This patch adds support for console output in the event of a panic() before the console is inited. The main purpose of this is to deal with a very early panic() which would otherwise cause a silent hang.

A new board_pre_console_panic() function is added to the board API. If provided by the board it will be called in the event of a panic before the console is ready. This function should turn on all available UARTs and output the string (plus a newline) if it possibly can.

Signed-off-by: Simon Glass sjg@chromium.org ---

README | 34 ++++++++++++++++++++++++++++++++++ include/common.h | 8 ++++++++ lib/vsprintf.c | 25 +++++++++++++++++++++++-- 3 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/README b/README index 84757a5..38ce52a 100644 --- a/README +++ b/README @@ -638,6 +638,40 @@ The following options need to be configured: 'Sane' compilers will generate smaller code if CONFIG_PRE_CON_BUF_SZ is a power of 2

+- Pre-console panic(): + Prior to the console being initialised, console output is + normally silently discarded. This can be annoying if a + panic() happens in this time. One reason for this might be + that you have CONFIG_OF_CONTROL defined but have not + provided a valid device tree for U-Boot. In general U-Boot's + console code cannot resolve this problem, since the console + has not been set up, and it may not be known which UART is + the console anyway (for example if this information is in + the device tree). + + The solution is to define a function called + board_pre_console_panic() for your board, which alerts the + user however it can. Hopefuly this will involve displaying + a message on available UARTs, or perhaps at least flashing + an LED. The function should be very careful to only output + to UARTs that are known to be unused for peripheral + interfaces, and change GPIOs that will have no ill effect + on the board. That said, it is fine to do something + destructive that will prevent the board from continuing to + boot, since it isn't going to... + + The function will need to output serial data directly, + since the console code is not functional yet. Note that if + the panic happens early enough, then it is possible that + board_init_f() (or even arch_cpu_init() on ARM) has not + been called yet. You should init all clocks, GPIOs, etc. + that are needed to get the string out. Baud rates will need + to default to something sensible. + + If your function returns, then the normal panic processing + will occur (it will either hang or reset depending on + CONFIG_PANIC_HANG). + - Safe printf() functions Define CONFIG_SYS_VSNPRINTF to compile in safe versions of the printf() functions. These are defined in diff --git a/include/common.h b/include/common.h index b588410..9db3a6a 100644 --- a/include/common.h +++ b/include/common.h @@ -285,6 +285,14 @@ extern ulong monitor_flash_len; int mac_read_from_eeprom(void); extern u8 _binary_dt_dtb_start[]; /* embedded device tree blob */

+/* + * Called during a panic() when no console is available. The board should do + * its best to get a message to the user any way it can. This function should + * return if it can, in which case the system will either hang or reset. + * See panic(). + */ +void board_pre_console_panic(const char *str); + /* common/flash.c */ void flash_perror (int);

diff --git a/lib/vsprintf.c b/lib/vsprintf.c index e38a4b7..a478ff5ab 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -33,6 +33,9 @@ const char hex_asc[] = "0123456789abcdef"; #define hex_asc_lo(x) hex_asc[((x) & 0x0f)] #define hex_asc_hi(x) hex_asc[((x) & 0xf0) >> 4]

+DECLARE_GLOBAL_DATA_PTR; + + static inline char *pack_hex_byte(char *buf, u8 byte) { *buf++ = hex_asc_hi(byte); @@ -777,13 +780,31 @@ int sprintf(char * buf, const char *fmt, ...) return i; }

+/* Provide a default function for when no console is available */ +static void __board_pre_console_panic(const char *msg) +{ + /* Just return since we can't access the console */ +} + +void board_pre_console_panic(const char *msg) __attribute__((weak, + alias("__board_pre_console_panic"))); + void panic(const char *fmt, ...) { + char str[CONFIG_SYS_PBSIZE]; va_list args; + va_start(args, fmt); - vprintf(fmt, args); - putc('\n'); + vsnprintf(str, sizeof(str), fmt, args); va_end(args); + + if (gd->have_console) { + puts(str); + putc('\n'); + } else { + board_pre_console_panic(str); + } + #if defined (CONFIG_PANIC_HANG) hang(); #else

This function is made available to board which want to display a message when a panic() occurs before the console is set up. This would otherwise result in a silent hang or reboot.

