Unverified Commit f98cabe3 authored by Haixu Cui's avatar Haixu Cui Committed by Mark Brown
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SPI: Add virtio SPI driver 



This is the virtio SPI Linux kernel driver.

Signed-off-by: default avatarHaixu Cui <quic_haixcui@quicinc.com>
Link: https://patch.msgid.link/20250908092348.1283552-4-quic_haixcui@quicinc.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 6a1f3390

MAINTAINERS

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@@ -26807,6 +26807,7 @@ VIRTIO SPI DRIVER 
M:	Haixu Cui <quic_haixcui@quicinc.com>

L:	virtualization@lists.linux.dev

S:	Maintained

F:	drivers/spi/spi-virtio.c

F:	include/uapi/linux/virtio_spi.h









VIRTUAL BOX GUEST DEVICE DRIVER

























drivers/spi/Kconfig



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@@ -1235,6 +1235,17 @@ config SPI_UNIPHIER

















	  If your SoC supports SCSSI, say Y here.



















config SPI_VIRTIO









	tristate "Virtio SPI Controller"









	depends on SPI_MASTER && VIRTIO









	help









	  If you say yes to this option, support will be included for the virtio









	  SPI controller driver. The hardware can be emulated by any device model









	  software according to the virtio protocol.



















	  This driver can also be built as a module. If so, the module









	  will be called spi-virtio.



















config SPI_XCOMM









	tristate "Analog Devices AD-FMCOMMS1-EBZ SPI-I2C-bridge driver"









	depends on I2C
































drivers/spi/Makefile



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@@ -159,6 +159,7 @@ spi-thunderx-objs			:= spi-cavium.o spi-cavium-thunderx.o







obj-$(CONFIG_SPI_THUNDERX)		+= spi-thunderx.o









obj-$(CONFIG_SPI_TOPCLIFF_PCH)		+= spi-topcliff-pch.o









obj-$(CONFIG_SPI_UNIPHIER)		+= spi-uniphier.o









obj-$(CONFIG_SPI_VIRTIO)		+= spi-virtio.o









obj-$(CONFIG_SPI_XCOMM)		+= spi-xcomm.o









obj-$(CONFIG_SPI_XILINX)		+= spi-xilinx.o









obj-$(CONFIG_SPI_XLP)			+= spi-xlp.o
































drivers/spi/spi-virtio.c
0 → 100644



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// SPDX-License-Identifier: GPL-2.0-only









/*









 * SPI bus driver for the Virtio SPI controller









 * Copyright (C) 2023 OpenSynergy GmbH









 * Copyright (C) 2025 Qualcomm Innovation Center, Inc. All rights reserved.









 */



















#include <linux/completion.h>









#include <linux/interrupt.h>









#include <linux/io.h>









#include <linux/module.h>









#include <linux/spi/spi.h>









#include <linux/stddef.h>









#include <linux/virtio.h>









#include <linux/virtio_ring.h>









#include <linux/virtio_spi.h>



















#define VIRTIO_SPI_MODE_MASK \









	(SPI_MODE_X_MASK | SPI_CS_HIGH | SPI_LSB_FIRST)



















struct virtio_spi_req {









	struct completion completion;









	const u8 *tx_buf;









	u8 *rx_buf;









	struct spi_transfer_head transfer_head	____cacheline_aligned;









	struct spi_transfer_result result;









};



















struct virtio_spi_priv {









	/* The virtio device we're associated with */









	struct virtio_device *vdev;









	/* Pointer to the virtqueue */









	struct virtqueue *vq;









	/* Copy of config space mode_func_supported */









	u32 mode_func_supported;









	/* Copy of config space max_freq_hz */









	u32 max_freq_hz;









};



















static void virtio_spi_msg_done(struct virtqueue *vq)









{









	struct virtio_spi_req *req;









	unsigned int len;



















	while ((req = virtqueue_get_buf(vq, &len)))









		complete(&req->completion);









}



















/*









 * virtio_spi_set_delays - Set delay parameters for SPI transfer









 *









 * This function sets various delay parameters for SPI transfer,









 * including delay after CS asserted, timing intervals between









 * adjacent words within a transfer, delay before and after CS









 * deasserted. It converts these delay parameters to nanoseconds









 * using spi_delay_to_ns and stores the results in spi_transfer_head









 * structure.









