diff options
Diffstat (limited to 'drivers/tty/serial/8250/8250_ce4100.c')
| -rw-r--r-- | drivers/tty/serial/8250/8250_ce4100.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_ce4100.c b/drivers/tty/serial/8250/8250_ce4100.c new file mode 100644 index 000000000000..81dfb2adbabd --- /dev/null +++ b/drivers/tty/serial/8250/8250_ce4100.c @@ -0,0 +1,93 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Intel CE4100 platform specific setup code + * + * (C) Copyright 2010 Intel Corporation + */ + +#include <linux/init.h> +#include <linux/io.h> +#include <linux/types.h> + +#include <asm/ce4100.h> +#include <asm/fixmap.h> +#include <asm/page.h> + +#include <linux/serial_reg.h> +#include <linux/serial_8250.h> + +static unsigned int mem_serial_in(struct uart_port *p, int offset) +{ + offset = offset << p->regshift; + return readl(p->membase + offset); +} + +/* + * The UART Tx interrupts are not set under some conditions and therefore serial + * transmission hangs. This is a silicon issue and has not been root caused. The + * workaround for this silicon issue checks UART_LSR_THRE bit and UART_LSR_TEMT + * bit of LSR register in interrupt handler to see whether at least one of these + * two bits is set, if so then process the transmit request. If this workaround + * is not applied, then the serial transmission may hang. This workaround is for + * errata number 9 in Errata - B step. +*/ +static u32 ce4100_mem_serial_in(struct uart_port *p, unsigned int offset) +{ + u32 ret, ier, lsr; + + ret = mem_serial_in(p, offset); + if (offset != UART_IIR || !(ret & UART_IIR_NO_INT)) + return ret; + + /* see if the TX interrupt should have really set */ + ier = mem_serial_in(p, UART_IER); + /* see if the UART's XMIT interrupt is enabled */ + if (!(ier & UART_IER_THRI)) + return ret; + + lsr = mem_serial_in(p, UART_LSR); + /* now check to see if the UART should be generating an interrupt (but isn't) */ + if (lsr & (UART_LSR_THRE | UART_LSR_TEMT)) + ret &= ~UART_IIR_NO_INT; + + return ret; +} + +static void ce4100_mem_serial_out(struct uart_port *p, unsigned int offset, u32 value) +{ + offset <<= p->regshift; + writel(value, p->membase + offset); +} + +static void ce4100_serial_fixup(int port, struct uart_port *up, u32 *capabilities) +{ +#ifdef CONFIG_EARLY_PRINTK + /* + * Override the legacy port configuration that comes from + * asm/serial.h. Using the ioport driver then switching to the + * PCI memmaped driver hangs the IOAPIC. + */ + if (up->iotype != UPIO_MEM32) { + up->uartclk = 14745600; + up->mapbase = 0xdffe0200; + set_fixmap_nocache(FIX_EARLYCON_MEM_BASE, up->mapbase & PAGE_MASK); + up->membase = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE); + up->membase += up->mapbase & ~PAGE_MASK; + up->mapbase += port * 0x100; + up->membase += port * 0x100; + up->iotype = UPIO_MEM32; + up->regshift = 2; + up->irq = 4; + } +#endif + up->iobase = 0; + up->serial_in = ce4100_mem_serial_in; + up->serial_out = ce4100_mem_serial_out; + + *capabilities |= (1 << 12); +} + +void __init sdv_serial_fixup(void) +{ + serial8250_set_isa_configurator(ce4100_serial_fixup); +} |