Boards should call tegra_pre_console_panic() and pass the UARTs which are available and safe for a message, as well as the selected clock and serial multiplier values. Defaults are available as CONFIG_DEFAULT_NS16550_CLK and CONFIG_DEFAULT_NS16550_MULT.

Signed-off-by: Simon Glass sjg@chromium.org ---

arch/arm/cpu/armv7/tegra2/board.c | 48 ++++++++++++++++++++++++++++++ arch/arm/include/asm/arch-tegra2/board.h | 13 ++++++++ include/configs/tegra2-common.h | 4 ++ 3 files changed, 65 insertions(+), 0 deletions(-)

diff --git a/arch/arm/cpu/armv7/tegra2/board.c b/arch/arm/cpu/armv7/tegra2/board.c index c9a7520..54963d0 100644 --- a/arch/arm/cpu/armv7/tegra2/board.c +++ b/arch/arm/cpu/armv7/tegra2/board.c @@ -22,6 +22,7 @@ */

#include <common.h> +#include <ns16550.h> #include <asm/io.h> #include "ap20.h" #include <asm/arch/board.h> @@ -137,3 +138,50 @@ void enable_caches(void) dcache_enable(); } #endif + +/* + * Possible UART locations: we ignore UARTC at 0x70006200 and UARTE at + * 0x70006400, since we don't have code to init them + */ +static const u32 uart_reg_addr[TEGRA_UART_COUNT] = { + NV_PA_APB_UARTA_BASE, + NV_PA_APB_UARTB_BASE, + 0, + NV_PA_APB_UARTD_BASE, +}; + +void tegra_pre_console_panic(int uart_ids, unsigned clock_freq, + unsigned multiplier, const char *str) +{ + int baudrate, divisor; + int i; + + /* Enable all permitted UARTs */ + tegra_setup_uarts(uart_ids); + + /* + * Now send the string out all the selected UARTs. We don't try all + * possible configurations, but this could be added if required. + */ + baudrate = CONFIG_BAUDRATE; + divisor = (clock_freq + (baudrate * (multiplier / 2))) / + (multiplier * baudrate); + + for (i = 0; i < TEGRA_UART_COUNT; i++) { + if (uart_ids & (1 << i)) { + NS16550_t regs = (NS16550_t)uart_reg_addr[i]; + const char *s; + + if (!regs) + continue; + NS16550_init(regs, divisor); + for (s = str; *s; s++) { + NS16550_putc(regs, *s); + if (*s == '\n') + NS16550_putc(regs, '\r'); + } + NS16550_putc(regs, '\n'); + NS16550_putc(regs, '\r'); + } + } +} diff --git a/arch/arm/include/asm/arch-tegra2/board.h b/arch/arm/include/asm/arch-tegra2/board.h index fb88517..fd2489f 100644 --- a/arch/arm/include/asm/arch-tegra2/board.h +++ b/arch/arm/include/asm/arch-tegra2/board.h @@ -41,6 +41,19 @@ enum { */ void tegra_setup_uarts(int uart_ids);

+/** + * Display a panic message on selected UARTs. + * + * This is called when we have no console yet but have hit a panic(). It + * is normally called from board_pre_console_panic(), which passes in the + * UARTs that we are permitted to output to. + * + * We display a message on each UART in the hope that one will reach the + * user. + */ +void tegra_pre_console_panic(int uart_ids, unsigned clock_freq, + unsigned multiplier, const char *str); + /* Setup UARTs for the board according to the selected config */ void board_init_uart_f(void);

diff --git a/include/configs/tegra2-common.h b/include/configs/tegra2-common.h index 837f859..14d7602 100644 --- a/include/configs/tegra2-common.h +++ b/include/configs/tegra2-common.h @@ -84,6 +84,10 @@ #define CONFIG_SYS_BAUDRATE_TABLE {4800, 9600, 19200, 38400, 57600,\ 115200}

+/* Default serial clock and multiplier */ +#define CONFIG_DEFAULT_NS16550_CLK V_NS16550_CLK +#define CONFIG_DEFAULT_NS16550_MULT 16 + /* * This parameter affects a TXFILLTUNING field that controls how much data is * sent to the latency fifo before it is sent to the wire. Without this