Message-ID: <20250930133131.13797-1-victor.duicu@microchip.com>
Date: Tue, 30 Sep 2025 16:31:29 +0300
From: <victor.duicu@...rochip.com>
To: <jic23@...nel.org>, <dlechner@...libre.com>, <nuno.sa@...log.com>,
	<andy@...nel.org>, <robh@...nel.org>, <krzk+dt@...nel.org>,
	<conor+dt@...nel.org>
CC: <marius.cristea@...rochip.com>, <victor.duicu@...rochip.com>,
	<linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<devicetree@...r.kernel.org>
Subject: [PATCH v6 0/2] add support for MCP998X

From: Victor Duicu <victor.duicu@...rochip.com>

Add support for Microchip MCP998X/33 and MCP998XD/33D Multichannel
Automotive Temperature Monitor Family.

The chips in the family have different numbers of external channels,
ranging from 1 (MCP9982) to 4 channels (MCP9985). Reading diodes in
anti-parallel connection is supported by MCP9984/85/33 and
MCP9984D/85D/33D. Dedicated hardware shutdown circuitry is present
only in MCP998XD and MCP9933D.

This driver was submitted in the IIO subsystem because the chips could use
interrupts to handle threshold events. Each chip supports 3 user
programmable limits per channel. The family is also capable of detecting
hottest diode and diode faults.
These features will be added in future patches.

Differences related to previous patch:
v6:
- in yaml first condition list part numbers instead
  of regular expression. Add ^ to regular expression.
- edit coding style and comments.
- use hex values in defines.
- remove MCP9982_TEMP_MEM_BLOCK_LOW and
  MCP9982_TEMP_MEM_BLOCK_HIGH.
- in MCP9982_CHAN() place macro parameters in ().
- move all variable definitions at the start of functions.
- in mcp9982_parse_fw_config() initialise iio_idx to 0.
- remove bit flags.
- in MCP9982_CHAN remove outer ().
- remove variable start in mcp9982_write_raw().
- replace constant in .max_register.
- use get_unaligned_be16 in mcp9982_read_raw().

v5:
- in yaml edit description of interrupts.
- add min and maxItems to reg.
- remove ideality parameter.
- use pattern recognition in conditionals.
- group conditions based on the chip.
- correct microchip,parasitic-res-on-channel3-4 to true.
- in driver include bitops.h.
- change name of some variables.
- rename mcp9982_parse_of_config() to mcp9982_parse_fw_config().
- implement bulk reading of temp registers.
- lock ideality parameter to default value.
- implement bit flags.
- add compound literal to MCP9982_CHAN.
- remove hysteresis parameter.
- edit comments.
- change values from int to bool in mcp9982_features.
- remove mcp9982_calc_all_3db_values() and hardcode values.
  When filter is OFF the 3db value is equal to frequency.
- add .max_register to regmap_config.
- remove devm_kcalloc().
- in mcp9982_read_avail() add an else branch to hw_thermal_shutdown
  check.
- in mcp9982_read_raw use USEC_PER_MSEC and set regmap_read_poll_timeout
  to never timeout.
  Replace switch with bitmap_weight.
- in mcp9982_read_label() remove unnecessary if.
- in mcp9982_write_raw() remove duplicated code.
- in mcp9982_init add error messages when APDD and RECD are incorrectly
  set.
- in mcp9982_parse_fw_config() add default for reg_nr.

v4:
- lock beta parameters to default value of beta-autodetect.
  Remove beta parameters and checks from devicetree.
- lock temperature range to extended.
  This change avoids the issue of the average filter using raw values
  with different scales when changing the range.
- change driver to wait an amount of time before reading a raw value
  to ensure it is valid.
- change driver to stop calculating the physical temp when reading
  in_tempx_raw. Reading from in_tempx_raw will return the raw value.
  The physical temp will be calculated with in_tempx_raw, scale and
  offset parameters.
- add scale parameter to channel definition.
- initialise chips with "D" to work in Run state and those without
  in Standby state.
- when activating the low pass filter for chips without "D",
  set the power state to RUN to ensure fresh values for the average.
- add minimum and maximum to microchip,beta1 and microchip,beta2 in yaml.
- rename microchip,resistance-comp-ch1-2-enable and
  microchip,resistance-comp-ch3-4-enable to
  microchip,parasitic-res-on-channel1-2
  and microchip,parasitic-res-on-channel3-4
  and edit description in yaml.
- add conditional logic to check if the chip supports APDD
  and force default values where necessary in yaml.
- edit comments and coding style.
- replace asm/div64.h with linux/math64.h.
- add delay.h to includes.
- redefine mcp9982_sampl_fr with new structure division.
- in mcp9982_priv remove dev_name,extended_temp_range and beta_values.
  Add run_state, wait_before_read, time_limit and pointer to chip
  structure to remove all instances of matching strings.
  Reorder parameters for memory optimization.
- in mcp9982_features add flags to know if the chip has thermal shutdown
  circuitry and supports APDD.
- in mcp9982_read_avail() rework verification of chip type in sampling
  frequency case.
- in mcp9982_read_raw() rework switch in low pass filter case.
- in mcp9982_parse_of_config() replace generic -EINVAL code
  with -E2BIG and -EOVERFLOW. 

