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Message-Id: <20250503-smc-6-15-v4-4-500b9b6546fc@svenpeter.dev>
Date: Sat, 03 May 2025 10:06:51 +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 4/9] mfd: Add Apple Silicon System Management Controller
From: Sven Peter <sven@...npeter.dev>
The System Management Controller (SMC) on Apple Silicon machines is a
piece of hardware that exposes various functionalities such as
temperature sensors, voltage/power meters, shutdown/reboot handling,
GPIOs and more.
Communication happens via a shared mailbox using the RTKit protocol
which is also used for other co-processors. The SMC protocol then allows
reading and writing many different keys which implement the various
features. The MFD core device handles this protocol and exposes it
to the sub-devices.
Some of the sub-devices are potentially also useful on pre-M1 Apple
machines and support for SMCs on these machines can be added at a later
time.
Co-developed-by: Hector Martin <marcan@...can.st>
Signed-off-by: Hector Martin <marcan@...can.st>
Signed-off-by: Sven Peter <sven@...npeter.dev>
---
MAINTAINERS | 2 +
drivers/mfd/Kconfig | 15 ++
drivers/mfd/Makefile | 1 +
drivers/mfd/macsmc.c | 657 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/mfd/macsmc.h | 337 +++++++++++++++++++++++
5 files changed, 1012 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 2c16b2fc3fec76104967530f487123485af1e777..831df43892a64c95e00c24d77b8aa2a6ec87e074 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2300,6 +2300,7 @@ F: drivers/input/touchscreen/apple_z2.c
F: drivers/iommu/apple-dart.c
F: drivers/iommu/io-pgtable-dart.c
F: drivers/irqchip/irq-apple-aic.c
+F: drivers/mfd/macsmc.c
F: drivers/nvme/host/apple.c
F: drivers/nvmem/apple-efuses.c
F: drivers/nvmem/apple-spmi-nvmem.c
@@ -2312,6 +2313,7 @@ F: drivers/video/backlight/apple_dwi_bl.c
F: drivers/watchdog/apple_wdt.c
F: include/dt-bindings/interrupt-controller/apple-aic.h
F: include/dt-bindings/pinctrl/apple.h
+F: include/linux/mfd/macsmc.h
F: include/linux/soc/apple/*
ARM/ARTPEC MACHINE SUPPORT
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 22b93631003943c393d9fe704748bc23f1905397..da56fc4f05b7b7e0a521fcd97bee087424ec4d5b 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -285,6 +285,21 @@ config MFD_CS42L43_SDW
Select this to support the Cirrus Logic CS42L43 PC CODEC with
headphone and class D speaker drivers over SoundWire.
+config MFD_MACSMC
+ tristate "Apple Silicon System Management Controller (SMC)"
+ select MFD_CORE
+ help
+ The System Management Controller (SMC) on Apple Silicon machines is a
+ piece of hardware that exposes various functionalities such as
+ temperature sensors, voltage/power meters, shutdown/reboot handling,
+ GPIOs and more.
+
+ Communication happens via a shared mailbox using the RTKit protocol
+ which is also used for other co-processors. The SMC protocol then
+ allows reading and writing many different keys which implement the
+ various features. The MFD core device handles this protocol and
+ exposes it to the sub-devices.
+
config MFD_MADERA
tristate "Cirrus Logic Madera codecs"
select MFD_CORE
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 948cbdf42a18b22a826f0b17fb8d5796a7ec8ba6..e9e2403d961a631d9d63a274e0e4f6457ae9e0f2 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_MFD_CS42L43_SDW) += cs42l43-sdw.o
obj-$(CONFIG_MFD_ENE_KB3930) += ene-kb3930.o
obj-$(CONFIG_MFD_EXYNOS_LPASS) += exynos-lpass.o
obj-$(CONFIG_MFD_GATEWORKS_GSC) += gateworks-gsc.o
+obj-$(CONFIG_MFD_MACSMC) += macsmc.o
obj-$(CONFIG_MFD_TI_LP873X) += lp873x.o
obj-$(CONFIG_MFD_TI_LP87565) += lp87565.o
diff --git a/drivers/mfd/macsmc.c b/drivers/mfd/macsmc.c
new file mode 100644
index 0000000000000000000000000000000000000000..59c2851b70f70a221434287cc99ef870a96f3659
--- /dev/null
+++ b/drivers/mfd/macsmc.c
@@ -0,0 +1,657 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple SMC (System Management Controller) MFD driver
