v3 - Add LTC4286 and LTC4287 binding document
- Add LTC4286 and LTC4287 driver
Delphine CC Chiu (2):
dt-bindings: hwmon: Add lltc ltc4286 driver bindings
hwmon: pmbus: Add ltc4286 driver
.../bindings/hwmon/lltc,ltc4286.yaml | 52 +++++
Documentation/hwmon/ltc4286.rst | 95 ++++++++++
MAINTAINERS | 10 +
drivers/hwmon/pmbus/Kconfig | 9 +
drivers/hwmon/pmbus/Makefile | 1 +
drivers/hwmon/pmbus/ltc4286.c | 178 ++++++++++++++++++
6 files changed, 345 insertions(+)
create mode 100644 Documentation/devicetree/bindings/hwmon/lltc,ltc4286.yaml
create mode 100644 Documentation/hwmon/ltc4286.rst
create mode 100644 drivers/hwmon/pmbus/ltc4286.c
--
2.25.1
Add a driver to support ltc4286 chip
Signed-off-by: Delphine CC Chiu <[email protected]>
Changelog:
v3 - Use dev_err_probe() instead of dev_err()
- The VRANGE_SELECT bit only be written if it actually changed
- Avoid the info pointer being overwritten
- Check the MBR value range to avoid overflow
- Revise ltc4286.rst to corrcet description
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 | 95 +++++++++++++++++
drivers/hwmon/pmbus/Kconfig | 9 ++
drivers/hwmon/pmbus/Makefile | 1 +
drivers/hwmon/pmbus/ltc4286.c | 178 ++++++++++++++++++++++++++++++++
4 files changed, 283 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..2cd149676d86
--- /dev/null
+++ b/Documentation/hwmon/ltc4286.rst
@@ -0,0 +1,95 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver ltc4286
+=====================
+
+Supported chips:
+
+ * Analog Devices LTC4286
+
+ Prefix: 'ltc4286'
+
+ Addresses scanned: -
+
+ Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ltc4286.pdf
+
+ * Analog Devices LTC4287
+
+ Prefix: 'ltc4287'
+
+ Addresses scanned: -
+
+ Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ltc4287.pdf
+
+Author: Delphine CC Chiu <[email protected]>
+
+
+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.
+
+======================= =======================================================
+in1_label "vin"
+in1_input Measured voltage.
+in1_alarm Input voltage alarm.
+in1_min Minimum input voltage.
+in1_max Maximum input voltage.
+
+in2_label "vout1"
+in2_input Measured voltage.
+in2_alarm Output voltage alarm.
+in2_min Minimum output voltage.
+in2_max Maximum output voltage.
+
+curr1_label "iout1"
+curr1_input Measured current.
+curr1_alarm Output current alarm.
+curr1_max Maximum current.
+
+power1_label "pin"
+power1_input Input power.
+power1_alarm Input power alarm.
+power1_max Maximum poewr.
+
+temp1_input Chip temperature.
+temp1_min Minimum chip temperature.
+temp1_max Maximum chip temperature.
+temp1_crit Critical chip temperature.
+temp1_alarm Chip temperature alarm.
