From: Rob Herring <robherring2@gmail.com> To: Catalin Marinas <catalin.marinas@arm.com> Cc: "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Jiri Slaby <jslaby@suse.cz>, Russell King <linux@arm.linux.org.uk>, Will Deacon <Will.Deacon@arm.com>, "x86@kernel.org" <x86@kernel.org>, Arnd Bergmann <arnd@arndb.de> Subject: Re: [PATCH 6/8] tty/serial: pl011: add generic earlycon support Date: Wed, 16 Apr 2014 17:14:28 -0500 [thread overview] Message-ID: <CAL_Jsq+rQA8p9oYk-Urh_z6MTqCy0RNr=k0nz7r0OTuMCPUNWA@mail.gmail.com> (raw) In-Reply-To: <20140324112821.GE3850@arm.com> On Mon, Mar 24, 2014 at 6:28 AM, Catalin Marinas <catalin.marinas@arm.com> wrote: > On Fri, Mar 21, 2014 at 09:08:46PM +0000, Rob Herring wrote: >> From: Rob Herring <robh@kernel.org> >> >> Add earlycon support for the pl011 serial port. This allows enabling >> the pl011 for console when early_params are processed. This is based >> on the arm64 earlyprintk support and is intended to replace it. >> >> Signed-off-by: Rob Herring <robh@kernel.org> >> Cc: Russell King <linux@arm.linux.org.uk> >> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >> Cc: Jiri Slaby <jslaby@suse.cz> >> --- >> Documentation/kernel-parameters.txt | 5 +++-- >> drivers/tty/serial/amba-pl011.c | 30 +++++++++++++++++++++++++++++- >> 2 files changed, 32 insertions(+), 3 deletions(-) >> >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt >> index 5ce8b7a..81bdd52 100644 >> --- a/Documentation/kernel-parameters.txt >> +++ b/Documentation/kernel-parameters.txt >> @@ -887,8 +887,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. >> uart[8250],io,<addr>[,options] >> uart[8250],mmio,<addr>[,options] >> uart[8250],mmio32,<addr>[,options] >> - Start an early, polled-mode console on the 8250/16550 >> - UART at the specified I/O port or MMIO address. >> + pl011,<addr> >> + Start an early, polled-mode console on a serial port >> + at the specified I/O port or MMIO address. 8250 >> MMIO inter-register address stride is either 8-bit >> (mmio) or 32-bit (mmio32). >> The options are the same as for ttyS, above. > > I think the last line is a bit misleading. Or did you intend to leave it > with the uart[8250] parameter? See below: How about this (excuse the gmail lack of tabs): earlycon= [KNL] Output early console device and options. uart[8250],io,<addr>[,options] uart[8250],mmio,<addr>[,options] uart[8250],mmio32,<addr>[,options] Start an early, polled-mode console on an 8250 serial port at the specified I/O port or MMIO address. 8250 MMIO inter-register address stride is either 8-bit (mmio) or 32-bit (mmio32). The options are the same as for ttyS, above. pl011,<addr> Start an early, polled-mode console on a pl011 serial port at the specified address. The pl011 serial port must already be setup and configured. Options are not yet supported. smh Use ARM semihosting calls for early console. > >> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c >> index d4eda24..4227c0a 100644 >> --- a/drivers/tty/serial/amba-pl011.c >> +++ b/drivers/tty/serial/amba-pl011.c > [...] >> +static int __init pl011_early_console_setup(struct earlycon_device *device, >> + const char *opt) >> +{ >> + if (!device->port.membase) >> + return -ENODEV; >> + >> + device->con->write = pl011_early_write; >> + return 0; >> +} >> +EARLYCON_DECLARE(pl011, pl011_early_console_setup); > > Here we expect the PL011 to be already initialised by the boot loader > and the kernel continues using the same settings. So maybe clarify this > in the pl011 kernel parameter doc and we can add proper configuration > using a separate patch. Enabling and setup would not be too hard, but either baud rate will always have to be configured or we'll have to specify the input clock rate too. The 8250 driver basically does the former or assumes a fixed clock. Adding any setup will also break any non-pl011 based SBSA compliant uart since the configuration registers are not standardized. I guess we can add "sbsauart" when/if that happens. Rob
