From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.82.175 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793264359; b=EJ/2AdzfpVYa4QfsDKKfNjPeUsYTzQgoz3n6ZQaRnL1PXXl/tFgh1fq8DyQPmtmiT2iR p2HndgqZvHWnxblxbUYKXQ3XaMtZr5+Xt1YOmPXxXNfwOffQ9hQ5QgnLw1T8XtSmmKwqR VCRQUcfwfuUilyhZs+1qNXe4oqOERW7mxtQapb9Et1u/e8dlNZFCI1o3FyB4Rb9fOaaqu MpFgCOe9+osL18dxVrCj2R7k2aG6ndEcFIQg7HJ/JxcZNwM3P2BmMyN4peK6afCOOzS9X CyXR+GOOL3Aq4mzmQ/KfJ49PTv6dQOl0PBXhDEDQaKb2g2FQGfJPS1felYXDQ7CuoHQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793264359; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: From:To:Cc:Subject:Date:Message-ID:X-Mailer:In-Reply-To:References: MIME-Version:Content-Transfer-Encoding; bh=Pf8vm5N7CuEKM9qQ3heupZiM07wEvXe0DI+wIb1mu6U=; b=Cp3LepJ54Bx9rG40LZkiX5Q5vnQc/FRQEStKboI4DAkr7ULR/en7+iYBkp9qrWMDOsEr G/5mSHqHRa4W1fDKvNflvTOtgDj8ZMbtywbLdjKjtZFRpBlWpC5QlJccJDXaR3M+CVdFy NVT/qxdwKlib3rAjzScNlE8p59RgiXaZ3WtnmnrFPyKenIkS5v9d6Q84N25c3/RNtLRwp SuTYTZpIkiX1swe+z+ymFpdudHLlBc8yvy5gllrf//yjEGjFIImVLS7eJFxFfwYHOdb/a hVx/pnA9DD584LDiJpzPcXcaMBcjvPGmLOV1zL4b/W+h0whUgSZzA1DXoAlZrwH6c0g== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=K2v0+3e3; arc=none smtp.remote-ip=74.125.82.175 Received: from mail-dy1-f175.google.com (mail-dy1-f175.google.com [74.125.82.175]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F1B35606A323 for ; Thu, 29 Oct 2026 08:59:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org F1B35606A323 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=K2v0+3e3 Received: by mail-dy1-f175.google.com with SMTP id 5a478bee46e88-36661f953e4so3068271eec.1 for ; Thu, 29 Oct 2026 01:59:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793264356; x=1793869156; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=Pf8vm5N7CuEKM9qQ3heupZiM07wEvXe0DI+wIb1mu6U=; b=K2v0+3e3EDuDJKYcecldqmNA0dnBAMPZ/tCas/ggAI7Q9myljmj86Fack4anqlW9GZ 6K3tBlVgm9GtLjXDQRpy1APoGWnXJD/B+KhPDsnfdH8ImOc/kzyXISK8TcWP4pESnqd7 BjPKKidjfszlk4nbNXKT0twyD6mIg1P3oZH2WiSQY94SpMNwXwAj/eUSDQVeKotcyZ/a 5fG2TYaBP2WgJShkf6EwW1a23l5WGLx/FAE7MQw1xOfYiT/Lv/qGw9s4X27pHmOgJyWO Bpc83FlmhfIEU9wky3diYsh98VQ4XH9A4Wb8sJqOAXH5pjP8pCdkFn6jTEVuZLdscTdO XNNQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793264356; x=1793869156; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=Pf8vm5N7CuEKM9qQ3heupZiM07wEvXe0DI+wIb1mu6U=; b=FfbBEYuEUT3ww4j99XtPINnapcrc80G36hKZ3zPtqgfakdbqgSr+exkxRXFrxzA33g UdpPKsbgaKN3/nHNFMIVrW3Pay5p1qY8fsJXv5lGBAKndJZ1kr392/SkIgU0ovV2/cOt DY0dl22npBiKfLOFZF31luVgeVm2gvx6e9m/U6r/wdGoUWcMiGOd3S5fvN1qZo2d/keh OEcifrBpIBZtO4ha8S78Xtq/okoDD/Pu8XTEv3XlZfxOO0g+m2ZvEfneqhlebRQolTZz ns32Bqk7ol0Md23tq9QC5dIrC3Clb/QX6zW8mlJsX3URE81EkNdtOMNxoMVRS6J95iw1 OWjA== X-Forwarded-Encrypted: i=1; AKwUvBwrgL+34F2ZpW5e6hl5W4fKkUGM/9OpXxkrLPt8jw19hParULgXwJd3xtRXHV4QE/sc5RHn2fYDAX8=@vger.kernel.org X-Gm-Message-State: AFq9FYJvecMMZdWzaIpFdQ7U9VJ/dc0csFw5UA/I0iLR9VmioSPrmpG7 1Y8B0g6x9yxesch+6YkTxmTvrio/ot7veTMU5aSl5/4gx7Spy06TJBY= X-Gm-Gg: AYBFou2sOZBp0pYUTHFoYALpTKoe2B8iSOV+H/kVWWYBP9qrhwdIPDRyqWZnLcbooHp TLagBPa9u+LbxZUCLMvIsFcB4n4UvJ88xIjw4NQOqxMQayWI1u7epwnlk6Zo5LYp9ewKtgpDic3 C33RK6yCCQhDc4zPhhCSrOioWL1Ln52u6Ie8zjRqsdqi0NwgXtmQiFhEiTmI6QLuKMp9yxWZISH jPIb8570V/o2lubxAJCCFEfY0tuNfOJTpn5f9cVSpEVItUCtunW6LwrEpmdzC51PWehdcohks7y Gm+kOEo4g9bql40p+5bRxwceN1bq80bV+tSnTtby3HK3wsvbt1XNt3oT9RrLxPPW1ZN6k52gbn/ hXpmYgY5p4RQYV1KpyDk2NpddtAT/IfC5d3rqCHWd/Zb2dJOMG6LapgT4gh1nvtk0BegenXdc1X ocYM5g9tEj3xngjS4uXTa3P2/v92BfJR4ynWuW9JDRQ2mBIWeJ4/BoXF14fjY2/n5ZwILykCLni CJiaPWGKUQ+ot2Warbby/Gn5fNmbCow6qTUQ/QJTwdGhnsGbwdtTJvUZANQncEW6RY/m2/bXMhs woDxzc29ncNNF+ZTTUDFV7qG36a6/1WNx89GHUY9kXfgARVnnKJ9QdWXoSCcmQ== X-Received: by 2002:a05:693c:4141:10b0:36a:3453:a356 with SMTP id 5a478bee46e88-36a3453a84dmr1973145eec.36.1793264356042; Thu, 29 Oct 2026 01:59:16 -0700 (PDT) Received: from at-Standard-PC-Q35-ICH9-2009 ([27.60.20.232]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36a23641e78sm16497937eec.0.2026.10.29.01.58.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Oct 2026 01:59:15 -0700 (PDT) From: Atharva Tiwari To: Cc: Atharva Tiwari , Bjorn Helgaas , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , "Rafael J. Wysocki" , Len Brown , Linus Walleij , Bartosz Golaszewski , Sven Peter , Janne Grunau , Neal Gompa , Guenter Roeck , Jonathan Cameron , David Lechner , =?UTF-8?q?Nuno=20S=C3=A1?= , Andy Shevchenko , Lee Jones , Pavel Machek , Griffin Kroah-Hartman , Hans de Goede , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , Sebastian Reichel , Alexandre Belloni , Wim Van Sebroeck , Jarkko Sakkinen , Mimi Zohar , Roberto Sassu , Dmitry Kasatkin , Eric Snowberg , Paul Moore , James Morris , "Serge E. Hallyn" , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, linux-gpio@vger.kernel.org, asahi@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-hwmon@vger.kernel.org, linux-iio@vger.kernel.org, linux-leds@vger.kernel.org, mfd@lists.linux.dev, platform-driver-x86@vger.kernel.org, linux-pm@vger.kernel.org, linux-rtc@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-integrity@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [RFC PATCH 07/14] rtc: add support for x86 macs in macsmc-rtc Date: Thu, 29 Oct 2026 04:52:04 -0400 Message-ID: <20261029085504.3547-8-atharvatiwarilinuxdev@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20261029085504.3547-1-atharvatiwarilinuxdev@gmail.com> References: <20261029085504.3547-1-atharvatiwarilinuxdev@gmail.com> X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Make macsmc-rtc work on Intel Macs. The ACPI RTC doesn't work correctly on T2 Macs, so the clock from the SMC is used instead. On these machines the time offset is kept in the SMC instead of NVMEM, and the clock rate is read from the SMC too. Signed-off-by: Atharva Tiwari --- drivers/rtc/rtc-macsmc.c | 126 ++++++++++++++++++++++++++++++++------- 1 file changed, 106 insertions(+), 20 