+======================= =======================================================
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..042d3af99489
--- /dev/null
+++ b/drivers/hwmon/pmbus/ltc4286.c
@@ -0,0 +1,178 @@
+// 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
+#define VRANGE_25P6 0
+
+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,
+};
+
+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) {
+ return dev_err_probe(&client->dev, ret,
+ "Failed to read manufacturer id\n");
+ }
+
+ /*
+ * 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,
+ "Manufacturer id mismatch\n");
+ }
+
+ ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
+ if (ret < 0) {
+ return dev_err_probe(&client->dev, ret,
+ "Failed to read manufacturer model\n");
+ }
+
+ 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 = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+ memcpy(info, <c4286_info, sizeof(*info));
+
+ /* Default of VRANGE_SELECT = 1, 102.4V */
+ if (device_property_read_bool(&client->dev, "adi,vrange-low-enable")) {
+ /* Setup MFR1 CONFIG register bit 1 VRANGE_SELECT */
+ ret = i2c_smbus_read_word_data(client, LTC4286_MFR_CONFIG1);
+ if (ret < 0) {
+ return dev_err_probe(
+ &client->dev, ret,
+ "Failed to read manufacturer configuration one\n");
+ }
+
+ 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");
+ }
+
+ info->m[PSC_VOLTAGE_IN] = 128;
+ info->m[PSC_VOLTAGE_OUT] = 128;
+ info->m[PSC_POWER] = 4 * rsense;
+ if (info->m[PSC_POWER] > INT_MAX)
+ return dev_err_probe(&client->dev, -ERANGE,
+ "Power coefficient overflow\n");
+ } else {
+ info->m[PSC_POWER] = rsense;
+ if (info->m[PSC_POWER] > INT_MAX)
+ return dev_err_probe(&client->dev, -ERANGE,
+ "Power coefficient overflow\n");
+ }
+
+ info->m[PSC_CURRENT_OUT] = 1024 * rsense;
+ 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 <[email protected]>");
+MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");
+MODULE_LICENSE("GPL");
--
2.25.1
On 10/31/23 00:21, Delphine CC Chiu wrote:
> Add a driver to support ltc4286 chip
>
> Signed-off-by: Delphine CC Chiu <[email protected]>
>
> Changelog:
> v3 - Use dev_err_probe() instead of dev_err()
> - The VRANGE_SELECT bit only be written if it actually changed
> - Avoid the info pointer being overwritten
> - Check the MBR value range to avoid overflow
> - Revise ltc4286.rst to corrcet description
> 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 | 95 +++++++++++++++++
Needs to be added to Documentation/hwmon/index.rst
> drivers/hwmon/pmbus/Kconfig | 9 ++
> drivers/hwmon/pmbus/Makefile | 1 +
> drivers/hwmon/pmbus/ltc4286.c | 178 ++++++++++++++++++++++++++++++++
> 4 files changed, 283 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..2cd149676d86
> --- /dev/null
> +++ b/Documentation/hwmon/ltc4286.rst
> @@ -0,0 +1,95 @@
> +.. SPDX-License-Identifier: GPL-2.0-or-later
> +
> +Kernel driver ltc4286
> +=====================
> +
> +Supported chips:
> +
> + * Analog Devices LTC4286
> +
> + Prefix: 'ltc4286'
> +
> + Addresses scanned: -
> +
> + Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ltc4286.pdf
> +
> + * Analog Devices LTC4287
> +
> + Prefix: 'ltc4287'
> +
> + Addresses scanned: -
> +
> + Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ltc4287.pdf
> +
> +Author: Delphine CC Chiu <[email protected]>
> +
> +
> +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.
> +
> +======================= =======================================================
> +in1_label "vin"
> +in1_input Measured voltage.
> +in1_alarm Input voltage alarm.
> +in1_min Minimum input voltage.
> +in1_max Maximum input voltage.
> +
> +in2_label "vout1"
> +in2_input Measured voltage.
> +in2_alarm Output voltage alarm.
> +in2_min Minimum output voltage.
> +in2_max Maximum output voltage.
> +
> +curr1_label "iout1"
> +curr1_input Measured current.
> +curr1_alarm Output current alarm.
> +curr1_max Maximum current.
> +
> +power1_label "pin"
> +power1_input Input power.
> +power1_alarm Input power alarm.
> +power1_max Maximum poewr.
> +
> +temp1_input Chip temperature.
> +temp1_min Minimum chip temperature.
> +temp1_max Maximum chip temperature.
> +temp1_crit Critical chip temperature.
> +temp1_alarm Chip temperature alarm.
> +======================= =======================================================
> 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.
Add empty line
> +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..042d3af99489
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/ltc4286.c
> @@ -0,0 +1,178 @@
> +// 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
> +#define VRANGE_25P6 0
> +
> +enum chips { ltc4286, ltc4287 };
Not really used anywhere and can be dropped.
