Re: [v4,3/6] pmbus: core: Add fan control support

From: Guenter Roeck
Date: Sun Nov 05 2017 - 09:40:08 EST

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Previous message: Chao Yu: "[PATCH 3/3] f2fs: keep isize once block is reserved cross EOF"
In reply to: Andrew Jeffery: "[PATCH v4 3/6] pmbus: core: Add fan control support"
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On Fri, Nov 03, 2017 at 03:53:03PM +1100, Andrew Jeffery wrote:
> Expose fanX_target, pwmX and pwmX_enable hwmon sysfs attributes.
>
> Fans in a PMBus device are driven by the configuration of two registers:
> FAN_CONFIG_x_y and FAN_COMMAND_x: FAN_CONFIG_x_y dictates how the fan
> and the tacho operate (if installed), while FAN_COMMAND_x sets the
> desired fan rate. The unit of FAN_COMMAND_x is dependent on the
> operational fan mode, RPM or PWM percent duty, as determined by the
> corresponding FAN_CONFIG_x_y.
>
> The mapping of fanX_target, pwmX and pwmX_enable onto FAN_CONFIG_x_y and
> FAN_COMMAND_x is implemented with the addition of virtual registers and
> generic implementations in the core:
>
> 1. PMBUS_VIRT_FAN_TARGET_x
> 2. PMBUS_VIRT_PWM_x
> 3. PMBUS_VIRT_PWM_ENABLE_x
>
> The virtual registers facilitate the necessary side-effects of each
> access. Examples of the read case, assuming m = 1, b = 0, R = 0:
>
> Read | With || Gives
> -------------------------------------------------------
> Attribute | FAN_CONFIG_x_y | FAN_COMMAND_y || Value
> ----------------------------------------------++-------
> fanX_target | ~PB_FAN_z_RPM | 0x0001 || 1
> pwm1 | ~PB_FAN_z_RPM | 0x0064 || 255
> pwmX_enable | ~PB_FAN_z_RPM | 0x0001 || 1
> fanX_target | PB_FAN_z_RPM | 0x0001 || 1
> pwm1 | PB_FAN_z_RPM | 0x0064 || 0
> pwmX_enable | PB_FAN_z_RPM | 0x0001 || 1
>
> And the write case:
>
> Write | With || Sets
> -------------+-------++----------------+---------------
> Attribute | Value || FAN_CONFIG_x_y | FAN_COMMAND_x
> -------------+-------++----------------+---------------
> fanX_target | 1 || PB_FAN_z_RPM | 0x0001
> pwmX | 255 || ~PB_FAN_z_RPM | 0x0064
> pwmX_enable | 1 || ~PB_FAN_z_RPM | 0x0064
>
> Also, the DIRECT mode scaling of some controllers is different between
> RPM and PWM percent duty control modes, so PSC_PWM is introduced to
> capture the necessary coefficients.
>
> Signed-off-by: Andrew Jeffery <andrew@xxxxxxxx>
> ---
> drivers/hwmon/pmbus/pmbus.h | 29 +++++
> drivers/hwmon/pmbus/pmbus_core.c | 224 ++++++++++++++++++++++++++++++++++++---
> 2 files changed, 238 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
> index 4efa2bd4f6d8..cdf3e288e626 100644
> --- a/drivers/hwmon/pmbus/pmbus.h
> +++ b/drivers/hwmon/pmbus/pmbus.h
> @@ -190,6 +190,28 @@ enum pmbus_regs {
> PMBUS_VIRT_VMON_UV_FAULT_LIMIT,
> PMBUS_VIRT_VMON_OV_FAULT_LIMIT,
> PMBUS_VIRT_STATUS_VMON,
> +
> + /*
> + * RPM and PWM Fan control
> + *
> + * Drivers wanting to expose PWM control must define the behaviour of
> + * PMBUS_VIRT_PWM_ENABLE_[1-4] in the {read,write}_word_data callback.
> + *
> + * pmbus core provides default implementations for
