diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index abf0814086a5..3d8032f752b8 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -61,6 +61,13 @@ #define DW_UART_QUIRK_IS_DMA_FC BIT(3) #define DW_UART_QUIRK_APMC0D08 BIT(4) #define DW_UART_QUIRK_CPR_VALUE BIT(5) +#define DW_UART_QUIRK_IER_KICK BIT(6) + +/* + * Number of consecutive IIR_NO_INT interrupts required to trigger interrupt + * storm prevention code. + */ +#define DW_UART_QUIRK_IER_KICK_THRES 4 struct dw8250_platform_data { u8 usr_reg; @@ -82,6 +89,8 @@ struct dw8250_data { unsigned int skip_autocfg:1; unsigned int uart_16550_compatible:1; + + u8 no_int_count; }; static inline struct dw8250_data *to_dw8250_data(struct dw8250_port_data *data) @@ -308,6 +317,29 @@ static u32 dw8250_serial_in32be(struct uart_port *p, unsigned int offset) return dw8250_modify_msr(p, offset, value); } +/* + * INTC10EE UART can IRQ storm while reporting IIR_NO_INT. Inducing IIR value + * change has been observed to break the storm. + * + * If Tx is empty (THRE asserted), we use here IER_THRI to cause IIR_NO_INT -> + * IIR_THRI transition. + */ +static void dw8250_quirk_ier_kick(struct uart_port *p) +{ + struct uart_8250_port *up = up_to_u8250p(p); + u32 lsr; + + if (up->ier & UART_IER_THRI) + return; + + lsr = serial_lsr_in(up); + if (!(lsr & UART_LSR_THRE)) + return; + + serial_port_out(p, UART_IER, up->ier | UART_IER_THRI); + serial_port_in(p, UART_LCR); /* safe, no side-effects */ + serial_port_out(p, UART_IER, up->ier); +} static int dw8250_handle_irq(struct uart_port *p) { @@ -318,18 +350,30 @@ static int dw8250_handle_irq(struct uart_port *p) unsigned int quirks = d->pdata->quirks; unsigned int status; + guard(uart_port_lock_irqsave)(p); + switch (FIELD_GET(DW_UART_IIR_IID, iir)) { case UART_IIR_NO_INT: + if (d->uart_16550_compatible || up->dma) + return 0; + + if (quirks & DW_UART_QUIRK_IER_KICK && + d->no_int_count == (DW_UART_QUIRK_IER_KICK_THRES - 1)) + dw8250_quirk_ier_kick(p); + d->no_int_count = (d->no_int_count + 1) % DW_UART_QUIRK_IER_KICK_THRES; + return 0; case UART_IIR_BUSY: /* Clear the USR */ serial_port_in(p, d->pdata->usr_reg); + d->no_int_count = 0; + return 1; } - guard(uart_port_lock_irqsave)(p); + d->no_int_count = 0; /* * There are ways to get Designware-based UARTs into a state where @@ -562,6 +606,14 @@ static void dw8250_reset_control_assert(void *data) reset_control_assert(data); } +static void dw8250_shutdown(struct uart_port *port) +{ + struct dw8250_data *d = to_dw8250_data(port->private_data); + + serial8250_do_shutdown(port); + d->no_int_count = 0; +} + static int dw8250_probe(struct platform_device *pdev) { struct uart_8250_port uart = {}, *up = &uart; @@ -689,10 +741,12 @@ static int dw8250_probe(struct platform_device *pdev) dw8250_quirks(p, data); /* If the Busy Functionality is not implemented, don't handle it */ - if (data->uart_16550_compatible) + if (data->uart_16550_compatible) { p->handle_irq = NULL; - else if (data->pdata) + } else if (data->pdata) { p->handle_irq = dw8250_handle_irq; + p->shutdown = dw8250_shutdown; + } dw8250_setup_dma_filter(p, data); @@ -824,6 +878,11 @@ static const struct dw8250_platform_data dw8250_skip_set_rate_data = { .quirks = DW_UART_QUIRK_SKIP_SET_RATE, }; +static const struct dw8250_platform_data dw8250_intc10ee = { + .usr_reg = DW_UART_USR, + .quirks = DW_UART_QUIRK_IER_KICK, +}; + static const struct of_device_id dw8250_of_match[] = { { .compatible = "snps,dw-apb-uart", .data = &dw8250_dw_apb }, { .compatible = "cavium,octeon-3860-uart", .data = &dw8250_octeon_3860_data }, @@ -853,7 +912,7 @@ static const struct acpi_device_id dw8250_acpi_match[] = { { "INT33C5", (kernel_ulong_t)&dw8250_dw_apb }, { "INT3434", (kernel_ulong_t)&dw8250_dw_apb }, { "INT3435", (kernel_ulong_t)&dw8250_dw_apb }, - { "INTC10EE", (kernel_ulong_t)&dw8250_dw_apb }, + { "INTC10EE", (kernel_ulong_t)&dw8250_intc10ee }, { }, }; MODULE_DEVICE_TABLE(acpi, dw8250_acpi_match);