> +
> +/*
> + * 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.
micro
> + * 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.
micro
> + * 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,
> +};
> +
> +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) {
> + return dev_err_probe(&client->dev, ret,
> + "Failed to read manufacturer id\n");
> + }
> +
> + /*
> + * 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,
> + "Manufacturer id mismatch\n");
> + }
> +
> + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);
> + if (ret < 0) {
> + return dev_err_probe(&client->dev, ret,
> + "Failed to read manufacturer model\n");
> + }
> +
> + 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 = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
> + if (!info)
> + return -ENOMEM;
> + memcpy(info, <c4286_info, sizeof(*info));
devm_kmemdup()
> +
> + /* Default of VRANGE_SELECT = 1, 102.4V */
> + if (device_property_read_bool(&client->dev, "adi,vrange-low-enable")) {
> + /* Setup MFR1 CONFIG register bit 1 VRANGE_SELECT */
> + ret = i2c_smbus_read_word_data(client, LTC4286_MFR_CONFIG1);
> + if (ret < 0) {
> + return dev_err_probe(
> + &client->dev, ret,
> + "Failed to read manufacturer configuration one\n");
> + }
> +
> + 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");
> + }
> +
> + info->m[PSC_VOLTAGE_IN] = 128;
> + info->m[PSC_VOLTAGE_OUT] = 128;
> + info->m[PSC_POWER] = 4 * rsense;
> + if (info->m[PSC_POWER] > INT_MAX)
This is too late. See below.
> + return dev_err_probe(&client->dev, -ERANGE,
> + "Power coefficient overflow\n");
> + } else {
> + info->m[PSC_POWER] = rsense;
> + if (info->m[PSC_POWER] > INT_MAX)
> + return dev_err_probe(&client->dev, -ERANGE,
> + "Power coefficient overflow\n");
This still needs to be written into the chip. There is no guarantee that
the chip is in its default configuration when the driver is loaded.
> + }
> +
> + info->m[PSC_CURRENT_OUT] = 1024 * rsense;
> + if (info->m[PSC_CURRENT_OUT] > INT_MAX)
This is too late. If rsense == INT_MAX, for example, 1024 * rsense
will be some negative number.
> + 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 <[email protected]>");
> +MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");
> +MODULE_LICENSE("GPL");
Add a device tree bindings for ltc4286 device.
Signed-off-by: Delphine CC Chiu <[email protected]>
Changelog:
v3 - Revise adi,vrange-select-25p6 to adi,vrange-low-enable
v2 - Revise vrange_select_25p6 to adi,vrange-select-25p6
- Add type for adi,vrange-select-25p6
- Revise rsense-micro-ohms to shunt-resistor-micro-ohms
---
.../bindings/hwmon/lltc,ltc4286.yaml | 52 +++++++++++++++++++
MAINTAINERS | 10 ++++
2 files changed, 62 insertions(+)
create mode 100644 Documentation/devicetree/bindings/hwmon/lltc,ltc4286.yaml
diff --git a/Documentation/devicetree/bindings/hwmon/lltc,ltc4286.yaml b/Documentation/devicetree/bindings/hwmon/lltc,ltc4286.yaml
new file mode 100644
index 000000000000..4695bca77c05
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/lltc,ltc4286.yaml
@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/lltc,ltc4286.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: LTC4286 power monitors
+
+maintainers:
+ - Delphine CC Chiu <[email protected]>
+
+properties:
+ compatible:
+ enum:
+ - lltc,ltc4286
+ - lltc,ltc4287
+
+ reg:
+ maxItems: 1
+
+ adi,vrange-low-enable:
+ description:
+ This property is a bool parameter to represent the
+ voltage range is 25.6 volts or 102.4 volts for
+ this chip.
+ The default is 102.4 volts.
