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115 lines
2.2 KiB
115 lines
2.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* Copyright (c) 2010, 2014 The Linux Foundation. All rights reserved. */ |
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#include <linux/console.h> |
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#include <linux/init.h> |
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#include <linux/serial.h> |
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#include <linux/serial_core.h> |
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#include <asm/dcc.h> |
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#include <asm/processor.h> |
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#include "hvc_console.h" |
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/* DCC Status Bits */ |
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#define DCC_STATUS_RX (1 << 30) |
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#define DCC_STATUS_TX (1 << 29) |
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static void dcc_uart_console_putchar(struct uart_port *port, int ch) |
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{ |
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while (__dcc_getstatus() & DCC_STATUS_TX) |
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cpu_relax(); |
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__dcc_putchar(ch); |
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} |
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static void dcc_early_write(struct console *con, const char *s, unsigned n) |
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{ |
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struct earlycon_device *dev = con->data; |
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uart_console_write(&dev->port, s, n, dcc_uart_console_putchar); |
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} |
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static int __init dcc_early_console_setup(struct earlycon_device *device, |
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const char *opt) |
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{ |
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device->con->write = dcc_early_write; |
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return 0; |
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} |
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EARLYCON_DECLARE(dcc, dcc_early_console_setup); |
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static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count) |
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{ |
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int i; |
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for (i = 0; i < count; i++) { |
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while (__dcc_getstatus() & DCC_STATUS_TX) |
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cpu_relax(); |
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__dcc_putchar(buf[i]); |
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} |
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return count; |
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} |
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static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count) |
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{ |
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int i; |
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for (i = 0; i < count; ++i) |
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if (__dcc_getstatus() & DCC_STATUS_RX) |
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buf[i] = __dcc_getchar(); |
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else |
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break; |
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return i; |
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} |
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static bool hvc_dcc_check(void) |
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{ |
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unsigned long time = jiffies + (HZ / 10); |
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/* Write a test character to check if it is handled */ |
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__dcc_putchar('\n'); |
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while (time_is_after_jiffies(time)) { |
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if (!(__dcc_getstatus() & DCC_STATUS_TX)) |
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return true; |
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} |
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return false; |
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} |
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static const struct hv_ops hvc_dcc_get_put_ops = { |
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.get_chars = hvc_dcc_get_chars, |
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.put_chars = hvc_dcc_put_chars, |
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}; |
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static int __init hvc_dcc_console_init(void) |
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{ |
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int ret; |
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if (!hvc_dcc_check()) |
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return -ENODEV; |
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/* Returns -1 if error */ |
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ret = hvc_instantiate(0, 0, &hvc_dcc_get_put_ops); |
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return ret < 0 ? -ENODEV : 0; |
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} |
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console_initcall(hvc_dcc_console_init); |
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static int __init hvc_dcc_init(void) |
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{ |
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struct hvc_struct *p; |
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if (!hvc_dcc_check()) |
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return -ENODEV; |
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p = hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128); |
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return PTR_ERR_OR_ZERO(p); |
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} |
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device_initcall(hvc_dcc_init);
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