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Message-ID: <11d33d66-b59e-3153-9233-447213d93171@roeck-us.net>
Date: Wed, 7 Apr 2021 20:44:28 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Václav Kubernát <kubernat@...net.cz>
Cc: Jean Delvare <jdelvare@...e.com>, Jonathan Corbet <corbet@....net>,
linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] hwmon: Add driver for fsp-3y PSUs and PDUs
On 4/7/21 7:34 PM, Václav Kubernát wrote:
> This patch adds support for these devices:
> - YH-5151E - the PDU
> - YM-2151E - the PSU
>
> The device datasheet says that the devices support PMBus 1.2, but in my
> testing, a lot of the commands aren't supported and if they are, they
> sometimes behave strangely or inconsistently. For example, writes to the
> PAGE command requires using PEC, otherwise the write won't work and the
> page won't switch, even though, the standard says that PEC is opiotnal.
> On the other hand, writes the SMBALERT don't require PEC. Because of
> this, the driver is mostly reverse engineered with the help of a tool
> called pmbus_peek written by David Brownell (and later adopted by my
> colleague Jan Kundrát).
>
> The device also has some sort of a timing issue when switching pages,
> which is explained further in the code.
>
> Because of this, the driver support is limited. It exposes only the
> values, that have been tested to work correctly.
>
> Signed-off-by: Václav Kubernát <kubernat@...net.cz>
> ---
> Documentation/hwmon/fsp-3y.rst | 26 ++++
> drivers/hwmon/pmbus/Kconfig | 10 ++
> drivers/hwmon/pmbus/Makefile | 1 +
> drivers/hwmon/pmbus/fsp-3y.c | 217 +++++++++++++++++++++++++++++++++
> 4 files changed, 254 insertions(+)
> create mode 100644 Documentation/hwmon/fsp-3y.rst
> create mode 100644 drivers/hwmon/pmbus/fsp-3y.c
>
> diff --git a/Documentation/hwmon/fsp-3y.rst b/Documentation/hwmon/fsp-3y.rst
> new file mode 100644
> index 000000000000..68a547021846
> --- /dev/null
> +++ b/Documentation/hwmon/fsp-3y.rst
> @@ -0,0 +1,26 @@
> +Kernel driver fsp3y
> +======================
> +Supported devices:
> + * 3Y POWER YH-5151E
> + * 3Y POWER YM-2151E
> +
> +Author: Václav Kubernát <kubernat@...net.cz>
> +
> +Description
> +-----------
> +This driver implements limited support for two 3Y POWER devices.
> +
> +Sysfs entries
> +-------------
> +in1_input input voltage
> +in2_input 12V output voltage
> +in3_input 5V output voltage
> +curr1_input input current
> +curr2_input 12V output current
> +curr3_input 5V output current
> +fan1_input fan rpm
> +temp1_input temperature 1
> +temp2_input temperature 2
> +temp3_input temperature 3
> +power1_input input power
> +power2_input output power
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index 03606d4298a4..9d12d446396c 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -56,6 +56,16 @@ config SENSORS_BEL_PFE
> This driver can also be built as a module. If so, the module will
> be called bel-pfe.
>
> +config SENSORS_FSP_3Y
> + tristate "FSP/3Y-Power power supplies"
> + help
> + If you say yes here you get hardware monitoring support for
> + FSP/3Y-Power hot-swap power supplies.
> + Supported models: YH-5151E, YM-2151E
> +
> + This driver can also be built as a module. If so, the module will
> + be called fsp-3y.