WARNING: multiple messages have this Message-ID (diff)
From: robherring2@gmail.com (Rob Herring) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 6/8] tty/serial: pl011: add generic earlycon support Date: Wed, 16 Apr 2014 17:14:28 -0500 [thread overview] Message-ID: <CAL_Jsq+rQA8p9oYk-Urh_z6MTqCy0RNr=k0nz7r0OTuMCPUNWA@mail.gmail.com> (raw) In-Reply-To: <20140324112821.GE3850@arm.com> On Mon, Mar 24, 2014 at 6:28 AM, Catalin Marinas <catalin.marinas@arm.com> wrote: > On Fri, Mar 21, 2014 at 09:08:46PM +0000, Rob Herring wrote: >> From: Rob Herring <robh@kernel.org> >> >> Add earlycon support for the pl011 serial port. This allows enabling >> the pl011 for console when early_params are processed. This is based >> on the arm64 earlyprintk support and is intended to replace it. >> >> Signed-off-by: Rob Herring <robh@kernel.org> >> Cc: Russell King <linux@arm.linux.org.uk> >> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >> Cc: Jiri Slaby <jslaby@suse.cz> >> --- >> Documentation/kernel-parameters.txt | 5 +++-- >> drivers/tty/serial/amba-pl011.c | 30 +++++++++++++++++++++++++++++- >> 2 files changed, 32 insertions(+), 3 deletions(-) >> >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt >> index 5ce8b7a..81bdd52 100644 >> --- a/Documentation/kernel-parameters.txt >> +++ b/Documentation/kernel-parameters.txt >> @@ -887,8 +887,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. >> uart[8250],io,<addr>[,options] >> uart[8250],mmio,<addr>[,options] >> uart[8250],mmio32,<addr>[,options] >> - Start an early, polled-mode console on the 8250/16550 >> - UART at the specified I/O port or MMIO address. >> + pl011,<addr> >> + Start an early, polled-mode console on a serial port >> + at the specified I/O port or MMIO address. 8250 >> MMIO inter-register address stride is either 8-bit >> (mmio) or 32-bit (mmio32). >> The options are the same as for ttyS, above. > > I think the last line is a bit misleading. Or did you intend to leave it > with the uart[8250] parameter? See below: How about this (excuse the gmail lack of tabs): earlycon= [KNL] Output early console device and options. uart[8250],io,<addr>[,options] uart[8250],mmio,<addr>[,options] uart[8250],mmio32,<addr>[,options] Start an early, polled-mode console on an 8250 serial port at the specified I/O port or MMIO address. 8250 MMIO inter-register address stride is either 8-bit (mmio) or 32-bit (mmio32). The options are the same as for ttyS, above. pl011,<addr> Start an early, polled-mode console on a pl011 serial port at the specified address. The pl011 serial port must already be setup and configured. Options are not yet supported. smh Use ARM semihosting calls for early console. > >> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c >> index d4eda24..4227c0a 100644 >> --- a/drivers/tty/serial/amba-pl011.c >> +++ b/drivers/tty/serial/amba-pl011.c > [...] >> +static int __init pl011_early_console_setup(struct earlycon_device *device, >> + const char *opt) >> +{ >> + if (!device->port.membase) >> + return -ENODEV; >> + >> + device->con->write = pl011_early_write; >> + return 0; >> +} >> +EARLYCON_DECLARE(pl011, pl011_early_console_setup); > > Here we expect the PL011 to be already initialised by the boot loader > and the kernel continues using the same settings. So maybe clarify this > in the pl011 kernel parameter doc and we can add proper configuration > using a separate patch. Enabling and setup would not be too hard, but either baud rate will always have to be configured or we'll have to specify the input clock rate too. The 8250 driver basically does the former or assumes a fixed clock. Adding any setup will also break any non-pl011 based SBSA compliant uart since the configuration registers are not standardized. I guess we can add "sbsauart" when/if that happens. Rob
