linux-stable/include/linux/serial_8250.h
Ilpo Järvinen 039d492637 serial: 8250: Toggle IER bits on only after irq has been set up
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: 40b36daad0 ("[PATCH] 8250 UART backup timer")
Reported-by: Lennert Buytenhek <buytenh@arista.com>
Tested-by: Lennert Buytenhek <buytenh@arista.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220922070005.2965-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-22 16:30:14 +02:00

195 lines
6.5 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* linux/include/linux/serial_8250.h
*
* Copyright (C) 2004 Russell King
*/
#ifndef _LINUX_SERIAL_8250_H
#define _LINUX_SERIAL_8250_H
#include <linux/serial_core.h>
#include <linux/serial_reg.h>
#include <linux/platform_device.h>
/*
* This is the platform device platform_data structure
*/
struct plat_serial8250_port {
unsigned long iobase; /* io base address */
void __iomem *membase; /* ioremap cookie or NULL */
resource_size_t mapbase; /* resource base */
unsigned int irq; /* interrupt number */
unsigned long irqflags; /* request_irq flags */
unsigned int uartclk; /* UART clock rate */
void *private_data;
unsigned char regshift; /* register shift */
unsigned char iotype; /* UPIO_* */
unsigned char hub6;
unsigned char has_sysrq; /* supports magic SysRq */
upf_t flags; /* UPF_* flags */
unsigned int type; /* If UPF_FIXED_TYPE */
unsigned int (*serial_in)(struct uart_port *, int);
void (*serial_out)(struct uart_port *, int, int);
void (*set_termios)(struct uart_port *,
struct ktermios *new,
const struct ktermios *old);
void (*set_ldisc)(struct uart_port *,
struct ktermios *);
unsigned int (*get_mctrl)(struct uart_port *);
int (*handle_irq)(struct uart_port *);
void (*pm)(struct uart_port *, unsigned int state,
unsigned old);
void (*handle_break)(struct uart_port *);
};
/*
* Allocate 8250 platform device IDs. Nothing is implied by
* the numbering here, except for the legacy entry being -1.
*/
enum {
PLAT8250_DEV_LEGACY = -1,
PLAT8250_DEV_PLATFORM,
PLAT8250_DEV_PLATFORM1,
PLAT8250_DEV_PLATFORM2,
PLAT8250_DEV_FOURPORT,
PLAT8250_DEV_ACCENT,
PLAT8250_DEV_BOCA,
PLAT8250_DEV_EXAR_ST16C554,
PLAT8250_DEV_HUB6,
PLAT8250_DEV_AU1X00,
PLAT8250_DEV_SM501,
};
struct uart_8250_dma;
struct uart_8250_port;
/**
* 8250 core driver operations
*
* @setup_irq() Setup irq handling. The universal 8250 driver links this
* port to the irq chain. Other drivers may @request_irq().
* @release_irq() Undo irq handling. The universal 8250 driver unlinks
* the port from the irq chain.
*/
struct uart_8250_ops {
int (*setup_irq)(struct uart_8250_port *);
void (*release_irq)(struct uart_8250_port *);
void (*setup_timer)(struct uart_8250_port *);
};
struct uart_8250_em485 {
struct hrtimer start_tx_timer; /* "rs485 start tx" timer */
struct hrtimer stop_tx_timer; /* "rs485 stop tx" timer */
struct hrtimer *active_timer; /* pointer to active timer */
struct uart_8250_port *port; /* for hrtimer callbacks */
unsigned int tx_stopped:1; /* tx is currently stopped */
};
/*
* This should be used by drivers which want to register
* their own 8250 ports without registering their own
* platform device. Using these will make your driver
* dependent on the 8250 driver.
*/
struct uart_8250_port {
struct uart_port port;
struct timer_list timer; /* "no irq" timer */
struct list_head list; /* ports on this IRQ */
u32 capabilities; /* port capabilities */
unsigned short bugs; /* port bugs */
bool fifo_bug; /* min RX trigger if enabled */
unsigned int tx_loadsz; /* transmit fifo load size */
unsigned char acr;
unsigned char fcr;
unsigned char ier;
unsigned char lcr;
unsigned char mcr;
unsigned char cur_iotype; /* Running I/O type */
unsigned int rpm_tx_active;
unsigned char canary; /* non-zero during system sleep
* if no_console_suspend
*/
unsigned char probe;
struct mctrl_gpios *gpios;
#define UART_PROBE_RSA (1 << 0)
/*
* Some bits in registers are cleared on a read, so they must
* be saved whenever the register is read but the bits will not
* be immediately processed.
*/
#define LSR_SAVE_FLAGS UART_LSR_BRK_ERROR_BITS
u16 lsr_saved_flags;
u16 lsr_save_mask;
#define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
unsigned char msr_saved_flags;
struct uart_8250_dma *dma;
const struct uart_8250_ops *ops;
/* 8250 specific callbacks */
int (*dl_read)(struct uart_8250_port *);
void (*dl_write)(struct uart_8250_port *, int);
struct uart_8250_em485 *em485;
void (*rs485_start_tx)(struct uart_8250_port *);
void (*rs485_stop_tx)(struct uart_8250_port *);
/* Serial port overrun backoff */
struct delayed_work overrun_backoff;
u32 overrun_backoff_time_ms;
};
static inline struct uart_8250_port *up_to_u8250p(struct uart_port *up)
{
return container_of(up, struct uart_8250_port, port);
}
int serial8250_register_8250_port(const struct uart_8250_port *);
void serial8250_unregister_port(int line);
void serial8250_suspend_port(int line);
void serial8250_resume_port(int line);
extern int early_serial_setup(struct uart_port *port);
extern int early_serial8250_setup(struct earlycon_device *device,
const char *options);
extern void serial8250_update_uartclk(struct uart_port *port,
unsigned int uartclk);
extern void serial8250_do_set_termios(struct uart_port *port,
struct ktermios *termios, const struct ktermios *old);
extern void serial8250_do_set_ldisc(struct uart_port *port,
struct ktermios *termios);
extern unsigned int serial8250_do_get_mctrl(struct uart_port *port);
extern int serial8250_do_startup(struct uart_port *port);
extern void serial8250_do_shutdown(struct uart_port *port);
extern void serial8250_do_pm(struct uart_port *port, unsigned int state,
unsigned int oldstate);
extern void serial8250_do_set_mctrl(struct uart_port *port, unsigned int mctrl);
extern void serial8250_do_set_divisor(struct uart_port *port, unsigned int baud,
unsigned int quot,
unsigned int quot_frac);
extern int fsl8250_handle_irq(struct uart_port *port);
int serial8250_handle_irq(struct uart_port *port, unsigned int iir);
u16 serial8250_rx_chars(struct uart_8250_port *up, u16 lsr);
void serial8250_read_char(struct uart_8250_port *up, u16 lsr);
void serial8250_tx_chars(struct uart_8250_port *up);
unsigned int serial8250_modem_status(struct uart_8250_port *up);
void serial8250_init_port(struct uart_8250_port *up);
void serial8250_set_defaults(struct uart_8250_port *up);
void serial8250_console_write(struct uart_8250_port *up, const char *s,
unsigned int count);
int serial8250_console_setup(struct uart_port *port, char *options, bool probe);
int serial8250_console_exit(struct uart_port *port);
extern void serial8250_set_isa_configurator(void (*v)
(int port, struct uart_port *up,
u32 *capabilities));
#ifdef CONFIG_SERIAL_8250_RT288X
unsigned int au_serial_in(struct uart_port *p, int offset);
void au_serial_out(struct uart_port *p, int offset, int value);
#endif
#endif