> +
> config SENSORS_IBM_CFFPS
> tristate "IBM Common Form Factor Power Supply"
> depends on LEDS_CLASS
> diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
> index 6a4ba0fdc1db..bfe218ad898f 100644
> --- a/drivers/hwmon/pmbus/Makefile
> +++ b/drivers/hwmon/pmbus/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_SENSORS_PMBUS) += pmbus.o
> obj-$(CONFIG_SENSORS_ADM1266) += adm1266.o
> obj-$(CONFIG_SENSORS_ADM1275) += adm1275.o
> obj-$(CONFIG_SENSORS_BEL_PFE) += bel-pfe.o
> +obj-$(CONFIG_SENSORS_FSP_3Y) += fsp-3y.o
> obj-$(CONFIG_SENSORS_IBM_CFFPS) += ibm-cffps.o
> obj-$(CONFIG_SENSORS_INSPUR_IPSPS) += inspur-ipsps.o
> obj-$(CONFIG_SENSORS_IR35221) += ir35221.o
> diff --git a/drivers/hwmon/pmbus/fsp-3y.c b/drivers/hwmon/pmbus/fsp-3y.c
> new file mode 100644
> index 000000000000..2c165e034fa8
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/fsp-3y.c
> @@ -0,0 +1,217 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Hardware monitoring driver for FSP 3Y-Power PSUs
> + *
> + * Copyright (c) 2021 Václav Kubernát, CESNET
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include "pmbus.h"
> +
> +#define YM2151_PAGE_12V_LOG 0x00
> +#define YM2151_PAGE_12V_REAL 0x00
> +#define YM2151_PAGE_5VSB_LOG 0x01
> +#define YM2151_PAGE_5VSB_REAL 0x20
> +#define YH5151E_PAGE_12V_LOG 0x00
> +#define YH5151E_PAGE_12V_REAL 0x00
> +#define YH5151E_PAGE_5V_LOG 0x01
> +#define YH5151E_PAGE_5V_REAL 0x10
> +#define YH5151E_PAGE_3V3_LOG 0x02
> +#define YH5151E_PAGE_3V3_REAL 0x11
> +
> +enum chips {
> + ym2151e,
> + yh5151e
> +};
> +
> +struct fsp3y_data {
> + struct pmbus_driver_info info;
> + enum chips chip;
> + int page;
> +};
> +
> +#define to_fsp3y_data(x) container_of(x, struct fsp3y_data, info)
> +
> +static int page_log_to_page_real(int page_log, enum chips chip)
> +{
> + switch (chip) {
> + case ym2151e:
> + switch (page_log) {
> + case YM2151_PAGE_12V_LOG:
> + return YM2151_PAGE_12V_REAL;
> + case YM2151_PAGE_5VSB_LOG:
> + return YM2151_PAGE_5VSB_REAL;
> + }
> + return -1;
> + case yh5151e:
> + switch (page_log) {
> + case YH5151E_PAGE_12V_LOG:
> + return YH5151E_PAGE_12V_REAL;
> + case YH5151E_PAGE_5V_LOG:
> + return YH5151E_PAGE_5V_LOG;
> + case YH5151E_PAGE_3V3_LOG:
> + return YH5151E_PAGE_3V3_REAL;
> + }
> + return -1;
> + }
> +
> + return -1;
> +}
> +
> +static int set_page(struct i2c_client *client, int page_log)
> +{
> + const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
> + struct fsp3y_data *data = to_fsp3y_data(info);
> + int rv;
> + int page_real = page_log_to_page_real(page_log, data->chip);
> +
> + if (page_log < 0)
> + return 0;
> +
I am quite sure this should be
if (page_real < 0)
return 0;
I would suggest to return an error code, though; if page_log_to_page_real()
indeed returns an error, the selected page is wrong, and the reported data
would be pretty much random. That should not really happen, but since you check
for the error code here you might as well do it right. Best would be to have
page_log_to_page_real() return, say, -EINVAL on error and implement the check
as follows.
