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mips: Add CPS_NS16550_WIDTH config 

On some platforms IO-memory might require to use a proper load/store
instructions (like Baikal-T1 IO-memory). To fix the cps-vec UART debug
printout let's add the CONFIG_CPS_NS16550_WIDTH config to determine which
instructions lb/sb, lh/sh or lw/sw are required for MMIO operations.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
This commit is contained in:
Serge Semin 2020-05-21 17:07:19 +03:00 committed by Thomas Bogendoerfer
parent 999079c851
commit ad42e0a8d4
2 changed files with 26 additions and 2 deletions
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10
arch/mips/Kconfig.debug
View File

@ -148,4 +148,14 @@ config MIPS_CPS_NS16550_SHIFT
form their addresses. That is, log base 2 of the span between
adjacent ns16550 registers in the system.
config MIPS_CPS_NS16550_WIDTH
int "UART Register Width"
default 1
help
ns16550 registers width. UART registers IO access methods will be
selected in accordance with this parameter. By setting it to 1, 2 or
4 UART registers will be accessed by means of lb/sb, lh/sh or lw/sw
instructions respectively. Any value not from that set activates
lb/sb instructions.
endif # MIPS_CPS_NS16550_BOOL

18
arch/mips/kernel/cps-vec-ns16550.S
View File

@ -14,16 +14,30 @@
#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: lw t0, UART_LSR_OFS(t9)
1: UART_L t0, UART_LSR_OFS(t9)
andi t0, t0, UART_LSR_TEMT
beqz t0, 1b
sb a0, UART_TX_OFS(t9)
UART_S a0, UART_TX_OFS(t9)
jr ra
END(_mips_cps_putc)