[PATCH v3 0/4] CAN TRANSCEIVER: Add support for CAN transceivers

[Aswath Govindraju <a-govindraju@ti.com>]

The following series of patches add support for CAN transceivers.

TCAN1042 has a standby signal that needs to be pulled high for
sending/receiving messages[1]. TCAN1043 has a enable signal along with
standby signal that needs to be pulled up for sending/receiving
messages[2], and other combinations of the two lines can be used to put the
transceiver in different states to reduce power consumption. On boards
like the AM654-idk and J721e-evm these signals are controlled using gpios.

Patch 1 rewords the comment that restricts max_link_rate attribute to have
units of Mbps.

Patch 2 adds an API for devm_of_phy_optional_get_by_index

Patch 3 models the transceiver as a phy device tree node with properties
for max bit rate supported, gpio properties for indicating gpio pin numbers
to which standby and enable signals are connected.

Patch 4 adds a generic driver to support CAN transceivers.

changes since v2:
- dropped 5 and 6 patches and to be sent via linux-can-next
- added static keyword for can_transceiver_phy_probe()
- changed enable gpio example to active high in patch 3
- Rearranged the file names in alphabetical order in Makefile
  and MAINTAINERS file

changes since v1:
- Added patch 1 (in v2) that rewords the comment that restrict
  max_link_rate attribute to have units of Mbps.
- Added patch 2 (in v2) that adds an API for
  devm_of_phy_optional_get_by_index
- Patch 1 (in v1)
  - updated MAINTAINERS file
- Patch 2 (in v1)
  - replaced m_can with CAN to make the driver independent of CAN driver
  - Added prefix CAN_TRANSCEIVER for EN_PRESENT and STB_PRESENT
  - Added new line before return statements in power_on() and power_off
  - Added error handling patch for devm_kzalloc()
  - used the max_link_rate attribute directly instead of dividing it by
    1000000
  - removed the spaces before GPIOD_OUT_LOW in devm_gpiod_get()
  - Corrected requested value for standby-gpios to GPIOD_OUT_HIGH
  - Updated MAINTAINERS file
- Patch 3 (in v1)
  - replaced minItems with maxItems
  - Removed phy-names property as there is only one phy
- Patch 4 (in v1)
  - replaced dev_warn with dev_info when no transceiver is found
  - Added struct phy * field in m_can_classdev struct
  - moved phy_power_on and phy_power_off to m_can_open and m_can_close
    respectively
  - Moved the check for max_bit_rate to generice transceiver driver

[1] - https://www.ti.com/lit/ds/symlink/tcan1042h.pdf
[2] - https://www.ti.com/lit/ds/symlink/tcan1043-q1.pdf

Aswath Govindraju (4):
  phy: core: Reword the comment specifying the units of max_link_rate to
    be Mbps
  phy: Add API for devm_of_phy_optional_get_by_index
  dt-bindings: phy: Add binding for TI TCAN104x CAN transceivers
  phy: phy-can-transceiver: Add support for generic CAN transceiver
    driver

 .../bindings/phy/ti,tcan104x-can.yaml         |  56 +++++++
 MAINTAINERS                                   |   2 +
 drivers/phy/Kconfig                           |   9 ++
 drivers/phy/Makefile                          |   1 +
 drivers/phy/phy-can-transceiver.c             | 146 ++++++++++++++++++
 drivers/phy/phy-core.c                        |  26 ++++
 include/linux/phy/phy.h                       |   4 +-
 7 files changed, 243 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/devicetree/bindings/phy/ti,tcan104x-can.yaml
 create mode 100644 drivers/phy/phy-can-transceiver.c

-- 
2.17.1