diff options
Diffstat (limited to 'drivers/console/aarch64/skeleton_console.S')
| -rw-r--r-- | drivers/console/aarch64/skeleton_console.S | 184 |
1 files changed, 128 insertions, 56 deletions
diff --git a/drivers/console/aarch64/skeleton_console.S b/drivers/console/aarch64/skeleton_console.S index 9db6157d..1b5d7393 100644 --- a/drivers/console/aarch64/skeleton_console.S +++ b/drivers/console/aarch64/skeleton_console.S @@ -4,99 +4,171 @@ * SPDX-License-Identifier: BSD-3-Clause */ #include <asm_macros.S> +#include <console_macros.S> /* - * This file contains a skeleton console implementation that can - * be used as basis for a real console implementation by platforms - * that do not contain PL011 hardware. + * This file contains a skeleton console driver that can be used as + * basis for a real console driver. Console drivers in Trusted Firmware + * can be instantiated multiple times. Each instance is described by a + * separate console_t structure which must be registered with the common + * console framework via console_register(). Console drivers should + * define a console_xxx_register() function that initializes a new + * console_t structure passed in from the caller and registers it after + * initializing the console hardware. Drivers may define their own + * structures extending console_t to store private driver information. + * Console drivers *MUST* take care that the console callbacks they + * implement only change registers allowed in the clobber lists defined + * in this file. (Note that in addition to the explicit clobber lists, + * any function may always clobber the intra-procedure-call registers + * X16 and X17, but may never depend on them retaining their values + * across any function call.) + * Platforms using drivers based on this template need to enable + * MULTI_CONSOLE_API := 1 in their platform.mk. */ - .globl console_core_init - .globl console_core_putc - .globl console_core_getc - .globl console_core_flush + .globl console_xxx_register + .globl console_xxx_putc + .globl console_xxx_getc + .globl console_xxx_flush /* ----------------------------------------------- - * int console_core_init(uintptr_t base_addr, - * unsigned int uart_clk, unsigned int baud_rate) - * Function to initialize the console without a - * C Runtime to print debug information. This - * function will be accessed by console_init and - * crash reporting. - * In: x0 - console base address - * w1 - Uart clock in Hz - * w2 - Baud rate - * Out: return 1 on success else 0 on error - * Clobber list : x1, x2 + * int console_xxx_register(console_xxx_t *console, + * ...additional parameters as desired...) + * Function to initialize and register the console. + * The caller needs to pass an empty console_xxx_t + * structure in which *MUST* be allocated in + * persistent memory (e.g. a global or static local + * variable, *NOT* on the stack). + * In : x0 - pointer to empty console_t structure + * x1 through x7: additional parameters as desired + * Out: x0 - 1 on success, 0 on error + * Clobber list : x0 - x7 * ----------------------------------------------- */ -func console_core_init - /* Check the input base address */ - cbz x0, core_init_fail - /* Check baud rate and uart clock for sanity */ - cbz w1, core_init_fail - cbz w2, core_init_fail - /* Insert implementation here */ - mov w0, #1 - ret -core_init_fail: - mov w0, wzr +func console_xxx_register + /* + * Store parameters (e.g. hardware base address) in driver-specific + * console_xxx_t structure field if they will need to be retrieved + * by later console callback (e.g. putc). + * Example: + */ + str x1, [x0, #CONSOLE_T_XXX_BASE] + str x2, [x0, #CONSOLE_T_XXX_SOME_OTHER_VALUE] + + /* + * Initialize console hardware, using x1 - x7 parameters as needed. + * Keep console_t pointer in x0 for later. + */ + + /* Macro to finish up registration and return (needs valid x0 + x30). */ + finish_console_register xxx + + /* Jump here if hardware init fails or parameters are invalid. */ +register_fail: + mov w0, #0 ret -endfunc console_core_init +endfunc console_xxx_register /* -------------------------------------------------------- - * int console_core_putc(int c, uintptr_t base_addr) + * int console_xxx_putc(int c, console_xxx_t *console) * Function to output a character over the console. It * returns the character printed on success or -1 on error. * In : w0 - character to be printed - * x1 - console base address - * Out : return -1 on error else return character. - * Clobber list : x2 + * x1 - pointer to console_t struct + * Out: w0 - printed character on success, < 0 on error. + * Clobber list : x0, x1, x2 * -------------------------------------------------------- */ -func console_core_putc - /* Check the input parameter */ - cbz x1, putc_error - /* Insert implementation here */ +func console_xxx_putc + /* + * Retrieve values we need (e.g. hardware base address) from + * console_xxx_t structure pointed to by x1. + * Example: + */ + ldr x1, [x1, #CONSOLE_T_XXX_BASE] + + /* + * Write w0 to hardware. + */ + ret + + /* Jump here if output fails for any reason. */ putc_error: mov w0, #-1 ret -endfunc console_core_putc +endfunc console_xxx_putc /* --------------------------------------------- - * int console_core_getc(uintptr_t base_addr) + * int console_xxx_getc(console_xxx_t *console) * Function to get a character from the console. - * It returns the character grabbed on success - * or -1 on error. - * In : x0 - console base address + * Even though console_getc() is blocking, this + * callback has to be non-blocking and always + * return immediately to allow polling multiple + * drivers concurrently. + * Returns the character grabbed on success, + * ERROR_NO_PENDING_CHAR if no character was + * available at this time, or any value + * between -2 and -127 if there was an error. + * In : x0 - pointer to console_t struct + * Out: w0 - character on success, + * ERROR_NO_PENDING_CHAR if no char, + * < -1 on error * Clobber list : x0, x1 * --------------------------------------------- */ -func console_core_getc - cbz x0, getc_error - /* Insert implementation here */ +func console_xxx_getc + /* + * Retrieve values we need (e.g. hardware base address) from + * console_xxx_t structure pointed to by x0. + * Example: + */ + ldr x1, [x0, #CONSOLE_T_XXX_BASE] + + /* + * Try to read character into w0 from hardware. + */ + ret + + /* Jump here if there is no character available at this time. */ +getc_no_char: + mov w0, #ERROR_NO_PENDING_CHAR + ret + + /* Jump here if there was any hardware error. */ getc_error: - mov w0, #-1 + mov w0, #-2 /* may pick error codes between -2 and -127 */ ret -endfunc console_core_getc +endfunc console_xxx_getc /* --------------------------------------------- - * int console_core_flush(uintptr_t base_addr) + * int console_xxx_flush(console_xxx_t *console) * Function to force a write of all buffered * data that hasn't been output. - * In : x0 - console base address - * Out : return -1 on error else return 0. - * Clobber list : x0, x1 + * In : x0 - pointer to console_xxx_t struct + * Out: w0 - 0 on success, < 0 on error + * Clobber list : x0, x1, x2, x3, x4, x5 * --------------------------------------------- */ -func console_core_flush - cbz x0, flush_error - /* Insert implementation here */ +func console_xxx_flush + /* + * Retrieve values we need (e.g. hardware base address) from + * console_xxx_t structure pointed to by x0. + * Example: + */ + ldr x1, [x0, #CONSOLE_T_XXX_BASE] + + /* + * Flush all remaining output from hardware FIFOs. Do not return until + * all data has been flushed or there was an unrecoverable error. + */ + mov w0, #0 ret + + /* Jump here if an unrecoverable error has been encountered. */ flush_error: mov w0, #-1 ret -endfunc console_core_flush +endfunc console_xxx_flush |