+ type: boolean
+
+ shunt-resistor-micro-ohms:
+ description:
+ Resistor value in micro-Ohm
+
+required:
+ - compatible
+ - reg
+ - shunt-resistor-micro-ohms
+
+additionalProperties: false
+
+examples:
+ - |
+ i2c {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ power-sensor@40 {
+ compatible = "lltc,ltc4286";
+ reg = <0x40>;
+ adi,vrange-low-enable;
+ shunt-resistor-micro-ohms = <300>;
+ };
+ };
diff --git a/MAINTAINERS b/MAINTAINERS
index 55d9d860f1a7..c60e29dc04ad 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12489,6 +12489,16 @@ S: Maintained
F: Documentation/hwmon/ltc4261.rst
F: drivers/hwmon/ltc4261.c
+LTC4286 HARDWARE MONITOR DRIVER
+M: Delphine CC Chiu <[email protected]>
+L: [email protected]
+S: Maintained
+F: Documentation/devicetree/bindings/hwmon/lltc,ltc4286.yaml
+F: Documentation/devicetree/bindings/hwmon/ltc4286.rst
+F: drivers/hwmon/pmbus/Kconfig
+F: drivers/hwmon/pmbus/Makefile
+F: drivers/hwmon/pmbus/ltc4286.c
+
LTC4306 I2C MULTIPLEXER DRIVER
M: Michael Hennerich <[email protected]>
L: [email protected]
--
2.25.1
> -----Original Message-----
> From: Guenter Roeck <[email protected]> On Behalf Of Guenter Roeck
> Sent: Wednesday, November 1, 2023 2:10 AM
> To: Delphine_CC_Chiu/WYHQ/Wiwynn <[email protected]>;
> [email protected]; Jean Delvare <[email protected]>; Jonathan Corbet
> <[email protected]>
> Cc: Rob Herring <[email protected]>; Krzysztof Kozlowski
> <[email protected]>; Conor Dooley <[email protected]>;
> [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]
> Subject: Re: [PATCH v3 2/2] hwmon: pmbus: Add ltc4286 driver
>
> Security Reminder: Please be aware that this email is sent by an external
> sender.
>
> On 10/31/23 00:21, Delphine CC Chiu wrote:
> > Add a driver to support ltc4286 chip
> >
> > Signed-off-by: Delphine CC Chiu <[email protected]>
> >
> > Changelog:
> > v3 - Use dev_err_probe() instead of dev_err()
> > - The VRANGE_SELECT bit only be written if it actually changed
> > - Avoid the info pointer being overwritten
> > - Check the MBR value range to avoid overflow
> > - Revise ltc4286.rst to corrcet description
> > 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 | 95 +++++++++++++++++
>
> Needs to be added to Documentation/hwmon/index.rst
We will add to Documentation/hwmon/index.rst
>
> > drivers/hwmon/pmbus/Kconfig | 9 ++
> > drivers/hwmon/pmbus/Makefile | 1 +
> > drivers/hwmon/pmbus/ltc4286.c | 178
> ++++++++++++++++++++++++++++++++
> > 4 files changed, 283 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..2cd149676d86
> > --- /dev/null
> > +++ b/Documentation/hwmon/ltc4286.rst
> > @@ -0,0 +1,95 @@
> > +.. 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%7C19174887b
> 0924
> > +
> 20a374208dbda3c8d3b%7Cda6e0628fc834caf9dd273061cbab167%7C0%7C0%
> 7C638
> > +
> 343725997659187%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiL
> CJQIjoi
> > +
> V2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=0Vi
> JT74
> > + gySA7E0eBm%2FOBDkVAxp72j1spi8UG8un6zW4%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%7C19174887b
> 0924
> > +
> 20a374208dbda3c8d3b%7Cda6e0628fc834caf9dd273061cbab167%7C0%7C0%
> 7C638
> > +
> 343725997659187%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiL
> CJQIjoi
> > +
> V2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=ZW
> BSxI9
> > + ZgOgKMTU0UhQal9OiYjAUTPLXijAZqzN%2Fuh0%3D&reserved=0
> > +
> > +Author: Delphine CC Chiu <[email protected]>
> > +
> > +
> > +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.
> > +
> > +=======================
> =======================================================
> > +in1_label "vin"
> > +in1_input Measured voltage.
> > +in1_alarm Input voltage alarm.
> > +in1_min Minimum input voltage.
> > +in1_max Maximum input voltage.
> > +
> > +in2_label "vout1"
> > +in2_input Measured voltage.
