> -----Original Message----- > From: Guenter Roeck <groeck7@xxxxxxxxx> On Behalf Of Guenter Roeck > Sent: Friday, October 27, 2023 12:28 AM > To: Delphine_CC_Chiu/WYHQ/Wiwynn <Delphine_CC_Chiu@xxxxxxxxxx>; > patrick@xxxxxxxxx; Jean Delvare <jdelvare@xxxxxxxx>; Jonathan Corbet > <corbet@xxxxxxx> > Cc: Rob Herring <robh+dt@xxxxxxxxxx>; Krzysztof Kozlowski > <krzysztof.kozlowski+dt@xxxxxxxxxx>; Conor Dooley <conor+dt@xxxxxxxxxx>; > linux-i2c@xxxxxxxxxxxxxxx; linux-hwmon@xxxxxxxxxxxxxxx; > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linux-doc@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v2 2/2] hwmon: pmbus: Add ltc4286 driver > > Security Reminder: Please be aware that this email is sent by an external > sender. > > On 10/26/23 01:15, Delphine CC Chiu wrote: > > Add a driver to support ltc4286 chip > > > > Signed-off-by: Delphine CC Chiu <Delphine_CC_Chiu@xxxxxxxxxx> > > > > Changelog: > > v2 - Revise Linear Technologies LTC4286 to > > Analog Devices LTC4286 in Kconfig > > - Add more description for this driver in Kconfig > > - Add some comments for MBR setting in ltc4286.c > > - Add ltc4286.rst > > --- > > Documentation/hwmon/ltc4286.rst | 79 ++++++++++++++++ > > drivers/hwmon/pmbus/Kconfig | 9 ++ > > drivers/hwmon/pmbus/Makefile | 1 + > > drivers/hwmon/pmbus/ltc4286.c | 160 > ++++++++++++++++++++++++++++++++ > > 4 files changed, 249 insertions(+) > > create mode 100644 Documentation/hwmon/ltc4286.rst > > create mode 100644 drivers/hwmon/pmbus/ltc4286.c > > > > diff --git a/Documentation/hwmon/ltc4286.rst > > b/Documentation/hwmon/ltc4286.rst new file mode 100644 index > > 000000000000..9cae50b7478d > > --- /dev/null > > +++ b/Documentation/hwmon/ltc4286.rst > > @@ -0,0 +1,79 @@ > > +.. SPDX-License-Identifier: GPL-2.0-or-later > > + > > +Kernel driver ltc4286 > > +===================== > > + > > +Supported chips: > > + > > + * Analog Devices LTC4286 > > + > > + Prefix: 'ltc4286' > > + > > + Addresses scanned: - > > + > > + Datasheet: > > + https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fww > > + > w.analog.com%2Fmedia%2Fen%2Ftechnical-documentation%2Fdata-sheets%2 > F > > + > ltc4286.pdf&data=05%7C01%7CWayne_SC_Liu%40wiwynn.com%7Cb749e252b > fb84 > > + > 24531ac08dbd640774e%7Cda6e0628fc834caf9dd273061cbab167%7C0%7C0% > 7C638 > > + > 339344747629221%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiL > CJQIjoi > > + > V2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=7s > HwFye > > + so39ED13H3KaxosVOMJT1Kswhwj38arystWQ%3D&reserved=0 > > + > > + * Analog Devices LTC4287 > > + > > + Prefix: 'ltc4287' > > + > > + Addresses scanned: - > > + > > + Datasheet: > > + https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fww > > + > w.analog.com%2Fmedia%2Fen%2Ftechnical-documentation%2Fdata-sheets%2 > F > > + > ltc4287.pdf&data=05%7C01%7CWayne_SC_Liu%40wiwynn.com%7Cb749e252b > fb84 > > + > 24531ac08dbd640774e%7Cda6e0628fc834caf9dd273061cbab167%7C0%7C0% > 7C638 > > + > 339344747629221%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiL > CJQIjoi > > + > V2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=31 > 402MZ > > + 9ONvkV8BsRRPxmTZNMU1yj1u%2F3NFVEpThFPI%3D&reserved=0 > > + > > +Author: Delphine CC Chiu <Delphine_CC_Chiu@xxxxxxxxxx> > > + > > + > > +Description > > +----------- > > + > > +This driver supports hardware monitoring for Analog Devices LTC4286 > > +and LTC4287 Hot-Swap Controller and Digital Power Monitors. > > + > > +LTC4286 and LTC4287 are hot-swap controllers that allow a circuit > > +board to be removed from or inserted into a live backplane. They also > > +feature current and voltage readback via an integrated 12 bit > > +analog-to-digital converter (ADC), accessed using a PMBus