kernel/linux.git/include/linux/serial_8250.h, branch v6.1.168

Revert "8250: add support for ASIX devices with a FIFO bug"

2023-07-23T11:49:43+00:00

commit a82d62f708545d22859584e0e0620da8e3759bbc upstream. This reverts commit eb26dfe8aa7eeb5a5aa0b7574550125f8aa4c3b3. Commit eb26dfe8aa7e ("8250: add support for ASIX devices with a FIFO bug") merged on Jul 13, 2012 adds a quirk for PCI_VENDOR_ID_ASIX (0x9710). But that ID is the same as PCI_VENDOR_ID_NETMOS defined in 1f8b061050c7 ("[PATCH] Netmos parallel/serial/combo support") merged on Mar 28, 2005. In pci_serial_quirks array, the NetMos entry always takes precedence over the ASIX entry even since it was initially merged, code in that commit is always unreachable. In my tests, adding the FIFO workaround to pci_netmos_init() makes no difference, and the vendor driver also does not have such workaround. Given that the code was never used for over a decade, it's safe to revert it. Also, the real PCI_VENDOR_ID_ASIX should be 0x125b, which is used on their newer AX99100 PCIe serial controllers released on 2016. The FIFO workaround should not be intended for these newer controllers, and it was never implemented in vendor driver. Fixes: eb26dfe8aa7e ("8250: add support for ASIX devices with a FIFO bug") Cc: stable Signed-off-by: Jiaqing Zhao Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20230619155743.827859-1-jiaqing.zhao@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: 8250: Toggle IER bits on only after irq has been set up

2022-09-22T14:30:14+00:00

Invoking TIOCVHANGUP on 8250_mid port on Ice Lake-D and then reopening the port triggers these faults during serial8250_do_startup(): DMAR: DRHD: handling fault status reg 3 DMAR: [DMA Write NO_PASID] Request device [00:1a.0] fault addr 0x0 [fault reason 0x05] PTE Write access is not set If the IRQ hasn't been set up yet, the UART will have zeroes in its MSI address/data registers. Disabling the IRQ at the interrupt controller won't stop the UART from performing a DMA write to the address programmed in its MSI address register (zero) when it wants to signal an interrupt. The UARTs (in Ice Lake-D) implement PCI 2.1 style MSI without masking capability, so there is no way to mask the interrupt at the source PCI function level, except disabling the MSI capability entirely, but that would cause it to fall back to INTx# assertion, and the PCI specification prohibits disabling the MSI capability as a way to mask a function's interrupt service request. The MSI address register is zeroed by the hangup as the irq is freed. The interrupt is signalled during serial8250_do_startup() performing a THRE test that temporarily toggles THRI in IER. The THRE test currently occurs before UART's irq (and MSI address) is properly set up. Refactor serial8250_do_startup() such that irq is set up before the THRE test. The current irq setup code is intermixed with the timer setup code. As THRE test must be performed prior to the timer setup, extract it into own function and call it only after the THRE test. The ->setup_timer() needs to be part of the struct uart_8250_ops in order to not create circular dependency between 8250 and 8250_base modules. Fixes: 40b36daad0ac ("[PATCH] 8250 UART backup timer") Reported-by: Lennert Buytenhek Tested-by: Lennert Buytenhek Reviewed-by: Andy Shevchenko Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220922070005.2965-1-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: Make ->set_termios() old ktermios const

2022-08-30T12:22:35+00:00

There should be no reason to adjust old ktermios which is going to get discarded anyway. Reviewed-by: Andy Shevchenko Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220816115739.10928-7-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: 8250: create lsr_save_mask

2022-06-27T12:44:20+00:00

Allow drivers to alter LSR save mask. Reviewed-by: Andy Shevchenko Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220624204210.11112-3-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: 8250: make saved LSR larger

2022-06-27T12:44:20+00:00

DW flags address received as BIT(8) in LSR. In order to not lose that on read, enlarge lsr_saved_flags to u16. Adjust lsr/status variables and related call chains to use u16. Technically, some of these type conversion would not be needed but it doesn't hurt to be consistent. Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220624204210.11112-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: 8250: Move Alpha-specific quirk out of the core

