The Blackfin JTAG has the ability to pass data via a back-channel without halting the processor. Utilize that channel to emulate a console.
Signed-off-by: Mike Frysinger vapier@gentoo.org --- common/devices.c | 3 + cpu/blackfin/Makefile | 9 ++-- cpu/blackfin/jtag-console.c | 125 +++++++++++++++++++++++++++++++++++++++++++ include/devices.h | 3 + 4 files changed, 136 insertions(+), 4 deletions(-) create mode 100644 cpu/blackfin/jtag-console.c
diff --git a/common/devices.c b/common/devices.c index ce3b7a0..38f1bbc 100644 --- a/common/devices.c +++ b/common/devices.c @@ -240,6 +240,9 @@ int devices_init (void) #ifdef CONFIG_NETCONSOLE drv_nc_init (); #endif +#ifdef CONFIG_JTAG_CONSOLE + drv_jtag_console_init (); +#endif
return (0); } diff --git a/cpu/blackfin/Makefile b/cpu/blackfin/Makefile index b90fb48..b4049ff 100644 --- a/cpu/blackfin/Makefile +++ b/cpu/blackfin/Makefile @@ -17,14 +17,15 @@ EXTRA := CEXTRA := initcode.o SEXTRA := start.o SOBJS := interrupt.o cache.o -COBJS := cpu.o traps.o interrupts.o reset.o serial.o watchdog.o +COBJS-y := cpu.o traps.o interrupts.o reset.o serial.o watchdog.o +COBJS-$(CONFIG_JTAG_CONSOLE) += jtag-console.o
ifeq ($(CONFIG_BFIN_BOOT_MODE),BFIN_BOOT_BYPASS) -COBJS += initcode.o +COBJS-y += initcode.o endif
-SRCS := $(SEXTRA:.o=.S) $(SOBJS:.o=.S) $(COBJS:.o=.c) -OBJS := $(addprefix $(obj),$(COBJS) $(SOBJS)) +SRCS := $(SEXTRA:.o=.S) $(SOBJS:.o=.S) $(COBJS-y:.o=.c) +OBJS := $(addprefix $(obj),$(COBJS-y) $(SOBJS)) EXTRA := $(addprefix $(obj),$(EXTRA)) CEXTRA := $(addprefix $(obj),$(CEXTRA)) SEXTRA := $(addprefix $(obj),$(SEXTRA)) diff --git a/cpu/blackfin/jtag-console.c b/cpu/blackfin/jtag-console.c new file mode 100644 index 0000000..44c0a83 --- /dev/null +++ b/cpu/blackfin/jtag-console.c @@ -0,0 +1,125 @@ +/* + * jtag-console.c - console driver over Blackfin JTAG + * + * Copyright (c) 2008 Analog Devices Inc. + * + * Licensed under the GPL-2 or later. + */ + +#include <common.h> +#include <devices.h> +#include <asm/blackfin.h> + +#ifndef CONFIG_JTAG_CONSOLE_TIMEOUT +# define CONFIG_JTAG_CONSOLE_TIMEOUT 100 +#endif + +/* The Blackfin tends to be much much faster than the JTAG hardware. */ +static void jtag_write_emudat(uint32_t emudat) +{ + static bool overflowed = false; + ulong timeout = get_timer(0) + CONFIG_JTAG_CONSOLE_TIMEOUT; + while (bfin_read_DBGSTAT() & 0x1) { + if (overflowed) + return; + if (timeout < get_timer(0)) + overflowed = true; + } + overflowed = false; + __asm__ __volatile__("emudat = %0;" : : "d"(emudat)); +} +/* Transmit a buffer. The format is: + * [32bit length][actual data] + */ +static void jtag_send(const char *c, uint32_t len) +{ + uint32_t i; + + if (len == 0) + return; + + /* First send the length */ + jtag_write_emudat(len); + + /* Then send the data */ + for (i = 0; i < len; i += 4) + jtag_write_emudat((c[i] << 0) | (c[i+1] << 8) | (c[i+2] << 16) | (c[i+3] << 24)); +} +static void jtag_putc(const char c) +{ + jtag_send(&c, 1); +} +static void jtag_puts(const char *s) +{ + jtag_send(s, strlen(s)); +} + +static int jtag_tstc(void) +{ + return (bfin_read_DBGSTAT() & 0x2); +} + +/* Receive a buffer. The format is: + * [32bit length][actual data] + */ +static size_t inbound_len; +static int leftovers_len; +static uint32_t leftovers; +static int jtag_getc(void) +{ + int ret; + uint32_t emudat; + + /* see if any data is left over */ + if (leftovers_len) { + --leftovers_len; + ret = leftovers & 0xff; + leftovers >>= 8; + return ret; + } + + /* wait for new data ! */ + while (!jtag_tstc()) + continue; + __asm__("%0 = emudat;" : "=d"(emudat)); + + if (inbound_len == 0) { + /* grab the length */ + inbound_len = emudat; + } else { + /* store the bytes */ + leftovers_len = min(4, inbound_len); + inbound_len -= leftovers_len; + leftovers = emudat; + } + + return jtag_getc(); +} + +int drv_jtag_console_init(void) +{ + device_t dev; + int ret; + + memset(&dev, 0x00, sizeof(dev)); + strcpy(dev.name, "jtag"); + dev.flags = DEV_FLAGS_OUTPUT | DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM; + dev.putc = jtag_putc; + dev.puts = jtag_puts; + dev.tstc = jtag_tstc; + dev.getc = jtag_getc; + + ret = device_register(&dev); + return (ret == 0 ? 1 : ret); +} + +#ifdef CONFIG_UART_CONSOLE_IS_JTAG +/* Since the JTAG is always available (at power on), allow it to fake a UART */ +void serial_set_baud(uint32_t baud) {} +void serial_setbrg(void) {} +int serial_init(void) { return 0; } +void serial_putc(const char c) __attribute__((alias("jtag_putc"))); +void serial_puts(const char *s) __attribute__((alias("jtag_puts"))); +int serial_tstc(void) __attribute__((alias("jtag_tstc"))); +int serial_getc(void) __attribute__((alias("jtag_getc"))); +#endif diff --git a/include/devices.h b/include/devices.h index 20ddfc4..84c4514 100644 --- a/include/devices.h +++ b/include/devices.h @@ -116,5 +116,8 @@ int drv_usbtty_init (void); #ifdef CONFIG_NETCONSOLE int drv_nc_init (void); #endif +#ifdef CONFIG_JTAG_CONSOLE +int drv_jtag_console_init (void); +#endif
#endif /* _DEVICES_H_ */