 * If the conversion fails, the function logs a warning message and









 * returns an error code.









 *       .   .      .    .    .   .   .   .   .   .









 * Delay + A +      + B  +    + C + D + E + F + A +









 *       .   .      .    .    .   .   .   .   .   .









 *    ___.   .      .    .    .   .   .___.___.   .









 * CS#   |___.______.____.____.___.___|   .   |___._____________









 *       .   .      .    .    .   .   .   .   .   .









 *       .   .      .    .    .   .   .   .   .   .









 * SCLK__.___.___NNN_____NNN__.___.___.___.___.___.___NNN_______









 *









 * NOTE: 1st transfer has two words, the delay between these two words are









 * 'B' in the diagram.









 *









 * A => struct spi_device -> cs_setup









 * B => max{struct spi_transfer -> word_delay, struct spi_device -> word_delay}









 *   Note: spi_device and spi_transfer both have word_delay, Linux









 *         choose the bigger one, refer to _spi_xfer_word_delay_update function









 * C => struct spi_transfer -> delay









 * D => struct spi_device -> cs_hold









 * E => struct spi_device -> cs_inactive









 * F => struct spi_transfer -> cs_change_delay









 *









 * So the corresponding relationship:









 * A   <===> cs_setup_ns (after CS asserted)









 * B   <===> word_delay_ns (delay between adjacent words within a transfer)









 * C+D <===> cs_delay_hold_ns (before CS deasserted)









 * E+F <===> cs_change_delay_inactive_ns (after CS deasserted, these two









 * values are also recommended in the Linux driver to be added up)









 */









static int virtio_spi_set_delays(struct spi_transfer_head *th,









				 struct spi_device *spi,









				 struct spi_transfer *xfer)









{









	int cs_setup;









	int cs_word_delay_xfer;









	int cs_word_delay_spi;









	int delay;









	int cs_hold;









	int cs_inactive;









	int cs_change_delay;



















	cs_setup = spi_delay_to_ns(&spi->cs_setup, xfer);









	if (cs_setup < 0) {









		dev_warn(&spi->dev, "Cannot convert cs_setup\n");









		return cs_setup;









	}









	th->cs_setup_ns = cpu_to_le32(cs_setup);



















	cs_word_delay_xfer = spi_delay_to_ns(&xfer->word_delay, xfer);









	if (cs_word_delay_xfer < 0) {









		dev_warn(&spi->dev, "Cannot convert cs_word_delay_xfer\n");









		return cs_word_delay_xfer;









	}









	cs_word_delay_spi = spi_delay_to_ns(&spi->word_delay, xfer);









	if (cs_word_delay_spi < 0) {









		dev_warn(&spi->dev, "Cannot convert cs_word_delay_spi\n");









		return cs_word_delay_spi;









	}



















	th->word_delay_ns = cpu_to_le32(max(cs_word_delay_spi, cs_word_delay_xfer));



















	delay = spi_delay_to_ns(&xfer->delay, xfer);









	if (delay < 0) {









		dev_warn(&spi->dev, "Cannot convert delay\n");









		return delay;









	}









	cs_hold = spi_delay_to_ns(&spi->cs_hold, xfer);









	if (cs_hold < 0) {









		dev_warn(&spi->dev, "Cannot convert cs_hold\n");









		return cs_hold;









	}









	th->cs_delay_hold_ns = cpu_to_le32(delay + cs_hold);



















	cs_inactive = spi_delay_to_ns(&spi->cs_inactive, xfer);









	if (cs_inactive < 0) {









		dev_warn(&spi->dev, "Cannot convert cs_inactive\n");









		return cs_inactive;









