a66ccfc253
Many older WMI drivers cannot be instantiated multiple times for two reasons: - they are using the legacy GUID-based WMI API - they are singletons (with global state) Prevent such WMI drivers from binding to WMI devices with a duplicated GUID, as this would mean that the WMI driver will be instantiated at least two times (one for the original GUID and one for the duplicated GUID). WMI drivers which can be instantiated multiple times can signal this by setting a flag inside struct wmi_driver. Tested on a ASUS Prime B650-Plus. Signed-off-by: Armin Wolf <W_Armin@gmx.de> Link: https://lore.kernel.org/r/20240226193557.2888-2-W_Armin@gmx.de Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
140 lines
3.3 KiB
C
140 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Slim Bootloader(SBL) firmware update signaling driver
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*
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* Slim Bootloader is a small, open-source, non UEFI compliant, boot firmware
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* optimized for running on certain Intel platforms.
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*
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* SBL exposes an ACPI-WMI device via /sys/bus/wmi/devices/<INTEL_WMI_SBL_GUID>.
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* This driver further adds "firmware_update_request" device attribute.
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* This attribute normally has a value of 0 and userspace can signal SBL
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* to update firmware, on next reboot, by writing a value of 1.
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*
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* More details of SBL firmware update process is available at:
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* https://slimbootloader.github.io/security/firmware-update.html
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*/
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#include <linux/acpi.h>
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#include <linux/device.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/sysfs.h>
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#include <linux/wmi.h>
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#define INTEL_WMI_SBL_GUID "44FADEB1-B204-40F2-8581-394BBDC1B651"
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static int get_fwu_request(struct device *dev, u32 *out)
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{
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union acpi_object *obj;
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obj = wmidev_block_query(to_wmi_device(dev), 0);
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if (!obj)
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return -ENODEV;
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if (obj->type != ACPI_TYPE_INTEGER) {
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dev_warn(dev, "wmidev_block_query returned invalid value\n");
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kfree(obj);
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return -EINVAL;
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}
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*out = obj->integer.value;
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kfree(obj);
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return 0;
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}
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static int set_fwu_request(struct device *dev, u32 in)
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{
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struct acpi_buffer input;
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acpi_status status;
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u32 value;
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value = in;
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input.length = sizeof(u32);
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input.pointer = &value;
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status = wmidev_block_set(to_wmi_device(dev), 0, &input);
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if (ACPI_FAILURE(status)) {
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dev_err(dev, "wmidev_block_set failed\n");
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return -ENODEV;
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}
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return 0;
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}
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static ssize_t firmware_update_request_show(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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u32 val;
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int ret;
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ret = get_fwu_request(dev, &val);
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if (ret)
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return ret;
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return sprintf(buf, "%d\n", val);
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}
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static ssize_t firmware_update_request_store(struct device *dev,
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struct device_attribute *attr,
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const char *buf, size_t count)
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{
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unsigned int val;
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int ret;
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ret = kstrtouint(buf, 0, &val);
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if (ret)
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return ret;
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/* May later be extended to support values other than 0 and 1 */
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if (val > 1)
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return -ERANGE;
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ret = set_fwu_request(dev, val);
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if (ret)
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return ret;
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return count;
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}
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static DEVICE_ATTR_RW(firmware_update_request);
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static struct attribute *firmware_update_attrs[] = {
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&dev_attr_firmware_update_request.attr,
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NULL
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};
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ATTRIBUTE_GROUPS(firmware_update);
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static int intel_wmi_sbl_fw_update_probe(struct wmi_device *wdev,
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const void *context)
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{
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dev_info(&wdev->dev, "Slim Bootloader signaling driver attached\n");
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return 0;
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}
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static void intel_wmi_sbl_fw_update_remove(struct wmi_device *wdev)
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{
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dev_info(&wdev->dev, "Slim Bootloader signaling driver removed\n");
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}
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static const struct wmi_device_id intel_wmi_sbl_id_table[] = {
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{ .guid_string = INTEL_WMI_SBL_GUID },
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{}
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};
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MODULE_DEVICE_TABLE(wmi, intel_wmi_sbl_id_table);
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static struct wmi_driver intel_wmi_sbl_fw_update_driver = {
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.driver = {
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.name = "intel-wmi-sbl-fw-update",
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.dev_groups = firmware_update_groups,
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},
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.probe = intel_wmi_sbl_fw_update_probe,
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.remove = intel_wmi_sbl_fw_update_remove,
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.id_table = intel_wmi_sbl_id_table,
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.no_singleton = true,
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};
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module_wmi_driver(intel_wmi_sbl_fw_update_driver);
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MODULE_AUTHOR("Jithu Joseph <jithu.joseph@intel.com>");
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MODULE_DESCRIPTION("Slim Bootloader firmware update signaling driver");
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MODULE_LICENSE("GPL v2");
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