void __init tcm_init()

in kernel/tcm.c [256:377]

• 91 lines of code
• 19 McCabe index (conditional complexity)

void __init tcm_init(void)
{
	u32 tcm_status;
	u8 dtcm_banks;
	u8 itcm_banks;
	size_t dtcm_code_sz = &__edtcm_data - &__sdtcm_data;
	size_t itcm_code_sz = &__eitcm_text - &__sitcm_text;
	char *start;
	char *end;
	char *ram;
	int ret;
	int i;

	/*
	 * Prior to ARMv5 there is no TCM, and trying to read the status
	 * register will hang the processor.
	 */
	if (cpu_architecture() < CPU_ARCH_ARMv5) {
		if (dtcm_code_sz || itcm_code_sz)
			pr_info("CPU TCM: %u bytes of DTCM and %u bytes of "
				"ITCM code compiled in, but no TCM present "
				"in pre-v5 CPU\n", dtcm_code_sz, itcm_code_sz);
		return;
	}

	tcm_status = read_cpuid_tcmstatus();

	/*
	 * This code only supports v6-compatible TCMTR implementations.
	 */
	if (tcm_status & TCMTR_FORMAT_MASK)
		return;

	dtcm_banks = (tcm_status >> 16) & 0x03;
	itcm_banks = (tcm_status & 0x03);

	register_undef_hook(&tcm_hook);

	/* Values greater than 2 for D/ITCM banks are "reserved" */
	if (dtcm_banks > 2)
		dtcm_banks = 0;
	if (itcm_banks > 2)
		itcm_banks = 0;

	/* Setup DTCM if present */
	if (dtcm_banks > 0) {
		for (i = 0; i < dtcm_banks; i++) {
			ret = setup_tcm_bank(0, i, dtcm_banks, &dtcm_end);
			if (ret)
				goto unregister;
		}
		/* This means you compiled more code than fits into DTCM */
		if (dtcm_code_sz > (dtcm_end - DTCM_OFFSET)) {
			pr_info("CPU DTCM: %u bytes of code compiled to "
				"DTCM but only %lu bytes of DTCM present\n",
				dtcm_code_sz, (dtcm_end - DTCM_OFFSET));
			goto no_dtcm;
		}
		/*
		 * This means that the DTCM sizes were 0 or the DTCM banks
		 * were inaccessible due to TrustZone configuration.
		 */
		if (!(dtcm_end - DTCM_OFFSET))
			goto no_dtcm;
		dtcm_res.end = dtcm_end - 1;
		request_resource(&iomem_resource, &dtcm_res);
		dtcm_iomap[0].length = dtcm_end - DTCM_OFFSET;
		iotable_init(dtcm_iomap, 1);
		/* Copy data from RAM to DTCM */
		start = &__sdtcm_data;
		end   = &__edtcm_data;
		ram   = &__dtcm_start;
		memcpy(start, ram, dtcm_code_sz);
		pr_debug("CPU DTCM: copied data from %p - %p\n",
			 start, end);
		dtcm_present = true;
	} else if (dtcm_code_sz) {
		pr_info("CPU DTCM: %u bytes of code compiled to DTCM but no "
			"DTCM banks present in CPU\n", dtcm_code_sz);
	}

no_dtcm:
	/* Setup ITCM if present */
	if (itcm_banks > 0) {
		for (i = 0; i < itcm_banks; i++) {
			ret = setup_tcm_bank(1, i, itcm_banks, &itcm_end);
			if (ret)
				goto unregister;
		}
		/* This means you compiled more code than fits into ITCM */
		if (itcm_code_sz > (itcm_end - ITCM_OFFSET)) {
			pr_info("CPU ITCM: %u bytes of code compiled to "
				"ITCM but only %lu bytes of ITCM present\n",
				itcm_code_sz, (itcm_end - ITCM_OFFSET));
			goto unregister;
		}
		/*
		 * This means that the ITCM sizes were 0 or the ITCM banks
		 * were inaccessible due to TrustZone configuration.
		 */
		if (!(itcm_end - ITCM_OFFSET))
			goto unregister;
		itcm_res.end = itcm_end - 1;
		request_resource(&iomem_resource, &itcm_res);
		itcm_iomap[0].length = itcm_end - ITCM_OFFSET;
		iotable_init(itcm_iomap, 1);
		/* Copy code from RAM to ITCM */
		start = &__sitcm_text;
		end   = &__eitcm_text;
		ram   = &__itcm_start;
		memcpy(start, ram, itcm_code_sz);
		pr_debug("CPU ITCM: copied code from %p - %p\n",
			 start, end);
		itcm_present = true;
	} else if (itcm_code_sz) {
		pr_info("CPU ITCM: %u bytes of code compiled to ITCM but no "
			"ITCM banks present in CPU\n", itcm_code_sz);
	}

unregister:
	unregister_undef_hook(&tcm_hook);
}