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      1 // SPDX-License-Identifier: GPL-2.0+
      2 /**
      3  * Copyright (c) 2017 Google, Inc
      4  */
      5 
      6 #include <common.h>
      7 #include <asm/arch/bootrom.h>
      8 #include <asm/arch/boot_mode.h>
      9 #include <asm/io.h>
     10 #include <asm/setjmp.h>
     11 #include <asm/system.h>
     12 
     13 /*
     14  * Force the jmp_buf to the data-section, as .bss will not be valid
     15  * when save_boot_params is invoked.
     16  */
     17 static jmp_buf brom_ctx __section(".data");
     18 
     19 static void _back_to_bootrom(enum rockchip_bootrom_cmd brom_cmd)
     20 {
     21 	longjmp(brom_ctx, brom_cmd);
     22 }
     23 
     24 void back_to_bootrom(enum rockchip_bootrom_cmd brom_cmd)
     25 {
     26 #if CONFIG_IS_ENABLED(LIBCOMMON_SUPPORT)
     27 	puts("Returning to boot ROM...\n");
     28 #endif
     29 	_back_to_bootrom(brom_cmd);
     30 }
     31 
     32 /*
     33  * we back to bootrom download mode if get a
     34  * BOOT_BROM_DOWNLOAD flag in boot mode register
     35  *
     36  * note: the boot mode register is configured by
     37  * application(next stage bootloader, kernel, etc),
     38  * and the bootrom never check this register, so we need
     39  * to check it and back to bootrom at very early bootstage(before
     40  * some basic configurations(such as interrupts) been
     41  * changed by TPL/SPL, as the bootrom download operation
     42  * relys on many default settings(such as interrupts) by
     43  * it's self.
     44  */
     45 static bool check_back_to_brom_dnl_flag(void)
     46 {
     47 	u32 boot_mode;
     48 
     49 	if (CONFIG_ROCKCHIP_BOOT_MODE_REG) {
     50 		boot_mode = readl(CONFIG_ROCKCHIP_BOOT_MODE_REG);
     51 		if (boot_mode == BOOT_BROM_DOWNLOAD) {
     52 			writel(0, CONFIG_ROCKCHIP_BOOT_MODE_REG);
     53 			return true;
     54 		}
     55 	}
     56 
     57 	return false;
     58 }
     59 
     60 /*
     61  * All Rockchip BROM implementations enter with a valid stack-pointer,
     62  * so this can safely be implemented in C (providing a single
     63  * implementation both for ARMv7 and AArch64).
     64  */
     65 int save_boot_params(void)
     66 {
     67 	int  ret = setjmp(brom_ctx);
     68 
     69 	switch (ret) {
     70 	case 0:
     71 		if (check_back_to_brom_dnl_flag())
     72 			_back_to_bootrom(BROM_BOOT_ENTER_DNL);
     73 		/*
     74 		 * This is the initial pass through this function
     75 		 * (i.e. saving the context), setjmp just setup up the
     76 		 * brom_ctx: transfer back into the startup-code at
     77 		 * 'save_boot_params_ret' and let the compiler know
     78 		 * that this will not return.
     79 		 */
     80 		save_boot_params_ret();
     81 		while (true)
     82 			/* does not return */;
     83 		break;
     84 
     85 	case BROM_BOOT_NEXTSTAGE:
     86 		/*
     87 		 * To instruct the BROM to boot the next stage, we
     88 		 * need to return 0 to it: i.e. we need to rewrite
     89 		 * the return code once more.
     90 		 */
     91 		ret = 0;
     92 		break;
     93 	case BROM_BOOT_ENTER_DNL:
     94 		/*
     95 		 * A non-zero return value will instruct the BROM enter
     96 		 * download mode.
     97 		 */
     98 		ret = 1;
     99 		break;
    100 	default:
    101 #if CONFIG_IS_ENABLED(LIBCOMMON_SUPPORT)
    102 		puts("FATAL: unexpected command to back_to_bootrom()\n");
    103 #endif
    104 		hang();
    105 	};
    106 
    107 	return ret;
    108 }
    109