Serial: silabs si4455 serial driver

This is a serial port driver for
Silicon Labs Si4455 Sub-GHz transciver.

The goal of this driver is to removing wires
between central(linux) device and remote serial devices/sensors, but keeping the original user software.
It represents regular serial interface for the user space.

Datasheet: https://www.silabs.com/documents/public/data-sheets/Si4455.pdf

changes v1:
- fixed: drivers: serial: si4455: coding style
- fixed: drivers: serial: si4455: error checking and order
- fixed: drivers: serial: si4455: remove unnecessary compatibility strings from si4455_dt_ids
- fixed: dt-bindings: rename sdn-gpios to shutdown-gpios

changes v2:
- fixed: drivers: serial: si4455: coding style

changes v3:
- fixed: drivers: serial: si4455: coding style
- fixed: drivers: serial: si4455: replace device configuration procedure (SI4455_IOC_SEZC ioctl call) with request_firmware(...). The firmware name comes from dt (silabs,ez-config)
- fixed: drivers: serial: si4455: replace transmit/receive channel select (SI4455_IOC_STXC/SI4455_IOC_SRXC ioctl calls)
with sysfs entries (tx_channel, rx_channel).
Initial values comes from dt (silabs,tx-channel and silabs,rx-channel)
- fixed: drivers: serial: si4455: replace package size setting (SI4455_IOC_SSIZ ioctl call) with sysfs entry (package_size). Initial value comes from dt (silabs,package-size)
- fixed: drivers: serial: si4455: replace getting last rssi (SI4455_IOC_GRSSI ioctl call) with sysfs entry (current_rssi)
- fixed: drivers: serial: si4455: remove si4455_api.h
and custom ioctl definitions
- fixed: dt-bindings: silabs,si4455: more detailed description
- added: dt-bindings: silabs,si4455: properties silabs,package-size, silabs,tx-channel, silabs,rx-channel, silabs,ez-config

changes v4:
- fixed: dt-bindings: silabs,si4455: $id
from http://devicetree.org/schemas/serial/silabs,si4455.yaml
to http://devicetree.org/schemas/staging/serial/silabs,si4455.yaml

changes v5:
- fixed: drivers: serial: si4455: coding style
- fixed: drivers: serial: si4455: remove struct si4455_one, members moved to struct si4455_port
- fixed: drivers: serial: si4455: fix line endings in dev_err and dev_dbg messages
- fixed: drivers: serial: si4455: remove unnecessary else { ... }
- fixed: drivers: serial: si4455: refactor si4455_do_work(...), xmit circular buffer handling and start tx moved to si4455_start_tx_xmit(...)
- fixed: drivers: serial: si4455: refactor si4455_configure
- fixed: drivers: serial: si4455: refactor interrupt handling,

remove unnecessary wrapper
- fixed: drivers: serial: si4455: modem line(si4455_get_mctrl) and tx buffer status(si4455_tx_empty) conditions and signaling
- fixed: drivers: serial: si4455: remove unsafe int to pointer conversion
- fixed: dt-bindings: silabs,si4455: $id
from http://devicetree.org/schemas/staging/serial/silabs,si4455.yaml
to http://devicetree.org/schemas/serial/silabs,si4455.yaml
- fixed: dt-bindings: silabs,si4455: serial.yaml reference added

Signed-off-by József Horváth <[email protected]>

---
 .../bindings/serial/silabs,si4455.yaml        |   98 ++

 MAINTAINERS                                   |    6 +
 drivers/tty/serial/Kconfig                    |    8 +
 drivers/tty/serial/Makefile                   |    1 +
 drivers/tty/serial/si4455.c                   | 1372 +++++++++++++++++
 5 files changed, 1485 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/serial/silabs,si4455.yaml
 create mode 100644 drivers/tty/serial/si4455.c

