From 0666cb86355731ebf6bf429c6f7e06c7b8e11b35 Mon Sep 17 00:00:00 2001
From: Oliver Kleinecke <okleinecke@web.de>
Date: Thu, 2 Jul 2026 05:44:09 +0200
Subject: [PATCH] [usb_uart] Add per-device-type maximum baud rate cap (#17259)

---
 esphome/components/usb_uart/__init__.py | 70 ++++++++++++++++---------
 1 file changed, 45 insertions(+), 25 deletions(-)

diff --git a/esphome/components/usb_uart/__init__.py b/esphome/components/usb_uart/__init__.py
index e42a2c092bb..a921b6fbf05 100644
--- a/esphome/components/usb_uart/__init__.py
+++ b/esphome/components/usb_uart/__init__.py
@@ -46,42 +46,59 @@ DEFAULT_BAUD_RATE = 9600
 
 
 class Type:
-    def __init__(self, name, vid, pid, cls, max_channels=1, baud_rate_required=True):
+    def __init__(
+        self,
+        name,
+        vid,
+        pid,
+        cls,
+        max_channels=1,
+        baud_rate_required=True,
+        max_baud=1_000_000,
+    ):
         self.name = name
         cls = cls or name
         self.vid = vid
         self.pid = pid
         self.cls = usb_uart_ns.class_(f"USBUartType{cls}", USBUartComponent)
-        self.max_channels = max_channels
+        self._max_channels = max_channels
         self.baud_rate_required = baud_rate_required
+        self.max_baud = max_baud
+
+    @property
+    def max_channels(self) -> int:
+        return (
+            3
+            if (
+                CORE.is_esp32
+                and get_esp32_variant() != VARIANT_ESP32P4
+                and self._max_channels > 3
+            )
+            else self._max_channels
+        )
 
 
 uart_types = (
     Type("CDC_ACM", 0, 0, "CdcAcm", 1, baud_rate_required=False),
-    Type("CH34X", 0x1A86, 0x55D5, "CH34X", 4),
-    Type("CH340", 0x1A86, 0x7523, "CH34X", 1),
-    Type("CP210X", 0x10C4, 0xEA60, "CP210X", 3),
+    Type("CH34X", 0x1A86, 0x55D5, "CH34X", 4, max_baud=2_000_000),
+    Type("CH340", 0x1A86, 0x7523, "CH34X", 1, max_baud=2_000_000),
+    Type("CP210X", 0x10C4, 0xEA60, "CP210X", 3, max_baud=2_000_000),
     Type("ESP_JTAG", 0x303A, 0x1001, "CdcAcm", 1, baud_rate_required=False),
-    Type("FT232", 0x0403, 0x6001, "FT23XX", 1),
-    Type("FT2232", 0x0403, 0x6010, "FT23XX", 2),
-    Type("FT4232", 0x0403, 0x6011, "FT23XX", 4),
-    Type("PL2303", 0x067B, 0x2303, "PL2303", 1),
-    Type("PL2303GB", 0x067B, 0x23B3, "PL2303", 1),
-    Type("PL2303GC", 0x067B, 0x23A3, "PL2303", 1),
-    Type("PL2303GE", 0x067B, 0x23E3, "PL2303", 1),
-    Type("PL2303GL", 0x067B, 0x23D3, "PL2303", 1),
-    Type("PL2303GS", 0x067B, 0x23F3, "PL2303", 1),
-    Type("PL2303GT", 0x067B, 0x23C3, "PL2303", 1),
+    Type("FT232", 0x0403, 0x6001, "FT23XX", 1, max_baud=3_000_000),
+    Type("FT2232", 0x0403, 0x6010, "FT23XX", 2, max_baud=12_000_000),
+    Type("FT4232", 0x0403, 0x6011, "FT23XX", 4, max_baud=12_000_000),
+    Type("PL2303", 0x067B, 0x2303, "PL2303", 1, max_baud=6_000_000),
+    Type("PL2303GB", 0x067B, 0x23B3, "PL2303", 1, max_baud=6_000_000),
+    Type("PL2303GC", 0x067B, 0x23A3, "PL2303", 1, max_baud=6_000_000),
+    Type("PL2303GE", 0x067B, 0x23E3, "PL2303", 1, max_baud=6_000_000),
+    Type("PL2303GL", 0x067B, 0x23D3, "PL2303", 1, max_baud=6_000_000),
+    Type("PL2303GS", 0x067B, 0x23F3, "PL2303", 1, max_baud=6_000_000),
+    Type("PL2303GT", 0x067B, 0x23C3, "PL2303", 1, max_baud=6_000_000),
     Type("STM32_VCP", 0x0483, 0x5740, "CdcAcm", 1, baud_rate_required=False),
 )
 
 
-def channel_schema(channels, baud_rate_required):
-    # For now S3 is restricted to 3 channels since each needs 2 endpoints, plus the control endpoint, and
-    # there are only a total of 8 endpoints available.
-    # This will need updating when the 8 channel devices that multiplex over an endpoint are added.
-    if CORE.is_esp32 and get_esp32_variant() != VARIANT_ESP32P4 and channels > 3:
-        channels = 3
+def channel_schema(type_: "Type") -> cv.Schema:
     return cv.Schema(
         {
             cv.Required(CONF_CHANNELS): cv.All(
@@ -94,11 +111,11 @@ def channel_schema(channels, baud_rate_required):
                             ),
                             (
                                 cv.Required(CONF_BAUD_RATE)
-                                if baud_rate_required
+                                if type_.baud_rate_required
                                 else cv.Optional(
                                     CONF_BAUD_RATE, default=DEFAULT_BAUD_RATE
                                 )
-                            ): cv.int_range(min=300, max=1000000),
+                            ): cv.int_range(min=300, max=type_.max_baud),
                             cv.Optional(CONF_STOP_BITS, default="1"): cv.enum(
                                 UART_STOP_BITS_OPTIONS, upper=True
                             ),
@@ -117,7 +134,10 @@ def channel_schema(channels, baud_rate_required):
                         }
                     )
                 ),
-                cv.Length(max=channels),
+                cv.Length(
+                    max=type_.max_channels,
+                    msg=f"Device type {type_.name} supports a maximum of {type_.max_channels} channels",
+                ),
             )
         }
     )
@@ -127,7 +147,7 @@ CONFIG_SCHEMA = cv.ensure_list(
     cv.typed_schema(
         {
             it.name: usb_device_schema(it.cls, it.vid, it.pid).extend(
-                channel_schema(it.max_channels, it.baud_rate_required)
+                channel_schema(it)
             )
             for it in uart_types
         },