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https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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f7a676a484
In one place in ce4100_mem_serial_in() the code may be replaced with mem_serial_in() call. Do it so and collapse two conditionals into one. Suggested-by: Jiri Slaby <jirislaby@kernel.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Jiri Slaby <jirislaby@kernel.org> Link: https://lore.kernel.org/r/20250701134200.2621898-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
94 lines
2.6 KiB
C
94 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Intel CE4100 platform specific setup code
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*
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* (C) Copyright 2010 Intel Corporation
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*/
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#include <linux/init.h>
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#include <linux/io.h>
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#include <linux/types.h>
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#include <asm/ce4100.h>
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#include <asm/fixmap.h>
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#include <asm/page.h>
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#include <linux/serial_reg.h>
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#include <linux/serial_8250.h>
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static unsigned int mem_serial_in(struct uart_port *p, int offset)
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{
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offset = offset << p->regshift;
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return readl(p->membase + offset);
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}
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/*
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* The UART Tx interrupts are not set under some conditions and therefore serial
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* transmission hangs. This is a silicon issue and has not been root caused. The
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* workaround for this silicon issue checks UART_LSR_THRE bit and UART_LSR_TEMT
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* bit of LSR register in interrupt handler to see whether at least one of these
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* two bits is set, if so then process the transmit request. If this workaround
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* is not applied, then the serial transmission may hang. This workaround is for
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* errata number 9 in Errata - B step.
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*/
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static u32 ce4100_mem_serial_in(struct uart_port *p, unsigned int offset)
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{
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u32 ret, ier, lsr;
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ret = mem_serial_in(p, offset);
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if (offset != UART_IIR || !(ret & UART_IIR_NO_INT))
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return ret;
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/* see if the TX interrupt should have really set */
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ier = mem_serial_in(p, UART_IER);
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/* see if the UART's XMIT interrupt is enabled */
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if (!(ier & UART_IER_THRI))
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return ret;
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lsr = mem_serial_in(p, UART_LSR);
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/* now check to see if the UART should be generating an interrupt (but isn't) */
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if (lsr & (UART_LSR_THRE | UART_LSR_TEMT))
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ret &= ~UART_IIR_NO_INT;
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return ret;
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}
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static void ce4100_mem_serial_out(struct uart_port *p, unsigned int offset, u32 value)
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{
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offset <<= p->regshift;
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writel(value, p->membase + offset);
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}
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static void ce4100_serial_fixup(int port, struct uart_port *up, u32 *capabilities)
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{
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#ifdef CONFIG_EARLY_PRINTK
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/*
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* Override the legacy port configuration that comes from
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* asm/serial.h. Using the ioport driver then switching to the
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* PCI memmaped driver hangs the IOAPIC.
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*/
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if (up->iotype != UPIO_MEM32) {
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up->uartclk = 14745600;
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up->mapbase = 0xdffe0200;
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set_fixmap_nocache(FIX_EARLYCON_MEM_BASE, up->mapbase & PAGE_MASK);
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up->membase = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
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up->membase += up->mapbase & ~PAGE_MASK;
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up->mapbase += port * 0x100;
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up->membase += port * 0x100;
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up->iotype = UPIO_MEM32;
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up->regshift = 2;
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up->irq = 4;
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}
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#endif
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up->iobase = 0;
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up->serial_in = ce4100_mem_serial_in;
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up->serial_out = ce4100_mem_serial_out;
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*capabilities |= (1 << 12);
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}
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void __init sdv_serial_fixup(void)
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{
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serial8250_set_isa_configurator(ce4100_serial_fixup);
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}
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