Date:   Sun, 6 Jun 2021 05:59:38 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Robert Marko <robert.marko@...tura.hr>
Cc:     robh+dt@...nel.org, jdelvare@...e.com, corbet@....net,
        trivial@...nel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-doc@...r.kernel.org, luka.perkov@...tura.hr,
        jmp@...phyte.org, pmenzel@...gen.mpg.de, buczek@...gen.mpg.de
Subject: Re: [PATCH v3 1/3] hwmon: (pmbus) Add driver for Delta DPS-920AB PSU

On Fri, Jun 04, 2021 at 05:36:10PM +0200, Robert Marko wrote:
> This adds support for the Delta DPS-920AB PSU.
> 
> Only missing feature is fan control which the PSU supports.
> 
> Signed-off-by: Robert Marko <robert.marko@...tura.hr>
> ---
> Changes in v3:
> * Use generic pmbus_read/write_word_data()
> * Correct word data return code
> * Cache PMBUS_MFR_ID and PMBUS_MFR_MODEL instead
> of reading them everytime that debugfs is read
> 
> Changes in v2:
> * Check for Manufacturer and Model
> * Restrict word read/write to supported only
> * Update documentation to reflect driver changes
> * Add basic debugfs entries
> 
>  Documentation/hwmon/dps920ab.rst |  73 +++++++++++
>  Documentation/hwmon/index.rst    |   1 +
>  drivers/hwmon/pmbus/Kconfig      |   9 ++
>  drivers/hwmon/pmbus/Makefile     |   1 +
>  drivers/hwmon/pmbus/dps920ab.c   | 207 +++++++++++++++++++++++++++++++
>  5 files changed, 291 insertions(+)
>  create mode 100644 Documentation/hwmon/dps920ab.rst
>  create mode 100644 drivers/hwmon/pmbus/dps920ab.c
> 
> diff --git a/Documentation/hwmon/dps920ab.rst b/Documentation/hwmon/dps920ab.rst
> new file mode 100644
> index 000000000000..c33b4cdc0a60
> --- /dev/null
> +++ b/Documentation/hwmon/dps920ab.rst
> @@ -0,0 +1,73 @@
> +.. SPDX-License-Identifier: GPL-2.0-or-later
> +
> +Kernel driver dps920ab
> +========================
> +
> +Supported chips:
> +
> +  * Delta DPS920AB
> +
> +    Prefix: 'dps920ab'
> +
> +    Addresses scanned: -
> +
> +Authors:
> +    Robert Marko <robert.marko@...tura.hr>
> +
> +
> +Description
> +-----------
> +
> +This driver implements support for Delta DPS920AB 920W 54V DC single output
> +power supply with PMBus support.
> +
> +The driver is a client driver to the core PMBus driver.
> +Please see Documentation/hwmon/pmbus.rst for details on PMBus client drivers.
> +
> +
> +Usage Notes
> +-----------
> +
> +This driver does not auto-detect devices. You will have to instantiate the
> +devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
> +details.
> +
> +
> +Sysfs entries
> +-------------
> +
> +======================= ======================================================
> +curr1_label		"iin"
> +curr1_input		Measured input current
> +curr1_alarm		Input current high alarm
> +
> +curr2_label		"iout1"
> +curr2_input		Measured output current
> +curr2_max		Maximum output current
> +curr2_rated_max		Maximum rated output current
> +
> +in1_label		"vin"
> +in1_input		Measured input voltage
> +in1_alarm		Input voltage alarm
> +
> +in2_label		"vout1"
> +in2_input		Measured output voltage
> +in2_rated_min		Minimum rated output voltage
> +in2_rated_max		Maximum rated output voltage
> +in2_alarm		Output voltage alarm
> +
> +power1_label		"pin"
> +power1_input		Measured input power
> +power1_alarm		Input power high alarm
> +
> +power2_label		"pout1"
> +power2_input		Measured output power
> +power2_rated_max	Maximum rated output power
> +
> +temp[1-3]_input		Measured temperature
> +temp[1-3]_alarm		Temperature alarm
> +
> +fan1_alarm		Fan 1 warning.
> +fan1_fault		Fan 1 fault.
> +fan1_input		Fan 1 speed in RPM.
> +======================= ======================================================
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 8d5a2df1ecb6..b24436f22052 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -54,6 +54,7 @@ Hardware Monitoring Kernel Drivers
>     dell-smm-hwmon
>     dme1737
>     drivetemp
> +   dps920ab

Alphabetic order please.

>     ds1621
>     ds620
>     emc1403
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index 32d2fc850621..865ade0aa205 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -66,6 +66,15 @@ config SENSORS_IBM_CFFPS
>  	  This driver can also be built as a module. If so, the module will
>  	  be called ibm-cffps.
>  
> +config SENSORS_DPS920AB
> +	tristate "Delta DPS920AB Power Supply"
> +	help
> +	  If you say yes here you get hardware monitoring support for Delta
> +	  DPS920AB Power Supplies.
> +
> +	  This driver can also be built as a module. If so, the module will
> +	  be called dps920ab.
> +
>  config SENSORS_INSPUR_IPSPS
>  	tristate "INSPUR Power System Power Supply"
>  	help
> diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
> index 6a4ba0fdc1db..f59ba0123d68 100644
> --- a/drivers/hwmon/pmbus/Makefile
> +++ b/drivers/hwmon/pmbus/Makefile
> @@ -9,6 +9,7 @@ obj-$(CONFIG_SENSORS_ADM1266)	+= adm1266.o
>  obj-$(CONFIG_SENSORS_ADM1275)	+= adm1275.o
>  obj-$(CONFIG_SENSORS_BEL_PFE)	+= bel-pfe.o
>  obj-$(CONFIG_SENSORS_IBM_CFFPS)	+= ibm-cffps.o
> +obj-$(CONFIG_SENSORS_DPS920AB)	+= dps920ab.o
>  obj-$(CONFIG_SENSORS_INSPUR_IPSPS) += inspur-ipsps.o
>  obj-$(CONFIG_SENSORS_IR35221)	+= ir35221.o
>  obj-$(CONFIG_SENSORS_IR38064)	+= ir38064.o
> diff --git a/drivers/hwmon/pmbus/dps920ab.c b/drivers/hwmon/pmbus/dps920ab.c
> new file mode 100644
> index 000000000000..5ae536cba302
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/dps920ab.c
> @@ -0,0 +1,207 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Driver for Delta DPS920AB PSU
> + *
> + * Copyright (C) 2021 Delta Networks, Inc.
> + * Copyright (C) 2021 Sartura Ltd.
> + */
> +
> +#include <linux/debugfs.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include "pmbus.h"
> +
> +struct dps920ab_data {
> +	struct i2c_client *client;
> +	struct dentry *debugfs_dir;
> +	char *mfr_model;
> +	char *mfr_id;
> +};
> +
> +static int dps920ab_read_word_data(struct i2c_client *client, int page, int phase, int reg)
> +{
> +	/*
> +	 * This masks commands which are not supported.
> +	 * PSU advertises that all features are supported,
> +	 * in reality that unfortunately is not true.
> +	 * So enable only those that the datasheet confirms.
> +	 */
> +	switch (reg) {
> +	case PMBUS_FAN_COMMAND_1:
> +	case PMBUS_IOUT_OC_WARN_LIMIT:
> +	case PMBUS_STATUS_WORD:
> +	case PMBUS_READ_VIN:
> +	case PMBUS_READ_IIN:
> +	case PMBUS_READ_VOUT:
> +	case PMBUS_READ_IOUT:
> +	case PMBUS_READ_TEMPERATURE_1:
> +	case PMBUS_READ_TEMPERATURE_2:
> +	case PMBUS_READ_TEMPERATURE_3:
> +	case PMBUS_READ_FAN_SPEED_1:
> +	case PMBUS_READ_POUT:
> +	case PMBUS_READ_PIN:
> +	case PMBUS_MFR_VOUT_MIN:
> +	case PMBUS_MFR_VOUT_MAX:
> +	case PMBUS_MFR_IOUT_MAX:
> +	case PMBUS_MFR_POUT_MAX:
> +		return pmbus_read_word_data(client, page, phase, reg);
> +	default:
> +		return -ENXIO;
> +	}
> +}
> +
> +static int dps920ab_write_word_data(struct i2c_client *client, int page, int reg,
> +				    u16 word)
> +{
> +	/*
> +	 * This masks commands which are not supported.
> +	 * PSU only has one R/W register and that is
> +	 * for the fan.
> +	 */
> +	switch (reg) {
> +	case PMBUS_FAN_COMMAND_1:
> +		return pmbus_write_word_data(client, page, reg, word);
> +	default:
> +		return -EACCES;
> +	}
> +}
> +
> +static struct pmbus_driver_info dps920ab_info = {
> +	.pages = 1,
> +
> +	.format[PSC_VOLTAGE_IN] = linear,
> +	.format[PSC_VOLTAGE_OUT] = linear,
> +	.format[PSC_CURRENT_IN] = linear,
> +	.format[PSC_CURRENT_OUT] = linear,
> +	.format[PSC_POWER] = linear,
> +	.format[PSC_FAN] = linear,
> +	.format[PSC_TEMPERATURE] = linear,
> +
> +	.func[0] =
> +		PMBUS_HAVE_VIN | PMBUS_HAVE_IIN | PMBUS_HAVE_PIN |
> +		PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT | PMBUS_HAVE_POUT |
> +		PMBUS_HAVE_TEMP  | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_TEMP3 |
> +		PMBUS_HAVE_FAN12 | PMBUS_HAVE_STATUS_FAN12 |
> +		PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_STATUS_IOUT |
> +		PMBUS_HAVE_STATUS_INPUT | PMBUS_HAVE_STATUS_TEMP,
> +	.read_word_data = dps920ab_read_word_data,
> +	.write_word_data = dps920ab_write_word_data,
> +};
> +
> +static int dps920ab_mfr_id_show(struct seq_file *s, void *data)
> +{
> +	struct dps920ab_data *priv = s->private;
> +
> +	seq_printf(s, "%s\n", priv->mfr_id);
> +
> +	return 0;
> +}
> +
> +DEFINE_SHOW_ATTRIBUTE(dps920ab_mfr_id);
> +
> +static int dps920ab_mfr_model_show(struct seq_file *s, void *data)
> +{
> +	struct dps920ab_data *priv = s->private;
> +
> +	seq_printf(s, "%s\n", priv->mfr_model);
> +
> +	return 0;
> +}
> +
> +DEFINE_SHOW_ATTRIBUTE(dps920ab_mfr_model);
> +
> +static void dps920ab_init_debugfs(struct dps920ab_data *data)
> +{
> +	struct dentry *root;
> +
> +	root = pmbus_get_debugfs_dir(data->client);
> +	if (!root)
> +		return;
> +
> +	data->debugfs_dir = debugfs_create_dir(data->client->name, root);

debugfs_dir is only used here. Please just use a local variable.

> +	if (!data->debugfs_dir)
> +		return;
> +
> +	debugfs_create_file("mfr_id",
> +			    0400,
> +			    data->debugfs_dir,
> +			    data,
> +			    &dps920ab_mfr_id_fops);
> +
> +	debugfs_create_file("mfr_model",
> +			    0400,
> +			    data->debugfs_dir,
> +			    data,
> +			    &dps920ab_mfr_model_fops);
> +}
> +
> +static int dps920ab_probe(struct i2c_client *client)
> +{
> +	u8 buf[I2C_SMBUS_BLOCK_MAX + 1];
> +	struct dps920ab_data *data;
> +	int ret;
> +
> +	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, buf);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "Failed to read Manufacturer ID\n");
> +		return ret;
> +	}
> +	if (ret != 5 || strncmp(buf, "DELTA", 5)) {
> +		buf[ret] = '\0';
> +		dev_err(&client->dev, "Unsupported Manufacturer ID '%s'\n", buf);
> +		return -ENODEV;
> +	}
> +	data->mfr_id = devm_kstrdup(&client->dev, buf, GFP_KERNEL);

There is no guarantee that the returned string is terminated.
For this to work, "buf[ret] = '\0';" needs to be ahead of the if
statement above.

> +	if (!data->mfr_id)
> +		return -ENOMEM;
> +
> +	ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, buf);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "Failed to read Manufacturer Model\n");
> +		return ret;
> +	}
> +	if (ret != 11 || strncmp(buf, "DPS-920AB", 9)) {
> +		buf[ret] = '\0';
> +		dev_err(&client->dev, "Unsupported Manufacturer Model '%s'\n", buf);
> +		return -ENODEV;
> +	}
> +	data->mfr_model = devm_kstrdup(&client->dev, buf, GFP_KERNEL);

Same as above.

> +	if (!data->mfr_model)
> +		return -ENOMEM;
> +
> +	ret = pmbus_do_probe(client, &dps920ab_info);
> +	if (ret)
> +		return ret;
> +
> +	data->client = client;

data->client is only used in dps920ab_init_debugfs(). Just pass 'client'
as additional argument to that function.

> +
> +	dps920ab_init_debugfs(data);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id __maybe_unused dps920ab_of_match[] = {
> +	{ .compatible = "delta,dps920ab", },
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(of, dps920ab_of_match);
> +
> +static struct i2c_driver dps920ab_driver = {
> +	.driver = {
> +		   .name = "dps920ab",
> +		   .of_match_table = of_match_ptr(dps920ab_of_match),
> +	},
> +	.probe_new = dps920ab_probe,
> +};
> +
> +module_i2c_driver(dps920ab_driver);
> +
> +MODULE_AUTHOR("Robert Marko <robert.marko@...tura.hr>");
> +MODULE_DESCRIPTION("PMBus driver for Delta DPS920AB PSU");
> +MODULE_LICENSE("GPL");
> -- 
> 2.31.1
> 

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