interface. > > + > > +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. > > + > > +The shunt value in micro-ohms can be set via device tree at > > +compile-time. Please refer to the > > +Documentation/devicetree/bindings/hwmon/lltc,ltc4286.yaml for bindings > if the device tree is used. > > + > > + > > +Platform data support > > +--------------------- > > + > > +The driver supports standard PMBus driver platform data. Please see > > +Documentation/hwmon/pmbus.rst for details. > > + > > + > > +Sysfs entries > > +------------- > > + > > +The following attributes are supported. Limits are read-write, > > +history reset attributes are write-only, all other attributes are read-only. > > + > > +======================= > ======================================================= > > +inX_label "vin1" or "vout1" depending on chip variant and > > + configuration. > > Is that a cut-and-paste ? I don't see it handled in the driver, and I don't > immediately see it in the datasheet. From the datasheet, it seems to me that > both are always present. We will revise to the correct description > > > +inX_input Measured voltage. > > + > > +curr1_label "iout1" > > +curr1_input Measured current. > > + > > +power1_label "pin1" > > +power1_input Input power. > > + > > +temp1_input Chip temperature. > > +======================= > > +======================================================= > > diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig > > index b4e93bd5835e..f2b53e8abc3c 100644 > > --- a/drivers/hwmon/pmbus/Kconfig > > +++ b/drivers/hwmon/pmbus/Kconfig > > @@ -226,6 +226,15 @@ config SENSORS_LTC3815 > > > > This driver can also be built as a module. If so, the module will > > be called ltc3815. > > +config SENSORS_LTC4286 > > + bool "Analog Devices LTC4286" > > + help > > + LTC4286 is an integrated solution for hot swap applications that > > + allows a board to be safely inserted and removed from a live > > + backplane. > > + This chip could be used to monitor voltage, current, ...etc. > > + If you say yes here you get hardware monitoring support for Analog > > + Devices LTC4286. > > > > config SENSORS_MAX15301 > > tristate "Maxim MAX15301" > > diff --git a/drivers/hwmon/pmbus/Makefile > > b/drivers/hwmon/pmbus/Makefile index 84ee960a6c2d..94e28f6d6a61 > 100644 > > --- a/drivers/hwmon/pmbus/Makefile > > +++ b/drivers/hwmon/pmbus/Makefile > > @@ -24,6 +24,7 @@ obj-$(CONFIG_SENSORS_LM25066) += > lm25066.o > > obj-$(CONFIG_SENSORS_LT7182S) += lt7182s.o > > obj-$(CONFIG_SENSORS_LTC2978) += ltc2978.o > > obj-$(CONFIG_SENSORS_LTC3815) += ltc3815.o > > +obj-$(CONFIG_SENSORS_LTC4286) += ltc4286.o > > obj-$(CONFIG_SENSORS_MAX15301) += max15301.o > > obj-$(CONFIG_SENSORS_MAX16064) += max16064.o > > obj-$(CONFIG_SENSORS_MAX16601) += max16601.o > > diff --git a/drivers/hwmon/pmbus/ltc4286.c > > b/drivers/hwmon/pmbus/ltc4286.c new file mode 100644 index > > 000000000000..e1d72fe9587c > > --- /dev/null > > +++ b/drivers/hwmon/pmbus/ltc4286.c > > @@ -0,0 +1,160 @@ > > +// SPDX-License-Identifier: GPL-2.0-or-later > > + > > +#include <linux/err.h> > > +#include <linux/i2c.h> > > +#include <linux/init.h> > > +#include <linux/kernel.h> > > +#include <linux/module.h> > > +#include <linux/pmbus.h> > > +#include "pmbus.h" > > + > > +/* LTC4286 register */ > > +#define LTC4286_MFR_CONFIG1 0xF2 > > + > > +/* LTC4286 configuration */ > > +#define VRANGE_SELECT_BIT BIT(1) > > + > > +#define LTC4286_MFR_ID_SIZE 3 > > + > > +enum chips { ltc4286, ltc4287 }; > > + > > +/* > > + * Initialize the MBR as default settings which is referred to > > +LTC4286 datasheet > > + * (March 22, 2022 version) table 3 page 16 */ static struct > > +pmbus_driver_info ltc4286_info = { > > + .pages = 