If the DCC driver loads, then disable user-space access to the DCC so that we don't have two entities trying to access the DCC at the same time.
Signed-off-by: Timur Tabi <[email protected]> --- arch/arm/include/asm/dcc.h | 15 +++++++++++++++ arch/arm64/include/asm/dcc.h | 11 +++++++++++ drivers/tty/hvc/hvc_dcc.c | 2 ++ 3 files changed, 28 insertions(+) diff --git a/arch/arm/include/asm/dcc.h b/arch/arm/include/asm/dcc.h index b74899d..c50056b 100644 --- a/arch/arm/include/asm/dcc.h +++ b/arch/arm/include/asm/dcc.h @@ -9,8 +9,11 @@ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ +#ifndef __ASM_DCC_H +#define __ASM_DCC_H #include <asm/barrier.h> +#include <asm/hardware/cp14.h> static inline u32 __dcc_getstatus(void) { @@ -39,3 +42,15 @@ static inline void __dcc_putchar(char c) : "r" (c)); isb(); } + +static inline void __dcc_initialize(void) +{ + u32 val; + + /* Disable user-space access to DCC */ + val = MRC14(0, c0, c1, 0); + val |= 1 << 12; /* DSCR[Comms] */ + MCR14(val, 0, c0, c1, 0); +} + +#endif diff --git a/arch/arm64/include/asm/dcc.h b/arch/arm64/include/asm/dcc.h index fcb8d7d..7843e62 100644 --- a/arch/arm64/include/asm/dcc.h +++ b/arch/arm64/include/asm/dcc.h @@ -49,4 +49,15 @@ static inline void __dcc_putchar(char c) isb(); } +static inline void __dcc_initialize(void) +{ + u32 val; + + /* Disable user-space access to DCC */ + asm ("mrs %0, mdscr_el1\n" + " orr %0, %0, #4096\n" /* Set the TDCC bit */ + " msr mdscr_el1, %0\n" + : "=r" (val)); +} + #endif diff --git a/drivers/tty/hvc/hvc_dcc.c b/drivers/tty/hvc/hvc_dcc.c index f8b8cf2..5ccafa4 100644 --- a/drivers/tty/hvc/hvc_dcc.c +++ b/drivers/tty/hvc/hvc_dcc.c @@ -231,6 +231,8 @@ static int __init hvc_dcc_console_init(void) if (!hvc_dcc_check()) return -ENODEV; + __dcc_initialize(); + /* Returns -1 if error */ ret = hvc_instantiate(0, 0, &hvc_dcc_get_put_ops); -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