	}









	cs_change_delay = spi_delay_to_ns(&xfer->cs_change_delay, xfer);









	if (cs_change_delay < 0) {









		dev_warn(&spi->dev, "Cannot convert cs_change_delay\n");









		return cs_change_delay;









	}









	th->cs_change_delay_inactive_ns =









		cpu_to_le32(cs_inactive + cs_change_delay);



















	return 0;









}



















static int virtio_spi_transfer_one(struct spi_controller *ctrl,









				   struct spi_device *spi,









				   struct spi_transfer *xfer)









{









	struct virtio_spi_priv *priv = spi_controller_get_devdata(ctrl);









	struct virtio_spi_req *spi_req __free(kfree) = NULL;









	struct spi_transfer_head *th;









	struct scatterlist sg_out_head, sg_out_payload;









	struct scatterlist sg_in_result, sg_in_payload;









	struct scatterlist *sgs[4];









	unsigned int outcnt = 0;









	unsigned int incnt = 0;









	int ret;



















	spi_req = kzalloc(sizeof(*spi_req), GFP_KERNEL);









	if (!spi_req)









		return -ENOMEM;



















	init_completion(&spi_req->completion);



















	th = &spi_req->transfer_head;



















	/* Fill struct spi_transfer_head */









	th->chip_select_id = spi_get_chipselect(spi, 0);









	th->bits_per_word = spi->bits_per_word;









	th->cs_change = xfer->cs_change;









	th->tx_nbits = xfer->tx_nbits;









	th->rx_nbits = xfer->rx_nbits;









	th->reserved[0] = 0;









	th->reserved[1] = 0;









	th->reserved[2] = 0;



















	static_assert(VIRTIO_SPI_CPHA == SPI_CPHA,









		      "VIRTIO_SPI_CPHA must match SPI_CPHA");









	static_assert(VIRTIO_SPI_CPOL == SPI_CPOL,









		      "VIRTIO_SPI_CPOL must match SPI_CPOL");









	static_assert(VIRTIO_SPI_CS_HIGH == SPI_CS_HIGH,









		      "VIRTIO_SPI_CS_HIGH must match SPI_CS_HIGH");









	static_assert(VIRTIO_SPI_MODE_LSB_FIRST == SPI_LSB_FIRST,









		      "VIRTIO_SPI_MODE_LSB_FIRST must match SPI_LSB_FIRST");



















	th->mode = cpu_to_le32(spi->mode & VIRTIO_SPI_MODE_MASK);









	if (spi->mode & SPI_LOOP)









		th->mode |= cpu_to_le32(VIRTIO_SPI_MODE_LOOP);



















	th->freq = cpu_to_le32(xfer->speed_hz);



















	ret = virtio_spi_set_delays(th, spi, xfer);









	if (ret)









		goto msg_done;



















	/* Set buffers */









	spi_req->tx_buf = xfer->tx_buf;









	spi_req->rx_buf = xfer->rx_buf;



















	/* Prepare sending of virtio message */









	init_completion(&spi_req->completion);



















	sg_init_one(&sg_out_head, th, sizeof(*th));









	sgs[outcnt] = &sg_out_head;









	outcnt++;



















	if (spi_req->tx_buf) {









		sg_init_one(&sg_out_payload, spi_req->tx_buf, xfer->len);









		sgs[outcnt] = &sg_out_payload;









		outcnt++;









	}



















	if (spi_req->rx_buf) {









		sg_init_one(&sg_in_payload, spi_req->rx_buf, xfer->len);









		sgs[outcnt] = &sg_in_payload;









		incnt++;









	}



















	sg_init_one(&sg_in_result, &spi_req->result,









		    sizeof(struct spi_transfer_result));









	sgs[outcnt + incnt] = &sg_in_result;









	incnt++;



















	ret = virtqueue_add_sgs(priv->vq, sgs, outcnt, incnt, spi_req,









				GFP_KERNEL);









	if (ret)









		goto msg_done;



















