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-rw-r--r--drivers/console/aarch64/skeleton_console.S170
1 files changed, 170 insertions, 0 deletions
diff --git a/drivers/console/aarch64/skeleton_console.S b/drivers/console/aarch64/skeleton_console.S
new file mode 100644
index 0000000..7ea2eec
--- /dev/null
+++ b/drivers/console/aarch64/skeleton_console.S
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+/*
+ * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#include <asm_macros.S>
+#include <console_macros.S>
+
+ /*
+ * This file contains a skeleton console driver that can be used as a
+ * 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* ensure 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.)
+ */
+
+ .globl console_xxx_register
+ .globl console_xxx_putc
+ .globl console_xxx_getc
+ .globl console_xxx_flush
+
+ /* -----------------------------------------------
+ * 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_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_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).
+ * If any of the argument is unspecified, then the corresponding
+ * entry in console_t is set to 0.
+ */
+ finish_console_register xxx putc=1, getc=1, flush=1
+
+ /* Jump here if hardware init fails or parameters are invalid. */
+register_fail:
+ mov w0, #0
+ ret
+endfunc console_xxx_register
+
+ /* --------------------------------------------------------
+ * 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 - pointer to console_t struct
+ * Out: w0 - printed character on success, < 0 on error.
+ * Clobber list : x0, x1, x2
+ * --------------------------------------------------------
+ */
+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_BASE]
+
+ /*
+ * Write w0 to hardware.
+ */
+
+ ret
+
+ /* Jump here if output fails for any reason. */
+putc_error:
+ mov w0, #-1
+ ret
+endfunc console_xxx_putc
+
+ /* ---------------------------------------------
+ * int console_xxx_getc(console_xxx_t *console)
+ * Function to get a character from the console.
+ * 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_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_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, #-2 /* may pick error codes between -2 and -127 */
+ ret
+endfunc console_xxx_getc
+
+ /* ---------------------------------------------
+ * void console_xxx_flush(console_xxx_t *console)
+ * Function to force a write of all buffered
+ * data that hasn't been output.
+ * In : x0 - pointer to console_xxx_t struct
+ * Out: void
+ * Clobber list : x0, x1, x2, x3, x4, x5
+ * ---------------------------------------------
+ */
+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_BASE]
+
+ /*
+ * Flush all remaining output from hardware FIFOs. Do not return until
+ * all data has been flushed or there was an unrecoverable error.
+ */
+
+ ret
+endfunc console_xxx_flush