deletions(-) diff --git a/drivers/rtc/rtc-macsmc.c b/drivers/rtc/rtc-macsmc.c index 8fe883066..37395c64c 100644 --- a/drivers/rtc/rtc-macsmc.c +++ b/drivers/rtc/rtc-macsmc.c @@ -2,9 +2,12 @@ /* * Apple SMC RTC driver * Copyright The Asahi Linux Contributors + * + * Copyright (C) 2026 Atharva Tiwari */ #include +#include #include #include #include @@ -20,13 +23,54 @@ /* 32768 Hz clock */ #define RTC_SEC_SHIFT 15 +static bool force_clkm; +module_param(force_clkm, bool, 0644); +MODULE_PARM_DESC(force_clkm, "Force CLKM Key, instead of trying to use CLKL"); + struct macsmc_rtc { struct device *dev; struct apple_smc *smc; struct rtc_device *rtc_dev; struct nvmem_cell *rtc_offset; + uint8_t shift; + bool async_rtc; }; +static int macsmc_rtc_read_clkl(struct macsmc_rtc *rtc, u64 *ctr) +{ + u64 request = 0xffffffffffffULL; + u64 response = 0; + int i, j, ret; + + for (i = 0; i < 4; i++) { + for (j = 0; j < 40; j++) { + ret = apple_smc_write(rtc->smc, SMC_KEY(CLKL), &request, RTC_BYTES); + if (ret == RTC_BYTES) + break; + } + if (ret != RTC_BYTES) + continue; + + msleep(20); + + for (j = 0; j < 20; j++) { + ret = apple_smc_read(rtc->smc, SMC_KEY(CLKL), &response, RTC_BYTES); + if (ret == RTC_BYTES) { + if ((response & 0x7fff) == 5 || (response & 0x7fff) == 6) + return -EAGAIN; + + if (response != 0xffffffffffffULL) { + *ctr = response; + return RTC_BYTES; + } + } + fsleep(1000); + } + } + + return -EIO; +} + static int macsmc_rtc_get_time(struct device *dev, struct rtc_time *tm) { struct macsmc_rtc *rtc = dev_get_drvdata(dev); @@ -36,25 +80,36 @@ static int macsmc_rtc_get_time(struct device *dev, struct rtc_time *tm) size_t len; int ret; - ret = apple_smc_read(rtc->smc, SMC_KEY(CLKM), &ctr, RTC_BYTES); + if (rtc->async_rtc && !force_clkm) + ret = macsmc_rtc_read_clkl(rtc, &ctr); + else + ret = apple_smc_read(rtc->smc, SMC_KEY(CLKM), &ctr, RTC_BYTES); + if (ret < 0) return ret; if (ret != RTC_BYTES) return -EIO; - p_off = nvmem_cell_read(rtc->rtc_offset, &len); - if (IS_ERR(p_off)) - return PTR_ERR(p_off); - if (len < RTC_BYTES) { + if (rtc->smc->is_acpi) { + ret = apple_smc_read(rtc->smc, SMC_KEY(CLKO), &off, RTC_BYTES); + if (ret < 0) + return ret; + if (ret != RTC_BYTES) + return -EIO; + } else { + p_off = nvmem_cell_read(rtc->rtc_offset, &len); + if (IS_ERR(p_off)) + return PTR_ERR(p_off); + if (len < RTC_BYTES) { + kfree(p_off); + return -EIO; + } + + memcpy(&off, p_off, RTC_BYTES); kfree(p_off); - return -EIO; } - - memcpy(&off, p_off, RTC_BYTES); - kfree(p_off); - /* Sign extend from 48 to 64 bits, then arithmetic shift right 15 bits to get seconds */ - now = sign_extend64(ctr + off, RTC_BITS - 1) >> RTC_SEC_SHIFT; + now = sign_extend64(ctr + off, RTC_BITS - 1) >> rtc->shift; rtc_time64_to_tm(now, tm); return ret; @@ -66,14 +121,20 @@ static int macsmc_rtc_set_time(struct device *dev, struct rtc_time *tm) u64 ctr = 0, off = 0; int ret; - ret = apple_smc_read(rtc->smc, SMC_KEY(CLKM), &ctr, RTC_BYTES); + if (rtc->async_rtc && !force_clkm) + ret = macsmc_rtc_read_clkl(rtc, &ctr); + else + ret = apple_smc_read(rtc->smc, SMC_KEY(CLKM), &ctr, RTC_BYTES); if (ret < 0) return ret; if (ret != RTC_BYTES) return -EIO; /* This sets the offset such that the set second begins now */ - off = (rtc_tm_to_time64(tm) << RTC_SEC_SHIFT) - ctr; + off = (rtc_tm_to_time64(tm) << rtc->shift) - ctr; + if (rtc->smc->is_acpi) + return (apple_smc_write(rtc->smc, SMC_KEY(CLKO), &off, RTC_BYTES) != RTC_BYTES); + return nvmem_cell_write(rtc->rtc_offset, &off, RTC_BYTES); } @@ -86,13 +147,15 @@ static int macsmc_rtc_probe(struct platform_device *pdev) { struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent); struct macsmc_rtc *rtc; + int ret; + uint32_t clkr = 0xFFFFFFFF; /* * MFD will probe this device even without a node in the device tree, * thus bail out early if the SMC on the current machines does not * support RTC and has no node in the device tree. */ - if (!pdev->dev.of_node) + if (!pdev->dev.of_node && !smc->is_acpi) return -ENODEV; rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL); @@ -102,18 +165,40 @@ static int macsmc_rtc_probe(struct platform_device *pdev) rtc->dev = &pdev->dev; rtc->smc = smc; - rtc->rtc_offset = devm_nvmem_cell_get(&pdev->dev, "rtc_offset"); - if (IS_ERR(rtc->rtc_offset)) - return dev_err_probe(&pdev->dev, PTR_ERR(rtc->rtc_offset), - "Failed to get rtc_offset NVMEM cell\n"); + if (!rtc->smc->is_acpi) { + rtc->rtc_offset = devm_nvmem_cell_get(&pdev->dev, "rtc_offset"); + if (IS_ERR(rtc->rtc_offset)) + return dev_err_probe(&pdev->dev, PTR_ERR(rtc->rtc_offset), + "Failed to get rtc_offset NVMEM cell\n"); + } + + if (rtc->smc->is_acpi) { + ret = apple_smc_read_u32(rtc->smc, SMC_KEY(CLKR), &clkr); + if (ret < 0 || clkr == 0xFFFFFFFF) + rtc->shift = RTC_SEC_SHIFT; + else + rtc->shift = ffs(clkr) - 1; + + if (apple_smc_key_exists(rtc->smc, SMC_KEY(CLKL))) { + u64 clkl; + + ret = apple_smc_read(rtc->smc, SMC_KEY(CLKL), &clkl, RTC_BYTES); + if (ret == RTC_BYTES && clkl != 0xFFFFFFFFFFFFFFFFULL) + rtc->async_rtc = true; + } + } else + rtc->shift = RTC_SEC_SHIFT; + + dev_info(&pdev->dev, "%u clock, using %s key\n", (clkr != 0xFFFFFFFF) ? clkr : 32768, + rtc->async_rtc ? "CLKL" : "CLKM"); rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev); if (IS_ERR(rtc->rtc_dev)) return PTR_ERR(rtc->rtc_dev); rtc->rtc_dev->ops = &macsmc_rtc_ops; - rtc->rtc_dev->range_min = S64_MIN >> (RTC_SEC_SHIFT + (64 - RTC_BITS)); - rtc->rtc_dev->range_max = S64_MAX >> (RTC_SEC_SHIFT + (64 - RTC_BITS)); + rtc->rtc_dev->range_min = S64_MIN >> (rtc->shift + (64 - RTC_BITS)); + rtc->rtc_dev->range_max = S64_MAX >> (rtc->shift + (64 - RTC_BITS)); platform_set_drvdata(pdev, rtc); @@ -138,3 +223,4 @@ module_platform_driver(macsmc_rtc_driver); MODULE_LICENSE("Dual MIT/GPL"); MODULE_DESCRIPTION("Apple SMC RTC driver"); MODULE_AUTHOR("Hector Martin "); +MODULE_ALIAS("platform:macsmc-rtc"); -- 2.55.0