2021-12-30T12:23:44+00:00

struct uart_8250_port contains mcr_mask and mcr_force members whose sole purpose is to work around an Alpha-specific quirk. This code doesn't belong in the core where it is executed by everyone else, so move it to a proper ->set_mctrl callback which is used on the affected Alpha machine only. The quirk was introduced in January 1995: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/diff/drivers/char/serial.c?h=1.1.83 The members in struct uart_8250_port were added in 2002: https://git.kernel.org/history/history/c/4524aad27854 The quirk applies to non-PCI Alphas and arch/alpha/Kconfig specifies "select FORCE_PCI if !ALPHA_JENSEN". So apparently the only affected machine is the EISA-based Jensen that Linus was working on back then: https://lore.kernel.org/all/CAHk-=wj1JWZ3sCrGz16nxEj7=0O+srMg6Ah3iPTDXSPKEws_SA@mail.gmail.com/ Up until now the quirk is not applied unless CONFIG_PCI is disabled. If users forget to do that or run a generic Alpha kernel, the serial ports aren't usable on Jensen. Avoid by confining the quirk to CONFIG_ALPHA_JENSEN instead of !CONFIG_PCI. On generic Alpha kernels, auto-detect at runtime whether the quirk needs to be applied. Cc: Russell King Cc: Ulrich Teichert Cc: Linus Torvalds Signed-off-by: Lukas Wunner Link: https://lore.kernel.org/r/b83d069cb516549b8a5420e097bb6bdd806f36fc.1640695609.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman

tty/serial: make port of serial8250_register_8250_port const

2021-05-20T14:59:14+00:00

After the previous patch, we can make port passed to serial8250_find_match_or_unused const. And then we can make const also port of serial8250_register_8250_port. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20210519072153.3859-2-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: serial: 8250: 8250_port: Move prototypes to shared location

2020-11-13T14:28:12+00:00

Fixes the following W=1 kernel build warning(s): drivers/tty/serial/8250/8250_port.c:349:14: warning: no previous prototype for ‘au_serial_in’ [-Wmissing-prototypes] drivers/tty/serial/8250/8250_port.c:359:6: warning: no previous prototype for ‘au_serial_out’ [-Wmissing-prototypes] Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: Mike Hudson Cc: linux-serial@vger.kernel.org Signed-off-by: Lee Jones Link: https://lore.kernel.org/r/20201112105857.2078977-3-lee.jones@linaro.org Signed-off-by: Greg Kroah-Hartman

serial: 8250: Add 8250 port clock update method

2020-07-29T15:14:38+00:00

Some platforms can be designed in a way so the UART port reference clock might be asynchronously changed at some point. In Baikal-T1 SoC this may happen due to the reference clock being shared between two UART ports, on the Allwinner SoC the reference clock is derived from the CPU clock, so any CPU frequency change should get to be known/reflected by/in the UART controller as well. But it's not enough to just update the uart_port->uartclk field of the corresponding UART port, the 8250 controller reference clock divisor should be altered so to preserve current baud rate setting. All of these things is done in a coherent way by calling the serial8250_update_uartclk() method provided in this patch. Though note that it isn't supposed to be called from within the UART port callbacks because the locks using to the protect the UART port data are already taken in there. Signed-off-by: Serge Semin Link: https://lore.kernel.org/r/20200723003357.26897-2-Sergey.Semin@baikalelectronics.ru Signed-off-by: Greg Kroah-Hartman

serial: 8250_port: Don't use power management for kernel console

2020-03-17T14:58:00+00:00

Doing any kind of power management for kernel console is really bad idea. First of all, it runs in poll and atomic mode. This fact attaches a limitation on the functions that might be called. For example, pm_runtime_get_sync() might sleep and thus can't be used. This call needs, for example, to bring the device to powered on state on the system, where the power on sequence may require on-atomic operations, such as Intel Cherrytrail with ACPI enumerated UARTs. That said, on ACPI enabled platforms it might even call firmware for a job. On the other hand pm_runtime_get() doesn't guarantee that device will become powered on fast enough. Besides that, imagine the case when console is about to print a kernel Oops and it's powered off. In such an emergency case calling the complex functions is not the best what we can do, taking into consideration that user wants to see at least something of the last kernel word before it passes away. Here we modify the 8250 console code to prevent runtime power management. Note, there is a behaviour change for OMAP boards. It will require to detach kernel console to become idle. Link: https://lists.openwall.net/linux-kernel/2018/09/29/65 Suggested-by: Russell King Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20200217114016.49856-6-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman