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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1043BC021B8 for ; Wed, 26 Feb 2025 15:22:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=LWoHU8hu46dRejoYbRwPdVFyOWD54ZJ4E158Xpmj8u8=; b=5BvTYVU0QheNrA7kqsVhJ7eM/r KyFIWBWEz2wlfrdGag5ZsoCD+ztzoAHyfecik05SDsmc+57BpRP2xyIB7oi03oLWVWBoDcB/38mXl JwYxAHzUIFNhzUUh9hHQo6XCRpdaGg4UxVNORdTbjvF2mk9i7MT3/zrwJfSdiZh4RxiPzWd9uAXR0 cwg3iIbAgVCarygHQJ5my2yBpQYKmohfpRXVkN7xr2j/y54MyvJ3+2Dx1jcS/3CmgQLux64vwKD9a Zr++jyrlfctT05SSJANjA7T8pfH+3syz+37KvXsGQ431IVj1iSOL/+uXJ65PV6WIUB7ZMSAjyaTkU qJr7dMNA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tnJF0-00000004FbF-0B2n; Wed, 26 Feb 2025 15:22:30 +0000 Received: from tor.source.kernel.org ([2600:3c04::f03c:95ff:fe5e:7468]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tnIPD-000000045Mt-0pa8 for linux-arm-kernel@lists.infradead.org; Wed, 26 Feb 2025 14:28:59 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id C523661226; Wed, 26 Feb 2025 14:28:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91DACC4CED6; Wed, 26 Feb 2025 14:28:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740580138; bh=imG2eoF7EhULeRCWxlkU478DrsG7zuM8IA1zXttiVIg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jOoWo6I4axjc7/g3HzbBnRFc+bA68ZZR3cVJiGZ4m/qgqjPAatfRVKgjcDg9ZZGQt PimKjt9TdT6ogmZnuyKrvpZckMidtvJ0PxOJNFPI2CiW1DBM8t6hhYYrlJj3hZrW4+ Y0+M+8c0TVPmzP2HAt5KWoP8LXTK9ytXg9B4f1HeUg+bVlZE4JgD4lUn4RNcYHQm76 qL8irsILkPnFzN4ukaj5mwEQl2ItHgXji0xyV+1/nrltYul0p1dHIc1cu0zIZLD7OI N2smNVVERmR8m7QXregyeB9z/xbQRf55L5mB+mim13MpOSJHcys2hX/gcPdvmgNcGY 4q11+sAs4NzaQ== Date: Wed, 26 Feb 2025 15:28:47 +0100 From: Lorenzo Pieralisi To: Elliot Berman Cc: Bjorn Andersson , Sebastian Reichel , Rob Herring , Conor Dooley , Vinod Koul , Andy Yan , Mark Rutland , Bartosz Golaszewski , Arnd Bergmann , Olof Johansson , Catalin Marinas , Will Deacon , cros-qcom-dts-watchers@chromium.org, Krzysztof Kozlowski , Konrad Dybcio , Satya Durga Srinivasu Prabhala , Melody Olvera , Shivendra Pratap , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Florian Fainelli , Stephen Boyd , linux-pm@vger.kernel.org, linux-arm-msm@vger.kernel.org Subject: Re: [PATCH v8 3/6] firmware: psci: Read and use vendor reset types Message-ID: References: <20241107-arm-psci-system_reset2-vendor-reboots-v8-0-e8715fa65cb5@quicinc.com> <20241107-arm-psci-system_reset2-vendor-reboots-v8-3-e8715fa65cb5@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241107-arm-psci-system_reset2-vendor-reboots-v8-3-e8715fa65cb5@quicinc.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Nov 07, 2024 at 03:38:27PM -0800, Elliot Berman wrote: > SoC vendors have different types of resets and are controlled through > various registers. For instance, Qualcomm chipsets can reboot to a > "download mode" that allows a RAM dump to be collected. Another example > is they also support writing a cookie that can be read by bootloader > during next boot. PSCI offers a mechanism, SYSTEM_RESET2, for these > vendor reset types to be implemented without requiring drivers for every > register/cookie. > > Add support in PSCI to statically map reboot mode commands from > userspace to a vendor reset and cookie value using the device tree. > > A separate initcall is needed to parse the devicetree, instead of using > psci_dt_init because mm isn't sufficiently set up to allocate memory. > > Reboot mode framework is close but doesn't quite fit with the > design and requirements for PSCI SYSTEM_RESET2. Some of these issues can > be solved but doesn't seem reasonable in sum: > 1. reboot mode registers against the reboot_notifier_list, which is too > early to call SYSTEM_RESET2. PSCI would need to remember the reset > type from the reboot-mode framework callback and use it > psci_sys_reset. > 2. reboot mode assumes only one cookie/parameter is described in the > device tree. SYSTEM_RESET2 uses 2: one for the type and one for > cookie. > 3. psci cpuidle driver already registers a driver against the > arm,psci-1.0 compatible. Refactoring would be needed to have both a > cpuidle and reboot-mode driver. > > Tested-by: Florian Fainelli > Signed-off-by: Elliot Berman > --- > drivers/firmware/psci/psci.c | 104 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 104 insertions(+) > > diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c > index 