From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B1EE1490BF0; Wed, 19 Aug 2026 17:21:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787160146; cv=none; b=KZvFUnlMl4k0ccH7DKH9GZAcrMtS5DOZtsOiT2aX+Ma1b5bbfxxrCBQ+N9huZWMbtlhj8qf07swMkj5400jqmmCZEExUL2WgP1gZKwjaVrpAmNixwlJW5TXvXpBkbP95vN4sergH6rJiMoWz35h3WcOnEk0tR5QYbz7OK1SnWQ4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787160146; c=relaxed/simple; bh=rYb7DZgQfBqxfPpuD4UDQwovj6NApHGQ1oi2WDhbXwk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=PZSsudk7f6vy3vSoIqMjmUNbGMqLpwaDfgnMPSCXLeCDNR5UMdQ91R6rz+apo4tadUE+ycVrsr3aGOrmTVPc6Zxl3YfdfUXK+Jvdxk+fi0yTOZWRNHjJGKYRX+3CN3KA0lrbps8F8JFKVQ1BItuM6lyWgT5VyA4aehK50+RxkuE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com; spf=pass smtp.mailfrom=oss.qualcomm.com; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b=ZiM31O/z; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b="ZiM31O/z" Received: from pps.filterd (m0279864.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 67JF1DQS3869753; Wed, 19 Aug 2026 17:21:10 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=qcppdkim1; bh= 8aYKwHBrHJ7ICON2PeaqhELeeDCIpfPPCZRWsY8FU8Q=; b=ZiM31O/zYODK04yl uQGCKKV38kApds9jnsXBOs2jefHewgD8pq4TroQ5Qj1ogbxUG/yJ+A5arze7eQj/ QHXdOdSTfFRtDetqdzgbGoR/b73zEjEwcMydnTxAGsZ7V4AEhydXDfyTXJMFDCN0 mYPdoRVF6li4yBR0tzxks8duARlfzPaIfYxci+1/qhFEI8Ud1MSnqvLKiirrqoUM Ws+3rF79BaOl2mVWsERJCmhLV/rKEzaY11Uqm7tQbjAS/RvIp01OUwrjWYRBxa9Y nW+k1yWdrAD0io1Fve1dfySXrg8bsrAZM+KD9xay0eBxDVXFSKTCJJZOV5UBwe5o MF1rPw== Received: from apblrppmta01.qualcomm.com (blr-bdr-fw-01_GlobalNAT_AllZones-Outside.qualcomm.com [103.229.18.19]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 4g5ervgru5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 19 Aug 2026 17:21:10 +0000 (GMT) Received: from pps.filterd (APBLRPPMTA01.qualcomm.com [127.0.0.1]) by APBLRPPMTA01.qualcomm.com (8.18.1.7/8.18.1.7) with ESMTP id 67JHL6cK027988; Wed, 19 Aug 2026 17:21:06 GMT Received: from pps.reinject (localhost [127.0.0.1]) by APBLRPPMTA01.qualcomm.com (PPS) with ESMTP id 4g2h6kdd9s-1; Wed, 19 Aug 2026 17:21:06 +0000 (GMT) Received: from APBLRPPMTA01.qualcomm.com (APBLRPPMTA01.qualcomm.com [127.0.0.1]) by pps.reinject (8.18.1.12/8.18.1.12) with ESMTP id 67JHL5e6027937; Wed, 19 Aug 2026 17:21:06 GMT Received: from hu-ffaruque-hyd.qualcomm.com (hu-ffaruque-hyd.qualcomm.com [10.147.245.31]) by APBLRPPMTA01.qualcomm.com (PPS) with ESMTP id 67JHL5jC027916; Wed, 19 Aug 2026 17:21:06 +0000 (GMT) From: Faruque Ansari Date: Wed, 19 Aug 2026 22:50:44 +0530 Subject: [PATCH v2 2/4] power: reset: add PSCRR NVMEM recorder Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260819-pscrr-provider-v2-2-9072383e0f4d@oss.qualcomm.com> References: <20260819-pscrr-provider-v2-0-9072383e0f4d@oss.qualcomm.com> In-Reply-To: <20260819-pscrr-provider-v2-0-9072383e0f4d@oss.qualcomm.com> To: Oleksij Rempel , Pengutronix Kernel Team , Sebastian Reichel , Rob Herring , Krzysztof Kozlowski , Wim Van Sebroeck , Guenter Roeck , Benson Leung , Tzung-Bi Shih , Srinivas Kandagatla , Daniel Lezcano Cc: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-watchdog@vger.kernel.org, kernel@pengutronix.de, Liam Girdwood , Mark Brown , "Rafael J. Wysocki" , Zhang Rui , Lukasz Luba , =?utf-8?q?S=C3=B8ren_Andersen?= , Guenter Roeck , Matti Vaittinen , Ahmad Fatoum , Andrew Morton , avaneesh.dwivedi@oss.qualcomm.com, Umang Chheda , Faruque Ansari X-Mailer: b4 0.15.2 X-QCInternal: smtphost X-QCInternal: smtphost X-Proofpoint-GUID: RdCnegqbKrTNggyN9hoUDWuolx9lAmO4 X-Authority-Analysis: v=2.4 cv=VZ3H+lp9 c=1 sm=1 tr=0 ts=6a85e606 cx=c_pps a=Ou0eQOY4+eZoSc0qltEV5Q==:117 a=Ou0eQOY4+eZoSc0qltEV5Q==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=DJpcGTmdVt4CTyJn9g5Z:22 a=EUspDBNiAAAA:8 a=HK-LrPc_DGzbyERBICQA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODE5MDEzNCBTYWx0ZWRfX3CV+QklcOHL8 fi4fxik+zMT7sjDGxZDZAxmAiMhW+D8bKBkns8MoF4rPPMyNiW/Xf816+xAUM+vbLtYjYXUsxFQ io7AEgkojcPnjy7wAQaXMfkqs3evWjBEHilXGc5U2yhg1ZY8ZhhRJJl5eM8I1LC2Yg27dt6Kr1f FIr+rmi2mdoDEGTVmiUTXfCtWc9452pidHvheofpk3sF+nmvL0nW4woJfNyD5WfRrz9p+C8GUW+ O7isu2+hCplpxrRwfLa7BiF1phOFAGlY8jmNnNvYgmlr/DF6fCiCIbC2FM7kPorJ0iudQJJK1cJ POmaoxTDx+upRJhp0JKxXbl8QFNaWxyUcUUaZ0gxxTXuSPyvVFNpV6s+M4HVeo8W9INwsACX+Id Xt8QnwXSxV+vMIIPE89Ce892kzCVGVZJ4l68QqYHLcw/1DcnU7hVzZiaOWpG8HIJkJNzhiiuI/I sX9yFRdtcFxO0SL31Kw== X-Proofpoint-ORIG-GUID: RdCnegqbKrTNggyN9hoUDWuolx9lAmO4 X-Proofpoint-Spam-Info: AW1haW4tMjYwODE5MDEzNCBTYWx0ZWRfXwsWmohM5Ihjw Tf8xpFCAyimn9FJcpckqYeWfg9WxCyhWkNxas9pB//y+TSZCwHVWWxzC54SFljHqT2tNsYeH1Cb i98xMSciW5kpfRQLSv2p6vnspKlFQXk= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-19_04,2026-08-19_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 spamscore=0 adultscore=0 clxscore=1011 lowpriorityscore=0 phishscore=0 bulkscore=0 priorityscore=1501 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608190134 Record the power state change reason into a small NVMEM cell (an RTC scratch register or EEPROM) and read it back on the next boot, so the cause survives a power cycle. The cell is a plain nvmem consumer reference and the reason value is stored directly. Co-developed-by: Oleksij Rempel Signed-off-by: Oleksij Rempel Signed-off-by: Faruque Ansari --- drivers/power/reset/pscrr/Kconfig | 14 +++ drivers/power/reset/pscrr/Makefile | 1 + drivers/power/reset/pscrr/pscrr-nvmem.c | 154 ++++++++++++++++++++++++++++++++ 3 files changed, 169 insertions(+) diff --git a/drivers/power/reset/pscrr/Kconfig b/drivers/power/reset/pscrr/Kconfig index 72de82731b53..bfcf04b0c8f5 100644 --- a/drivers/power/reset/pscrr/Kconfig +++ b/drivers/power/reset/pscrr/Kconfig @@ -31,3 +31,17 @@ menuconfig PSCRR unless hardware provides the reset cause. If unsure, say N. + +if PSCRR + +config PSCRR_NVMEM + tristate "PSCRR NVMEM recorder provider" + depends on NVMEM + help + PSCRR recorder that stores the power state change reason in a + small NVMEM cell (such as an RTC scratch register) and reads it + back on the next boot, so the cause survives a power cycle. + + If unsure, say N. + +endif # PSCRR diff --git a/drivers/power/reset/pscrr/Makefile b/drivers/power/reset/pscrr/Makefile index e5530a858971..95c80c80c7da 100644 --- a/drivers/power/reset/pscrr/Makefile +++ b/drivers/power/reset/pscrr/Makefile @@ -1,2 +1,3 @@ # SPDX-License-Identifier: GPL-2.0 obj-$(CONFIG_PSCRR) += pscrr.o +obj-$(CONFIG_PSCRR_NVMEM) += pscrr-nvmem.o diff --git a/drivers/power/reset/pscrr/pscrr-nvmem.c b/drivers/power/reset/pscrr/pscrr-nvmem.c new file mode 100644 index 000000000000..1c3145c0d058 --- /dev/null +++ b/drivers/power/reset/pscrr/pscrr-nvmem.c @@ -0,0 +1,154 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * pscrr-nvmem.c - NVMEM recorder provider for PSCRR + * + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. + * Copyright (C) 2025 Pengutronix, Oleksij Rempel + */ + +#include +#include +#include +#include +#include +#include + +struct pscrr_nvmem { + struct nvmem_cell *cell; + enum psc_reason reason; +}; + +static int pscrr_nvmem_cell_read(struct pscrr_nvmem *priv, u8 *out) +{ + size_t len; + void *buf; + + buf = nvmem_cell_read(priv->cell, &len); + if (IS_ERR(buf)) + return PTR_ERR(buf); + + *out = len ? *(u8 *)buf : 0; + kfree(buf); + + return 0; +} + +static int pscrr_nvmem_cell_write(struct pscrr_nvmem *priv, u8 val) +{ + int ret; + + /* nvmem_cell_write() returns the byte count on success, not 0. */ + ret = nvmem_cell_write(priv->cell, &val, sizeof(val)); + + return ret < 0 ? ret : 0; +} + +static int pscrr_nvmem_read_reasons(struct pscrr_provider *p, + unsigned long *reasons) +{ + struct pscrr_nvmem *priv = p->priv; + + /* + * Report the reason latched at probe (or overwritten by a later + * record); the cell itself was cleared at probe, so it is not read + * live here. + */ + set_bit(READ_ONCE(priv->reason), reasons); + + return 0; +} + +static int pscrr_nvmem_write_reason(struct pscrr_provider *p, + enum psc_reason reason) +{ + struct pscrr_nvmem *priv = p->priv; + int ret; + + if (reason >= PSCR_REASON_COUNT) + return -EINVAL; + + ret = pscrr_nvmem_cell_write(priv, reason); + if (ret) + return ret; + + WRITE_ONCE(priv->reason, reason); + + return 0; +} + +static const struct pscrr_provider_ops pscrr_nvmem_ops = { + .read_reasons = pscrr_nvmem_read_reasons, + .write_reason = pscrr_nvmem_write_reason, +}; + +static int pscrr_nvmem_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct pscrr_nvmem *priv; + size_t bytes, bits; + u8 val; + int ret; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->cell = devm_nvmem_cell_get(dev, "pscr"); + if (IS_ERR(priv->cell)) + return dev_err_probe(dev, PTR_ERR(priv->cell), + "failed to get the pscr nvmem cell\n"); + + ret = nvmem_cell_get_size(priv->cell, &bytes, &bits); + if (ret) + return ret; + + /* The reason is a single byte; a bit cell still occupies one. */ + if ((bytes ?: DIV_ROUND_UP(bits, 8)) != sizeof(val)) + return dev_err_probe(dev, -EINVAL, + "unsupported pscr nvmem cell size\n"); + + /* + * The cell survives resets, so at boot it still holds whatever the + * previous session recorded before it went down. Latch that as this + * boot's reason, then clear the cell back to PSCR_UNKNOWN: if this + * session is later cut short by an abrupt reset that never runs the + * recorder (watchdog power-cycle, sudden power loss), the next boot + * reads "unknown" instead of a stale reason left over from an earlier + * cycle. + */ + ret = pscrr_nvmem_cell_read(priv, &val); + if (ret) + return dev_err_probe(dev, ret, + "failed to read the pscr nvmem cell\n"); + + priv->reason = val < PSCR_REASON_COUNT ? val : PSCR_UNKNOWN; + + ret = pscrr_nvmem_cell_write(priv, PSCR_UNKNOWN); + if (ret) + return dev_err_probe(dev, ret, + "failed to clear the pscr nvmem cell\n"); + + return PTR_ERR_OR_ZERO(devm_pscrr_provider_register(dev, "nvmem", + &pscrr_nvmem_ops, NULL, + priv)); +} + +static const struct of_device_id pscrr_nvmem_of_match[] = { + { .compatible = "pscrr-nvmem" }, + { } +}; +MODULE_DEVICE_TABLE(of, pscrr_nvmem_of_match); + +static struct platform_driver pscrr_nvmem_driver = { + .probe = pscrr_nvmem_probe, + .driver = { + .name = "pscrr-nvmem", + .of_match_table = pscrr_nvmem_of_match, + }, +}; +module_platform_driver(pscrr_nvmem_driver); + +MODULE_AUTHOR("Oleksij Rempel "); +MODULE_AUTHOR("Faruque Ansari "); +MODULE_DESCRIPTION("NVMEM recorder provider for PSCRR"); +MODULE_LICENSE("GPL"); -- 2.34.1