> + * PMBUS_VIRT_FAN_TARGET_[1-4] and PMBUS_VIRT_PWM_[1-4].
> + */
> + PMBUS_VIRT_FAN_TARGET_1,
> + PMBUS_VIRT_FAN_TARGET_2,
> + PMBUS_VIRT_FAN_TARGET_3,
> + PMBUS_VIRT_FAN_TARGET_4,
> + PMBUS_VIRT_PWM_1,
> + PMBUS_VIRT_PWM_2,
> + PMBUS_VIRT_PWM_3,
> + PMBUS_VIRT_PWM_4,
> + PMBUS_VIRT_PWM_ENABLE_1,
> + PMBUS_VIRT_PWM_ENABLE_2,
> + PMBUS_VIRT_PWM_ENABLE_3,
> + PMBUS_VIRT_PWM_ENABLE_4,
> };
>
> /*
> @@ -223,6 +245,8 @@ enum pmbus_regs {
> #define PB_FAN_1_RPM BIT(6)
> #define PB_FAN_1_INSTALLED BIT(7)
>
> +enum pmbus_fan_mode { percent = 0, rpm };
> +
> /*
> * STATUS_BYTE, STATUS_WORD (lower)
> */
> @@ -313,6 +337,7 @@ enum pmbus_sensor_classes {
> PSC_POWER,
> PSC_TEMPERATURE,
> PSC_FAN,
> + PSC_PWM,
> PSC_NUM_CLASSES /* Number of power sensor classes */
> };
>
> @@ -339,6 +364,8 @@ enum pmbus_sensor_classes {
> #define PMBUS_HAVE_STATUS_FAN34 BIT(17)
> #define PMBUS_HAVE_VMON BIT(18)
> #define PMBUS_HAVE_STATUS_VMON BIT(19)
> +#define PMBUS_HAVE_PWM12 BIT(20)
> +#define PMBUS_HAVE_PWM34 BIT(21)
>
> enum pmbus_data_format { linear = 0, direct, vid };
> enum vrm_version { vr11 = 0, vr12, vr13 };
> @@ -413,6 +440,8 @@ int pmbus_write_byte_data(struct i2c_client *client, int page, u8 reg,
> u8 value);
> int pmbus_update_byte_data(struct i2c_client *client, int page, u8 reg,
> u8 mask, u8 value);
> +int pmbus_update_fan(struct i2c_client *client, int page, int id,
> + u8 config, u8 mask, u16 command);
> void pmbus_clear_faults(struct i2c_client *client);
> bool pmbus_check_byte_register(struct i2c_client *client, int page, int reg);
> bool pmbus_check_word_register(struct i2c_client *client, int page, int reg);
> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> index 302f0aef59de..55838b69e99a 100644
> --- a/drivers/hwmon/pmbus/pmbus_core.c
> +++ b/drivers/hwmon/pmbus/pmbus_core.c
> @@ -64,6 +64,7 @@ struct pmbus_sensor {
> u16 reg; /* register */
> enum pmbus_sensor_classes class; /* sensor class */
> bool update; /* runtime sensor update needed */
> + bool convert; /* Whether or not to apply linear/vid/direct */
> int data; /* Sensor data.
> Negative if there was a read error */
> };
> @@ -128,6 +129,27 @@ struct pmbus_debugfs_entry {
> u8 reg;
> };
>
> +static const int pmbus_fan_rpm_mask[] = {
> + PB_FAN_1_RPM,
> + PB_FAN_2_RPM,
> + PB_FAN_1_RPM,
> + PB_FAN_2_RPM,
> +};
> +
> +static const int pmbus_fan_config_registers[] = {
> + PMBUS_FAN_CONFIG_12,
> + PMBUS_FAN_CONFIG_12,
> + PMBUS_FAN_CONFIG_34,
> + PMBUS_FAN_CONFIG_34
> +};
> +
> +static const int pmbus_fan_command_registers[] = {
> + PMBUS_FAN_COMMAND_1,
> + PMBUS_FAN_COMMAND_2,
> + PMBUS_FAN_COMMAND_3,
> + PMBUS_FAN_COMMAND_4,
> +};
> +
> void pmbus_clear_cache(struct i2c_client *client)
> {
> struct pmbus_data *data = i2c_get_clientdata(client);
> @@ -198,6 +220,31 @@ int pmbus_write_word_data(struct i2c_client *client, u8 page, u8 reg, u16 word)
> }
> EXPORT_SYMBOL_GPL(pmbus_write_word_data);
>
> +int pmbus_update_fan(struct i2c_client *client, int page, int id,
> + u8 config, u8 mask, u16 command)

Please make sure continuation lines are aligned to '(' where possible.