	/* Simple implementation: There can be only one transfer in flight */









	virtqueue_kick(priv->vq);



















	wait_for_completion(&spi_req->completion);



















	/* Read result from message and translate return code */









	switch (spi_req->result.result) {









	case VIRTIO_SPI_TRANS_OK:









		break;









	case VIRTIO_SPI_PARAM_ERR:









		ret = -EINVAL;









		break;









	case VIRTIO_SPI_TRANS_ERR:









		ret = -EIO;









		break;









	default:









		ret = -EIO;









		break;









	}



















msg_done:









	if (ret)









		ctrl->cur_msg->status = ret;



















	return ret;









}



















static void virtio_spi_read_config(struct virtio_device *vdev)









{









	struct spi_controller *ctrl = dev_get_drvdata(&vdev->dev);









	struct virtio_spi_priv *priv = vdev->priv;









	u8 cs_max_number;









	u8 tx_nbits_supported;









	u8 rx_nbits_supported;



















	cs_max_number = virtio_cread8(vdev, offsetof(struct virtio_spi_config,









						     cs_max_number));









	ctrl->num_chipselect = cs_max_number;



















	/* Set the mode bits which are understood by this driver */









	priv->mode_func_supported =









		virtio_cread32(vdev, offsetof(struct virtio_spi_config,









					      mode_func_supported));









	ctrl->mode_bits = priv->mode_func_supported &









			  (VIRTIO_SPI_CS_HIGH | VIRTIO_SPI_MODE_LSB_FIRST);









	if (priv->mode_func_supported & VIRTIO_SPI_MF_SUPPORT_CPHA_1)









		ctrl->mode_bits |= VIRTIO_SPI_CPHA;









	if (priv->mode_func_supported & VIRTIO_SPI_MF_SUPPORT_CPOL_1)









		ctrl->mode_bits |= VIRTIO_SPI_CPOL;









	if (priv->mode_func_supported & VIRTIO_SPI_MF_SUPPORT_LSB_FIRST)









		ctrl->mode_bits |= SPI_LSB_FIRST;









	if (priv->mode_func_supported & VIRTIO_SPI_MF_SUPPORT_LOOPBACK)









		ctrl->mode_bits |= SPI_LOOP;









	tx_nbits_supported =









		virtio_cread8(vdev, offsetof(struct virtio_spi_config,









					     tx_nbits_supported));









	if (tx_nbits_supported & VIRTIO_SPI_RX_TX_SUPPORT_DUAL)









		ctrl->mode_bits |= SPI_TX_DUAL;









	if (tx_nbits_supported & VIRTIO_SPI_RX_TX_SUPPORT_QUAD)









		ctrl->mode_bits |= SPI_TX_QUAD;









	if (tx_nbits_supported & VIRTIO_SPI_RX_TX_SUPPORT_OCTAL)









		ctrl->mode_bits |= SPI_TX_OCTAL;









	rx_nbits_supported =









		virtio_cread8(vdev, offsetof(struct virtio_spi_config,









					     rx_nbits_supported));









	if (rx_nbits_supported & VIRTIO_SPI_RX_TX_SUPPORT_DUAL)









		ctrl->mode_bits |= SPI_RX_DUAL;









	if (rx_nbits_supported & VIRTIO_SPI_RX_TX_SUPPORT_QUAD)









		ctrl->mode_bits |= SPI_RX_QUAD;









	if (rx_nbits_supported & VIRTIO_SPI_RX_TX_SUPPORT_OCTAL)









		ctrl->mode_bits |= SPI_RX_OCTAL;



















	ctrl->bits_per_word_mask =









		virtio_cread32(vdev, offsetof(struct virtio_spi_config,









					      bits_per_word_mask));



















	priv->max_freq_hz =









		virtio_cread32(vdev, offsetof(struct virtio_spi_config,









					      max_freq_hz));









}



















static int virtio_spi_find_vqs(struct virtio_spi_priv *priv)









{









	struct virtqueue *vq;



















	vq = virtio_find_single_vq(priv->vdev, virtio_spi_msg_done, "spi-rq");









	if (IS_ERR(vq))









		return PTR_ERR(vq);









	priv->vq = vq;









	return 0;









}



















/* Function must not be called before virtio_spi_find_vqs() has been run */









static void virtio_spi_del_vq(void *data)









{









	struct virtio_device *vdev = data;



















	virtio_reset_device(vdev);









	vdev->config->del_vqs(vdev);









}



















static int virtio_spi_probe(struct virtio_device *vdev)









{









	struct virtio_spi_priv *priv;









	struct spi_controller *ctrl;









	int ret;



















	ctrl = devm_spi_alloc_host(&vdev->dev, sizeof(*priv));









	if (!ctrl)









		return -ENOMEM;



















	priv = spi_controller_get_devdata(ctrl);









	priv->vdev = vdev;









	vdev->priv = priv;



















	device_set_node(&ctrl->dev, dev_fwnode(&vdev->dev));



















	dev_set_drvdata(&vdev->dev, ctrl);



















	virtio_spi_read_config(vdev);



















	ctrl->transfer_one = virtio_spi_transfer_one;



















	ret = virtio_spi_find_vqs(priv);









	if (ret)









		return dev_err_probe(&vdev->dev, ret, "Cannot setup virtqueues\n");



















	/* Register cleanup for virtqueues using devm */









	ret = devm_add_action_or_reset(&vdev->dev, virtio_spi_del_vq, vdev);









	if (ret)









		return dev_err_probe(&vdev->dev, ret, "Cannot register virtqueue cleanup\n");



















	/* Use devm version to register controller */









	ret = devm_spi_register_controller(&vdev->dev, ctrl);









	if (ret)









		return dev_err_probe(&vdev->dev, ret, "Cannot register controller\n");



















	return 0;









}



















static int virtio_spi_freeze(struct device *dev)









{









	struct spi_controller *ctrl = dev_get_drvdata(dev);









	struct virtio_device *vdev = dev_to_virtio(dev);









	int ret;



















	ret = spi_controller_suspend(ctrl);









	if (ret) {









		dev_warn(dev, "cannot suspend controller (%d)\n", ret);









		return ret;









	}



















	virtio_spi_del_vq(vdev);









	return 0;









}



















static int virtio_spi_restore(struct device *dev)









{









	struct spi_controller *ctrl = dev_get_drvdata(dev);









	struct virtio_device *vdev = dev_to_virtio(dev);









	int ret;



















	ret = virtio_spi_find_vqs(vdev->priv);









	if (ret) {









		dev_err(dev, "problem starting vqueue (%d)\n", ret);









		return ret;









	}



















	ret = spi_controller_resume(ctrl);









	if (ret)









		dev_err(dev, "problem resuming controller (%d)\n", ret);



















	return ret;









}



















static struct virtio_device_id virtio_spi_id_table[] = {









	{ VIRTIO_ID_SPI, VIRTIO_DEV_ANY_ID },









	{}









};









MODULE_DEVICE_TABLE(virtio, virtio_spi_id_table);



















static const struct dev_pm_ops virtio_spi_pm_ops = {









	.freeze = pm_sleep_ptr(virtio_spi_freeze),









	.restore = pm_sleep_ptr(virtio_spi_restore),









};



















static struct virtio_driver virtio_spi_driver = {









	.driver = {









		.name = KBUILD_MODNAME,









		.pm = &virtio_spi_pm_ops,









	},









	.id_table = virtio_spi_id_table,









	.probe = virtio_spi_probe,









};









module_virtio_driver(virtio_spi_driver);



















MODULE_AUTHOR("OpenSynergy GmbH");









MODULE_AUTHOR("Haixu Cui <quic_haixcui@quicinc.com>");









MODULE_LICENSE("GPL");









MODULE_DESCRIPTION("Virtio SPI bus driver");