From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8EFFA382380; Sun, 30 Aug 2026 08:35:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788078945; cv=none; b=sk/RXfFv+1Gqys0id5E8Mlg22Lw8f1AWnJEJZs0VDWnJQEQTO+xqxOSnba256029FsrMyY/ly4f5m3gvqp4lhDEUB4ERvijVKTgaWHUdlq1nEharFLZeDfi+8vw/TE/ONN6pAU/v9Rw+pR6qR6vsbr+3Et/481CIbMoOPejRyiY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788078945; c=relaxed/simple; bh=4ImRa1XNESIUl/suhHZTEHPObbGsxkW/TyzIC8DOkeM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=YyxV/xhoNwJ6ARpp3K0x9aGarmLZjrV/FcsQPp4XkRwxpHa3JDkqC4VANdIftM0gyKnfcBquZLvbcC0m8gPWpSYfnUts6vC9sgtYuoXZiAqAgvqJMdrKrK8419a0ahRhqU/A54l1PMAKzrKhW7AgiBJXDZ6KiAMXZWZSxr3cvks= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bkHlSqYn; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bkHlSqYn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D784E1F000E9; Sun, 30 Aug 2026 08:35:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788078944; bh=hTFCf+/WK7bUzDOulou6SgSDwFha6MKK5QsGq8xUtuQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=bkHlSqYnZEO5cbaeV4uD7xXqe/YGRrKTPWZ92KWx2jJW+Db1PJe+haQKq1/8p38JM 3MFVg4xSUhR6ggeZYtFKjubYPXh0DyNv5J8xQvsp/P0miFhOOcmNsvPtCsUnm1WWvI xHXgU46KHW5kchkLGRutsumBdjd6z+FyUEMp9ibwmy4SY947uz9taLC9JN/gN0V9XR QyP9x0qMcpffL0DzL0W38+tmZWz6DX//yZpq0q19sgxr3t9R02U8Tjtssia8/AvPWy fiXL1qx7I0+ka/sfHxQWKF1G58jIT71cEH84tKDUOzOzQDArlXKoAcH/Z4pFzYTwZ3 95oeYQeoWPQFw== Message-ID: <417251d0-c2cc-4e10-940d-b75ab20acdec@kernel.org> Date: Sun, 30 Aug 2026 10:35:39 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/2] soc: starfive: Add JHB100 UART Routing driver To: Changhuang Liang , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org References: <20260830065118.51551-1-changhuang.liang@starfivetech.com> <20260830065118.51551-3-changhuang.liang@starfivetech.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 30/08/2026 08:51, Changhuang Liang wrote: > Add driver support for JHB100 UART Routing control, allowing runtime > configuration of RX muxes between UART controllers and I/O pins. > > A sysfs interface is provided for easy checking and updating of routing > paths. > > Signed-off-by: Changhuang Liang > --- > .../sysfs-driver-starfive-jhb100-uart-routing | 45 +++ > MAINTAINERS | 7 + > drivers/soc/starfive/Kconfig | 1 + > drivers/soc/starfive/Makefile | 1 + > drivers/soc/starfive/uart-routing/Kconfig | 14 + > drivers/soc/starfive/uart-routing/Makefile | 2 + > .../uart-routing/jhb100-uart-routing.c | 262 ++++++++++++++++++ > 7 files changed, 332 insertions(+) > create mode 100644 Documentation/ABI/testing/sysfs-driver-starfive-jhb100-uart-routing > create mode 100644 drivers/soc/starfive/uart-routing/Kconfig > create mode 100644 drivers/soc/starfive/uart-routing/Makefile > create mode 100644 drivers/soc/starfive/uart-routing/jhb100-uart-routing.c > > diff --git a/Documentation/ABI/testing/sysfs-driver-starfive-jhb100-uart-routing b/Documentation/ABI/testing/sysfs-driver-starfive-jhb100-uart-routing > new file mode 100644 > index 000000000000..2844133bea1b > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-driver-starfive-jhb100-uart-routing > @@ -0,0 +1,45 @@ > +What: /sys/bus/platform/drivers/starfive-jhb100-uart-routing/\*/uart\* > +Date: August 2026 > +Contact: Changhuang Liang > +Description: Selects the RX source of the UARTx device. > + > + When read, each file shows the list of available options with currently > + selected option marked by brackets "[]". The list of available options > + depends on the selected file. > + > + e.g. > + cat /sys/bus/platform/drivers/starfive-jhb100-uart-routing/\*.uart-routing/uart1 > + io0 [io1] io2 io3 io4 io5 io6 io7 io8 io9 io10 io11 io12 io13 io14 uart0 uart1 > + uart2 uart3 uart4 uart5 uart6 uart7 uart8 uart9 uart10 uart11 uart12 uart13 uart14 > + > + In this case, UART1 gets its input from IO1 (physical serial port 1). > + > + To switch the RX source of UART1 to UART2, write the desired source to the file: > + echo uart2 > /sys/bus/platform/drivers/starfive-jhb100-uart-routing/*.uart-routing/uart1 > + > + This indicates that UART1 now receives its input from UART2. > + > +Users: OpenBMC. Proposed changes should be mailed to > + openbmc@lists.ozlabs.org > + > +What: /sys/bus/platform/drivers/starfive-jhb100-uart-routing/\*/io\* > +Date: August 2026 > +Contact: Changhuang Liang > +Description: Selects the RX source of IOx serial port. The current selection > + will be marked by brackets "[]". The list of available options > + depends on the selected file. > + > + e.g. > + cat /sys/bus/platform/drivers/starfive-jhb100-uart-routing/\*.uart-routing/io9 > + uart0 uart1 uart2 uart3 uart4 uart5 uart6 uart7 uart8 [uart9] uart10 uart11 uart12 > + uart13 uart14 io0 io1 io2 io3 io4 io5 io6 io7 io8 io9 io10 io11 io12 io13 io14 > + > + In this case, IO9 (physical serial port 9) gets its input from UART9. > + > + To switch the RX source of IO9 to UART10, write the desired source to the file: > + echo uart10 > /sys/bus/platform/drivers/starfive-jhb100-uart-routing/*.uart-routing/io9 > + > + This indicates that IO9 now receives its input from UART10. > + > +Users: OpenBMC. Proposed changes should be mailed to > + openbmc@lists.ozlabs.org drivers/soc/ should not define user-space interfaces. This is not the place for them. You need to route user-spaces interfaces only through one of other approved subsystems, after their review. This looks like pin multiplexing interface. Best regards, Krzysztof