[PATCH v6 0/4] serial: 8250_dw: Add support for UltraRISC DP1000 UART

[Jia Wang]

This patch series adds support for the UltraRISC DP1000 UART controller.

The series includes four patches. The first two are preparatory cleanups;
the last two add the DP1000 compatible and fixed CPR handling.

The patches have been tested on an UltraRISC DP1000 development board with
Linux v7.1-rc1, verifying basic UART functionality.

Signed-off-by: Jia Wang <wangjia at ultrarisc.com>
---
Changes in v6:
- Patch 2:
  * Simplify the FIFO size -> CPR FIFO_MODE helper.
- Patch 4:
  * Use the updated FIFO helper.
- Link to v5: https://patch.msgid.link/20260428-ultrarisc-serial-v5-0-97de63b1e3eb@ultrarisc.com

Changes in v5:
- Rebased onto Linux v7.1-rc1.
- Patch 1:
  * Reorder and document the moved DesignWare register/bit definitions.
- Patch 2:
  * Add a FIFO size -> CPR FIFO_MODE helper and use it for RZ/N1.
- Patch 4:
  * Use the FIFO_MODE helper for DP1000.
- Link to v4: https://patch.msgid.link/20260424-ultrarisc-serial-v4-0-1765a0b4c4a0@ultrarisc.com

Changes in v4:
- Added two preparatory patches before the original series, shifting patch
  numbers (former 1/2 -> now 3/4).
- Patch 1:
  * Move all DesignWare UART register/field definitions into 8250_dwlib.h
    for shared use with 8250_dw.
- Patch 2:
  * Converted the Renesas RZ/N1 CPR magic value to use DW_UART_CPR_* macros
    and FIELD_PREP_CONST().
- Patch 4:
  * Converted the UltraRISC DP1000 CPR magic value to use
    DW_UART_CPR_* macros and FIELD_PREP_CONST() (value unchanged).
- Link to v3: https://patch.msgid.link/20260421-ultrarisc-serial-v3-0-3d7f09c2420e@ultrarisc.com

Changes in v3:
- Rebased on Linux v7.0-rc7.
- Patch 1:
   * Removed separate `items` entry for DP1000, merging it into the
     existing `enum` to comply with the schema.
   * Updated commit message to describe DP1000 UART hardware differences.
- Patch 2:
   * Drop the custom quirk for missing CPR register.
   * Switch to using DW_UART_QUIRK_CPR_VALUE to provide a fixed CPR value.
- Link to v2: https://patch.msgid.link/20260316-ultrarisc-serial-v2-0-6ab3e7fa891c@ultrarisc.com

Changes in v2:
- Rebased on Linux v7.0-rc4 (previously on v7.0-rc2).
- Reordered patch series: DT binding patch comes before driver changes.
- Updated commit message for DT binding patch.
- Link to v1: https://patch.msgid.link/20260316-ultrarisc-serial-v1-0-c464f3e933a5@ultrarisc.com

---
Jia Wang (4):
      serial: 8250_dwlib: move DesignWare register definitions to header
      serial: 8250_dw: build Renesas RZN1 CPR value from DW_UART_CPR_* definitions
      dt-bindings: serial: snps-dw-apb-uart: Add UltraRISC DP1000 UART
      serial: 8250_dw: Use a fixed CPR value for UltraRISC DP1000 UART

 .../bindings/serial/snps-dw-apb-uart.yaml          |  1 +
 drivers/tty/serial/8250/8250_dw.c                  | 31 +++++----
 drivers/tty/serial/8250/8250_dwlib.c               | 49 ---------------
 drivers/tty/serial/8250/8250_dwlib.h               | 73 ++++++++++++++++++++++
 4 files changed, 93 insertions(+), 61 deletions(-)
---
base-commit: 3b3bea6d4b9c162f9e555905d96b8c1da67ecd5b
change-id: 20260309-ultrarisc-serial-64ff637edf26

Best regards,
--  
Jia Wang <wangjia at ultrarisc.com>