> +{
> + int from, rv;
> + u8 to;
> +
> + from = pmbus_read_byte_data(client, page,
> + pmbus_fan_config_registers[id]);
> + if (from < 0)
> + return from;
> +
> + to = (from & ~mask) | (config & mask);
> +
> + if (to != from) {
> + rv = pmbus_write_byte_data(client, page,
> + pmbus_fan_config_registers[id], to);
> + if (rv < 0)
> + return rv;
> + }
> +
> + return pmbus_write_word_data(client, page,
> + pmbus_fan_command_registers[id], command);
> +}
> +EXPORT_SYMBOL_GPL(pmbus_update_fan);
> +
> /*
> * _pmbus_write_word_data() is similar to pmbus_write_word_data(), but checks if
> * a device specific mapping function exists and calls it if necessary.
> @@ -214,8 +261,40 @@ static int _pmbus_write_word_data(struct i2c_client *client, int page, int reg,
> if (status != -ENODATA)
> return status;
> }
> - if (reg >= PMBUS_VIRT_BASE)
> - return -ENXIO;
> + if (reg >= PMBUS_VIRT_BASE) {
> + int id, bit;
> +
> + switch (reg) {
> + case PMBUS_VIRT_FAN_TARGET_1:
> + case PMBUS_VIRT_FAN_TARGET_2:
> + case PMBUS_VIRT_FAN_TARGET_3:
> + case PMBUS_VIRT_FAN_TARGET_4:

Maybe
case PMBUS_VIRT_FAN_TARGET_1 ... PMBUS_VIRT_FAN_TARGET_4:

> + id = reg - PMBUS_VIRT_FAN_TARGET_1;
> + bit = pmbus_fan_rpm_mask[id];
> + status = pmbus_update_fan(client, page, id, bit, bit,
> + word);
> + break;
> + case PMBUS_VIRT_PWM_1:
> + case PMBUS_VIRT_PWM_2:
> + case PMBUS_VIRT_PWM_3:
> + case PMBUS_VIRT_PWM_4:
> + {
> + u32 command = word;

Please move command up and drop the {.

Why u32 ? The value should be bound to 0..255 (if it isn't and a larger
value is accepted we have overflow issues).

> +
> + id = reg - PMBUS_VIRT_PWM_1;
> + bit = pmbus_fan_rpm_mask[id];
> + command *= 100;
> + command /= 255;
> + status = pmbus_update_fan(client, page, id, 0, bit,
> + command);
> + break;
> + }
> + default:
> + status = -ENXIO;
> + break;
> + }
> + return status;

Please move this code to a separate function.

> + }
> return pmbus_write_word_data(client, page, reg, word);
> }
>
> @@ -231,6 +310,9 @@ int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg)
> }
> EXPORT_SYMBOL_GPL(pmbus_read_word_data);
>
> +static int pmbus_get_fan_command(struct i2c_client *client, int page, int id,
> + enum pmbus_fan_mode mode);
> +
> /*
> * _pmbus_read_word_data() is similar to pmbus_read_word_data(), but checks if
> * a device specific mapping function exists and calls it if necessary.
> @@ -246,8 +328,42 @@ static int _pmbus_read_word_data(struct i2c_client *client, int page, int reg)
> if (status != -ENODATA)
> return status;
> }
> - if (reg >= PMBUS_VIRT_BASE)
> - return -ENXIO;
> + if (reg >= PMBUS_VIRT_BASE) {
> + int id;
> +
> + switch (reg) {
> + case PMBUS_VIRT_FAN_TARGET_1:
> + case PMBUS_VIRT_FAN_TARGET_2:
> + case PMBUS_VIRT_FAN_TARGET_3:
> + case PMBUS_VIRT_FAN_TARGET_4:

Since there is an implied assumption that those are sequential,
how about the following ?

case PMBUS_VIRT_FAN_TARGET_1 ... PMBUS_VIRT_FAN_TARGET_4:

> + id = reg - PMBUS_VIRT_FAN_TARGET_1;

This warrants a comment in the definition of PMBUS_VIRT_FAN_TARGET_X
and PMBUS_VIRT_PWM_X stating that the definitions must be in sequence.