+ *
+ * Copyright The Asahi Linux Contributors
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/math.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/macsmc.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/soc/apple/rtkit.h>
+#include <linux/unaligned.h>
+
+#define SMC_ENDPOINT 0x20
+
+/* We don't actually know the true size here but this seem reasonable */
+#define SMC_SHMEM_SIZE 0x1000
+#define SMC_MAX_SIZE 255
+
+#define SMC_MSG_READ_KEY 0x10
+#define SMC_MSG_WRITE_KEY 0x11
+#define SMC_MSG_GET_KEY_BY_INDEX 0x12
+#define SMC_MSG_GET_KEY_INFO 0x13
+#define SMC_MSG_INITIALIZE 0x17
+#define SMC_MSG_NOTIFICATION 0x18
+#define SMC_MSG_RW_KEY 0x20
+
+#define SMC_DATA GENMASK_ULL(63, 32)
+#define SMC_WSIZE GENMASK_ULL(31, 24)
+#define SMC_SIZE GENMASK_ULL(23, 16)
+#define SMC_ID GENMASK_ULL(15, 12)
+#define SMC_MSG GENMASK_ULL(7, 0)
+#define SMC_RESULT SMC_MSG
+
+#define SMC_RECV_TIMEOUT 500
+
+static const struct mfd_cell apple_smc_devs[] = {
+ MFD_CELL_OF("macsmc-gpio", NULL, NULL, 0, 0, "apple,smc-gpio"),
+ MFD_CELL_OF("macsmc-reboot", NULL, NULL, 0, 0, "apple,smc-reboot"),
+};
+
+static int apple_smc_cmd_locked(struct apple_smc *smc, u64 cmd, u64 arg,
+ u64 size, u64 wsize, u32 *ret_data)
+{
+ int ret;
+ u64 msg;
+ u8 result;
+
+ lockdep_assert_held(&smc->mutex);
+
+ if (!smc->alive)
+ return -EIO;
+ if (smc->atomic_mode)
+ return -EIO;
+
+ reinit_completion(&smc->cmd_done);
+
+ smc->msg_id = (smc->msg_id + 1) & 0xf;
+ msg = (FIELD_PREP(SMC_MSG, cmd) |
+ FIELD_PREP(SMC_SIZE, size) |
+ FIELD_PREP(SMC_WSIZE, wsize) |
+ FIELD_PREP(SMC_ID, smc->msg_id) |
+ FIELD_PREP(SMC_DATA, arg));
+
+ ret = apple_rtkit_send_message(smc->rtk, SMC_ENDPOINT, msg, NULL, false);
+ if (ret < 0) {
+ dev_err(smc->dev, "Failed to send command\n");
+ return ret;
+ }
+
+ do {
+ if (wait_for_completion_timeout(&smc->cmd_done,
+ msecs_to_jiffies(SMC_RECV_TIMEOUT)) == 0) {
+ dev_err(smc->dev, "Command timed out (%llx)", msg);
+ return -ETIMEDOUT;
+ }
+ if (FIELD_GET(SMC_ID, smc->cmd_ret) == smc->msg_id)
+ break;
+ dev_err(smc->dev, "Command sequence mismatch (expected %d, got %d)\n",
+ smc->msg_id, (unsigned int)FIELD_GET(SMC_ID, smc->cmd_ret));
+ } while (1);
+
+ result = FIELD_GET(SMC_RESULT, smc->cmd_ret);
+ if (result != 0)
+ return -result;
+
+ if (ret_data)
+ *ret_data = FIELD_GET(SMC_DATA, smc->cmd_ret);
+
+ return FIELD_GET(SMC_SIZE, smc->cmd_ret);
+}
+
+static int apple_smc_cmd(struct apple_smc *smc, u64 cmd, u64 arg,
+ u64 size, u64 wsize, u32 *ret_data)
+{
+ guard(mutex)(&smc->mutex);
+
+ return apple_smc_cmd_locked(smc, cmd, arg, size, wsize, ret_data);
+}
+
+static int apple_smc_rw_locked(struct apple_smc *smc, smc_key key,
+ const void *wbuf, size_t wsize,
+ void *rbuf, size_t rsize)
+{
+ int ret;
+ u64 cmd;
+ u64 smc_size, smc_wsize;
+ u32 rdata;
+
+ lockdep_assert_held(&smc->mutex);
+
+ dev_dbg(smc->dev, "SMC key: %p4ch, wsize: %zu, rsize: %zu\n", &key, wsize, rsize);
+
+ if (rsize > SMC_MAX_SIZE)
+ return -EINVAL;
+ if (wsize > SMC_MAX_SIZE)
+ return -EINVAL;
+
+ if (rsize && wsize) {
+ cmd = SMC_MSG_RW_KEY;
+ memcpy_toio(smc->shmem.iomem, wbuf, wsize);
+ smc_size = rsize;
+ smc_wsize = wsize;
+ } else if (wsize && !rsize) {
+ cmd = SMC_MSG_WRITE_KEY;
+ memcpy_toio(smc->shmem.iomem, wbuf, wsize);
+ /*
+ * Setting size to the length we want to write and wsize to 0
+ * looks silly but that's how the SMC protocol works ¯\_(ツ)_/¯
+ */
+ smc_size = wsize;
+ smc_wsize = 0;
+ } else if (!wsize && rsize) {
+ cmd = SMC_MSG_READ_KEY;
+ smc_size = rsize;
+ smc_wsize = 0;
+ } else {
+ return -EINVAL;
+ }
+
+ ret = apple_smc_cmd_locked(smc, cmd, key, smc_size, smc_wsize, &rdata);
+ if (ret < 0)
+ return ret;
+
+ if (rsize) {
+ /*
+ * Small data <= 4 bytes is returned as part of the reply
+ * message which is sent over the mailbox FIFO. Everything
+ * bigger has to be copied from SRAM which is mapped as
+ * Device memory.
