Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755314AbaDUVxt (ORCPT ); Mon, 21 Apr 2014 17:53:49 -0400 Received: from mail-yh0-f47.google.com ([209.85.213.47]:48795 "EHLO mail-yh0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755258AbaDUVxm (ORCPT ); Mon, 21 Apr 2014 17:53:42 -0400 From: Alex Elder To: bcm@fixthebug.org, mporter@linaro.org Cc: bcm-kernel-feedback-list@broadcom.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 09/10] ARM: bcm: rewrite commentary for bcm_kona_do_smc() Date: Mon, 21 Apr 2014 16:53:10 -0500 Message-Id: <1398117191-2433-10-git-send-email-elder@linaro.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1398117191-2433-1-git-send-email-elder@linaro.org> References: <1398117191-2433-1-git-send-email-elder@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The block of comments in bcm_kona_do_smc() are somewhat confusing. This patch attempts to clarify what's going on. Signed-off-by: Alex Elder Reviewed-by: Tim Kryger Reviewed-by: Markus Mayer Reviewed-by: Matt Porter --- arch/arm/mach-bcm/bcm_kona_smc.c | 38 ++++++++++++++++++++++++++++---------- 1 file changed, 28 insertions(+), 10 deletions(-) diff --git a/arch/arm/mach-bcm/bcm_kona_smc.c b/arch/arm/mach-bcm/bcm_kona_smc.c index cc81c86..a55a7ec 100644 --- a/arch/arm/mach-bcm/bcm_kona_smc.c +++ b/arch/arm/mach-bcm/bcm_kona_smc.c @@ -77,16 +77,34 @@ int __init bcm_kona_smc_init(void) } /* - * Since interrupts are disabled in the open mode, we must keep - * interrupts disabled in secure mode by setting R5=0x3. If interrupts - * are enabled in open mode, we can set R5=0x0 to allow interrupts in - * secure mode. If we did this, the secure monitor would return back - * control to the open mode to handle the interrupt prior to completing - * the secure service. If this happened, R12 would not be - * SEC_EXIT_NORMAL and we would need to call SMC again after resetting - * R5 (it gets clobbered by the secure monitor) and setting R4 to - * SSAPI_RET_FROM_INT_SERV to indicate that we want the secure monitor - * to finish up the previous uncompleted secure service. + * int bcm_kona_do_smc(u32 service_id, u32 buffer_addr) + * + * Only core 0 can run the secure monitor code. If an "smc" request + * is initiated on a different core it must be redirected to core 0 + * for execution. We rely on the caller to handle this. + * + * Each "smc" request supplies a service id and the address of a + * buffer containing parameters related to the service to be + * performed. A flags value defines the behavior of the level 2 + * cache and interrupt handling while the secure monitor executes. + * + * Parameters to the "smc" request are passed in r4-r6 as follows: + * r4 service id + * r5 flags (SEC_ROM_*) + * r6 physical address of buffer with other parameters + * + * Execution of an "smc" request produces two distinct results. + * + * First, the secure monitor call itself (regardless of the specific + * service request) can succeed, or can produce an error. When an + * "smc" request completes this value is found in r12; it should + * always be SEC_EXIT_NORMAL. + * + * In addition, the particular service performed produces a result. + * The values that should be expected depend on the service. We + * therefore return this value to the caller, so it can handle the + * request result appropriately. This result value is found in r0 + * when the "smc" request completes. */ static int bcm_kona_do_smc(u32 service_id, u32 buffer_phys) { -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/