> + status = pmbus_get_fan_command(client, page, id, rpm);
> + break;
> + case PMBUS_VIRT_PWM_1:
> + case PMBUS_VIRT_PWM_2:
> + case PMBUS_VIRT_PWM_3:
> + case PMBUS_VIRT_PWM_4:

Same as above.

> + {
> + int rv;

Please move the declaration up and drop the {.

> +
> + id = reg - PMBUS_VIRT_PWM_1;
> + rv = pmbus_get_fan_command(client, page, id, percent);
> + if (rv < 0)
> + return rv;
> +
Is this guaranteed to be <= 100 ?

> + rv *= 255;
> + rv /= 100;
> +
> + status = rv;
> + break;
> + }
> + default:
> + status = -ENXIO;
> + break;
> + }

Please move this code to a separate function.

> +
> + return status;
> + }
> return pmbus_read_word_data(client, page, reg);
> }
>
> @@ -314,6 +430,28 @@ static int _pmbus_read_byte_data(struct i2c_client *client, int page, int reg)
> return pmbus_read_byte_data(client, page, reg);
> }
>
> +static int pmbus_get_fan_command(struct i2c_client *client, int page, int id,
> + enum pmbus_fan_mode mode)

Maybe better pmbus_get_fan_get_speed_rpm to clarify that we are not
really interested in the command register value but but in speed or rpm ?

> +{
> + int config;
> +
> + config = _pmbus_read_byte_data(client, page,
> + pmbus_fan_config_registers[id]);
> + if (config < 0)
> + return config;
> +
> + /*
> + * We can't meaningfully translate between PWM and RPM, so if the
> + * attribute mode (fan[1-*]_target is RPM, pwm[1-*] and pwm[1-*]_enable
> + * are PWM) doesn't match the hardware mode, then report 0 instead.
> + */
> + if ((mode == rpm) != (!!(config & pmbus_fan_rpm_mask[id])))
> + return 0;

Please drop the unnecessary ().

I am not too happy about this - the user has no means to specify pwm or
fan target speed _before_ changing the mode. It would be better to report
(and accept) cached values in that situation, and update the actual value
as the mode is changed.

> +
> + return _pmbus_read_word_data(client, page,
> + pmbus_fan_command_registers[id]);
> +}
> +
> static void pmbus_clear_fault_page(struct i2c_client *client, int page)
> {
> _pmbus_write_byte(client, page, PMBUS_CLEAR_FAULTS);
> @@ -515,7 +653,7 @@ static long pmbus_reg2data_direct(struct pmbus_data *data,
> /* X = 1/m * (Y * 10^-R - b) */
> R = -R;
> /* scale result to milli-units for everything but fans */
> - if (sensor->class != PSC_FAN) {
> + if (!(sensor->class == PSC_FAN || sensor->class == PSC_PWM)) {

Please use positive logic

if (sensor->class != PSC_FAN && sensor->class != PSC_PWM)

It is (at least for me) much easier to read.

> R += 3;
> b *= 1000;
> }
> @@ -569,6 +707,9 @@ static long pmbus_reg2data(struct pmbus_data *data, struct pmbus_sensor *sensor)
> {
> long val;
>
> + if (!sensor->convert)
> + return sensor->data;
> +
> switch (data->info->format[sensor->class]) {
> case direct:
> val = pmbus_reg2data_direct(data, sensor);
> @@ -672,7 +813,7 @@ static u16 pmbus_data2reg_direct(struct pmbus_data *data,
> }
>
> /* Calculate Y = (m * X + b) * 10^R */
> - if (sensor->class != PSC_FAN) {
> + if (!(sensor->class == PSC_FAN || sensor->class == PSC_PWM)) {

Same as above.