if (page_real < 0)
return page_real;
> + if (data->page != page_real) {
> + rv = pmbus_set_page(client, page_real, 0xff);
> + if (rv < 0)
> + return rv;
> +
> + data->page = page_real;
> +
> + /* Testing showed that the device has a timing issue. After
> + * setting a page, it takes a while, before the device actually
> + * gives the correct values from the correct page. 20 ms was
> + * tested to be enough to not give wrong values (15 ms wasn't
> + * enough)
> + */
> + usleep_range(20000, 30000);
> + }
> +
> + return 0;
> +}
> +
> +static int fsp3y_read_byte_data(struct i2c_client *client, int page, int reg)
> +{
> + int rv;
> +
> + rv = set_page(client, page);
> + if (rv < 0)
> + return rv;
> +
> + return i2c_smbus_read_byte_data(client, reg);
> +}
> +
> +static int fsp3y_read_word_data(struct i2c_client *client, int page, int phase, int reg)
> +{
> + int rv;
> +
> + switch (reg) {
> + case PMBUS_READ_FAN_SPEED_1:
> + case PMBUS_READ_IIN:
> + case PMBUS_READ_IOUT:
> + case PMBUS_READ_PIN:
> + case PMBUS_READ_POUT:
> + case PMBUS_READ_TEMPERATURE_1:
> + case PMBUS_READ_TEMPERATURE_2:
> + case PMBUS_READ_TEMPERATURE_3:
> + case PMBUS_READ_VIN:
> + case PMBUS_READ_VOUT:
> + case PMBUS_STATUS_WORD:
> + break;
> + default:
> + return -ENXIO;
> + }
> +
> + rv = set_page(client, page);
> + if (rv < 0)
> + return rv;
> +
> + return i2c_smbus_read_word_data(client, reg);
> +}
> +
> +struct pmbus_driver_info fsp3y_info[] = {
> + [ym2151e] = {
> + .pages = 2,
> + .func[YM2151_PAGE_12V_LOG] =
> + PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
> + PMBUS_HAVE_PIN | PMBUS_HAVE_POUT |
> + PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2 |
> + PMBUS_HAVE_VIN | PMBUS_HAVE_IIN |
> + PMBUS_HAVE_FAN12,
> + .func[YM2151_PAGE_5VSB_LOG] =
> + PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT,
> + PMBUS_HAVE_IIN,
> + .read_word_data = fsp3y_read_word_data,
> + .read_byte_data = fsp3y_read_byte_data,
> + },
> + [yh5151e] = {
> + .pages = 3,
> + .func[YH5151E_PAGE_12V_LOG] =
> + PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
> + PMBUS_HAVE_POUT |
> + PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_TEMP3,
> + .func[YH5151E_PAGE_5V_LOG] =
> + PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
> + PMBUS_HAVE_POUT,
> + .func[YH5151E_PAGE_3V3_LOG] =
> + PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
> + PMBUS_HAVE_POUT,
> + .read_word_data = fsp3y_read_word_data,
> + .read_byte_data = fsp3y_read_byte_data,
> + }
> +};
> +
> +static int fsp3y_probe(struct i2c_client *client)
> +{
> + struct fsp3y_data *data;
> + int rv;
> + u8 buf[I2C_SMBUS_BLOCK_MAX];
> +
> + data = devm_kzalloc(&client->dev, sizeof(struct fsp3y_data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + rv = i2c_smbus_read_byte_data(client, PMBUS_PAGE);
> + if (rv < 0)
> + return rv;
> + data->page = rv;
> +
> + rv = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, buf);
> + if (rv < 0)
> + return rv;
> + if (rv != 8)
> + return -ENODEV;
> +
> + if (!strncmp(buf, "YM-2151E", strlen("YM-2151E")))
> + data->chip = ym2151e;
> + else if (!strncmp(buf, "YH-5151E", strlen("YH-5151E")))
> + data->chip = yh5151e;
> + else
> + return -ENODEV;
> +
> + data->info = fsp3y_info[data->chip];
> +
> + return pmbus_do_probe(client, &data->info);
> +}
> +
> +static const struct i2c_device_id pmbus_id[] = {
> + {"fsp3y", 0},
Normally you would have something like
{"ym2151e", ym2151e},
{"yh5151e", yh5151e},
to match specific supplies. The probe function should then warn
if there is a mismatch. See other pmbus drivers for examples.
Guenter
> + {}
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, pmbus_id);
> +
> +/* This is the driver that will be inserted */
> +static struct i2c_driver fsp3y_driver = {
> + .driver = {
> + .name = "fsp3y",
> + },
> + .probe_new = fsp3y_probe,
> + .id_table = pmbus_id
> +};
> +
> +module_i2c_driver(fsp3y_driver);
> +
> +MODULE_AUTHOR("Václav Kubernát");
> +MODULE_DESCRIPTION("PMBus driver for FSP/3Y-Power power supplies");
> +MODULE_LICENSE("GPL");
>
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