drivers/mfd/macsmc.c - pub/scm/linux/kernel/git/stable/linux-stable-rc - Git at Google

 // 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/overflow.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_TIMEOUT_MS		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)
 {
 	u8 result;
 	int ret;
 	u64 msg;

 	lockdep_assert_held(&smc->mutex);

 	if (smc->boot_stage != APPLE_SMC_INITIALIZED)
 		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) {
 		dev_err(smc->dev, "Failed to send command\n");
 		return ret;
 	}

 	if (wait_for_completion_timeout(&smc->cmd_done, msecs_to_jiffies(SMC_TIMEOUT_MS)) <= 0) {
 		dev_err(smc->dev, "Command timed out (%llx)", msg);
 		return -ETIMEDOUT;
 	}

 	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)
 		return -EIO;

 	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)
 {
 	u64 smc_size, smc_wsize;
 	u32 rdata;
 	int ret;
 	u64 cmd;

 	lockdep_assert_held(&smc->mutex);

 	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_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);
 	u8 result;
 	int ret;
 	u64 msg;

 	if (size > SMC_MAX_SIZE || size == 0)
 		return -EINVAL;

 	if (smc->boot_stage != APPLE_SMC_INITIALIZED)
 		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)
 		return -EIO;

 	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;

 	smc->boot_stage = APPLE_SMC_ERROR_CRASHED;
 	dev_err(smc->dev, "SMC crashed! Your system will reboot in a few seconds...\n");
 }

 static int apple_smc_rtkit_shmem_setup(void *cookie, struct apple_rtkit_shmem *bfr)
 {
 	struct apple_smc *smc = cookie;
 	size_t bfr_end;

 	if (!bfr->iova) {
 		dev_err(smc->dev, "RTKit wants a RAM buffer\n");
 		return -EIO;
 	}

 	if (check_add_overflow(bfr->iova, bfr->size - 1, &bfr_end))
 		return -EFAULT;

 	if (bfr->iova < smc->sram->start || bfr->iova > smc->sram->end ||
 	    bfr_end > smc->sram->end) {
 		dev_err(smc->dev, "RTKit buffer request outside SRAM region: [0x%llx, 0x%llx]\n",
 			(unsigned long long)bfr->iova,
 			(unsigned long long)bfr_end);
 		return -EFAULT;
 	}

 	bfr->iomem = smc->sram_base + (bfr->iova - smc->sram->start);
 	bfr->is_mapped = true;

 	return 0;
 }

 static bool apple_smc_rtkit_recv_early(void *cookie, u8 endpoint, u64 message)
 {
 	struct apple_smc *smc = cookie;

 	if (endpoint != SMC_ENDPOINT) {
 		dev_warn(smc->dev, "Received message for unknown endpoint 0x%x\n", endpoint);
 		return false;
 	}

 	if (smc->boot_stage == APPLE_SMC_BOOTING) {
 		int ret;

 		smc->shmem.iova = message;
 		smc->shmem.size = SMC_SHMEM_SIZE;
 		ret = apple_smc_rtkit_shmem_setup(smc, &smc->shmem);
 		if (ret < 0) {
 			smc->boot_stage = APPLE_SMC_ERROR_NO_SHMEM;
 			dev_err(smc->dev, "Failed to initialize shared memory (%d)\n", ret);
 		} else {
 			smc->boot_stage = APPLE_SMC_INITIALIZED;
 		}
 		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;

 	if (endpoint != SMC_ENDPOINT) {
 		dev_warn(smc->dev, "Received message for unknown endpoint 0x%x\n", endpoint);
 		return;
 	}

 	if (FIELD_GET(SMC_MSG, message) != SMC_MSG_NOTIFICATION) {
 		dev_warn(smc->dev, "Received unknown message from worker: 0x%llx\n", message);
 		return;
 	}

 	blocking_notifier_call_chain(&smc->event_handlers, FIELD_GET(SMC_DATA, message), 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,
 };

 static void apple_smc_rtkit_shutdown(void *data)
 {
 	struct apple_smc *smc = data;

 	/* Shut down SMC firmware, if it's not completely wedged */
 	if (apple_rtkit_is_running(smc->rtk))
 		apple_rtkit_quiesce(smc->rtk);
 }

 static void apple_smc_disable_notifications(void *data)
 {
 	struct apple_smc *smc = data;

 	apple_smc_write_flag(smc, SMC_KEY(NTAP), false);
 }

 static int apple_smc_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct apple_smc *smc;
 	u32 count;
 	int ret;

 	smc = devm_kzalloc(dev, sizeof(*smc), GFP_KERNEL);
 	if (!smc)
 		return -ENOMEM;

 	smc->dev = &pdev->dev;
 	smc->sram_base = devm_platform_get_and_ioremap_resource(pdev, 1, &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");

 	smc->boot_stage = APPLE_SMC_BOOTING;
 	ret = apple_rtkit_wake(smc->rtk);
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to wake up SMC");

 	ret = devm_add_action_or_reset(dev, apple_smc_rtkit_shutdown, smc);
 	if (ret)
 		return ret;

 	ret = apple_rtkit_start_ep(smc->rtk, SMC_ENDPOINT);
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to start SMC endpoint");

 	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)
 		return dev_err_probe(dev, ret, "Failed to send init message");

 	if (wait_for_completion_timeout(&smc->init_done, msecs_to_jiffies(SMC_TIMEOUT_MS)) == 0) {
 		dev_err(dev, "Timed out initializing SMC");
 		return -ETIMEDOUT;
 	}

 	if (smc->boot_stage != APPLE_SMC_INITIALIZED) {
 		dev_err(dev, "SMC failed to boot successfully, boot stage=%d\n", smc->boot_stage);
 		return -EIO;
 	}

 	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)
 		return dev_err_probe(smc->dev, ret, "Failed to get key count");
 	smc->key_count = be32_to_cpu(count);

 	/* Enable notifications */
 	apple_smc_write_flag(smc, SMC_KEY(NTAP), true);
 	ret = devm_add_action_or_reset(dev, apple_smc_disable_notifications, smc);
 	if (ret)
 		return ret;

 	ret = devm_mfd_add_devices(smc->dev, PLATFORM_DEVID_NONE,
 				   apple_smc_devs, ARRAY_SIZE(apple_smc_devs),
 				   NULL, 0, NULL);
 	if (ret)
 		return dev_err_probe(smc->dev, ret, "Failed to register sub-devices");


 	return 0;
 }

 static const struct of_device_id apple_smc_of_match[] = {
 	{ .compatible = "apple,t8103-smc" },
 	{ .compatible = "apple,smc" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, apple_smc_of_match);

 static struct platform_driver apple_smc_driver = {
 	.driver = {
 		.name = "macsmc",
 		.of_match_table = apple_smc_of_match,
 	},
 	.probe = apple_smc_probe,
 };
 module_platform_driver(apple_smc_driver);

 MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
 MODULE_AUTHOR("Sven Peter <sven@kernel.org>");
 MODULE_LICENSE("Dual MIT/GPL");
 MODULE_DESCRIPTION("Apple SMC driver");
	// 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/overflow.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_TIMEOUT_MS 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)
	{
	u8 result;
	int ret;
	u64 msg;

	lockdep_assert_held(&smc->mutex);

	if (smc->boot_stage != APPLE_SMC_INITIALIZED)
	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) {
	dev_err(smc->dev, "Failed to send command\n");
	return ret;
	}

	if (wait_for_completion_timeout(&smc->cmd_done, msecs_to_jiffies(SMC_TIMEOUT_MS)) <= 0) {
	dev_err(smc->dev, "Command timed out (%llx)", msg);
	return -ETIMEDOUT;
	}

	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)
	return -EIO;

	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)
	{
	u64 smc_size, smc_wsize;
	u32 rdata;
	int ret;
	u64 cmd;

	lockdep_assert_held(&smc->mutex);

	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_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);
	u8 result;
	int ret;
	u64 msg;

	if (size > SMC_MAX_SIZE \|\| size == 0)
	return -EINVAL;

	if (smc->boot_stage != APPLE_SMC_INITIALIZED)
	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)
	return -EIO;

	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;

	smc->boot_stage = APPLE_SMC_ERROR_CRASHED;
	dev_err(smc->dev, "SMC crashed! Your system will reboot in a few seconds...\n");
	}

	static int apple_smc_rtkit_shmem_setup(void cookie, struct apple_rtkit_shmem bfr)
	{
	struct apple_smc *smc = cookie;
	size_t bfr_end;

	if (!bfr->iova) {
	dev_err(smc->dev, "RTKit wants a RAM buffer\n");
	return -EIO;
	}

	if (check_add_overflow(bfr->iova, bfr->size - 1, &bfr_end))
	return -EFAULT;

	if (bfr->iova < smc->sram->start \|\| bfr->iova > smc->sram->end \|\|
	bfr_end > smc->sram->end) {
	dev_err(smc->dev, "RTKit buffer request outside SRAM region: [0x%llx, 0x%llx]\n",
	(unsigned long long)bfr->iova,
	(unsigned long long)bfr_end);
	return -EFAULT;
	}

	bfr->iomem = smc->sram_base + (bfr->iova - smc->sram->start);
	bfr->is_mapped = true;

	return 0;
	}

	static bool apple_smc_rtkit_recv_early(void *cookie, u8 endpoint, u64 message)
	{
	struct apple_smc *smc = cookie;

	if (endpoint != SMC_ENDPOINT) {
	dev_warn(smc->dev, "Received message for unknown endpoint 0x%x\n", endpoint);
	return false;
	}

	if (smc->boot_stage == APPLE_SMC_BOOTING) {
	int ret;

	smc->shmem.iova = message;
	smc->shmem.size = SMC_SHMEM_SIZE;
	ret = apple_smc_rtkit_shmem_setup(smc, &smc->shmem);
	if (ret < 0) {
	smc->boot_stage = APPLE_SMC_ERROR_NO_SHMEM;
	dev_err(smc->dev, "Failed to initialize shared memory (%d)\n", ret);
	} else {
	smc->boot_stage = APPLE_SMC_INITIALIZED;
	}
	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;

	if (endpoint != SMC_ENDPOINT) {
	dev_warn(smc->dev, "Received message for unknown endpoint 0x%x\n", endpoint);
	return;
	}

	if (FIELD_GET(SMC_MSG, message) != SMC_MSG_NOTIFICATION) {
	dev_warn(smc->dev, "Received unknown message from worker: 0x%llx\n", message);
	return;
	}

	blocking_notifier_call_chain(&smc->event_handlers, FIELD_GET(SMC_DATA, message), 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,
	};

	static void apple_smc_rtkit_shutdown(void *data)
	{
	struct apple_smc *smc = data;

	/* Shut down SMC firmware, if it's not completely wedged */
	if (apple_rtkit_is_running(smc->rtk))
	apple_rtkit_quiesce(smc->rtk);
	}

	static void apple_smc_disable_notifications(void *data)
	{
	struct apple_smc *smc = data;

	apple_smc_write_flag(smc, SMC_KEY(NTAP), false);
	}

	static int apple_smc_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct apple_smc *smc;
	u32 count;
	int ret;

	smc = devm_kzalloc(dev, sizeof(*smc), GFP_KERNEL);
	if (!smc)
	return -ENOMEM;

	smc->dev = &pdev->dev;
	smc->sram_base = devm_platform_get_and_ioremap_resource(pdev, 1, &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");

	smc->boot_stage = APPLE_SMC_BOOTING;
	ret = apple_rtkit_wake(smc->rtk);
	if (ret)
	return dev_err_probe(dev, ret, "Failed to wake up SMC");

	ret = devm_add_action_or_reset(dev, apple_smc_rtkit_shutdown, smc);
	if (ret)
	return ret;

	ret = apple_rtkit_start_ep(smc->rtk, SMC_ENDPOINT);
	if (ret)
	return dev_err_probe(dev, ret, "Failed to start SMC endpoint");

	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)
	return dev_err_probe(dev, ret, "Failed to send init message");

	if (wait_for_completion_timeout(&smc->init_done, msecs_to_jiffies(SMC_TIMEOUT_MS)) == 0) {
	dev_err(dev, "Timed out initializing SMC");
	return -ETIMEDOUT;
	}

	if (smc->boot_stage != APPLE_SMC_INITIALIZED) {
	dev_err(dev, "SMC failed to boot successfully, boot stage=%d\n", smc->boot_stage);
	return -EIO;
	}

	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)
	return dev_err_probe(smc->dev, ret, "Failed to get key count");
	smc->key_count = be32_to_cpu(count);

	/* Enable notifications */
	apple_smc_write_flag(smc, SMC_KEY(NTAP), true);
	ret = devm_add_action_or_reset(dev, apple_smc_disable_notifications, smc);
	if (ret)
	return ret;

	ret = devm_mfd_add_devices(smc->dev, PLATFORM_DEVID_NONE,
	apple_smc_devs, ARRAY_SIZE(apple_smc_devs),
	NULL, 0, NULL);
	if (ret)
	return dev_err_probe(smc->dev, ret, "Failed to register sub-devices");


	return 0;
	}

	static const struct of_device_id apple_smc_of_match[] = {
	{ .compatible = "apple,t8103-smc" },
	{ .compatible = "apple,smc" },
	{},
	};
	MODULE_DEVICE_TABLE(of, apple_smc_of_match);

	static struct platform_driver apple_smc_driver = {
	.driver = {
	.name = "macsmc",
	.of_match_table = apple_smc_of_match,
	},
	.probe = apple_smc_probe,
	};
	module_platform_driver(apple_smc_driver);

	MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
	MODULE_AUTHOR("Sven Peter <sven@kernel.org>");
	MODULE_LICENSE("Dual MIT/GPL");
	MODULE_DESCRIPTION("Apple SMC driver");