mirror of
https://github.com/AuxXxilium/arc-lkm.git
synced 2024-11-23 14:50:57 +07:00
105 lines
2.9 KiB
C
Executable File
105 lines
2.9 KiB
C
Executable File
#define SHIM_NAME "UART fixer"
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#include "uart_fixer.h"
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#include "shim_base.h"
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#include "../common.h"
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#include "../config/runtime_config.h" //STD_COM*
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#include "../config/platform_types.h" //hw_config
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#include "../internal/call_protected.h" //early_serial_setup()
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#include "../internal/override/override_symbol.h" //overriding uart_match_port()
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#include <linux/serial_8250.h> //serial8250_unregister_port
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#ifdef DBG_DISABLE_UART_SWAP_FIX
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static int noinline uart_swap_hw_output(unsigned int from, unsigned char to)
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{
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pr_loc_wrn("UART swapping needed for the platform but forcefully disabled via DBG_DISABLE_UART_SWAP");
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return 0;
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}
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#elif defined(UART_BUG_SWAPPED)
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#include "../internal/uart/uart_swapper.h"
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#else
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static int noinline uart_swap_hw_output(unsigned int from, unsigned char to)
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{
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pr_loc_bug("Called %s from uart_fixer context when UART_BUG_SWAPPED is not set", __FUNCTION__);
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return -EINVAL;
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}
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#endif
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static bool ttyS0_force_initted = false; //Was ttyS0 forcefully initialized by us?
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static bool serial_swapped = false; //Whether ttyS0 and ttyS1 were swapped
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/**
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* On some platforms (e.g. 918+) the first serial port appears to not be functional as it's not initialized properly.
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*
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* It is speculated that it has to do with "CONFIG_SYNO_X86_TTY_CONSOLE_OUTPUT=y" but it's not confirmed. If this is not
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* fixed by this function setting kernel console output to ttyS0 will result in earlycon working as expected (as it
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* doesn't use the normal 8250 driver) with nothing being transmitted as soon as earlycon is switched to the proper
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* "console=" port.
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*/
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static int fix_muted_ttyS0(void)
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{
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int out = 0;
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struct uart_port port = {
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.iobase = STD_COM1_IOBASE,
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.uartclk = STD_COMX_BAUD * 16,
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.irq = STD_COM1_IRQ,
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.flags = STD_COMX_FLAGS
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};
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if ((out = _early_serial_setup(&port)) != 0) {
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pr_loc_err("Failed to register ttyS0 to hw port @ %lx", port.iobase);
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return out;
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}
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pr_loc_dbg("Fixed muted ttyS0 to hw port @ %lx", port.iobase);
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ttyS0_force_initted = true;
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return out;
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}
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/**
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* Reverses what fix_muted_ttyS0() did
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*/
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static int mute_ttyS0(void)
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{
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pr_loc_dbg("Re-muting ttyS0");
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serial8250_unregister_port(0);
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return 0;
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}
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int register_uart_fixer(const hw_config_uart_fixer *hw)
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{
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shim_reg_in();
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int out = 0;
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if (
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(hw->swap_serial && (out = uart_swap_hw_output(1, 0)) != 0) ||
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(hw->reinit_ttyS0 && (out = fix_muted_ttyS0()) != 0)
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) {
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pr_loc_err("Failed to register UART fixer");
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return out;
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}
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serial_swapped = hw->swap_serial;
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shim_reg_ok();
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return out;
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}
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int unregister_uart_fixer(void)
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{
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shim_ureg_in();
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int out = 0;
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if (
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(serial_swapped && (out = uart_swap_hw_output(0, 1)) != 0) ||
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(ttyS0_force_initted && (out = mute_ttyS0()) != 0)
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) {
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pr_loc_err("Failed to unregister UART fixer");
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return out;
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}
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shim_ureg_ok();
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return out;
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} |