1, > > + .format[PSC_VOLTAGE_IN] = direct, > > + .format[PSC_VOLTAGE_OUT] = direct, > > + .format[PSC_CURRENT_OUT] = direct, > > + .format[PSC_POWER] = direct, > > + .format[PSC_TEMPERATURE] = direct, > > + .m[PSC_VOLTAGE_IN] = 32, > > + .b[PSC_VOLTAGE_IN] = 0, > > + .R[PSC_VOLTAGE_IN] = 1, > > + .m[PSC_VOLTAGE_OUT] = 32, > > + .b[PSC_VOLTAGE_OUT] = 0, > > + .R[PSC_VOLTAGE_OUT] = 1, > > + .m[PSC_CURRENT_OUT] = 1024, > > + .b[PSC_CURRENT_OUT] = 0, > > + /* > > + * The rsense value used in MBR formula in LTC4286 datasheet > should be ohm unit. > > + * However, the rsense value that user input is mirco ohm. > > + * Thus, the MBR setting which involves rsense should be shifted by 6 > digits. > > + */ > > + .R[PSC_CURRENT_OUT] = 3 - 6, > > + .m[PSC_POWER] = 1, > > + .b[PSC_POWER] = 0, > > + /* > > + * The rsense value used in MBR formula in LTC4286 datasheet > should be ohm unit. > > + * However, the rsense value that user input is mirco ohm. > > + * Thus, the MBR setting which involves rsense should be shifted by 6 > digits. > > + */ > > + .R[PSC_POWER] = 4 - 6, > > + .m[PSC_TEMPERATURE] = 1, > > + .b[PSC_TEMPERATURE] = 273, > > + .R[PSC_TEMPERATURE] = 0, > > + .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | > PMBUS_HAVE_IOUT | > > + PMBUS_HAVE_PIN | PMBUS_HAVE_TEMP | > PMBUS_HAVE_STATUS_VOUT | > > + PMBUS_HAVE_STATUS_IOUT | > PMBUS_HAVE_STATUS_TEMP, }; > > + > > The datasheet for LTC4286 (in the PMBus description talks about LSB 21.3 > mV/RSENSE > for IOUT_OC_WARN_LIMIT and 2.8/RSENSE for PIN_OP_WARN_LIMIT. This > contradicts > data elsewhere in the datasheet which uses above coefficients for both > LTC4286 > and LTC4287. I don't know if the datasheet is wrong, but this needs to be > clarified. > If the datasheet is wrong, that needs to be mentioned above. If the limit > registers > use different coefficients, local code will be needed to adjust values when > reading / > writing the registers to have it match coefficients. We have sent an e-mail about this question. > > > +static const struct i2c_device_id ltc4286_id[] = { { "ltc4286", ltc4286 }, > > + { "ltc4287", > ltc4287 }, > > + {} }; > > +MODULE_DEVICE_TABLE(i2c, ltc4286_id); > > + > > +static int ltc4286_probe(struct i2c_client *client) > > +{ > > + int ret; > > + const struct i2c_device_id *mid; > > + u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1]; > > + struct pmbus_driver_info *info; > > + u32 rsense; > > + > > + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, > block_buffer); > > + if (ret < 0) { > > + dev_err(&client->dev, "failed to read manufacturer id\n"); > > Why not use dev_err_probe() here ? We will use dev_err_probe() instead of dev_err() > > > + return ret; > > + } > > + > > + /* > > + * Refer to ltc4286 datasheet page 20 > > + * the manufacturer id is LTC > > + */ > > + if (ret != LTC4286_MFR_ID_SIZE || > > + strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) { > > + return dev_err_probe(&client->dev, ret, > > + "failed to read manufacturer > id\n"); > > This is misleading. It didn't _fail_ to read the manufacturer ID. We will revise to "Manufacturer id mismatch" > > > + } > > + > > + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, > block_buffer); > > + if (ret < 0) { > > + dev_err(&client->dev, "failed to read manufacturer > model\n"); > > Why not use dev_err_probe() here ? We will use dev_err_probe() instead of dev_err() > > > + return ret; > > + } > > + > > + for (mid = ltc4286_id; mid->name[0]; mid++) { > > + if (!strncasecmp(mid->name, block_buffer, > strlen(mid->name))) > > + break; > > + } > > This is pointless code. If the ID is not found, mid will point after > the end of the array, and then what ? > > The purpose of such code is to validate if the chip is actually the one > referenced in the match function and at least warn if that is not the case. > It should never accept a chip which is _known_ to not be supported. We will revise as below for (mid = ltc4286_id; mid->name[0]; mid++) { if (!strncasecmp(mid->name, block_buffer, strlen(mid->name))) break; } if (!mid->name[0]) return dev_err_probe(&client->dev, -ENODEV, "Unsupported device\n"); > > > + > > + ret = of_property_read_u32(client->dev.of_node, > > + "shunt-resistor-micro-ohms", > &rsense); > > + if (ret < 0) > > + return ret; > > + > > + if (rsense == 0) > > + return -EINVAL; > > + > > + info = <c4286_info; > > + > > + /* Default of VRANGE_SELECT = 1, 102.4V */ > > + if (device_property_read_bool(&client->dev, > "adi,vrange-select-25p6")) { > > What if the adi,vrange-select-25p6 property is not provided, but the chip > is programmed for this range ? The binding document tells programmers how to fill the dts. Thus, programmers must fill this property if their system is 25.6 volts voltage range. > > > + /* Setup MFR1 CONFIG register bit 1 VRANGE_SELECT */ > > + ret = i2c_smbus_read_word_data(client, > LTC4286_MFR_CONFIG1); > > + if (ret < 0) { > > + dev_err(&client->dev, > > + "failed to read manufacturer > configuration one\n"); > + return ret; > > + } > > + > > + ret &= ~VRANGE_SELECT_BIT; /* VRANGE_SELECT = 0, > 25.6V */ > > + ret = i2c_smbus_write_word_data(client, > LTC4286_MFR_CONFIG1, > > + ret); > > This should only be written if it actually changed. We will revise as below if ((ret & VRANGE_SELECT_BIT) != VRANGE_25P6) { ret &= ~VRANGE_SELECT_BIT; /* VRANGE_SELECT = 0, 25.6V */ ret = i2c_smbus_write_word_data( client, LTC4286_MFR_CONFIG1, ret); if (ret < 0) return dev_err_probe(&client->dev, ret, "Failed to set vrange\n"); } Moreover, we will check the behavior about this register with vendor. > > > + if (ret < 0) { > > + dev_err(&client->dev, "failed to set vrange\n"); > > + return ret; > > + } > > + > > + info->m[PSC_VOLTAGE_IN] = 128; > > + info->m[PSC_VOLTAGE_OUT] = 128; > > + info->m[PSC_POWER] = 4 * rsense; > > You can not overwrite ltc4286_info because there might be several chips > in the system with different sense resistor values and range > configurations. We will add below to replace the line info = <c4286_info; info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL); if (!info) return -ENOMEM; memcpy(info, <c4286_info, sizeof(*info)); > > Also, the above (and the calculation in the code below) will overflow > with too-large sense register values. We will add below to check if the 4*rsense overflow or not. if (info->m[PSC_POWER] > INT_MAX) return dev_err_probe(&client->dev, -ERANGE, "Power coefficient overflow\n"); > > > + } else > > + info->m[PSC_POWER] = rsense; > > Please run checkpatch --strict on your patches. We will run checkpatch --strict to check our patch. > > > + > > + info->m[PSC_CURRENT_OUT] = 1024 * rsense; > > Any rsense value larger than MAXINT / 1024 will overflow. if (info->m[PSC_CURRENT_OUT] > INT_MAX) return dev_err_probe(&client->dev, -ERANGE, "Current coefficient overflow\n"); > > > + > > + return pmbus_do_probe(client, info); > > +} > > + > > +static const struct of_device_id ltc4286_of_match[] = { > > + { .compatible = "lltc,ltc4286" }, > > + { .compatible = "lltc,ltc4287" }, > > + {} > > +}; > > + > > +static struct i2c_driver ltc4286_driver = { > > + .driver = { > > + .name = "ltc4286", > > + .of_match_table = ltc4286_of_match, > > + }, > > + .probe = ltc4286_probe, > > + .id_table = ltc4286_id, > > +}; > > + > > +module_i2c_driver(ltc4286_driver); > > + > > +MODULE_AUTHOR("Delphine CC Chiu > <Delphine_CC_Chiu@xxxxxxxxxx>"); > > +MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles"); > > +MODULE_LICENSE("GPL");