next prev parent reply other threads:[~2014-04-16 22:14 UTC|newest] Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-03-21 21:08 [PATCH 0/8] Generic serial earlycon Rob Herring 2014-03-21 21:08 ` Rob Herring [not found] ` < 201403221054.39799.arnd@arndb.de> [not found] ` < CAL_JsqKjGjyYypwneCmNc1qeKe0ZOG9gz3QSJ37-HwHXKu3iRA@mail.gmail.com> [not found] ` < 20140329001732.BECE2C41FF4@trevor.secretlab.ca> 2014-03-21 21:08 ` [PATCH 1/8] x86: move FIX_EARLYCON_MEM kconfig into x86 Rob Herring 2014-03-21 21:08 ` Rob Herring 2014-03-21 21:08 ` Rob Herring 2014-03-21 21:08 ` [PATCH 2/8] arm64: add FIXMAP_PAGE_NOCACHE definition Rob Herring 2014-03-21 21:08 ` Rob Herring 2014-03-24 11:13 ` Catalin Marinas 2014-03-24 11:13 ` Catalin Marinas 2014-03-24 11:13 ` Catalin Marinas 2014-03-21 21:08 ` [PATCH 3/8] arm64: enable FIX_EARLYCON_MEM kconfig Rob Herring 2014-03-21 21:08 ` Rob Herring 2014-03-24 11:38 ` Catalin Marinas 2014-03-24 11:38 ` Catalin Marinas 2014-03-24 11:38 ` Catalin Marinas 2014-03-21 21:08 ` [PATCH 4/8] tty/serial: add generic serial earlycon Rob Herring 2014-03-21 21:08 ` Rob Herring 2014-03-24 11:22 ` Catalin Marinas 2014-03-24 11:22 ` Catalin Marinas 2014-03-24 11:22 ` Catalin Marinas 2014-03-24 11:29 ` Arnd Bergmann 2014-03-24 11:29 ` Arnd Bergmann 2014-03-24 13:36 ` Rob Herring 2014-03-24 13:36 ` Rob Herring 2014-03-24 13:36 ` Rob Herring 2014-03-24 15:42 ` Arnd Bergmann 2014-03-24 15:42 ` Arnd Bergmann 2014-03-24 15:42 ` Arnd Bergmann 2014-04-17 18:27 ` Rob Herring 2014-04-17 18:27 ` Rob Herring 2014-04-17 18:27 ` Rob Herring 2014-04-17 20:16 ` Alan Cox 2014-04-17 20:16 ` Alan Cox 2014-04-17 20:16 ` Alan Cox 2014-04-19 11:32 ` Arnd Bergmann 2014-04-19 11:32 ` Arnd Bergmann 2014-04-19 11:32 ` Arnd Bergmann 2014-03-21 21:08 ` [PATCH 5/8] tty/serial: convert 8250 to generic earlycon Rob Herring 2014-03-21 21:08 ` Rob Herring 2014-03-21 21:08 ` [PATCH 6/8] tty/serial: pl011: add generic earlycon support Rob Herring 2014-03-21 21:08 ` Rob Herring 2014-03-24 11:28 ` Catalin Marinas 2014-03-24 11:28 ` Catalin Marinas 2014-03-24 11:28 ` Catalin Marinas 2014-04-16 22:14 ` Rob Herring [this message] 2014-04-16 22:14 ` Rob Herring 2014-04-16 22:14 ` Rob Herring 2014-04-23 16:39 ` Catalin Marinas 2014-04-23 16:39 ` Catalin Marinas 2014-04-23 16:39 ` Catalin Marinas 2014-03-21 21:08 ` [PATCH 7/8] tty/serial: add arm64 semihosting earlycon Rob Herring 2014-03-21 21:08 ` Rob Herring 2014-03-23 20:04 ` Nicolas Pitre 2014-03-23 20:04 ` Nicolas Pitre 2014-03-23 20:23 ` Arnd Bergmann 2014-03-23 20:23 ` Arnd Bergmann 2014-03-23 21:48 ` Nicolas Pitre 2014-03-23 21:48 ` Nicolas Pitre 2014-03-24 11:38 ` Catalin Marinas 2014-03-24 11:38 ` Catalin Marinas 2014-03-24 11:38 ` Catalin Marinas 2014-03-24 11:48 ` Catalin Marinas 2014-03-24 11:48 ` Catalin Marinas 2014-03-24 11:48 ` Catalin Marinas 2014-03-21 21:08 ` [PATCH 8/8] arm64: remove arch specific earlyprintk Rob Herring 2014-03-21 21:08 ` Rob Herring 2014-03-22 9:54 ` [PATCH 0/8] Generic serial earlycon Arnd Bergmann 2014-03-22 9:54 ` Arnd Bergmann 2014-03-22 9:54 ` Arnd Bergmann 2014-03-22 14:14 ` Rob Herring 2014-03-22 14:14 ` Rob Herring 2014-03-22 14:14 ` Rob Herring 2014-03-22 22:01 ` Arnd Bergmann 2014-03-22 22:01 ` Arnd Bergmann 2014-03-22 22:01 ` Arnd Bergmann 2014-03-23 15:09 ` Rob Herring 2014-03-23 15:09 ` Rob Herring 2014-03-23 15:09 ` Rob Herring 2014-03-23 19:49 ` Arnd Bergmann 2014-03-23 19:49 ` Arnd Bergmann 2014-03-23 19:49 ` Arnd Bergmann 2014-03-29 0:17 ` Grant Likely 2014-03-29 0:17 ` Grant Likely 2014-03-29 0:17 ` Grant Likely 2014-03-29 14:33 ` Rob Herring 2014-03-29 14:33 ` Rob Herring 2014-03-29 14:33 ` Rob Herring 2014-03-29 15:34 ` Grant Likely 2014-03-29 15:34 ` Grant Likely 2014-03-29 15:34 ` Grant Likely
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