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Diffstat (limited to 'arch/mips/kernel/cps-vec-ns16550.S')
| -rw-r--r-- | arch/mips/kernel/cps-vec-ns16550.S | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/arch/mips/kernel/cps-vec-ns16550.S b/arch/mips/kernel/cps-vec-ns16550.S new file mode 100644 index 000000000..30725e1df --- /dev/null +++ b/arch/mips/kernel/cps-vec-ns16550.S @@ -0,0 +1,212 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright (C) 2015 Imagination Technologies + * Author: Paul Burton <paul.burton@mips.com> + */ + +#include <asm/addrspace.h> +#include <asm/asm.h> +#include <asm/asm-offsets.h> +#include <asm/mipsregs.h> +#include <asm/regdef.h> +#include <linux/serial_reg.h> + +#define UART_TX_OFS (UART_TX << CONFIG_MIPS_CPS_NS16550_SHIFT) +#define UART_LSR_OFS (UART_LSR << CONFIG_MIPS_CPS_NS16550_SHIFT) + +#if CONFIG_MIPS_CPS_NS16550_WIDTH == 1 +# define UART_L lb +# define UART_S sb +#elif CONFIG_MIPS_CPS_NS16550_WIDTH == 2 +# define UART_L lh +# define UART_S sh +#elif CONFIG_MIPS_CPS_NS16550_WIDTH == 4 +# define UART_L lw +# define UART_S sw +#else +# define UART_L lb +# define UART_S sb +#endif + +/** + * _mips_cps_putc() - write a character to the UART + * @a0: ASCII character to write + * @t9: UART base address + */ +LEAF(_mips_cps_putc) +1: UART_L t0, UART_LSR_OFS(t9) + andi t0, t0, UART_LSR_TEMT + beqz t0, 1b + UART_S a0, UART_TX_OFS(t9) + jr ra + END(_mips_cps_putc) + +/** + * _mips_cps_puts() - write a string to the UART + * @a0: pointer to NULL-terminated ASCII string + * @t9: UART base address + * + * Write a null-terminated ASCII string to the UART. + */ +NESTED(_mips_cps_puts, 0, ra) + move s7, ra + move s6, a0 + +1: lb a0, 0(s6) + beqz a0, 2f + jal _mips_cps_putc + PTR_ADDIU s6, s6, 1 + b 1b + +2: jr s7 + END(_mips_cps_puts) + +/** + * _mips_cps_putx4 - write a 4b hex value to the UART + * @a0: the 4b value to write to the UART + * @t9: UART base address + * + * Write a single hexadecimal character to the UART. + */ +NESTED(_mips_cps_putx4, 0, ra) + andi a0, a0, 0xf + li t0, '0' + blt a0, 10, 1f + li t0, 'a' + addiu a0, a0, -10 +1: addu a0, a0, t0 + b _mips_cps_putc + END(_mips_cps_putx4) + +/** + * _mips_cps_putx8 - write an 8b hex value to the UART + * @a0: the 8b value to write to the UART + * @t9: UART base address + * + * Write an 8 bit value (ie. 2 hexadecimal characters) to the UART. + */ +NESTED(_mips_cps_putx8, 0, ra) + move s3, ra + move s2, a0 + srl a0, a0, 4 + jal _mips_cps_putx4 + move a0, s2 + move ra, s3 + b _mips_cps_putx4 + END(_mips_cps_putx8) + +/** + * _mips_cps_putx16 - write a 16b hex value to the UART + * @a0: the 16b value to write to the UART + * @t9: UART base address + * + * Write a 16 bit value (ie. 4 hexadecimal characters) to the UART. + */ +NESTED(_mips_cps_putx16, 0, ra) + move s5, ra + move s4, a0 + srl a0, a0, 8 + jal _mips_cps_putx8 + move a0, s4 + move ra, s5 + b _mips_cps_putx8 + END(_mips_cps_putx16) + +/** + * _mips_cps_putx32 - write a 32b hex value to the UART + * @a0: the 32b value to write to the UART + * @t9: UART base address + * + * Write a 32 bit value (ie. 8 hexadecimal characters) to the UART. + */ +NESTED(_mips_cps_putx32, 0, ra) + move s7, ra + move s6, a0 + srl a0, a0, 16 + jal _mips_cps_putx16 + move a0, s6 + move ra, s7 + b _mips_cps_putx16 + END(_mips_cps_putx32) + +#ifdef CONFIG_64BIT + +/** + * _mips_cps_putx64 - write a 64b hex value to the UART + * @a0: the 64b value to write to the UART + * @t9: UART base address + * + * Write a 64 bit value (ie. 16 hexadecimal characters) to the UART. + */ +NESTED(_mips_cps_putx64, 0, ra) + move sp, ra + move s8, a0 + dsrl32 a0, a0, 0 + jal _mips_cps_putx32 + move a0, s8 + move ra, sp + b _mips_cps_putx32 + END(_mips_cps_putx64) + +#define _mips_cps_putxlong _mips_cps_putx64 + +#else /* !CONFIG_64BIT */ + +#define _mips_cps_putxlong _mips_cps_putx32 + +#endif /* !CONFIG_64BIT */ + +/** + * mips_cps_bev_dump() - dump relevant exception state to UART + * @a0: pointer to NULL-terminated ASCII string naming the exception + * + * Write information that may be useful in debugging an exception to the + * UART configured by CONFIG_MIPS_CPS_NS16550_*. As this BEV exception + * will only be run if something goes horribly wrong very early during + * the bringup of a core and it is very likely to be unsafe to perform + * memory accesses at that point (cache state indeterminate, EVA may not + * be configured, coherence may be disabled) let alone have a stack, + * this is all written in assembly using only registers & unmapped + * uncached access to the UART registers. + */ +LEAF(mips_cps_bev_dump) + move s0, ra + move s1, a0 + + li t9, CKSEG1ADDR(CONFIG_MIPS_CPS_NS16550_BASE) + + PTR_LA a0, str_newline + jal _mips_cps_puts + PTR_LA a0, str_bev + jal _mips_cps_puts + move a0, s1 + jal _mips_cps_puts + PTR_LA a0, str_newline + jal _mips_cps_puts + PTR_LA a0, str_newline + jal _mips_cps_puts + +#define DUMP_COP0_REG(reg, name, sz, _mfc0) \ + PTR_LA a0, 8f; \ + jal _mips_cps_puts; \ + _mfc0 a0, reg; \ + jal _mips_cps_putx##sz; \ + PTR_LA a0, str_newline; \ + jal _mips_cps_puts; \ + TEXT(name) + + DUMP_COP0_REG(CP0_CAUSE, "Cause: 0x", 32, mfc0) + DUMP_COP0_REG(CP0_STATUS, "Status: 0x", 32, mfc0) + DUMP_COP0_REG(CP0_EBASE, "EBase: 0x", long, MFC0) + DUMP_COP0_REG(CP0_BADVADDR, "BadVAddr: 0x", long, MFC0) + DUMP_COP0_REG(CP0_BADINSTR, "BadInstr: 0x", 32, mfc0) + + PTR_LA a0, str_newline + jal _mips_cps_puts + jr s0 + END(mips_cps_bev_dump) + +.pushsection .data +str_bev: .asciiz "BEV Exception: " +str_newline: .asciiz "\r\n" +.popsection |