Skip to content

Commit

Permalink
hwmon: (ltc2978) Add polling for chips requiring it
Browse files Browse the repository at this point in the history 
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>
  • Loading branch information
Michael Jones authored and Guenter Roeck committed Aug 19, 2015
1 parent d830e27 commit e04d1ce
Showing 1 changed file with 101 additions and 10 deletions.
111 changes: 101 additions & 10 deletions drivers/hwmon/pmbus/ltc2978.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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>
Expand All @@ -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
Expand Down Expand Up @@ -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
Expand All @@ -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)
{
Expand All @@ -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;
Expand All @@ -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;
Expand All @@ -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,
Expand All @@ -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;
}
Expand All @@ -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
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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
Expand Down

0 comments on commit e04d1ce

Please sign in to comment.