> R -= 3; /* Adjust R and b for data in milli-units */
> b *= 1000;
> }
> @@ -703,6 +844,9 @@ static u16 pmbus_data2reg(struct pmbus_data *data,
> {
> u16 regval;
>
> + if (!sensor->convert)
> + return val;
> +
> switch (data->info->format[sensor->class]) {
> case direct:
> regval = pmbus_data2reg_direct(data, sensor, val);
> @@ -925,12 +1069,18 @@ static struct pmbus_sensor *pmbus_add_sensor(struct pmbus_data *data,
> return NULL;
> a = &sensor->attribute;
>
> - snprintf(sensor->name, sizeof(sensor->name), "%s%d_%s",
> - name, seq, type);
> + if (type)
> + snprintf(sensor->name, sizeof(sensor->name), "%s%d_%s",
> + name, seq, type);
> + else
> + snprintf(sensor->name, sizeof(sensor->name), "%s%d",
> + name, seq);
> +
> sensor->page = page;
> sensor->reg = reg;
> sensor->class = class;
> sensor->update = update;
> + sensor->convert = true;
> pmbus_dev_attr_init(a, sensor->name,
> readonly ? S_IRUGO : S_IRUGO | S_IWUSR,
> pmbus_show_sensor, pmbus_set_sensor);
> @@ -1592,13 +1742,6 @@ static const int pmbus_fan_registers[] = {
> PMBUS_READ_FAN_SPEED_4
> };
>
> -static const int pmbus_fan_config_registers[] = {
> - PMBUS_FAN_CONFIG_12,
> - PMBUS_FAN_CONFIG_12,
> - PMBUS_FAN_CONFIG_34,
> - PMBUS_FAN_CONFIG_34
> -};
> -
> static const int pmbus_fan_status_registers[] = {
> PMBUS_STATUS_FAN_12,
> PMBUS_STATUS_FAN_12,
> @@ -1621,6 +1764,48 @@ static const u32 pmbus_fan_status_flags[] = {
> };
>
> /* Fans */
> +static int pmbus_add_fan_ctrl(struct i2c_client *client,
> + struct pmbus_data *data, int index, int page, int id,
> + u8 config)
> +{
> + struct pmbus_sensor *sensor;
> + int rv;
> +
> + rv = _pmbus_read_word_data(client, page,
> + pmbus_fan_command_registers[id]);
> + if (rv < 0)
> + return rv;
> +
> + sensor = pmbus_add_sensor(data, "fan", "target", index, page,
> + PMBUS_VIRT_FAN_TARGET_1 + id, PSC_FAN,
> + true, false);
> +
> + if (!sensor)
> + return -ENOMEM;
> +
> + if (!((data->info->func[page] & PMBUS_HAVE_PWM12) ||
> + (data->info->func[page] & PMBUS_HAVE_PWM34)))

why not just the following ?

if (!(data->info->func[page] & (PMBUS_HAVE_PWM12 | PMBUS_HAVE_PWM34)))

Also, doesn't this add attributes for 1,2 even if only 3,4 are
supported, and 3,4 even if only 1,2 are supported ?

> + return 0;
> +
> + sensor = pmbus_add_sensor(data, "pwm", NULL, index, page,
> + PMBUS_VIRT_PWM_1 + id, PSC_PWM,
> + true, false);
> +
> + if (!sensor)
> + return -ENOMEM;
> +
> + sensor = pmbus_add_sensor(data, "pwm", "enable", index, page,
> + PMBUS_VIRT_PWM_ENABLE_1 + id, PSC_PWM,
> + true, false);
> +
> + if (!sensor)
> + return -ENOMEM;
> +
> + sensor->convert = false;

convert should be a new parameter to pmbus_add_sensor().

> +
> + return 0;
> +}
> +
> static int pmbus_add_fan_attributes(struct i2c_client *client,
> struct pmbus_data *data)
> {
> @@ -1658,6 +1843,15 @@ static int pmbus_add_fan_attributes(struct i2c_client *client,
> PSC_FAN, true, true) == NULL)
> return -ENOMEM;
>
> + /* Fan control */
> + if (pmbus_check_word_register(client, page,
> + pmbus_fan_command_registers[f])) {
> + ret = pmbus_add_fan_ctrl(client, data, index,
> + page, f, regval);
> + if (ret < 0)
> + return ret;
> + }
> +
> /*
> * Each fan status register covers multiple fans,
> * so we have to do some magic.

Next message: Ingo Molnar: "[GIT PULL] perf fixes"
Previous message: Chao Yu: "[PATCH 3/3] f2fs: keep isize once block is reserved cross EOF"
In reply to: Andrew Jeffery: "[PATCH v4 3/6] pmbus: core: Add fan control support"
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