> > +in2_alarm Output voltage alarm.
> > +in2_min Minimum output voltage.
> > +in2_max Maximum output voltage.
> > +
> > +curr1_label "iout1"
> > +curr1_input Measured current.
> > +curr1_alarm Output current alarm.
> > +curr1_max Maximum current.
> > +
> > +power1_label "pin"
> > +power1_input Input power.
> > +power1_alarm Input power alarm.
> > +power1_max Maximum poewr.
> > +
> > +temp1_input Chip temperature.
> > +temp1_min Minimum chip temperature.
> > +temp1_max Maximum chip temperature.
> > +temp1_crit Critical chip temperature.
> > +temp1_alarm Chip temperature alarm.
> > +=======================
> > +=======================================================
> > 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.
>
> Add empty line
We will add empty line here
>
> > +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..042d3af99489
> > --- /dev/null
> > +++ b/drivers/hwmon/pmbus/ltc4286.c
> > @@ -0,0 +1,178 @@
> > +// 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
> > +#define VRANGE_25P6 0
> > +
> > +enum chips { ltc4286, ltc4287 };
>
> Not really used anywhere and can be dropped.
We use this enum in v3 line 63-64
>
> > +
> > +/*
> > + * 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.
>
> micro
We will revise this typo
>
> > + * 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.
>
> micro
We will revise this typo
>
> > + * 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, };
> > +
> > +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) {
> > + return dev_err_probe(&client->dev, ret,
> > + "Failed to read manufacturer
> id\n");
> > + }
> > +
> > + /*
> > + * 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,
> > + "Manufacturer id mismatch\n");
> > + }
> > +
> > + ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL,
> block_buffer);
> > + if (ret < 0) {
> > + return dev_err_probe(&client->dev, ret,
> > + "Failed to read manufacturer
> model\n");
> > + }
> > +
> > + 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 = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
> > + if (!info)
> > + return -ENOMEM;
> > + memcpy(info, <c4286_info, sizeof(*info));
>
> devm_kmemdup()
We will revise as below
info = devm_kmemdup(&client->dev, <c4286_info, sizeof(*info), GFP_KERNEL);
if (!info)
return -ENOMEM;
>
> > +
> > + /* Default of VRANGE_SELECT = 1, 102.4V */
> > + if (device_property_read_bool(&client->dev, "adi,vrange-low-enable"))
> {
> > + /* Setup MFR1 CONFIG register bit 1 VRANGE_SELECT */
> > + ret = i2c_smbus_read_word_data(client,
> LTC4286_MFR_CONFIG1);
> > + if (ret < 0) {
> > + return dev_err_probe(
> > + &client->dev, ret,
> > + "Failed to read manufacturer
> configuration one\n");
> > + }
> > +
> > + 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");
> > + }
> > +
> > + info->m[PSC_VOLTAGE_IN] = 128;
> > + info->m[PSC_VOLTAGE_OUT] = 128;
> > + info->m[PSC_POWER] = 4 * rsense;
> > + if (info->m[PSC_POWER] > INT_MAX)
>
> This is too late. See below.
We will check sooner.
>
> > + return dev_err_probe(&client->dev, -ERANGE,
> > + "Power coefficient
> overflow\n");
> > + } else {
> > + info->m[PSC_POWER] = rsense;
> > + if (info->m[PSC_POWER] > INT_MAX)
> > + return dev_err_probe(&client->dev, -ERANGE,
> > + "Power coefficient
> > + overflow\n");
>
> This still needs to be written into the chip. There is no guarantee that the chip
> is in its default configuration when the driver is loaded.
We will check sooner.
>
> > + }
> > +
> > + info->m[PSC_CURRENT_OUT] = 1024 * rsense;
> > + if (info->m[PSC_CURRENT_OUT] > INT_MAX)
>
> This is too late. If rsense == INT_MAX, for example, 1024 * rsense will be some
> negative number.
We will check sooner.
>
> > + 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
> <[email protected]>");
> > +MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");
> > +MODULE_LICENSE("GPL");