v3:
- move beta parameters to devicetree.
- change the name of the interrupts and add
  check to match them to the device in yaml.
- remove label for device and remove "0x" from
  channel registers in example in yaml.
- edit comments in yaml and driver.
- add minItems to interrupts in yaml.
- rename microchip,recd12 and microchip,recd34 to
  microchip,resistance-comp-ch1-2-enable
  and microchip,resistance-comp-ch3-4-enable.
- rename microchip,apdd-state to microchip,enable-anti-parallel.
- add static to mcp9982_3db_values_map_tbl to fix
  kernel test robot warning.
- in mcp9982_init() add check to ensure that hardware
  shutdown feature can't be overridden.
- replace div_u64_rem with do_div and add
  asm/div64.h to includes.
- remove unused includes.
- add iio_chan_spec in the macro definition of MCP9982_CHAN.
- remove MCP9982_EXT_BETA_ENBL.
- in mcp9982_init() replace regmap_assign_bits
  with regmap_write when setting beta compensation.
- remove custom attribute enable_extended_temp_range and
  map it to IIO_CHAN_INFO_OFFSET.
- add unsigned to int variables that allow it.
- reorder parameters in mcp9982_priv, change some
  from int to bool, add const to labels and add dev_name.
- add check for chips with "D" in the name to not
  allow sampling frequencies lower than 1 to
  prevent overriding of hardware shutdown.
- remove mcp9982_attributes.
- move mcp9982_calc_all_3db_values() to before
  mcp9982_init().
- use MICRO instead of number constant.
- in mcp9982_write_raw replace ">=" with "==".
- rename index2 to idx in mcp9982_read_raw().
- remove i2c_set_clientdata() in mcp9982_probe().
- since there are no more custom ABI attributes
  the testing file was removed.

v2:
- move hysteresis, extended temperature range and beta parameters
  from devicetree into user space.
- edit comments in yaml and driver.
- remove "|" in descpriptions, remove "+" from PatternProperties in yaml.
- add default to microchip,ideality-factor, delete blank lines and wrap to
  80 chars in yaml.
- remove variables with upper case.
- add check for microchip,apdd-state and microchip,recd34 in yaml.
- improve coding style in driver code.
- add includes for all functions used.
- rename MCP9982_INT_HIGH_BYTE_ADDR to MCP9982_INT_VALUE_ADDR and
  MCP9982_INT_LOW_BYTE_ADDR to MCP9982_FRAC_VALUE_ADDR.
- remove custom attribute running_average_window and
  running_average_window_available and map them to a low pass filter.
- update sysfs-bus-iio-temperature-mcp9982 to reflect current
  driver attributes and point to next kernel version (6.17).
- use compound literal to define driver channels.
- replace device_property_read_string() with i2c_get_match_data() to read
  chip name from devicetree.
- remove MCP9982_DEV_ATTR and mcp9982_prep_custom_attributes().
- remove client, chip_name, iio_info from mcp9982_priv.
- replace sprintf() with sysfs_emit().
- remove error messages which are triggered by keyboard input.
- replace devm_kzalloc() with devm_kcalloc(), array mcp9982_chip_config[]
  with individual structures, device_property_present() with
  device_property_read_bool().
- reordered parameters in mcp9982_features and mcp9982_priv to optimize
  memory allocation.
- remove .endianness from channel properties.
- change name of some parameters in mcp9982_priv.
- add check for reg value 0 from devicetree (channel 0 is for internal
  temperature and can't be disabled).

v1:
- initial version.

Victor Duicu (2):
  dt-bindings: iio: temperature: add support for MCP998X
  iio: temperature: add support for MCP998X

 .../iio/temperature/microchip,mcp9982.yaml    | 190 ++++
 MAINTAINERS                                   |   7 +
 drivers/iio/temperature/Kconfig               |  10 +
 drivers/iio/temperature/Makefile              |   1 +
 drivers/iio/temperature/mcp9982.c             | 862 ++++++++++++++++++
 5 files changed, 1070 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/temperature/microchip,mcp9982.yaml
 create mode 100644 drivers/iio/temperature/mcp9982.c


base-commit: 561285d048053fec8a3d6d1e3ddc60df11c393a0
-- 
2.48.1

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