drivers/firmware/arm_scmi/smc.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * System Control and Management Interface (SCMI) Message SMC/HVC
  * Transport driver
  *
  * Copyright 2020 NXP
  */

 #include <linux/arm-smccc.h>
 #include <linux/atomic.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/limits.h>
 #include <linux/processor.h>
 #include <linux/slab.h>

 #include "common.h"

 /*
  * The shmem address is split into 4K page and offset.
  * This is to make sure the parameters fit in 32bit arguments of the
  * smc/hvc call to keep it uniform across smc32/smc64 conventions.
  * This however limits the shmem address to 44 bit.
  *
  * These optional parameters can be used to distinguish among multiple
  * scmi instances that are using the same smc-id.
  * The page parameter is passed in r1/x1/w1 register and the offset parameter
  * is passed in r2/x2/w2 register.
  */

 #define SHMEM_SIZE (SZ_4K)
 #define SHMEM_SHIFT 12
 #define SHMEM_PAGE(x) (_UL((x) >> SHMEM_SHIFT))
 #define SHMEM_OFFSET(x) ((x) & (SHMEM_SIZE - 1))

 /**
  * struct scmi_smc - Structure representing a SCMI smc transport
  *
  * @irq: An optional IRQ for completion
  * @cinfo: SCMI channel info
  * @shmem: Transmit/Receive shared memory area
  * @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
  *		Used when NOT operating in atomic mode.
  * @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
  *	      Used when operating in atomic mode.
  * @func_id: smc/hvc call function id
  * @param_page: 4K page number of the shmem channel
  * @param_offset: Offset within the 4K page of the shmem channel
  * @cap_id: smc/hvc doorbell's capability id to be used on Qualcomm virtual
  *	    platforms
  */

 struct scmi_smc {
 	int irq;
 	struct scmi_chan_info *cinfo;
 	struct scmi_shared_mem __iomem *shmem;
 	/* Protect access to shmem area */
 	struct mutex shmem_lock;
 #define INFLIGHT_NONE	MSG_TOKEN_MAX
 	atomic_t inflight;
 	unsigned long func_id;
 	unsigned long param_page;
 	unsigned long param_offset;
 	unsigned long cap_id;
 };

 static irqreturn_t smc_msg_done_isr(int irq, void *data)
 {
 	struct scmi_smc *scmi_info = data;

 	scmi_rx_callback(scmi_info->cinfo,
 			 shmem_read_header(scmi_info->shmem), NULL);

 	return IRQ_HANDLED;
 }

 static bool smc_chan_available(struct device_node *of_node, int idx)
 {
 	struct device_node *np = of_parse_phandle(of_node, "shmem", 0);
 	if (!np)
 		return false;

 	of_node_put(np);
 	return true;
 }

 static inline void smc_channel_lock_init(struct scmi_smc *scmi_info)
 {
 	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
 		atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
 	else
 		mutex_init(&scmi_info->shmem_lock);
 }

 static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight)
 {
 	int ret;

 	ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq);

 	return ret == INFLIGHT_NONE;
 }

 static inline void
 smc_channel_lock_acquire(struct scmi_smc *scmi_info,
 			 struct scmi_xfer *xfer __maybe_unused)
 {
 	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
 		spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight));
 	else
 		mutex_lock(&scmi_info->shmem_lock);
 }

 static inline void smc_channel_lock_release(struct scmi_smc *scmi_info)
 {
 	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
 		atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
 	else
 		mutex_unlock(&scmi_info->shmem_lock);
 }

 static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
 			  bool tx)
 {
 	struct device *cdev = cinfo->dev;
 	unsigned long cap_id = ULONG_MAX;
 	struct scmi_smc *scmi_info;
 	resource_size_t size;
 	struct resource res;
 	struct device_node *np;
 	u32 func_id;
 	int ret;

 	if (!tx)
 		return -ENODEV;

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

 	np = of_parse_phandle(cdev->of_node, "shmem", 0);
 	if (!of_device_is_compatible(np, "arm,scmi-shmem")) {
 		of_node_put(np);
 		return -ENXIO;
 	}

 	ret = of_address_to_resource(np, 0, &res);
 	of_node_put(np);
 	if (ret) {
 		dev_err(cdev, "failed to get SCMI Tx shared memory\n");
 		return ret;
 	}

 	size = resource_size(&res);
 	scmi_info->shmem = devm_ioremap(dev, res.start, size);
 	if (!scmi_info->shmem) {
 		dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
 		return -EADDRNOTAVAIL;
 	}

