Commit 9715efb8 authored by Linus Walleij's avatar Linus Walleij Committed by Russell King
Browse files

ARM: 6984/1: enhance TCM robustness 



The PB11MPCore reports "3" DTCM banks, but anything above 2 is an
"undefined" value, so push this to become 0. Further add some checks
if code is compiled to TCM even if there is no D/ITCM present in the
system, and if we can really fit the compiled code. We don't do the
BUG() since it's not helpful, it's better to deal with non-present
TCM dynamically. If there is nothing compiled to the TCM and no TCM
is detected, it will now just shut up even if TCM support is enabled.

Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent e4b63810

arch/arm/kernel/tcm.c

+39 −8
Original line number Diff line number Diff line
@@ -134,6 +134,10 @@ static int __init setup_tcm_bank(u8 type, u8 bank, u8 banks, 
			(tcm_region & 1) ? "" : "not ");

	}



	/* Not much fun you can do with a size 0 bank */

	if (tcm_size == 0)

		return 0;



	/* Force move the TCM bank to where we want it, enable */

	tcm_region = *offset | (tcm_region & 0x00000ffeU) | 1;
@@ -165,12 +169,20 @@ void __init tcm_init(void) 
	u32 tcm_status = read_cpuid_tcmstatus();

	u8 dtcm_banks = (tcm_status >> 16) & 0x03;

	u8 itcm_banks = (tcm_status & 0x03);

	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;



	/* 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++) {
@@ -178,6 +190,13 @@ void __init tcm_init(void) 
			if (ret)

				return;

		}

		/* 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;

		}

		dtcm_res.end = dtcm_end - 1;

		request_resource(&iomem_resource, &dtcm_res);

		dtcm_iomap[0].length = dtcm_end - DTCM_OFFSET;
@@ -186,12 +205,15 @@ void __init tcm_init(void) 
		start = &__sdtcm_data;

		end   = &__edtcm_data;

		ram   = &__dtcm_start;

		/* This means you compiled more code than fits into DTCM */

		BUG_ON((end - start) > (dtcm_end - DTCM_OFFSET));

		memcpy(start, ram, (end-start));

		pr_debug("CPU DTCM: copied data from %p - %p\n", start, end);

		memcpy(start, ram, dtcm_code_sz);

		pr_debug("CPU DTCM: copied data from %p - %p\n",

			 start, end);

	} 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++) {
@@ -199,6 +221,13 @@ void __init tcm_init(void) 
			if (ret)

				return;

		}

		/* 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));

			return;

		}

		itcm_res.end = itcm_end - 1;

		request_resource(&iomem_resource, &itcm_res);

		itcm_iomap[0].length = itcm_end - ITCM_OFFSET;
@@ -207,10 +236,12 @@ void __init tcm_init(void) 
		start = &__sitcm_text;

		end   = &__eitcm_text;

		ram   = &__itcm_start;

		/* This means you compiled more code than fits into ITCM */

		BUG_ON((end - start) > (itcm_end - ITCM_OFFSET));

		memcpy(start, ram, (end-start));

		pr_debug("CPU ITCM: copied code from %p - %p\n", start, end);

		memcpy(start, ram, itcm_code_sz);

		pr_debug("CPU ITCM: copied code from %p - %p\n",

			 start, end);

	} 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);

	}

}

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