The dual tachometer feature is implemented in hardware with a TACHSEL
input to indicate the rotor under measurement, and exposed on the device
by extending the READ_FAN_SPEED_1 word with two extra bytes*. The need
to read the non-standard four-byte response leads to a cut-down
implementation of i2c_smbus_xfer_emulated() included in the driver.
Further, to expose the second rotor tachometer value to userspace the
values are exposed through virtual pages. We re-route accesses to
FAN_CONFIG_1_2 and READ_FAN_SPEED_1 on undefined (in hardware) pages
23-28 to the same registers on pages 0-5, and with the latter command we
extract the value from the second word of the four-byte response.
* The documentation recommends the slower rotor be associated with
TACHSEL=0, which provides the first word of the response. The TACHSEL=0
measurement is used by the controller's closed-loop fan management.
Signed-off-by: Andrew Jeffery <andrew@xxxxxxxx>
---
Documentation/hwmon/max31785 | 8 ++-
drivers/hwmon/pmbus/max31785.c | 159 ++++++++++++++++++++++++++++++++++++++++-
2 files changed, 163 insertions(+), 4 deletions(-)
diff --git a/Documentation/hwmon/max31785 b/Documentation/hwmon/max31785
index e9edbf11948f..8e75efc5e4b9 100644
--- a/Documentation/hwmon/max31785
+++ b/Documentation/hwmon/max31785
@@ -17,8 +17,9 @@ management with temperature and remote voltage sensing. Various fan control
features are provided, including PWM frequency control, temperature hysteresis,
dual tachometer measurements, and fan health monitoring.
-For dual rotor fan configuration, the MAX31785 exposes the slowest rotor of the
-two in the fan[1-4]_input attributes.
+For dual-rotor configurations the MAX31785A exposes the second rotor tachometer
+readings in attributes fan[5-8]_input. By contrast the MAX31785 only exposes
+the slowest rotor measurement, and does so in the fan[1-4]_input attributes.
Usage Notes
-----------
@@ -31,7 +32,8 @@ Sysfs attributes
fan[1-4]_alarm Fan alarm.
fan[1-4]_fault Fan fault.
-fan[1-4]_input Fan RPM.
+fan[1-8]_input Fan RPM. On the MAX31785A, inputs 5-8 correspond to the
+ second rotor of fans 1-4
fan[1-4]_target Fan input target
in[1-6]_crit Critical maximum output voltage
diff --git a/drivers/hwmon/pmbus/max31785.c b/drivers/hwmon/pmbus/max31785.c
index 0d97ddf67079..2ca7febb2843 100644
--- a/drivers/hwmon/pmbus/max31785.c
+++ b/drivers/hwmon/pmbus/max31785.c
@@ -16,10 +16,82 @@
enum max31785_regs {
MFR_REVISION = 0x9b,
+ MFR_FAN_CONFIG = 0xf1,
};
+#define MAX31785 0x3030
+#define MAX31785A 0x3040
+
+#define MFR_FAN_CONFIG_DUAL_TACH BIT(12)
+
#define MAX31785_NR_PAGES 23
+static int max31785_read_byte_data(struct i2c_client *client, int page,
+ int reg)
+{
+ switch (reg) {
+ case PMBUS_VOUT_MODE:
+ if (page < MAX31785_NR_PAGES)
+ return -ENODATA;
+
+ return -ENOTSUPP;
+ case PMBUS_FAN_CONFIG_12:
+ if (page < MAX31785_NR_PAGES)
+ return -ENODATA;
+
+ return pmbus_read_byte_data(client, page - MAX31785_NR_PAGES,
+ reg);
+ }
+
+ return -ENODATA;
+}
+
+static int max31785_write_byte(struct i2c_client *client, int page, u8 value)
+{
+ if (page < MAX31785_NR_PAGES)
+ return -ENODATA;
+
+ return -ENOTSUPP;
+}
+
+static int max31785_read_long_data(struct i2c_client *client, int page,
+ int reg, u32 *data)
+{
+ unsigned char cmdbuf[1];
+ unsigned char rspbuf[4];
+ int rc;
+
+ struct i2c_msg msg[2] = {
+ {
+ .addr = client->addr,
+ .flags = 0,
+ .len = sizeof(cmdbuf),
+ .buf = cmdbuf,
+ },
+ {
+ .addr = client->addr,
+ .flags = I2C_M_RD,
+ .len = sizeof(rspbuf),
+ .buf = rspbuf,
+ },
+ };
+
+ cmdbuf[0] = reg;
+
+ rc = pmbus_set_page(client, page);
+ if (rc < 0)
+ return rc;
+
+ rc = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
+ if (rc < 0)
+ return rc;
