From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 73B81C33CAF for ; Thu, 16 Jan 2020 18:49:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4D5812072E for ; Thu, 16 Jan 2020 18:49:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579200586; bh=Kqk6fl6f5LB8HMHeUsBnSkg3ZQMA6NTi9LKibYodp1M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=tPSo7f7gJRbcOqi0Yv44j/IINvPdLfMA1yE9J7fI6T8DvPf9Ebovd3sHy6UeAAQSi UNJuPuXUO5nV/WTkxTEcIezMQ4k2dN3OkVQTmNdv2gHj1Hn5kmDrFP3bqqhD62piDh Hy5AyqMbR0Y3csKOLgsPw4t2at0gZSXlw9jfuOvE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389663AbgAPRJU (ORCPT ); Thu, 16 Jan 2020 12:09:20 -0500 Received: from mail.kernel.org ([198.145.29.99]:44708 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389635AbgAPRJP (ORCPT ); Thu, 16 Jan 2020 12:09:15 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7217021D56; Thu, 16 Jan 2020 17:09:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579194554; bh=Kqk6fl6f5LB8HMHeUsBnSkg3ZQMA6NTi9LKibYodp1M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aAbdnb4yE2Pz6f4szPh27+ZCQM3txynKywa5dHxd4APcz1TkUBqdNhSkB5jVRe4Xj 8N1w6Y1OjTlcePvhA6SrNNvVampeozlxJvWZvCcKkr/X3o06kOdJS9kCBp7zeeYWTz C6mQanpOAnMcFsrUCISIAO866Ab3mVCQ7U0Y9lFo= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Bryan O'Donoghue , Leonard Crestez , Srinivas Kandagatla , Greg Kroah-Hartman , Sasha Levin , linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 4.19 436/671] nvmem: imx-ocotp: Change TIMING calculation to u-boot algorithm Date: Thu, 16 Jan 2020 12:01:14 -0500 Message-Id: <20200116170509.12787-173-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200116170509.12787-1-sashal@kernel.org> References: <20200116170509.12787-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Bryan O'Donoghue [ Upstream commit 159dbaf57b2f4f67ecb59b2c87d071e45ed41d7e ] The RELAX field of the OCOTP block is turning out as a zero on i.MX8MM. This messes up the subsequent re-load of the fuse shadow registers. After some discussion with people @ NXP its clear we have missed a trick here in Linux. The OCOTP fuse programming time has a physical minimum 'burn time' that is not related to the ipg_clk. We need to define the RELAX, STROBE_READ and STROBE_PROG fields in terms of desired timings to allow for the burn-in to safely complete. Right now only the RELAX field is calculated in terms of an absolute time and we are ending up with a value of zero. This patch inherits the u-boot timings for the OCOTP_TIMING calculation on the i.MX6 and i.MX8. Those timings are known to work and critically specify values such as STROBE_PROG as a minimum timing. Fixes: 0642bac7da42 ("nvmem: imx-ocotp: add write support") Signed-off-by: Bryan O'Donoghue Suggested-by: Leonard Crestez Reviewed-by: Leonard Crestez Signed-off-by: Srinivas Kandagatla Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/nvmem/imx-ocotp.c | 36 ++++++++++++++++++++++++++++++++---- 1 file changed, 32 insertions(+), 4 deletions(-) diff --git a/drivers/nvmem/imx-ocotp.c b/drivers/nvmem/imx-ocotp.c index 04421a73f74a..09281aca86c2 100644 --- a/drivers/nvmem/imx-ocotp.c +++ b/drivers/nvmem/imx-ocotp.c @@ -50,7 +50,9 @@ #define IMX_OCOTP_BM_CTRL_ERROR 0x00000200 #define IMX_OCOTP_BM_CTRL_REL_SHADOWS 0x00000400 -#define DEF_RELAX 20 /* > 16.5ns */ +#define TIMING_STROBE_PROG_US 10 /* Min time to blow a fuse */ +#define TIMING_STROBE_READ_NS 37 /* Min time before read */ +#define TIMING_RELAX_NS 17 #define DEF_FSOURCE 1001 /* > 1000 ns */ #define DEF_STROBE_PROG 10000 /* IPG clocks */ #define IMX_OCOTP_WR_UNLOCK 0x3E770000 @@ -182,12 +184,38 @@ static void imx_ocotp_set_imx6_timing(struct ocotp_priv *priv) * fields with timing values to match the current frequency of the * ipg_clk. OTP writes will work at maximum bus frequencies as long * as the HW_OCOTP_TIMING parameters are set correctly. + * + * Note: there are minimum timings required to ensure an OTP fuse burns + * correctly that are independent of the ipg_clk. Those values are not + * formally documented anywhere however, working from the minimum + * timings given in u-boot we can say: + * + * - Minimum STROBE_PROG time is 10 microseconds. Intuitively 10 + * microseconds feels about right as representative of a minimum time + * to physically burn out a fuse. + * + * - Minimum STROBE_READ i.e. the time to wait post OTP fuse burn before + * performing another read is 37 nanoseconds + * + * - Minimum RELAX timing is 17 nanoseconds. This final RELAX minimum + * timing is not entirely clear the documentation says "This + * count value specifies the time to add to all default timing + * parameters other than the Tpgm and Trd. It is given in number + * of ipg_clk periods." where Tpgm and Trd refer to STROBE_PROG + * and STROBE_READ respectively. What the other timing parameters + * are though, is not specified. Experience shows a zero RELAX + * value will mess up a re-load of the shadow registers post OTP + * burn. */ clk_rate = clk_get_rate(priv->clk); - relax = clk_rate / (1000000000 / DEF_RELAX) - 1; - strobe_prog = clk_rate / (1000000000 / 10000) + 2 * (DEF_RELAX + 1) - 1; - strobe_read = clk_rate / (1000000000 / 40) + 2 * (DEF_RELAX + 1) - 1; + relax = DIV_ROUND_UP(clk_rate * TIMING_RELAX_NS, 1000000000) - 1; + strobe_read = DIV_ROUND_UP(clk_rate * TIMING_STROBE_READ_NS, + 1000000000); + strobe_read += 2 * (relax + 1) - 1; + strobe_prog = DIV_ROUND_CLOSEST(clk_rate * TIMING_STROBE_PROG_US, + 1000000); + strobe_prog += 2 * (relax + 1) - 1; timing = readl(priv->base + IMX_OCOTP_ADDR_TIMING) & 0x0FC00000; timing |= strobe_prog & 0x00000FFF; -- 2.20.1