[PATCH v6 2/2] hwmon: pmbus: Add ltc4286 driver

From: Delphine CC Chiu
Date: Tue Nov 21 2023 - 00:08:32 EST

Add a driver to support ltc4286 chip

Signed-off-by: Delphine CC Chiu <Delphine_CC_Chiu@xxxxxxxxxx>
---
Changelog:
v6 - Check VRANGE_SELECT before driver loading
v5 - Check the overflow when reading rsense
- Set default rsense value
v4 - Add empty line before "config SENSORS_LTC4286" in Kconfig
- Add ltc4286 to Documentation/hwmon/index.rst
- Revise comment typo
- Use devm_kmemdup instead of memcpy
- Check MBR value before writting into
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/index.rst | 1 +
Documentation/hwmon/ltc4286.rst | 95 +++++++++++++++++
drivers/hwmon/pmbus/Kconfig | 10 ++
drivers/hwmon/pmbus/Makefile | 1 +
drivers/hwmon/pmbus/ltc4286.c | 183 ++++++++++++++++++++++++++++++++
5 files changed, 290 insertions(+)
create mode 100644 Documentation/hwmon/ltc4286.rst
create mode 100644 drivers/hwmon/pmbus/ltc4286.c

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 72f4e6065bae..080827cc4c34 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -128,6 +128,7 @@ Hardware Monitoring Kernel Drivers
ltc4245
ltc4260
ltc4261
+ ltc4286
max127
max15301
max16064
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 <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.
+
+======================= =======================================================
+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..2d4f972e5a65 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -227,6 +227,16 @@ 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"
help
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..e43e05579be1
--- /dev/null
+++ b/drivers/hwmon/pmbus/ltc4286.c
@@ -0,0 +1,183 @@
+// 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_102P4 1
+
+/*
+ * 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 micro 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 micro 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", 0 },
+ { "ltc4287", 1 },
+ {}
+};
+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");
+
+ if (of_property_read_u32(client->dev.of_node,
+ "shunt-resistor-micro-ohms", &rsense))
+ rsense = 300; /* 0.3 mOhm if not set via DT */
+
+ if (rsense == 0)
+ return -EINVAL;
+
+ /* Check for the latter MBR value won't overflow */
+ if (rsense > (INT_MAX / 1024))
+ return -EINVAL;
+
+ info = devm_kmemdup(&client->dev, &ltc4286_info, sizeof(*info),
+ GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+
+ /* Check MFR1 CONFIG register bit 1 VRANGE_SELECT before driver loading */
+ 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 (device_property_read_bool(&client->dev, "adi,vrange-low-enable")) {
+ /* The voltage range is 102.4 volts now */
+ if (ret == VRANGE_102P4) {
+ /* Set MFR1 CONFIG register bit 1 VRANGE_SELECT */
+ ret &= ~VRANGE_SELECT_BIT; /* VRANGE_SELECT = 0, 25.6 volts */
+ 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;
+ } else {
+ /* The voltage range is 25.6 volts now */
+ if (ret != VRANGE_102P4) {
+ /* Set MFR1 CONFIG register bit 1 VRANGE_SELECT */
+ ret |= VRANGE_SELECT_BIT; /* VRANGE_SELECT = 1, 102.4 volts */
+ 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_POWER] = rsense;
+ }
+
+ info->m[PSC_CURRENT_OUT] = 1024 * rsense;
+
+ 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");
--
2.25.1