From 6b1a98d1c4851235d9b6764b3f7b7db7909fc760 Mon Sep 17 00:00:00 2001 From: Jamie Iles Date: Tue, 16 Aug 2011 17:47:46 +0100 Subject: [PATCH] tty: serial8250: add helpers for the DesignWare 8250 The Synopsys DesignWare 8250 is an 8250 that has an extra interrupt that gets raised when writing to the LCR when busy. To handle this we need special serial_out, serial_in and handle_irq methods. Add a new function serial8250_use_designware_io() that configures a uart_port with these accessors. Cc: Alan Cox Acked-by: Arnd Bergmann Signed-off-by: Jamie Iles Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250_dw.c | 99 ++++++++++++++++++++++++++++++++++++ drivers/tty/serial/Kconfig | 7 +++ drivers/tty/serial/Makefile | 1 + include/linux/serial_8250.h | 8 +++ 4 files changed, 115 insertions(+) create mode 100644 drivers/tty/serial/8250_dw.c diff --git a/drivers/tty/serial/8250_dw.c b/drivers/tty/serial/8250_dw.c new file mode 100644 index 000000000000..e25782aeec7a --- /dev/null +++ b/drivers/tty/serial/8250_dw.c @@ -0,0 +1,99 @@ +/* + * Synopsys DesignWare specific 8250 operations. + * + * Copyright 2011 Picochip, Jamie Iles. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * The Synopsys DesignWare 8250 has an extra feature whereby it detects if the + * LCR is written whilst busy. If it is, then a busy detect interrupt is + * raised, the LCR needs to be rewritten and the uart status register read. + */ +#include +#include +#include +#include +#include + +struct dw8250_data { + int last_lcr; +}; + +static void dw8250_serial_out(struct uart_port *p, int offset, int value) +{ + struct dw8250_data *d = p->private_data; + + if (offset == UART_LCR) + d->last_lcr = value; + + offset <<= p->regshift; + writeb(value, p->membase + offset); +} + +static unsigned int dw8250_serial_in(struct uart_port *p, int offset) +{ + offset <<= p->regshift; + + return readb(p->membase + offset); +} + +static void dw8250_serial_out32(struct uart_port *p, int offset, + int value) +{ + struct dw8250_data *d = p->private_data; + + if (offset == UART_LCR) + d->last_lcr = value; + + offset <<= p->regshift; + writel(value, p->membase + offset); +} + +static unsigned int dw8250_serial_in32(struct uart_port *p, int offset) +{ + offset <<= p->regshift; + + return readl(p->membase + offset); +} + +/* Offset for the DesignWare's UART Status Register. */ +#define UART_USR 0x1f + +static int dw8250_handle_irq(struct uart_port *p) +{ + struct dw8250_data *d = p->private_data; + unsigned int iir = p->serial_in(p, UART_IIR); + + if (serial8250_handle_irq(p, iir)) { + return 1; + } else if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) { + /* Clear the USR and write the LCR again. */ + (void)p->serial_in(p, UART_USR); + p->serial_out(p, d->last_lcr, UART_LCR); + + return 1; + } + + return 0; +} + +int serial8250_use_designware_io(struct uart_port *up) +{ + up->private_data = kzalloc(sizeof(struct dw8250_data), GFP_KERNEL); + if (!up->private_data) + return -ENOMEM; + + if (up->iotype == UPIO_MEM32) { + up->serial_out = dw8250_serial_out32; + up->serial_in = dw8250_serial_in32; + } else { + up->serial_out = dw8250_serial_out; + up->serial_in = dw8250_serial_in; + } + up->handle_irq = dw8250_handle_irq; + + return 0; +} diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index a9b307f582e1..d2d1cc2329b7 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -267,6 +267,13 @@ config SERIAL_8250_RM9K port hardware found on MIPS RM9122 and similar processors. If unsure, say N. +config SERIAL_8250_DW + bool "Support for Synopsys DesignWare 8250 quirks" + depends on SERIAL_8250 + help + Selecting this option will enable handling of the extra features + present in the Synopsys DesignWare APB UART. + comment "Non-8250 serial port support" config SERIAL_AMBA_PL010 diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile index 78748136ccc8..7b59958f50ec 100644 --- a/drivers/tty/serial/Makefile +++ b/drivers/tty/serial/Makefile @@ -28,6 +28,7 @@ obj-$(CONFIG_SERIAL_8250_BOCA) += 8250_boca.o obj-$(CONFIG_SERIAL_8250_EXAR_ST16C554) += 8250_exar_st16c554.o obj-$(CONFIG_SERIAL_8250_HUB6) += 8250_hub6.o obj-$(CONFIG_SERIAL_8250_MCA) += 8250_mca.o +obj-$(CONFIG_SERIAL_8250_DW) += 8250_dw.o obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o obj-$(CONFIG_SERIAL_CLPS711X) += clps711x.o diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h index 1f05bbeac01e..09e2dbcd7ca3 100644 --- a/include/linux/serial_8250.h +++ b/include/linux/serial_8250.h @@ -86,5 +86,13 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir); extern void serial8250_set_isa_configurator(void (*v) (int port, struct uart_port *up, unsigned short *capabilities)); +#ifndef SERIAL_8250_DW +extern int serial8250_use_designware_io(struct uart_port *up); +#else +static inline int serial8250_use_designware_io(struct uart_port *up) +{ + return -EIO; +} +#endif #endif -- GitLab