 	ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
 	if (ret < 0)
 		return ret;

 	if (of_device_is_compatible(dev->of_node, "qcom,scmi-smc")) {
 		void __iomem *ptr = (void __iomem *)scmi_info->shmem + size - 8;
 		/* The capability-id is kept in last 8 bytes of shmem.
 		 *     +-------+ <-- 0
 		 *     | shmem |
 		 *     +-------+ <-- size - 8
 		 *     | capId |
 		 *     +-------+ <-- size
 		 */
 		memcpy_fromio(&cap_id, ptr, sizeof(cap_id));
 	}

 	if (of_device_is_compatible(dev->of_node, "arm,scmi-smc-param")) {
 		scmi_info->param_page = SHMEM_PAGE(res.start);
 		scmi_info->param_offset = SHMEM_OFFSET(res.start);
 	}
 	/*
 	 * If there is an interrupt named "a2p", then the service and
 	 * completion of a message is signaled by an interrupt rather than by
 	 * the return of the SMC call.
 	 */
 	scmi_info->irq = of_irq_get_byname(cdev->of_node, "a2p");
 	if (scmi_info->irq > 0) {
 		ret = request_irq(scmi_info->irq, smc_msg_done_isr,
 				  IRQF_NO_SUSPEND, dev_name(dev), scmi_info);
 		if (ret) {
 			dev_err(dev, "failed to setup SCMI smc irq\n");
 			return ret;
 		}
 	} else {
 		cinfo->no_completion_irq = true;
 	}

 	scmi_info->func_id = func_id;
 	scmi_info->cap_id = cap_id;
 	scmi_info->cinfo = cinfo;
 	smc_channel_lock_init(scmi_info);
 	cinfo->transport_info = scmi_info;

 	return 0;
 }

 static int smc_chan_free(int id, void *p, void *data)
 {
 	struct scmi_chan_info *cinfo = p;
 	struct scmi_smc *scmi_info = cinfo->transport_info;

 	/*
 	 * Different protocols might share the same chan info, so a previous
 	 * smc_chan_free call might have already freed the structure.
 	 */
 	if (!scmi_info)
 		return 0;

 	/* Ignore any possible further reception on the IRQ path */
 	if (scmi_info->irq > 0)
 		free_irq(scmi_info->irq, scmi_info);

 	cinfo->transport_info = NULL;
 	scmi_info->cinfo = NULL;

 	return 0;
 }

 static int smc_send_message(struct scmi_chan_info *cinfo,
 			    struct scmi_xfer *xfer)
 {
 	struct scmi_smc *scmi_info = cinfo->transport_info;
 	struct arm_smccc_res res;

 	/*
 	 * Channel will be released only once response has been
 	 * surely fully retrieved, so after .mark_txdone()
 	 */
 	smc_channel_lock_acquire(scmi_info, xfer);

 	shmem_tx_prepare(scmi_info->shmem, xfer, cinfo);

 	if (scmi_info->cap_id != ULONG_MAX)
 		arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->cap_id, 0,
 				     0, 0, 0, 0, 0, &res);
 	else
 		arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->param_page,
 				     scmi_info->param_offset, 0, 0, 0, 0, 0,
 				     &res);

 	/* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
 	if (res.a0) {
 		smc_channel_lock_release(scmi_info);
 		return -EOPNOTSUPP;
 	}

 	return 0;
 }

 static void smc_fetch_response(struct scmi_chan_info *cinfo,
 			       struct scmi_xfer *xfer)
 {
 	struct scmi_smc *scmi_info = cinfo->transport_info;

 	shmem_fetch_response(scmi_info->shmem, xfer);
 }

 static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,
 			    struct scmi_xfer *__unused)
 {
 	struct scmi_smc *scmi_info = cinfo->transport_info;

 	smc_channel_lock_release(scmi_info);
 }

 static const struct scmi_transport_ops scmi_smc_ops = {
 	.chan_available = smc_chan_available,
 	.chan_setup = smc_chan_setup,
 	.chan_free = smc_chan_free,
 	.send_message = smc_send_message,
 	.mark_txdone = smc_mark_txdone,
 	.fetch_response = smc_fetch_response,
 };

 const struct scmi_desc scmi_smc_desc = {
 	.ops = &scmi_smc_ops,
 	.max_rx_timeout_ms = 30,
 	.max_msg = 20,
 	.max_msg_size = 128,
 	/*
 	 * Setting .sync_cmds_atomic_replies to true for SMC assumes that,
 	 * once the SMC instruction has completed successfully, the issued
 	 * SCMI command would have been already fully processed by the SCMI
 	 * platform firmware and so any possible response value expected
 	 * for the issued command will be immmediately ready to be fetched
 	 * from the shared memory area.
 	 */
 	.sync_cmds_completed_on_ret = true,
 	.atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
 };
	// SPDX-License-Identifier: GPL-2.0
	/*
	* System Control and Management Interface (SCMI) Message SMC/HVC
	* Transport driver
	*
	* Copyright 2020 NXP
	*/

	#include <linux/arm-smccc.h>
	#include <linux/atomic.h>
	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/interrupt.h>
	#include <linux/mutex.h>
	#include <linux/of.h>
	#include <linux/of_address.h>
	#include <linux/of_irq.h>
	#include <linux/limits.h>
	#include <linux/processor.h>
	#include <linux/slab.h>

	#include "common.h"

	/*
	* The shmem address is split into 4K page and offset.
	* This is to make sure the parameters fit in 32bit arguments of the
	* smc/hvc call to keep it uniform across smc32/smc64 conventions.
	* This however limits the shmem address to 44 bit.
	*
	* These optional parameters can be used to distinguish among multiple
	* scmi instances that are using the same smc-id.
	* The page parameter is passed in r1/x1/w1 register and the offset parameter
	* is passed in r2/x2/w2 register.
	*/

	#define SHMEM_SIZE (SZ_4K)
	#define SHMEM_SHIFT 12
	#define SHMEM_PAGE(x) (_UL((x) >> SHMEM_SHIFT))
	#define SHMEM_OFFSET(x) ((x) & (SHMEM_SIZE - 1))

	/**
	* struct scmi_smc - Structure representing a SCMI smc transport
	*
	* @irq: An optional IRQ for completion
	* @cinfo: SCMI channel info
	* @shmem: Transmit/Receive shared memory area
	* @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
	* Used when NOT operating in atomic mode.
	* @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
	* Used when operating in atomic mode.
	* @func_id: smc/hvc call function id
	* @param_page: 4K page number of the shmem channel
	* @param_offset: Offset within the 4K page of the shmem channel
	* @cap_id: smc/hvc doorbell's capability id to be used on Qualcomm virtual
	* platforms
	*/

	struct scmi_smc {
	int irq;
	struct scmi_chan_info *cinfo;
	struct scmi_shared_mem __iomem *shmem;
	/* Protect access to shmem area */
	struct mutex shmem_lock;
	#define INFLIGHT_NONE MSG_TOKEN_MAX
	atomic_t inflight;
	unsigned long func_id;
	unsigned long param_page;
	unsigned long param_offset;
	unsigned long cap_id;
	};

	static irqreturn_t smc_msg_done_isr(int irq, void *data)
	{
	struct scmi_smc *scmi_info = data;

	scmi_rx_callback(scmi_info->cinfo,
	shmem_read_header(scmi_info->shmem), NULL);

	return IRQ_HANDLED;
	}

	static bool smc_chan_available(struct device_node *of_node, int idx)
	{
	struct device_node *np = of_parse_phandle(of_node, "shmem", 0);
	if (!np)
	return false;

	of_node_put(np);
	return true;
	}

	static inline void smc_channel_lock_init(struct scmi_smc *scmi_info)
	{
	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
	atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
	else
	mutex_init(&scmi_info->shmem_lock);
	}

	static bool smc_xfer_inflight(struct scmi_xfer xfer, atomic_t inflight)
	{
	int ret;

	ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq);

	return ret == INFLIGHT_NONE;
	}

	static inline void
	smc_channel_lock_acquire(struct scmi_smc *scmi_info,
	struct scmi_xfer *xfer __maybe_unused)
	{
	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
	spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight));
	else
	mutex_lock(&scmi_info->shmem_lock);
	}

	static inline void smc_channel_lock_release(struct scmi_smc *scmi_info)
	{
	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
	atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
	else
	mutex_unlock(&scmi_info->shmem_lock);
	}

	static int smc_chan_setup(struct scmi_chan_info cinfo, struct device dev,
	bool tx)
	{
	struct device *cdev = cinfo->dev;
	unsigned long cap_id = ULONG_MAX;
	struct scmi_smc *scmi_info;
	resource_size_t size;
	struct resource res;
	struct device_node *np;
	u32 func_id;
	int ret;

	if (!tx)
	return -ENODEV;

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

	np = of_parse_phandle(cdev->of_node, "shmem", 0);
	if (!of_device_is_compatible(np, "arm,scmi-shmem")) {
	of_node_put(np);
	return -ENXIO;
	}

	ret = of_address_to_resource(np, 0, &res);
	of_node_put(np);
	if (ret) {
	dev_err(cdev, "failed to get SCMI Tx shared memory\n");
	return ret;
	}

	size = resource_size(&res);
	scmi_info->shmem = devm_ioremap(dev, res.start, size);
	if (!scmi_info->shmem) {
	dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
	return -EADDRNOTAVAIL;
	}

	ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
	if (ret < 0)
	return ret;

	if (of_device_is_compatible(dev->of_node, "qcom,scmi-smc")) {
	void __iomem ptr = (void __iomem )scmi_info->shmem + size - 8;
	/* The capability-id is kept in last 8 bytes of shmem.
	* +-------+ <-- 0
	* \| shmem \|
	* +-------+ <-- size - 8
	* \| capId \|
	* +-------+ <-- size
	*/
	memcpy_fromio(&cap_id, ptr, sizeof(cap_id));
	}

	if (of_device_is_compatible(dev->of_node, "arm,scmi-smc-param")) {
	scmi_info->param_page = SHMEM_PAGE(res.start);
	scmi_info->param_offset = SHMEM_OFFSET(res.start);
	}
	/*
	* If there is an interrupt named "a2p", then the service and
	* completion of a message is signaled by an interrupt rather than by
	* the return of the SMC call.
	*/
	scmi_info->irq = of_irq_get_byname(cdev->of_node, "a2p");
	if (scmi_info->irq > 0) {
	ret = request_irq(scmi_info->irq, smc_msg_done_isr,
	IRQF_NO_SUSPEND, dev_name(dev), scmi_info);
	if (ret) {
	dev_err(dev, "failed to setup SCMI smc irq\n");
	return ret;
	}
	} else {
	cinfo->no_completion_irq = true;
	}

	scmi_info->func_id = func_id;
	scmi_info->cap_id = cap_id;
	scmi_info->cinfo = cinfo;
	smc_channel_lock_init(scmi_info);
	cinfo->transport_info = scmi_info;

	return 0;
	}

	static int smc_chan_free(int id, void p, void data)
	{
	struct scmi_chan_info *cinfo = p;
	struct scmi_smc *scmi_info = cinfo->transport_info;

	/*
	* Different protocols might share the same chan info, so a previous
	* smc_chan_free call might have already freed the structure.
	*/
	if (!scmi_info)
	return 0;

	/* Ignore any possible further reception on the IRQ path */
	if (scmi_info->irq > 0)
	free_irq(scmi_info->irq, scmi_info);

	cinfo->transport_info = NULL;
	scmi_info->cinfo = NULL;

	return 0;
	}

	static int smc_send_message(struct scmi_chan_info *cinfo,
	struct scmi_xfer *xfer)
	{
	struct scmi_smc *scmi_info = cinfo->transport_info;
	struct arm_smccc_res res;

	/*
	* Channel will be released only once response has been
	* surely fully retrieved, so after .mark_txdone()
	*/
	smc_channel_lock_acquire(scmi_info, xfer);

	shmem_tx_prepare(scmi_info->shmem, xfer, cinfo);

	if (scmi_info->cap_id != ULONG_MAX)
	arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->cap_id, 0,
	0, 0, 0, 0, 0, &res);
	else
	arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->param_page,
	scmi_info->param_offset, 0, 0, 0, 0, 0,
	&res);

	/* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
	if (res.a0) {
	smc_channel_lock_release(scmi_info);
	return -EOPNOTSUPP;
	}

	return 0;
	}

	static void smc_fetch_response(struct scmi_chan_info *cinfo,
	struct scmi_xfer *xfer)
	{
	struct scmi_smc *scmi_info = cinfo->transport_info;

	shmem_fetch_response(scmi_info->shmem, xfer);
	}

	static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,
	struct scmi_xfer *__unused)
	{
	struct scmi_smc *scmi_info = cinfo->transport_info;

	smc_channel_lock_release(scmi_info);
	}

	static const struct scmi_transport_ops scmi_smc_ops = {
	.chan_available = smc_chan_available,
	.chan_setup = smc_chan_setup,
	.chan_free = smc_chan_free,
	.send_message = smc_send_message,
	.mark_txdone = smc_mark_txdone,
	.fetch_response = smc_fetch_response,
	};

	const struct scmi_desc scmi_smc_desc = {
	.ops = &scmi_smc_ops,
	.max_rx_timeout_ms = 30,
	.max_msg = 20,
	.max_msg_size = 128,
	/*
	* Setting .sync_cmds_atomic_replies to true for SMC assumes that,
	* once the SMC instruction has completed successfully, the issued
	* SCMI command would have been already fully processed by the SCMI
	* platform firmware and so any possible response value expected
	* for the issued command will be immmediately ready to be fetched
	* from the shared memory area.
	*/
	.sync_cmds_completed_on_ret = true,
	.atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
	};