+ */
+ if (rsize <= 4)
+ memcpy(rbuf, &rdata, rsize);
+ else
+ memcpy_fromio(rbuf, smc->shmem.iomem, rsize);
+ }
+
+ return ret;
+}
+
+int apple_smc_read(struct apple_smc *smc, smc_key key, void *buf, size_t size)
+{
+ guard(mutex)(&smc->mutex);
+
+ return apple_smc_rw_locked(smc, key, NULL, 0, buf, size);
+}
+EXPORT_SYMBOL(apple_smc_read);
+
+int apple_smc_write(struct apple_smc *smc, smc_key key, void *buf, size_t size)
+{
+ guard(mutex)(&smc->mutex);
+
+ return apple_smc_rw_locked(smc, key, buf, size, NULL, 0);
+}
+EXPORT_SYMBOL(apple_smc_write);
+
+int apple_smc_rw(struct apple_smc *smc, smc_key key, void *wbuf, size_t wsize,
+ void *rbuf, size_t rsize)
+{
+ guard(mutex)(&smc->mutex);
+
+ return apple_smc_rw_locked(smc, key, wbuf, wsize, rbuf, rsize);
+}
+EXPORT_SYMBOL(apple_smc_rw);
+
+int apple_smc_get_key_by_index(struct apple_smc *smc, int index, smc_key *key)
+{
+ int ret;
+
+ ret = apple_smc_cmd(smc, SMC_MSG_GET_KEY_BY_INDEX, index, 0, 0, key);
+
+ *key = swab32(*key);
+ return ret;
+}
+EXPORT_SYMBOL(apple_smc_get_key_by_index);
+
+int apple_smc_get_key_info(struct apple_smc *smc, smc_key key, struct apple_smc_key_info *info)
+{
+ u8 key_info[6];
+ int ret;
+
+ ret = apple_smc_cmd(smc, SMC_MSG_GET_KEY_INFO, key, 0, 0, NULL);
+ if (ret >= 0 && info) {
+ memcpy_fromio(key_info, smc->shmem.iomem, sizeof(key_info));
+ info->size = key_info[0];
+ info->type_code = get_unaligned_be32(&key_info[1]);
+ info->flags = key_info[5];
+ }
+ return ret;
+}
+EXPORT_SYMBOL(apple_smc_get_key_info);
+
+int apple_smc_find_first_key_index(struct apple_smc *smc, smc_key key)
+{
+ int start, count;
+
+ /* return early if the key is out of bounds */
+ if (key <= smc->first_key)
+ return 0;
+ if (key > smc->last_key)
+ return smc->key_count;
+
+ /* binary search to find index of first SMC key bigger or equal to key */
+ start = 0;
+ count = smc->key_count;
+ while (count > 1) {
+ int ret;
+ smc_key pkey;
+ int pivot = start + ((count - 1) >> 1);
+
+ ret = apple_smc_get_key_by_index(smc, pivot, &pkey);
+ if (ret < 0)
+ return ret;
+
+ if (pkey == key)
+ return pivot;
+
+ pivot++;
+
+ if (pkey < key) {
+ count -= pivot - start;
+ start = pivot;
+ } else {
+ count = pivot - start;
+ }
+ }
+
+ return start;
+}
+EXPORT_SYMBOL(apple_smc_find_first_key_index);
+
+int apple_smc_read_f32_scaled(struct apple_smc *smc, smc_key key, int *p, int scale)
+{
+ u32 fval;
+ u64 val;
+ int ret, exp;
+
+ /* pretend the 4 bytes returned by SMC are a 32bit unsigned integer */
+ ret = apple_smc_read_u32(smc, key, &fval);
+ if (ret < 0)
+ return ret;
+
+ /* extract exponent and fraction from the IEEE 754 32bit float */
+ val = ((u64)((fval & GENMASK(22, 0)) | BIT(23)));
+ exp = ((fval >> 23) & 0xff) - 127 - 23;
+
+ /* move fraction to target scale */
+ if (scale < 0) {
+ val <<= 32;
+ exp -= 32;
+ val /= -scale;
+ } else {
+ val *= scale;
+ }
+
+ /* apply exponent if possible and fall back to 0 / U64_MAX on overflow */
+ if (exp > 63)
+ val = U64_MAX;
+ else if (exp < -63)
+ val = 0;
+ else if (exp < 0)
+ val >>= -exp;
+ else if (exp != 0 && (val & ~((1UL << (64 - exp)) - 1))) /* overflow */
+ val = U64_MAX;
+ else
+ val <<= exp;
+
+ /* handle IEEE 754 32bit float sign bit and catch possible overflows */
+ if (fval & BIT(31)) {
+ if (val > (-(s64)INT_MIN))
+ *p = INT_MIN;
+ else
+ *p = -val;
+ } else {
+ if (val > INT_MAX)
+ *p = INT_MAX;
+ else
+ *p = val;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(apple_smc_read_f32_scaled);
+
+int apple_smc_read_ioft_scaled(struct apple_smc *smc, smc_key key, u64 *p,
+ int scale)
+{
+ u64 val;
+ int ret;
+
+ ret = apple_smc_read_u64(smc, key, &val);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * The value val is represented in 48.16 fixed-point format, where
+ * the upper 48 bits represent the integer part and the lower 16 bits
+ * represent the fractional part. Dividing by 1 << 16 extracts the
+ * integer part by discarding the fractional portion.
+ * To scale the value as requested mult_frac is used to multiply val
+ * by the scaling factor while dividing by 1 << 16 in a single step.
