From patchwork Thu Aug 24 19:20:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Kaiser X-Patchwork-Id: 716637 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93D41EE49A6 for ; Thu, 24 Aug 2023 19:24:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243181AbjHXTYJ (ORCPT ); Thu, 24 Aug 2023 15:24:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234088AbjHXTXu (ORCPT ); Thu, 24 Aug 2023 15:23:50 -0400 Received: from viti.kaiser.cx (viti.kaiser.cx [IPv6:2a01:238:43fe:e600:cd0c:bd4a:7a3:8e9f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF1951BDF; Thu, 24 Aug 2023 12:23:48 -0700 (PDT) Received: from dslb-188-097-211-187.188.097.pools.vodafone-ip.de ([188.97.211.187] helo=martin-debian-2.paytec.ch) by viti.kaiser.cx with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1qZFvl-00036P-Io; Thu, 24 Aug 2023 21:23:45 +0200 From: Martin Kaiser To: Herbert Xu Cc: Alexander Stein , linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Martin Kaiser Subject: [PATCH v2 5/6] hwrng: imx-rngc - use polling for initial seed Date: Thu, 24 Aug 2023 21:20:58 +0200 Message-Id: <20230824192059.1569591-6-martin@kaiser.cx> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230824192059.1569591-1-martin@kaiser.cx> References: <20230824192059.1569591-1-martin@kaiser.cx> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Use polling instead of interrupt + completion to wait until the initial seed was calculated. This should take about 30ms. Call readl_poll_timeout and set the poll interval to the recommended maximum of 20ms. readl_poll_timeout uses usleep_range, this is based on a hrtimer. The task will we put to sleep while waiting, this does not burn CPU cycles by waiting in the foreground. Signed-off-by: Martin Kaiser --- v2: - use shorter timeout and polling interval - readl_poll_timeout does not wait in the foreground drivers/char/hw_random/imx-rngc.c | 27 +++++++++------------------ 1 file changed, 9 insertions(+), 18 deletions(-) diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c index c2582673427d..3a3f0f923bed 100644 --- a/drivers/char/hw_random/imx-rngc.c +++ b/drivers/char/hw_random/imx-rngc.c @@ -166,34 +166,29 @@ static irqreturn_t imx_rngc_irq(int irq, void *priv) static int imx_rngc_init(struct hwrng *rng) { struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng); - u32 cmd, ctrl; + u32 cmd, ctrl, status, err_reg; int ret; /* clear error */ cmd = readl(rngc->base + RNGC_COMMAND); writel(cmd | RNGC_CMD_CLR_ERR, rngc->base + RNGC_COMMAND); - imx_rngc_irq_unmask(rngc); - /* create seed, repeat while there is some statistical error */ do { /* seed creation */ cmd = readl(rngc->base + RNGC_COMMAND); writel(cmd | RNGC_CMD_SEED, rngc->base + RNGC_COMMAND); - ret = wait_for_completion_timeout(&rngc->rng_op_done, - usecs_to_jiffies(RNGC_SEED_TIMEOUT)); - if (!ret) { - ret = -ETIMEDOUT; - goto err; - } + ret = readl_poll_timeout(rngc->base + RNGC_STATUS, status, + status & RNGC_STATUS_SEED_DONE, 20000, RNGC_SEED_TIMEOUT); + if (ret < 0) + return ret; - } while (rngc->err_reg == RNGC_ERROR_STATUS_STAT_ERR); + err_reg = readl(rngc->base + RNGC_ERROR); + } while (err_reg == RNGC_ERROR_STATUS_STAT_ERR); - if (rngc->err_reg) { - ret = -EIO; - goto err; - } + if (err_reg) + return -EIO; /* * enable automatic seeding, the rngc creates a new seed automatically @@ -209,10 +204,6 @@ static int imx_rngc_init(struct hwrng *rng) * we mask the interrupt ourselves if we return an error */ return 0; - -err: - imx_rngc_irq_mask_clear(rngc); - return ret; } static void imx_rngc_cleanup(struct hwrng *rng)