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54 lines
1.2 KiB
54 lines
1.2 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* 8250/16550-type serial ports prom_putchar() |
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* |
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* Copyright (C) 2010 Yoichi Yuasa <[email protected]> |
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*/ |
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#include <linux/io.h> |
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#include <linux/serial_core.h> |
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#include <linux/serial_reg.h> |
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#include <asm/setup.h> |
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static void __iomem *serial8250_base; |
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static unsigned int serial8250_reg_shift; |
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static unsigned int serial8250_tx_timeout; |
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void setup_8250_early_printk_port(unsigned long base, unsigned int reg_shift, |
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unsigned int timeout) |
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{ |
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serial8250_base = (void __iomem *)base; |
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serial8250_reg_shift = reg_shift; |
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serial8250_tx_timeout = timeout; |
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} |
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static inline u8 serial_in(int offset) |
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{ |
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return readb(serial8250_base + (offset << serial8250_reg_shift)); |
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} |
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static inline void serial_out(int offset, char value) |
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{ |
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writeb(value, serial8250_base + (offset << serial8250_reg_shift)); |
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} |
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void prom_putchar(char c) |
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{ |
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unsigned int timeout; |
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int status, bits; |
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if (!serial8250_base) |
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return; |
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timeout = serial8250_tx_timeout; |
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bits = UART_LSR_TEMT | UART_LSR_THRE; |
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do { |
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status = serial_in(UART_LSR); |
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if (--timeout == 0) |
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break; |
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} while ((status & bits) != bits); |
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if (timeout) |
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serial_out(UART_TX, c); |
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}
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