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Mon, 3 Mar 2025 21:09:16 GMT Received: from hu-eberman-lv.qualcomm.com (10.49.16.6) by nasanex01b.na.qualcomm.com (10.46.141.250) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Mon, 3 Mar 2025 13:09:15 -0800 From: Elliot Berman Date: Mon, 3 Mar 2025 13:08:31 -0800 Subject: [PATCH v9 2/5] firmware: psci: Read and use vendor reset types Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <20250303-arm-psci-system_reset2-vendor-reboots-v9-2-b2cf4a20feda@oss.qualcomm.com> References: <20250303-arm-psci-system_reset2-vendor-reboots-v9-0-b2cf4a20feda@oss.qualcomm.com> In-Reply-To: <20250303-arm-psci-system_reset2-vendor-reboots-v9-0-b2cf4a20feda@oss.qualcomm.com> To: Bjorn Andersson , Sebastian Reichel , Rob Herring , Conor Dooley , Vinod Koul , Andy Yan , Lorenzo Pieralisi , "Mark Rutland" , Bartosz Golaszewski , Arnd Bergmann , "Olof Johansson" , Catalin Marinas , "Will Deacon" , , "Krzysztof Kozlowski" , Konrad Dybcio , Konrad Dybcio CC: Srinivas Kandagatla , "Satya Durga Srinivasu Prabhala" , Melody Olvera , Shivendra Pratap , , , , Florian Fainelli , Stephen Boyd , , , Elliot Berman , Elliot Berman , "Elliot Berman" X-Mailer: b4 0.14.2 X-ClientProxiedBy: nalasex01b.na.qualcomm.com (10.47.209.197) To nasanex01b.na.qualcomm.com (10.46.141.250) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: Dy0srntGd2FtcRzeb990AFSn2yysLBEJ X-Proofpoint-ORIG-GUID: Dy0srntGd2FtcRzeb990AFSn2yysLBEJ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1093,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-03_10,2025-03-03_04,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 mlxlogscore=999 spamscore=0 phishscore=0 mlxscore=0 priorityscore=1501 bulkscore=0 lowpriorityscore=0 malwarescore=0 impostorscore=0 adultscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502100000 definitions=main-2503030163 From: Elliot Berman 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. Signed-off-by: Elliot Berman --- drivers/firmware/psci/psci.c | 105 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 105 insertions(+) diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c index a1ebbe9b73b136218e9d9f9b8daa7756b3ab2fbe..6f8c47deaec0225f26704e1f3bcad52603127a85 100644 --- a/drivers/firmware/psci/psci.c +++ b/drivers/firmware/psci/psci.c @@ -80,6 +80,14 @@ static u32 psci_cpu_suspend_feature; static bool psci_system_reset2_supported; static bool psci_system_off2_hibernate_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 & @@ -306,9 +314,39 @@ static int get_set_conduit_method(const struct device_node *np) return 0; } +static int 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 0; + } + } + + return -ENOENT; +} + static int psci_sys_reset(struct notifier_block *nb, unsigned long action, void *data) { + /* + * try to do the vendor system_reset2 + * If there wasn't a matching command, fall back to architectural resets + */ + if (data && !psci_vendor_system_reset2(data)) + return NOTIFY_DONE; + if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) && psci_system_reset2_supported) { /* @@ -795,6 +833,73 @@ 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; + + 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; + } + + param->mode = kstrdup_const(prop->name + len, GFP_KERNEL); + if (!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;