_to_val(int data)
 {
@@ -126,7 +208,7 @@ static int ltc_get_max(struct ltc2978_data *data, struct i2c_client *client,
 {
        int ret;
 
-       ret = pmbus_read_word_data(client, page, reg);
+       ret = ltc_read_word_data(client, page, reg);
        if (ret >= 0) {
                if (lin11_to_val(ret) > lin11_to_val(*pmax))
                        *pmax = ret;
@@ -140,7 +222,7 @@ static int ltc_get_min(struct ltc2978_data *data, struct i2c_client *client,
 {
        int ret;
 
-       ret = pmbus_read_word_data(client, page, reg);
+       ret = ltc_read_word_data(client, page, reg);
        if (ret >= 0) {
                if (lin11_to_val(ret) < lin11_to_val(*pmin))
                        *pmin = ret;
@@ -162,7 +244,7 @@ static int ltc2978_read_word_data_common(struct i2c_client *client, int page,
                                  &data->vin_max);
                break;
        case PMBUS_VIRT_READ_VOUT_MAX:
-               ret = pmbus_read_word_data(client, page, LTC2978_MFR_VOUT_PEAK);
+               ret = ltc_read_word_data(client, page, LTC2978_MFR_VOUT_PEAK);
                if (ret >= 0) {
                        /*
                         * VOUT is 16 bit unsigned with fixed exponent,
@@ -184,6 +266,9 @@ static int ltc2978_read_word_data_common(struct i2c_client *client, int page,
                ret = 0;
                break;
        default:
+               ret = ltc_wait_ready(client);
+               if (ret < 0)
+                       return ret;
                ret = -ENODATA;
                break;
        }
@@ -202,7 +287,7 @@ static int ltc2978_read_word_data(struct i2c_client *client, int page, int reg)
                                  &data->vin_min);
                break;
        case PMBUS_VIRT_READ_VOUT_MIN:
-               ret = pmbus_read_word_data(client, page, LTC2978_MFR_VOUT_MIN);
+               ret = ltc_read_word_data(client, page, LTC2978_MFR_VOUT_MIN);
                if (ret >= 0) {
                        /*
                         * VOUT_MIN is known to not be supported on some lots
@@ -353,9 +438,9 @@ static int ltc2978_clear_peaks(struct ltc2978_data *data,
        int ret;
 
        if (has_clear_peaks(data))
-               ret = pmbus_write_byte(client, 0, LTC3880_MFR_CLEAR_PEAKS);
+               ret = ltc_write_byte(client, 0, LTC3880_MFR_CLEAR_PEAKS);
        else
-               ret = pmbus_write_byte(client, page, PMBUS_CLEAR_FAULTS);
+               ret = ltc_write_byte(client, page, PMBUS_CLEAR_FAULTS);
 
        return ret;
 }
@@ -403,6 +488,9 @@ static int ltc2978_write_word_data(struct i2c_client *client, int page,
                ret = ltc2978_clear_peaks(data, client, page);
                break;
        default:
+               ret = ltc_wait_ready(client);
+               if (ret < 0)
+                       return ret;
                ret = -ENODATA;
                break;
        }
@@ -530,6 +618,9 @@ static int ltc2978_probe(struct i2c_client *client,
 
        info = &data->info;
        info->write_word_data = ltc2978_write_word_data;
+       info->write_byte = ltc_write_byte;
+       info->read_word_data = ltc_read_word_data;
+       info->read_byte_data = ltc_read_byte_data;
 
        data->vin_min = 0x7bff;
        data->vin_max = 0x7c00;
@@ -588,7 +679,7 @@ static int ltc2978_probe(struct i2c_client *client,
        case ltc3880:
        case ltc3887:
        case ltm4676:
-               data->features |= FEAT_CLEAR_PEAKS;
+               data->features |= FEAT_CLEAR_PEAKS | FEAT_NEEDS_POLLING;
                info->read_word_data = ltc3880_read_word_data;
                info->pages = LTC3880_NUM_PAGES;
                info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN
@@ -603,7 +694,7 @@ static int ltc2978_probe(struct i2c_client *client,
                  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
                break;
        case ltc3882:
-               data->features |= FEAT_CLEAR_PEAKS;
+               data->features |= FEAT_CLEAR_PEAKS | FEAT_NEEDS_POLLING;
                info->read_word_data = ltc3880_read_word_data;
                info->pages = LTC3880_NUM_PAGES;
                info->func[0] = PMBUS_HAVE_VIN
@@ -618,7 +709,7 @@ static int ltc2978_probe(struct i2c_client *client,
                  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
                break;
        case ltc3883:
-               data->features |= FEAT_CLEAR_PEAKS;
+               data->features |= FEAT_CLEAR_PEAKS | FEAT_NEEDS_POLLING;
                info->read_word_data = ltc3883_read_word_data;
                info->pages = LTC3883_NUM_PAGES;
                info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN
@@ -629,7 +720,7 @@ static int ltc2978_probe(struct i2c_client *client,
                  | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_STATUS_TEMP;
                break;
        case ltc3886:
-               data->features |= FEAT_CLEAR_PEAKS;
+               data->features |= FEAT_CLEAR_PEAKS | FEAT_NEEDS_POLLING;
                info->read_word_data = ltc3883_read_word_data;
                info->pages = LTC3880_NUM_PAGES;
                info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN