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Message-Id: <20250503-smc-6-15-v4-6-500b9b6546fc@svenpeter.dev>
Date: Sat, 03 May 2025 10:06:53 +0000
From: Sven Peter via B4 Relay <devnull+sven.svenpeter.dev@...nel.org>
To: Sven Peter <sven@...npeter.dev>, Janne Grunau <j@...nau.net>,
Alyssa Rosenzweig <alyssa@...enzweig.io>, Neal Gompa <neal@...pa.dev>,
Hector Martin <marcan@...can.st>, Linus Walleij <linus.walleij@...aro.org>,
Bartosz Golaszewski <brgl@...ev.pl>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, Sebastian Reichel <sre@...nel.org>,
Lee Jones <lee@...nel.org>, Marc Zyngier <maz@...nel.org>,
"Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
Cc: asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: [PATCH v4 6/9] power: reset: macsmc-reboot: Add driver for
rebooting via Apple SMC
From: Hector Martin <marcan@...can.st>
This driver implements the reboot/shutdown support exposed by the SMC
on Apple Silicon machines, such as Apple M1 Macs.
Signed-off-by: Hector Martin <marcan@...can.st>
Signed-off-by: Sven Peter <sven@...npeter.dev>
---
MAINTAINERS | 1 +
drivers/power/reset/Kconfig | 11 ++
drivers/power/reset/Makefile | 1 +
drivers/power/reset/macsmc-reboot.c | 362 ++++++++++++++++++++++++++++++++++++
4 files changed, 375 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 5a52d5ada993c1b339fe1bdd1cda532faeeb9749..2ba2669ee249030f30e51654e96578a6ad557657 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2306,6 +2306,7 @@ F: drivers/nvme/host/apple.c
F: drivers/nvmem/apple-efuses.c
F: drivers/nvmem/apple-spmi-nvmem.c
F: drivers/pinctrl/pinctrl-apple-gpio.c
+F: drivers/power/reset/macsmc-reboot.c
F: drivers/pwm/pwm-apple.c
F: drivers/soc/apple/*
F: drivers/spi/spi-apple.c
diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index 60bf0ca64cf395cd18238fc626611c74d29844ee..6e8dfff64fdc001d09b6c00630cd8b7e2fafdd8e 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -128,6 +128,17 @@ config POWER_RESET_LINKSTATION
Say Y here if you have a Buffalo LinkStation LS421D/E.
+config POWER_RESET_MACSMC
+ tristate "Apple SMC reset/power-off driver"
+ depends on ARCH_APPLE || COMPILE_TEST
+ depends on MFD_MACSMC
+ depends on OF
+ help
+ This driver supports reset and power-off on Apple Mac machines
+ that implement this functionality via the SMC.
+
+ Say Y here if you have an Apple Silicon Mac.
+
config POWER_RESET_MSM
bool "Qualcomm MSM power-off driver"
depends on ARCH_QCOM
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index 10782d32e1da39f4b8b4566e8a885f2e13f65130..887dd9e49b7293b69b9429ddc0c1571194a153cf 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o
obj-$(CONFIG_POWER_RESET_HISI) += hisi-reboot.o
obj-$(CONFIG_POWER_RESET_LINKSTATION) += linkstation-poweroff.o
+obj-$(CONFIG_POWER_RESET_MACSMC) += macsmc-reboot.o
obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
obj-$(CONFIG_POWER_RESET_MT6323) += mt6323-poweroff.o
obj-$(CONFIG_POWER_RESET_QCOM_PON) += qcom-pon.o
diff --git a/drivers/power/reset/macsmc-reboot.c b/drivers/power/reset/macsmc-reboot.c
new file mode 100644
index 0000000000000000000000000000000000000000..64b9bd292a7b8e5dc23f26e389fca87006480052
--- /dev/null
+++ b/drivers/power/reset/macsmc-reboot.c
@@ -0,0 +1,362 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple SMC Reboot/Poweroff Handler
+ * Copyright The Asahi Linux Contributors
+ */
+
+#include <linux/delay.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/macsmc.h>
+#include <linux/module.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/slab.h>
+
+struct macsmc_reboot_nvmem {
+ struct nvmem_cell *shutdown_flag;
+ struct nvmem_cell *pm_setting;
+ struct nvmem_cell *boot_stage;
+ struct nvmem_cell *boot_error_count;
+ struct nvmem_cell *panic_count;
+};
+
+static const char * const nvmem_names[] = {
+ "shutdown_flag",
+ "pm_setting",
+ "boot_stage",
+ "boot_error_count",
+ "panic_count",
+};
+
+enum boot_stage {
+ BOOT_STAGE_SHUTDOWN = 0x00, /* Clean shutdown */
+ BOOT_STAGE_IBOOT_DONE = 0x2f, /* Last stage of bootloader */
+ BOOT_STAGE_KERNEL_STARTED = 0x30, /* Normal OS booting */
+};
+
+enum pm_setting {
+ PM_SETTING_AC_POWER_RESTORE = 0x02,
+ PM_SETTING_AC_POWER_OFF = 0x03,
+};
+
+static const char * const ac_power_modes[] = { "off", "restore" };
+
+static int ac_power_mode_map[] = {
+ PM_SETTING_AC_POWER_OFF,
+ PM_SETTING_AC_POWER_RESTORE,
+};
+
+struct macsmc_reboot {
+ struct device *dev;
+ struct apple_smc *smc;
+ struct notifier_block reboot_notify;
+
+ union {
+ struct macsmc_reboot_nvmem nvm;
+ struct nvmem_cell *nvm_cells[ARRAY_SIZE(nvmem_names)];
+ };
+};
+
+/* Helpers to read/write a u8 given a struct nvmem_cell */
+static int nvmem_cell_get_u8(struct nvmem_cell *cell)
+{
+ size_t len;
+ u8 val;
+ void *ret = nvmem_cell_read(cell, &len);
+
+ if (IS_ERR(ret))
+ return PTR_ERR(ret);
+
+ if (len < 1) {
+ kfree(ret);
+ return -EINVAL;
+ }
+
+ val = *(u8 *)ret;
+ kfree(ret);
+ return val;
+}
+
+static int nvmem_cell_set_u8(struct nvmem_cell *cell, u8 val)
+{
+ return nvmem_cell_write(cell, &val, sizeof(val));
+}
+
+static ssize_t macsmc_ac_power_mode_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t n)
+{
+ struct macsmc_reboot *reboot = dev_get_drvdata(dev);
+ int mode;
+ int ret;
+
+ mode = sysfs_match_string(ac_power_modes, buf);
+ if (mode < 0)
+ return mode;
+
+ ret = nvmem_cell_set_u8(reboot->nvm.pm_setting, ac_power_mode_map[mode]);
+ if (ret < 0)
+ return ret;
+
+ return n;
+}
+
+static ssize_t macsmc_ac_power_mode_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct macsmc_reboot *reboot = dev_get_drvdata(dev);
+ int len = 0;
+ int i;
+ int mode = nvmem_cell_get_u8(reboot->nvm.pm_setting);
+
+ if (mode < 0)
+ return mode;
+
+ for (i = 0; i < ARRAY_SIZE(ac_power_mode_map); i++)
+ if (mode == ac_power_mode_map[i])
+ len += scnprintf(buf+len, PAGE_SIZE-len,
+ "[%s] ", ac_power_modes[i]);
+ else
+ len += scnprintf(buf+len, PAGE_SIZE-len,
+ "%s ", ac_power_modes[i]);
+ buf[len-1] = '\n';
+ return len;
+}
+static DEVICE_ATTR(ac_power_mode, 0644, macsmc_ac_power_mode_show,
+ macsmc_ac_power_mode_store);
+
+/*
+ * SMC 'MBSE' key actions:
+ *
+ * 'offw' - shutdown warning
+ * 'slpw' - sleep warning
+ * 'rest' - restart warning
+ * 'off1' - shutdown (needs PMU bit set to stay on)
+ * 'susp' - suspend
+ * 'phra' - restart ("PE Halt Restart Action"?)
+ * 'panb' - panic beginning
+ * 'pane' - panic end
+ */
+
+static int macsmc_prepare_atomic(struct sys_off_data *data)
+{
+ struct macsmc_reboot *reboot = data->cb_data;
+
+ dev_info(reboot->dev, "Preparing SMC for atomic mode\n");
+
+ apple_smc_enter_atomic(reboot->smc);
+ return NOTIFY_OK;
+}
+
+static int macsmc_power_off(struct sys_off_data *data)
+{
+ struct macsmc_reboot *reboot = data->cb_data;
+
+ dev_info(reboot->dev, "Issuing power off (off1)\n");
+
+ if (apple_smc_write_u32_atomic(reboot->smc, SMC_KEY(MBSE), SMC_KEY(off1)) < 0) {
+ dev_err(reboot->dev, "Failed to issue MBSE = off1 (power_off)\n");
+ } else {
+ mdelay(100);
+ WARN_ON(1);
+ }
+
+ return NOTIFY_OK;
+}
+
+static int macsmc_restart(struct sys_off_data *data)
+{
+ struct macsmc_reboot *reboot = data->cb_data;
+
+ dev_info(reboot->dev, "Issuing restart (phra)\n");
+
+ if (apple_smc_write_u32_atomic(reboot->smc, SMC_KEY(MBSE), SMC_KEY(phra)) < 0) {
+ dev_err(reboot->dev, "Failed to issue MBSE = phra (restart)\n");
+ } else {
+ mdelay(100);
+ WARN_ON(1);
+ }
+
+ return NOTIFY_OK;
+}
+
+static int macsmc_reboot_notify(struct notifier_block *this, unsigned long action, void *data)
+{
+ struct macsmc_reboot *reboot = container_of(this, struct macsmc_reboot, reboot_notify);
+ u32 val;
+ u8 shutdown_flag;
+
+ switch (action) {
+ case SYS_RESTART:
+ val = SMC_KEY(rest);
+ shutdown_flag = 0;
+ break;
+ case SYS_POWER_OFF:
+ val = SMC_KEY(offw);
+ shutdown_flag = 1;
+ break;
+ default:
+ return NOTIFY_DONE;
+ }
+
+ dev_info(reboot->dev, "Preparing for reboot (%p4ch)\n", &val);
+
+ /* On the Mac Mini, this will turn off the LED for power off */
+ if (apple_smc_write_u32(reboot->smc, SMC_KEY(MBSE), val) < 0)
+ dev_err(reboot->dev, "Failed to issue MBSE = %p4ch (reboot_prepare)\n", &val);
+
+ /* Set the boot_stage to 0, which means we're doing a clean shutdown/reboot. */
+ if (reboot->nvm.boot_stage &&
+ nvmem_cell_set_u8(reboot->nvm.boot_stage, BOOT_STAGE_SHUTDOWN) < 0)
+ dev_err(reboot->dev, "Failed to write boot_stage\n");
+
+ /*
+ * Set the PMU flag to actually reboot into the off state.
+ * Without this, the device will just reboot. We make it optional in case it is no longer
+ * necessary on newer hardware.
+ */
+ if (reboot->nvm.shutdown_flag &&
+ nvmem_cell_set_u8(reboot->nvm.shutdown_flag, shutdown_flag) < 0)
+ dev_err(reboot->dev, "Failed to write shutdown_flag\n");
+
+ return NOTIFY_OK;
+}
+
+static void macsmc_power_init_error_counts(struct macsmc_reboot *reboot)
+{
+ int boot_error_count, panic_count;
+
+ if (!reboot->nvm.boot_error_count || !reboot->nvm.panic_count)
+ return;
+
+ boot_error_count = nvmem_cell_get_u8(reboot->nvm.boot_error_count);
+ if (boot_error_count < 0) {
+ dev_err(reboot->dev, "Failed to read boot_error_count (%d)\n", boot_error_count);
+ return;
+ }
+
+ panic_count = nvmem_cell_get_u8(reboot->nvm.panic_count);
+ if (panic_count < 0) {
+ dev_err(reboot->dev, "Failed to read panic_count (%d)\n", panic_count);
+ return;
+ }
+
+ if (!boot_error_count && !panic_count)
+ return;
+
+ dev_warn(reboot->dev, "PMU logged %d boot error(s) and %d panic(s)\n",
+ boot_error_count, panic_count);
+
+ if (nvmem_cell_set_u8(reboot->nvm.panic_count, 0) < 0)
+ dev_err(reboot->dev, "Failed to reset panic_count\n");
+ if (nvmem_cell_set_u8(reboot->nvm.boot_error_count, 0) < 0)
+ dev_err(reboot->dev, "Failed to reset boot_error_count\n");
+}
+
+static int macsmc_reboot_probe(struct platform_device *pdev)
+{
+ struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
+ struct macsmc_reboot *reboot;
+ int ret, i;
+
+ /* Ignore devices without this functionality */
+ if (!apple_smc_key_exists(smc, SMC_KEY(MBSE)))
+ return -ENODEV;
+
+ reboot = devm_kzalloc(&pdev->dev, sizeof(*reboot), GFP_KERNEL);
+ if (!reboot)
+ return -ENOMEM;
+
+ reboot->dev = &pdev->dev;
+ reboot->smc = smc;
+
+ platform_set_drvdata(pdev, reboot);
+
+ pdev->dev.of_node = of_get_child_by_name(pdev->dev.parent->of_node, "reboot");
+
+ for (i = 0; i < ARRAY_SIZE(nvmem_names); i++) {
+ struct nvmem_cell *cell;
+
+ cell = devm_nvmem_cell_get(&pdev->dev,
+ nvmem_names[i]);
+ if (IS_ERR(cell)) {
+ if (PTR_ERR(cell) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+ dev_warn(&pdev->dev, "Missing NVMEM cell %s (%ld)\n",
+ nvmem_names[i], PTR_ERR(cell));
+ /* Non fatal, we'll deal with it */
+ cell = NULL;
+ }
+ reboot->nvm_cells[i] = cell;
+ }
+
+ /* Set the boot_stage to indicate we're running the OS kernel */
+ if (reboot->nvm.boot_stage &&
+ nvmem_cell_set_u8(reboot->nvm.boot_stage, BOOT_STAGE_KERNEL_STARTED) < 0)
+ dev_err(reboot->dev, "Failed to write boot_stage\n");
+
+ /* Display and clear the error counts */
+ macsmc_power_init_error_counts(reboot);
+
+ reboot->reboot_notify.notifier_call = macsmc_reboot_notify;
+
+ ret = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_POWER_OFF_PREPARE,
+ SYS_OFF_PRIO_HIGH, macsmc_prepare_atomic, reboot);
+ if (ret)
+ return dev_err_probe(&pdev->dev, ret,
+ "Failed to register power-off prepare handler\n");
+ ret = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_POWER_OFF, SYS_OFF_PRIO_HIGH,
+ macsmc_power_off, reboot);
+ if (ret)
+ return dev_err_probe(&pdev->dev, ret,
+ "Failed to register power-off handler\n");
+
+
+ ret = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_RESTART_PREPARE,
+ SYS_OFF_PRIO_HIGH, macsmc_prepare_atomic, reboot);
+ if (ret)
+ return dev_err_probe(&pdev->dev, ret,
+ "Failed to register restart prepare handler\n");
+ ret = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_RESTART, SYS_OFF_PRIO_HIGH,
+ macsmc_restart, reboot);
+ if (ret)
+ return dev_err_probe(&pdev->dev, ret, "Failed to register restart handler\n");
+
+ ret = devm_register_reboot_notifier(&pdev->dev, &reboot->reboot_notify);
+ if (ret)
+ return dev_err_probe(&pdev->dev, ret, "Failed to register reboot notifier\n");
+
+ dev_info(&pdev->dev, "Handling reboot and poweroff requests via SMC\n");
+
+ if (device_create_file(&pdev->dev, &dev_attr_ac_power_mode))
+ dev_warn(&pdev->dev, "could not create sysfs file\n");
+
+ return 0;
+}
+
+static void macsmc_reboot_remove(struct platform_device *pdev)
+{
+ device_remove_file(&pdev->dev, &dev_attr_ac_power_mode);
+}
+
+static const struct of_device_id macsmc_reboot_of_table[] = {
+ { .compatible = "apple,smc-reboot", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, macsmc_reboot_of_table);
+
+static struct platform_driver macsmc_reboot_driver = {
+ .driver = {
+ .name = "macsmc-reboot",
+ .of_match_table = macsmc_reboot_of_table,
+ },
+ .probe = macsmc_reboot_probe,
+ .remove = macsmc_reboot_remove,
+};
+module_platform_driver(macsmc_reboot_driver);
+
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_DESCRIPTION("Apple SMC reboot/poweroff driver");
+MODULE_AUTHOR("Hector Martin <marcan@...can.st>");
+MODULE_ALIAS("platform:macsmc-reboot");
--
2.34.1
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