Documentation/devicetree/bindings/serial/silabs,si4455.yaml new file +56 -0

new file mode 100644
index 000000000000..ddff67e6a667
@@ -0,0 +1,98 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/serial/silabs,si4455.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Silicon Labs Si4455 device tree bindings
+
+maintainers:
+  - József Horváth <[email protected]>
+
+description:
+  This document is for describing the required device tree parameters for si4455 serial driver.
+  The si4455 driver tries to represent the Silicon Labs Si4455 sub-GHz transceiver device
+  like a serial port. The required parameters for proper operation are described below.
+  https://www.silabs.com/documents/public/data-sheets/Si4455.pdf
+
+allOf:
+  - $ref: "serial.yaml#"
+
+properties:
+  compatible:
+    const: silabs,si4455
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  spi-max-frequency:
+    description: maximum clock frequency on SPI port
+    maximum: 500000
+
+  shutdown-gpios:
+    description: gpio pin for SDN
+    maxItems: 1
+
+  silabs,package-size:
+    description:
+      Radio payload length, variable packet length is not supported by driver.
+      This value should equal with EZConfig payload length.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 64
+    minimum: 1
+
+  silabs,tx-channel:
+    description:
+      Radio transmit channel selection.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 255
+    minimum: 0
+
+  silabs,rx-channel:
+    description:
+      Radio receive channel selection.

Documentation/devicetree/bindings/serial/silabs,si4455.yaml new file +32 -0

+
+required:
+  - reg
+  - interrupts
+  - spi-max-frequency
+  - shutdown-gpios
+  - silabs,package-size
+  - silabs,tx-channel
+  - silabs,rx-channel
+  - silabs,ez-config
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      si4455_0: serial@0 {
+        compatible = "silabs,si4455";
+        reg = <0>;
+        interrupt-parent = <&gpio>;
+        interrupts = <7 2>;
+        shutdown-gpios = <&gpio 26 1>;
+        spi-max-frequency = <300000>;
+        silabs,package-size = <30>;
+        silabs,tx-channel = <1>;
+        silabs,rx-channel = <2>;
+        silabs,ez-config = "si4455_spi0_0.ez.bin";
+      };
+    };
+...

Quoted 4 lines · József Horváth

This is a serial port driver for
Silicon Labs Si4455 Sub-GHz transciver.

- fixed: dt-bindings: silabs,si4455: serial.yaml reference added

The revision history should be after the '---' so it is not in the git history when applied.

Quoted 3 lines

Signed-off-by József Horváth <[email protected]>

---
 .../bindings/serial/silabs,si4455.yaml        |   98 ++

Please make the binding a separate patch.

Documentation/devicetree/bindings/serial/silabs,si4455.yaml line 66

Quoted 7 lines

 MAINTAINERS                                   |    6 +

Documentation/devicetree/bindings/serial/silabs,si4455.yaml new file +6 -0

+  silabs,ez-config:
+    description:
+      Radio configuration data file name.
+    $ref: /schemas/types.yaml#/definitions/string
+    items:
+      pattern: ^[0-9a-z\._\-]{1,255}$

We use 'firmware-name' property for this purpose.

Looks good otherwise.

Quoted 25 lines

Documentation/devicetree/bindings/serial/silabs,si4455.yaml new file +24 -0

+
+required:
+  - reg
+  - interrupts
+  - spi-max-frequency
+  - shutdown-gpios
+  - silabs,package-size
+  - silabs,tx-channel
+  - silabs,rx-channel
+  - silabs,ez-config
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      si4455_0: serial@0 {
+        compatible = "silabs,si4455";
+        reg = <0>;
+        interrupt-parent = <&gpio>;
+        interrupts = <7 2>;
+        shutdown-gpios = <&gpio 26 1>;

Documentation/devicetree/bindings/serial/silabs,si4455.yaml line 98

Quoted 8 lines

Documentation/devicetree/bindings/serial/silabs,si4455.yaml new file +8 -0

+        spi-max-frequency = <300000>;
+        silabs,package-size = <30>;
+        silabs,tx-channel = <1>;
+        silabs,rx-channel = <2>;
+        silabs,ez-config = "si4455_spi0_0.ez.bin";
+      };
+    };
+...