2328ca58bba61fdb677ac20a1a7447882cd0cf22..e60e3f8749c5a6732c51d23a2c1f453361132d9a 100644 > --- a/drivers/firmware/psci/psci.c > +++ b/drivers/firmware/psci/psci.c > @@ -79,6 +79,14 @@ struct psci_0_1_function_ids get_psci_0_1_function_ids(void) > static u32 psci_cpu_suspend_feature; > static bool psci_system_reset2_supported; > > +struct psci_reset_param { > + const char *mode; > + u32 reset_type; > + u32 cookie; > +}; > +static struct psci_reset_param *psci_reset_params __ro_after_init; > +static size_t num_psci_reset_params __ro_after_init; > + > static inline bool psci_has_ext_power_state(void) > { > return psci_cpu_suspend_feature & > @@ -305,9 +313,38 @@ static int get_set_conduit_method(const struct device_node *np) > return 0; > } > > +static void psci_vendor_system_reset2(const char *cmd) > +{ > + unsigned long ret; > + size_t i; > + > + for (i = 0; i < num_psci_reset_params; i++) { > + if (!strcmp(psci_reset_params[i].mode, cmd)) { > + ret = invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), > + psci_reset_params[i].reset_type, > + psci_reset_params[i].cookie, 0); > + /* > + * if vendor reset fails, log it and fall back to > + * architecture reset types > + */ > + pr_err("failed to perform reset \"%s\": %ld\n", cmd, > + (long)ret); > + return; > + } > + } > +} > + > static int psci_sys_reset(struct notifier_block *nb, unsigned long action, > void *data) > { > + /* > + * try to do the vendor system_reset2 > + * If the reset fails or there wasn't a match on the command, > + * fall back to architectural resets > + */ > + if (data && num_psci_reset_params) > + psci_vendor_system_reset2(data); Mulling over this. If a command (data) was provided and a PSCI vendor reset parsed at boot, if the vendor reset fails, isn't it correct to just fail reboot instead of falling back to architectural resets ? What's missing is defining the "contract" between the LINUX_REBOOT_CMD_RESTART2 arg parameter and the kernel reboot type that is executed. I do wonder whether this is an opportunity to deprecate reboot_mode altogether on arm64 (I think that the relationship between REBOOT_WARM and REBOOT_SOFT with PSCI arch warm reset is already loose - let alone falling back to cold reset if reboot_mode == REBOOT_GPIO - which does not make any sense at all simply because REBOOT_GPIO is ill-defined to say the least). Thoughts ? Thanks, Lorenzo > + > if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) && > psci_system_reset2_supported) { > /* > @@ -750,6 +787,73 @@ static const struct of_device_id psci_of_match[] __initconst = { > {}, > }; > > +#define REBOOT_PREFIX "mode-" > + > +static int __init psci_init_system_reset2_modes(void) > +{ > + const size_t len = strlen(REBOOT_PREFIX); > + struct psci_reset_param *param; > + struct device_node *psci_np __free(device_node) = NULL; > + struct device_node *np __free(device_node) = NULL; > + struct property *prop; > + size_t count = 0; > + u32 magic[2]; > + int num; > + > + if (!psci_system_reset2_supported) > + return 0; > + > + psci_np = of_find_matching_node(NULL, psci_of_match); > + if (!psci_np) > + return 0; > + > + np = of_find_node_by_name(psci_np, "reset-types"); > + if (!np) > + return 0; > + > + for_each_property_of_node(np, prop) { > + if (strncmp(prop->name, REBOOT_PREFIX, len)) > + continue; > + num = of_property_count_u32_elems(np, prop->name); > + if (num != 1 && num != 2) > + continue; > + > + count++; > + } > + > + param = psci_reset_params = > + kcalloc(count, sizeof(*psci_reset_params), GFP_KERNEL); > + if (!psci_reset_params) > + return -ENOMEM; > + > + for_each_property_of_node(np, prop) { > + if (strncmp(prop->name, REBOOT_PREFIX, len)) > + continue; > + > + param->mode = kstrdup_const(prop->name + len, GFP_KERNEL); > + if (!param->mode) > + continue; > + > + num = of_property_read_variable_u32_array(np, prop->name, magic, > + 1, ARRAY_SIZE(magic)); > + if (num < 0) { > + pr_warn("Failed to parse vendor reboot mode %s\n", > + param->mode); > + kfree_const(param->mode); > + continue; > + } > + > + /* Force reset type to be in vendor space */ > + param->reset_type = PSCI_1_1_RESET_TYPE_VENDOR_START | magic[0]; > + param->cookie = num > 1 ? magic[1] : 0; > + param++; > + num_psci_reset_params++; > + } > + > + return 0; > +} > +arch_initcall(psci_init_system_reset2_modes); > + > int __init psci_dt_init(void) > { > struct device_node *np; > > -- > 2.34.1 >