+ */
+ *p = mult_frac(val, scale, (1<<16));
+
+ return 0;
+}
+EXPORT_SYMBOL(apple_smc_read_ioft_scaled);
+
+int apple_smc_enter_atomic(struct apple_smc *smc)
+{
+ guard(mutex)(&smc->mutex);
+
+ /*
+ * Disable notifications since this is called before shutdown and no
+ * notification handler will be able to handle the notification
+ * using atomic operations only. Also ignore any failure here
+ * because we're about to shut down or reboot anyway.
+ * We can't use apple_smc_write_flag here since that would try to lock
+ * smc->mutex again.
+ */
+ const u8 flag = 0;
+
+ apple_smc_rw_locked(smc, SMC_KEY(NTAP), &flag, sizeof(flag), NULL, 0);
+
+ smc->atomic_mode = true;
+
+ return 0;
+}
+EXPORT_SYMBOL(apple_smc_enter_atomic);
+
+int apple_smc_write_atomic(struct apple_smc *smc, smc_key key, void *buf, size_t size)
+{
+ guard(spinlock_irqsave)(&smc->lock);
+ int ret;
+ u64 msg;
+ u8 result;
+
+ if (size > SMC_MAX_SIZE || size == 0)
+ return -EINVAL;
+
+ if (!smc->alive)
+ return -EIO;
+ if (!smc->atomic_mode)
+ return -EIO;
+
+ memcpy_toio(smc->shmem.iomem, buf, size);
+ smc->msg_id = (smc->msg_id + 1) & 0xf;
+ msg = (FIELD_PREP(SMC_MSG, SMC_MSG_WRITE_KEY) |
+ FIELD_PREP(SMC_SIZE, size) |
+ FIELD_PREP(SMC_ID, smc->msg_id) |
+ FIELD_PREP(SMC_DATA, key));
+ smc->atomic_pending = true;
+
+ ret = apple_rtkit_send_message(smc->rtk, SMC_ENDPOINT, msg, NULL, true);
+ if (ret < 0) {
+ dev_err(smc->dev, "Failed to send command (%d)\n", ret);
+ return ret;
+ }
+
+ while (smc->atomic_pending) {
+ ret = apple_rtkit_poll(smc->rtk);
+ if (ret < 0) {
+ dev_err(smc->dev, "RTKit poll failed (%llx)", msg);
+ return ret;
+ }
+ udelay(100);
+ }
+
+ if (FIELD_GET(SMC_ID, smc->cmd_ret) != smc->msg_id) {
+ dev_err(smc->dev, "Command sequence mismatch (expected %d, got %d)\n",
+ smc->msg_id, (unsigned int)FIELD_GET(SMC_ID, smc->cmd_ret));
+ return -EIO;
+ }
+
+ result = FIELD_GET(SMC_RESULT, smc->cmd_ret);
+ if (result != 0)
+ return -result;
+
+ return FIELD_GET(SMC_SIZE, smc->cmd_ret);
+}
+EXPORT_SYMBOL(apple_smc_write_atomic);
+
+static void apple_smc_rtkit_crashed(void *cookie, const void *bfr, size_t bfr_len)
+{
+ struct apple_smc *smc = cookie;
+
+ dev_err(smc->dev, "SMC crashed! Your system will reboot in a few seconds...\n");
+ smc->alive = false;
+}
+
+static int apple_smc_rtkit_shmem_setup(void *cookie, struct apple_rtkit_shmem *bfr)
+{
+ struct apple_smc *smc = cookie;
+ struct resource res = {
+ .start = bfr->iova,
+ .end = bfr->iova + bfr->size - 1,
+ .name = "rtkit_map",
+ .flags = smc->sram->flags,
+ };
+
+ if (!bfr->iova) {
+ dev_err(smc->dev, "RTKit wants a RAM buffer\n");
+ return -EIO;
+ }
+
+ if (res.end < res.start || !resource_contains(smc->sram, &res)) {
+ dev_err(smc->dev,
+ "RTKit buffer request outside SRAM region: %pR", &res);
+ return -EFAULT;
+ }
+
+ bfr->iomem = smc->sram_base + (res.start - smc->sram->start);
+ bfr->is_mapped = true;
+
+ return 0;
+}
+
+static void apple_smc_rtkit_shmem_destroy(void *cookie, struct apple_rtkit_shmem *bfr)
+{
+ // no-op
+}
+
+static bool apple_smc_rtkit_recv_early(void *cookie, u8 endpoint, u64 message)
+{
+ struct apple_smc *smc = cookie;
+
+ if (endpoint != SMC_ENDPOINT) {
+ dev_err(smc->dev, "Received message for unknown endpoint 0x%x\n", endpoint);
+ return false;
+ }
+
+ if (!smc->initialized) {
+ int ret;
+
+ smc->shmem.iova = message;
+ smc->shmem.size = SMC_SHMEM_SIZE;
+ ret = apple_smc_rtkit_shmem_setup(smc, &smc->shmem);
+ if (ret < 0)
+ dev_err(smc->dev, "Failed to initialize shared memory\n");
+ else
+ smc->alive = true;
+ smc->initialized = true;
+ complete(&smc->init_done);
+ } else if (FIELD_GET(SMC_MSG, message) == SMC_MSG_NOTIFICATION) {
+ /* Handle these in the RTKit worker thread */
+ return false;
+ } else {
+ smc->cmd_ret = message;
+ if (smc->atomic_pending)
+ smc->atomic_pending = false;
+ else
+ complete(&smc->cmd_done);
+ }
+
+ return true;
+}
+
+static void apple_smc_rtkit_recv(void *cookie, u8 endpoint, u64 message)
+{
+ struct apple_smc *smc = cookie;
+ uint32_t event;
+
+ if (endpoint != SMC_ENDPOINT) {
+ dev_err(smc->dev, "Received message for unknown endpoint 0x%x\n", endpoint);
+ return;
+ }
+
+ if (FIELD_GET(SMC_MSG, message) != SMC_MSG_NOTIFICATION) {
+ dev_err(smc->dev, "Received unknown message from worker: 0x%llx\n", message);
+ return;
+ }
+
+ event = FIELD_GET(SMC_DATA, message);
+ dev_dbg(smc->dev, "Event: 0x%08x\n", event);
+ blocking_notifier_call_chain(&smc->event_handlers, event, NULL);
+}
+
+static const struct apple_rtkit_ops apple_smc_rtkit_ops = {
+ .crashed = apple_smc_rtkit_crashed,
+ .recv_message = apple_smc_rtkit_recv,
+ .recv_message_early = apple_smc_rtkit_recv_early,
+ .shmem_setup = apple_smc_rtkit_shmem_setup,
+ .shmem_destroy = apple_smc_rtkit_shmem_destroy,
+};
+
+static int apple_smc_platform_probe(struct platform_device *pdev)
+{
+ int ret;
+ u32 count;
+ struct apple_smc *smc;
+ struct device *dev = &pdev->dev;
+
+ smc = devm_kzalloc(dev, sizeof(*smc), GFP_KERNEL);
+ if (!smc)
+ return -ENOMEM;
+
+ smc->dev = &pdev->dev;
+ smc->sram = platform_get_resource_byname(pdev, IORESOURCE_MEM, "sram");
+ if (!smc->sram)
+ return dev_err_probe(dev, EIO,
+ "No SRAM region");
+
+ smc->sram_base = devm_ioremap_resource(dev, smc->sram);
+ if (IS_ERR(smc->sram_base))
+ return dev_err_probe(dev, PTR_ERR(smc->sram_base),
+ "Failed to map SRAM region");
+
+ smc->rtk =
+ devm_apple_rtkit_init(dev, smc, NULL, 0, &apple_smc_rtkit_ops);
+ if (IS_ERR(smc->rtk))
+ return dev_err_probe(dev, PTR_ERR(smc->rtk),
+ "Failed to initialize RTKit");
+
+ ret = apple_rtkit_wake(smc->rtk);
+ if (ret != 0)
+ return dev_err_probe(dev, ret,
+ "Failed to wake up SMC");
+
+ ret = apple_rtkit_start_ep(smc->rtk, SMC_ENDPOINT);
+ if (ret != 0) {
+ ret = dev_err_probe(dev, ret,
+ "Failed to start SMC endpoint");
+ goto cleanup;
+ }
+
+ init_completion(&smc->init_done);
+ init_completion(&smc->cmd_done);
+
+ ret = apple_rtkit_send_message(smc->rtk, SMC_ENDPOINT,
+ FIELD_PREP(SMC_MSG, SMC_MSG_INITIALIZE), NULL, false);
+ if (ret < 0) {
+ ret = dev_err_probe(dev, ret, "Failed to send init message");
+ goto cleanup;
+ }
+
+ if (wait_for_completion_timeout(&smc->init_done,
+ msecs_to_jiffies(SMC_RECV_TIMEOUT)) == 0) {
+ ret = -ETIMEDOUT;
+ dev_err(dev, "Timed out initializing SMC");
+ goto cleanup;
+ }
+
+ if (!smc->alive) {
+ ret = -EIO;
+ goto cleanup;
+ }
+
+ dev_set_drvdata(&pdev->dev, smc);
+ BLOCKING_INIT_NOTIFIER_HEAD(&smc->event_handlers);
+
+ ret = apple_smc_read_u32(smc, SMC_KEY(#KEY), &count);
+ if (ret) {
+ ret = dev_err_probe(smc->dev, ret, "Failed to get key count");
+ goto cleanup;
+ }
+ smc->key_count = be32_to_cpu(count);
+
+ ret = apple_smc_get_key_by_index(smc, 0, &smc->first_key);
+ if (ret) {
+ ret = dev_err_probe(smc->dev, ret, "Failed to get first key");
+ goto cleanup;
+ }
+
+ ret = apple_smc_get_key_by_index(smc, smc->key_count - 1, &smc->last_key);
+ if (ret) {
+ ret = dev_err_probe(smc->dev, ret, "Failed to get last key");
+ goto cleanup;
+ }
+
+ /* Enable notifications */
+ apple_smc_write_flag(smc, SMC_KEY(NTAP), true);
+
+ dev_info(smc->dev, "Initialized (%d keys %p4ch ... %p4ch)\n",
+ smc->key_count, &smc->first_key, &smc->last_key);
+
+ ret = mfd_add_devices(smc->dev, -1,
+ apple_smc_devs, ARRAY_SIZE(apple_smc_devs),
+ NULL, 0, NULL);
+ if (ret) {
+ ret = dev_err_probe(smc->dev, ret, "Subdevice initialization failed");
+ goto cleanup;
+ }
+
+ return 0;
+
+cleanup:
+ /* Try to shut down RTKit, if it's not completely wedged */
+ if (apple_rtkit_is_running(smc->rtk))
+ apple_rtkit_quiesce(smc->rtk);
+
+ return ret;
+}
+
+static void apple_smc_platform_remove(struct platform_device *pdev)
+{
+ struct apple_smc *smc = platform_get_drvdata(pdev);
+
+ mfd_remove_devices(smc->dev);
+
+ /* Disable notifications */
+ apple_smc_write_flag(smc, SMC_KEY(NTAP), false);
+
+ /* Shut down SMC firmware */
+ if (apple_rtkit_is_running(smc->rtk))
+ apple_rtkit_quiesce(smc->rtk);
+}
+
+static const struct of_device_id apple_smc_of_match[] = {
+ { .compatible = "apple,smc" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, apple_smc_of_match);
+
+static struct platform_driver apple_smc_driver = {
+ .driver = {
+ .name = "mfd-macsmc",
+ .owner = THIS_MODULE,
+ .of_match_table = apple_smc_of_match,
+ },
+ .probe = apple_smc_platform_probe,
+ .remove = apple_smc_platform_remove,
+};
+module_platform_driver(apple_smc_driver);
+
+MODULE_AUTHOR("Hector Martin <marcan@...can.st>");
+MODULE_AUTHOR("Sven Peter <sven@...npeter.dev>");
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_DESCRIPTION("Apple SMC driver");
diff --git a/include/linux/mfd/macsmc.h b/include/linux/mfd/macsmc.h
new file mode 100644
index 0000000000000000000000000000000000000000..0b24b8e44dcb4564b50e6d2145f23f23321139c1
--- /dev/null
+++ b/include/linux/mfd/macsmc.h
@@ -0,0 +1,337 @@
+/* SPDX-License-Identifier: GPL-2.0-only OR MIT */
+/*
+ * Apple SMC (System Management Controller) core definitions
+ *
+ * Copyright (C) The Asahi Linux Contributors
+ */
+
+#ifndef _LINUX_MFD_MACSMC_H
+#define _LINUX_MFD_MACSMC_H
+
+#include <linux/soc/apple/rtkit.h>
+
+/**
+ * typedef smc_key - Alias for u32 to be used for SMC keys
+ *
+ * SMC keys are 32bit integers containing packed ASCII characters in natural
+ * integer order, i.e. 0xAABBCCDD, which represent the FourCC ABCD.
+ * The SMC driver is designed with this assumption and ensures the right
+ * endianness is used when these are stored to memory and sent to or received
+ * from the actual SMC firmware (which can be done in either shared memory or
+ * as 64bit mailbox message on Apple Silicon).
+ * Internally, SMC stores these keys in a table sorted lexicographically and
+ * allows resolving an index into this table to the corresponding SMC key.
+ * Thus, storing keys as u32 is very convenient as it allows to e.g. use
+ * normal comparison operators which directly map to the natural order used
+ * by SMC firmware.
+ *
+ * This simple type alias is introduced to allow easy recognition of SMC key
+ * variables and arguments.
+ */
+typedef u32 smc_key;
+
+/**
+ * SMC_KEY - Convert FourCC SMC keys in source code to smc_key
+ *
+ * This macro can be used to easily define FourCC SMC keys in source code
+ * and convert these to u32 / smc_key, e.g. SMC_KEY(NTAP) will expand to
+ * 0x4e544150.
+ */
+#define SMC_KEY(s) (smc_key)(_SMC_KEY(#s))
+#define _SMC_KEY(s) (((s)[0] << 24) | ((s)[1] << 16) | ((s)[2] << 8) | (s)[3])
+
+#define APPLE_SMC_READABLE BIT(7)
+#define APPLE_SMC_WRITABLE BIT(6)
+#define APPLE_SMC_FUNCTION BIT(4)
+
+/**
+ * struct apple_smc_key_info - information for a SMC key as returned by SMC
+ * @size: size of the buffer associated with this key
+ * @type_code: FourCC code indicating the type for this key.
+ * Known types:
+ * ch8*: ASCII string
+ * flag: boolean, 1 or 0
+ * flt: 32-bit single-precision IEEE 754 float
+ * hex: binary data
+ * ioft: 64bit unsigned fixed-point intger (48.16)
+ * si8, ui8, si16, ui16, si32, ui32, si64, ui64: signed/unsigned 8-/16-/32-/64-bit integer
+ * @flags: bitfield encoding flags (APPLE_SMC_{READABLE,WRITABLE,FUNCTION})
+ */
+struct apple_smc_key_info {
+ u8 size;
+ u32 type_code;
+ u8 flags;
+};
+
+/**
+ * struct apple_smc
+ * @dev: underlying device struct for the physical backend device
+ * @key_count: number of available SMC keys
+ * @first_key: first valid SMC key
+ * @last_key: last valid SMC key
+ * @event_handlers: notifier call chain for events received from SMC
+ * @rtk: pointer to Apple RTKit instance
+ * @init_done: completion for initialization
+ * @initialized: flag indicating if SMC is initialized
+ * @alive: flag indicating if SMC is alive
+ * @sram: pointer to SRAM resource
+ * @sram_base: SRAM base address
+ * @shmem: RTKit shared memory structure for SRAM
+ * @msg_id: current message id for commands, will be incremented for each command
+ * @atomic_mode: flag set when atomic mode is entered
+ * @atomic_pending: flag indicating pending atomic command
+ * @cmd_done: completion for command execution in non-atomic mode
+ * @cmd_ret: return value from SMC for last command
+ * @mutex: mutex for non-atomic mode
+ * @lock: spinlock for atomic mode
+ */
+struct apple_smc {
+ struct device *dev;
+
+ u32 key_count;
+ smc_key first_key;
+ smc_key last_key;
+
+ struct blocking_notifier_head event_handlers;
+
+ struct apple_rtkit *rtk;
+
+ struct completion init_done;
+ bool initialized;
+ bool alive;
+
+ struct resource *sram;
+ void __iomem *sram_base;
+ struct apple_rtkit_shmem shmem;
+
+ unsigned int msg_id;
+
+ bool atomic_mode;
+ bool atomic_pending;
+ struct completion cmd_done;
+ u64 cmd_ret;
+
+ struct mutex mutex;
+ spinlock_t lock;
+};
+
+/**
+ * apple_smc_read - read size bytes from given SMC key into buf
+ * @smc: pointer to apple_smc struct
+ * @key: smc_key to be read
+ * @buf: buffer into which size bytes of data will be read from SMC
+ * @size: number of bytes to be read into buf
+ *
+ * Return: Zero on success, negative errno on error
+ */
+int apple_smc_read(struct apple_smc *smc, smc_key key, void *buf, size_t size);
+
+/**
+ * apple_smc_write - write size bytes into given SMC key from buf
+ * @smc: pointer to apple_smc struct
+ * @key: smc_key data will be written to
+ * @buf: buffer from which size bytes of data will be written to SMC
+ * @size: number of bytes to be written
+ *
+ * Return: Zero on success, negative errno on error
+ */
+int apple_smc_write(struct apple_smc *smc, smc_key key, void *buf, size_t size);
+
+/**
+ * apple_smc_enter_atomic - enter atomic mode to be able to use apple_smc_write_atomic
+ * @smc: pointer to apple_smc struct
+ *
+ * This function switches the SMC backend to atomic mode which allows the
+ * use of apple_smc_write_atomic while disabling *all* other functions.
+ * This is only used for shutdown/reboot which requires writing to a SMC
+ * key from atomic context.
+ *
+ * Return: Zero on success, negative errno on error
+ */
+int apple_smc_enter_atomic(struct apple_smc *smc);
+
+/**
+ * apple_smc_write_atomic - write size bytes into given SMC key from buf without sleeping
+ * @smc: pointer to apple_smc struct
+ * @key: smc_key data will be written to
+ * @buf: buffer from which size bytes of data will be written to SMC
+ * @size: number of bytes to be written
+ *
+ * Note that this function will fail if apple_smc_enter_atomic hasn't been
+ * called before.
+ *
+ * Return: Zero on success, negative errno on error
+ */
+int apple_smc_write_atomic(struct apple_smc *smc, smc_key key, void *buf, size_t size);
+
+/**
+ * apple_smc_rw - write and then read using the given SMC key
+ * @smc: pointer to apple_smc struct
+ * @key: smc_key data will be written to
+ * @wbuf: buffer from which size bytes of data will be written to SMC
+ * @wsize: number of bytes to be written
+ * @rbuf: buffer to which size bytes of data will be read from SMC
+ * @rsize: number of bytes to be read
+ *
+ * Return: Zero on success, negative errno on error
+ */
+int apple_smc_rw(struct apple_smc *smc, smc_key key, void *wbuf, size_t wsize,
+ void *rbuf, size_t rsize);
+
+/**
+ * apple_smc_get_key_by_index - given an index return the corresponding SMC key
+ * @smc: pointer to apple_smc struct
+ * @index: index to be resolved
+ * @key: buffer for SMC key to be returned
+ *
+ * Return: Zero on success, negative errno on error
+ */
+int apple_smc_get_key_by_index(struct apple_smc *smc, int index, smc_key *key);
+
+/**
+ * apple_smc_get_key_info - get key information from SMC
+ * @smc: pointer to apple_smc struct
+ * @key: key to acquire information for
+ * @info: pointer to struct apple_smc_key_info which will be filled
+ *
+ * Return: Zero on success, negative errno on error
+ */
+int apple_smc_get_key_info(struct apple_smc *smc, smc_key key, struct apple_smc_key_info *info);
+
+/**
+ * apple_smc_find_first_key_index - find index of first SMC key bigger or equal to key
+ * @smc: pointer to apple_smc struct
+ * @key: smc_key to be found
+ *
+ * SMC keys are represented using either FourCC (which is stored as
+ * uint32_t / smc_key in this driver) or an index into the table of available
+ * keys which is sorted lexicographically.
+ * This function takes a FourCC key and uses binary search to find the
+ * index of the first SMC key that is lexicographically equal or bigger than the
+ * given input.
+ * This is required for e.g. the GPIO driver: GPIO keys start with gP
+ * and the driver has to find the first such key (by calling this function with
+ * key = SMC_KEY(gP00)) to be able to enumerate and register all available GPIOs
+ * at probe time.
+ *
+ * Return: Index of the first smc key that's bigger or equal to the given key.
+ *
+ * If the key is smaller than the first available key zero will be returned.
+ * If the key is bigger than the last available key smc->key_count (i.e. an out
+ * of bounds key) will be returned.
+ */
+int apple_smc_find_first_key_index(struct apple_smc *smc, smc_key key);
+
+/**
+ * apple_smc_key_exists - check if the given SMC key exists
+ * @smc: pointer to apple_smc struct
+ * @key: smc_key to be checked
+ */
+static inline bool apple_smc_key_exists(struct apple_smc *smc, smc_key key)
+{
+ return apple_smc_get_key_info(smc, key, NULL) >= 0;
+}
+
+#define APPLE_SMC_TYPE_OPS(type) \
+ static inline int apple_smc_read_##type(struct apple_smc *smc, smc_key key, type *p) \
+ { \
+ int ret = apple_smc_read(smc, key, p, sizeof(*p)); \
+ return (ret < 0) ? ret : ((ret != sizeof(*p)) ? -EINVAL : 0); \
+ } \
+ static inline int apple_smc_write_##type(struct apple_smc *smc, smc_key key, type p) \
+ { \
+ return apple_smc_write(smc, key, &p, sizeof(p)); \
+ } \
+ static inline int apple_smc_write_##type##_atomic(struct apple_smc *smc, smc_key key, type p) \
+ { \
+ return apple_smc_write_atomic(smc, key, &p, sizeof(p)); \
+ } \
+ static inline int apple_smc_rw_##type(struct apple_smc *smc, smc_key key, \
+ type w, type *r) \
+ { \
+ int ret = apple_smc_rw(smc, key, &w, sizeof(w), r, sizeof(*r)); \
+ return (ret < 0) ? ret : ((ret != sizeof(*r)) ? -EINVAL : 0); \
+ }
+
+APPLE_SMC_TYPE_OPS(u64)
+APPLE_SMC_TYPE_OPS(u32)
+APPLE_SMC_TYPE_OPS(u16)
+APPLE_SMC_TYPE_OPS(u8)
+APPLE_SMC_TYPE_OPS(s64)
+APPLE_SMC_TYPE_OPS(s32)
+APPLE_SMC_TYPE_OPS(s16)
+APPLE_SMC_TYPE_OPS(s8)
+
+static inline int apple_smc_read_flag(struct apple_smc *smc, smc_key key, bool *flag)
+{
+ u8 val;
+ int ret = apple_smc_read_u8(smc, key, &val);
+
+ if (ret < 0)
+ return ret;
+
+ *flag = val ? true : false;
+ return ret;
+}
+
+static inline int apple_smc_write_flag(struct apple_smc *smc, smc_key key, bool state)
+{
+ return apple_smc_write_u8(smc, key, state ? 1 : 0);
+}
+
+static inline int apple_smc_write_flag_atomic(struct apple_smc *smc, smc_key key, bool state)
+{
+ return apple_smc_write_u8_atomic(smc, key, state ? 1 : 0);
+}
+
+/**
+ * apple_smc_read_f32_scaled - read a float value from SMC and scale to a regular integer
+ * @smc: pointer to apple_smc struct
+ * @key: key to be read
+ * @p: pointer to integer that will be overwritten with the read value
+ * @scale: target scale
+ *
+ * Read a float value from the given SMC key and scale it to the given order
+ * of magnitude. If the value is smaller than the given scale zero will be
+ * used. If the value overflows an integer at the given scale p will be set to
+ * U64_MAX.
+ *
+ * This is useful for e.g. reading power consumption, which is reported by SMC
+ * in Watt (W) as a floating point number, and scale it to uW like so:
+ *
+ * apple_smc_read_f32_scaled(smc, SMC_KEY(PSTR), &power_uW, 1000000);
+ *
+ * At that scale, noise starts to dominate the power measurements anyway and
+ * there's no reason to deal with floats.
+ *
+ * Return: Zero on success, negative errno on error
+ */
+int apple_smc_read_f32_scaled(struct apple_smc *smc, smc_key key, int *p, int scale);
+
+/**
+ * apple_smc_read_ioft_scaled - read a 48.16 fixed point from SMC and scale to a regular integer
+ * @smc: pointer to apple_smc struct
+ * @key: key to be read
+ * @p: pointer to integer that will be overwritten with the read value
+ * @scale: target scale
+ *
+ * Read a 48.16 fixed point value from the given SMC key and scale it to the
+ * given order of magnitude. If the value is smaller than the given scale zero
+ * will be used. If the value overflows an integer at the given scale p will be
+ * set to U64_MAX.
+ *
+ * This is useful for e.g. reading temperature, which is reported by SMC in
+ * degrees as a 48.16 fixed point number, and scale it to milli-degrees Celsius
+ * like so:
+ *
+ * apple_smc_read_ioft_scaled(smc, SMC_KEY(TR0Z), &temperature_mC, 1000);
+ *
+ * Reporting temperature with more precision runs into measurements errors and
+ * isn't very useful such that using a simple integer instead of fixed point
+ * numbers is reasonable.
+ *
+ * Return: Zero on success, negative errno on error
+ */
+int apple_smc_read_ioft_scaled(struct apple_smc *smc, smc_key key, u64 *p, int scale);
+
+#endif
--
2.34.1
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