+
+ *data = (rspbuf[0] << (0 * 8)) | (rspbuf[1] << (1 * 8)) |
+ (rspbuf[2] << (2 * 8)) | (rspbuf[3] << (3 * 8));
+
+ return rc;
+}
+
static int max31785_get_pwm(struct i2c_client *client, int page)
{
int config;
@@ -76,7 +148,25 @@ static int max31785_read_word_data(struct i2c_client *client, int page,
int rv;
switch (reg) {
+ case PMBUS_READ_FAN_SPEED_1:
+ {
+ u32 val;
+
+ if (page < MAX31785_NR_PAGES)
+ return -ENODATA;
+
+ rv = max31785_read_long_data(client, page - MAX31785_NR_PAGES,
+ reg, &val);
+ if (rv < 0)
+ return rv;
+
+ rv = (val >> 16) & 0xffff;
+ break;
+ }
case PMBUS_VIRT_PWM_1:
+ if (page >= MAX31785_NR_PAGES)
+ return -ENOTSUPP;
+
rv = max31785_get_pwm(client, page);
if (rv < 0)
return rv;
@@ -85,10 +175,13 @@ static int max31785_read_word_data(struct i2c_client *client, int page,
rv /= 100;
break;
case PMBUS_VIRT_PWM_ENABLE_1:
+ if (page >= MAX31785_NR_PAGES)
+ return -ENOTSUPP;
+
rv = max31785_get_pwm_mode(client, page);
break;
default:
- rv = -ENODATA;
+ rv = (page >= MAX31785_NR_PAGES) ? -ENXIO : -ENODATA;
break;
}
@@ -100,6 +193,9 @@ static const int max31785_pwm_modes[] = { 0x7fff, 0x2710, 0xffff };
static int max31785_write_word_data(struct i2c_client *client, int page,
int reg, u16 word)
{
+ if (page >= MAX31785_NR_PAGES)
+ return -ENXIO;
+
switch (reg) {
case PMBUS_VIRT_PWM_ENABLE_1:
if (word >= ARRAY_SIZE(max31785_pwm_modes))
@@ -127,7 +223,9 @@ static const struct pmbus_driver_info max31785_info = {
.pages = MAX31785_NR_PAGES,
.write_word_data = max31785_write_word_data,
+ .read_byte_data = max31785_read_byte_data,
.read_word_data = max31785_read_word_data,
+ .write_byte = max31785_write_byte,
/* RPM */
.format[PSC_FAN] = direct,
@@ -174,6 +272,55 @@ static const struct pmbus_driver_info max31785_info = {
.func[22] = MAX31785_VOUT_FUNCS,
};
+static int max31785_configure(struct i2c_client *client,
+ const struct i2c_device_id *id,
+ struct pmbus_driver_info *info)
+{
+ struct device *dev = &client->dev;
+ bool dual_tach = false;
+ int ret;
+ int i;
+
+ ret = i2c_smbus_read_word_data(client, MFR_REVISION);
+ if (ret < 0)
+ return ret;
+
+ if (!strcmp("max31785a", id->name)) {
+ if (ret == MAX31785A)
+ dual_tach = true;
+ else
+ dev_warn(dev, "Expected max3175a, found max31785: cannot provide secondary tachometer readings\n");
+ } else if (!strcmp("max31785", id->name)) {
+ if (ret == MAX31785A)
+ dev_info(dev, "Expected max31785, found max3175a: suppressing secondary tachometer attributes\n");
+ } else {
+ return -EINVAL;
+ }
+
+ if (!dual_tach)
+ return 0;
+
+ for (i = 0; i <= 5; i++) {
+ ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
+ if (ret < 0)
+ return ret;
+
+ ret = i2c_smbus_read_word_data(client, MFR_FAN_CONFIG);
+ if (ret < 0)
+ return ret;
+
+ if (ret & MFR_FAN_CONFIG_DUAL_TACH) {
+ int virtual = MAX31785_NR_PAGES + i;
+
+ info->pages = max(info->pages, virtual + 1);
+ info->func[virtual] |= PMBUS_HAVE_FAN12;
+ info->func[virtual] |= PMBUS_PAGE_VIRTUAL;
+ }
+ }
+
+ return 0;
+}
+
static int max31785_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
@@ -181,6 +328,12 @@ static int max31785_probe(struct i2c_client *client,
struct pmbus_driver_info *info;
s64 ret;
+ if (!i2c_check_functionality(client->adapter,
+ I2C_FUNC_SMBUS_BYTE_DATA |
+ I2C_FUNC_SMBUS_WORD_DATA |
+ I2C_FUNC_SMBUS_BLOCK_DATA))
+ return -ENODEV;
+
info = devm_kzalloc(dev, sizeof(struct pmbus_driver_info), GFP_KERNEL);
if (!info)
return -ENOMEM;
@@ -191,6 +344,10 @@ static int max31785_probe(struct i2c_client *client,
if (ret < 0)
return ret;
+ ret = max31785_configure(client, id, info);
+ if (ret < 0)
+ return ret;
+
return pmbus_do_probe(client, id, info);
}
--
2.11.0
--
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