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Commit 3165ec33 authored by Xianbin Zhu's avatar Xianbin Zhu Committed by Gerrit - the friendly Code Review server
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i2c: add virtual i2c driver 



add virtual i2c driver for virtualization platform.

Change-Id: I5aafa3b9db1e06d990b25a393f54f8763e73f9aa
Signed-off-by: default avatarXianbin Zhu <xianzhu@codeaurora.org>
parent 2258de68

drivers/i2c/busses/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -1347,4 +1347,10 @@ config I2C_ZX2967 
	  This driver can also be built as a module. If so, the module will be

	  called i2c-zx2967.



config VIRTIO_I2C

        tristate "VIRTIO_I2C"

        depends on VIRTIO

        help

          If you say yes to this option, the virtio i2c will be supported.



endmenu

drivers/i2c/busses/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -115,6 +115,7 @@ obj-$(CONFIG_I2C_XLP9XX) += i2c-xlp9xx.o 
obj-$(CONFIG_I2C_RCAR)		+= i2c-rcar.o

obj-$(CONFIG_I2C_MSM_V2)        += i2c-msm-v2.o

obj-$(CONFIG_I2C_ZX2967)	+= i2c-zx2967.o

obj-$(CONFIG_VIRTIO_I2C)	+= virtio-i2c.o



# External I2C/SMBus adapter drivers

obj-$(CONFIG_I2C_DIOLAN_U2C)	+= i2c-diolan-u2c.o

drivers/i2c/busses/virtio-i2c.c

0 → 100644
+356 −0
Original line number Diff line number Diff line 
/* Copyright (c) 2019, The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only version 2 as published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 */



#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/kthread.h>

#include <linux/scatterlist.h>

#include <linux/dma-mapping.h>

#include <linux/interrupt.h>

#include <linux/slab.h>

#include <linux/idr.h>

#include <linux/jiffies.h>

#include <linux/sched.h>

#include <linux/wait.h>

#include <linux/spinlock.h>

#include <linux/virtio.h>

#include <uapi/linux/virtio_ids.h>

#include <linux/virtio_config.h>

#include <linux/i2c.h>



#define I2C_ADAPTER_NR	0x00



#define I2C_VIRTIO_RD		0x01

#define I2C_VIRTIO_WR		0x02

#define I2C_VIRTIO_RDWR		0x03



/**

 * struct virtio_i2c - virtio i2c device

 * @adapter: i2c adapter

 * @vdev: the virtio device

 * @vq: i2c virtqueue

 */

struct virtio_i2c {

	struct i2c_adapter adapter;

	struct virtio_device *vdev;

	struct virtqueue *vq;

	wait_queue_head_t inq;

};



struct i2c_transfer_head {

	u32 type; /* read or write from or to slave */

	u32 addr; /* slave addr */

	u32 length; /* buffer length */

	u32 total_length; /* merge write and read will use this segment */

};



struct i2c_transfer_end {

	u32 result; /* return value from backend */

};



struct virtio_i2c_req {

	struct i2c_transfer_head head;

	char   *buf;

	struct i2c_transfer_end  end;

};



static int virti2c_transfer(struct virtio_i2c *vi2c,

	struct virtio_i2c_req *i2c_req)

{

	struct virtqueue *vq = vi2c->vq;

	struct scatterlist outhdr, bufhdr, inhdr, *sgs[3];

	unsigned int num_out = 0, num_in = 0, err, len;

	struct virtio_i2c_req *req_handled = NULL;



	/* send the head queue to the backend */

	sg_init_one(&outhdr, &i2c_req->head, sizeof(i2c_req->head));

	sgs[num_out++] = &outhdr;



	/* send the buffer queue to the backend */

	sg_init_one(&bufhdr, i2c_req->buf,

		(i2c_req->head.type == I2C_VIRTIO_RDWR) ?

			i2c_req->head.total_length : i2c_req->head.length);

	if (i2c_req->head.type & I2C_VIRTIO_WR)

		sgs[num_out++] = &bufhdr;

	else

		sgs[num_out + num_in++] = &bufhdr;



	/* send the result queue to the backend */

	sg_init_one(&inhdr, &i2c_req->end, sizeof(i2c_req->end));

	sgs[num_out + num_in++] = &inhdr;



	/* call the virtqueue function */

	err = virtqueue_add_sgs(vq, sgs, num_out, num_in, i2c_req, GFP_KERNEL);

	if (err)

		goto req_exit;



	/* Tell Host to go! */

	err = virtqueue_kick(vq);



	wait_event(vi2c->inq,

		(req_handled = virtqueue_get_buf(vq, &len)));



	if (i2c_req->head.type == I2C_VIRTIO_RDWR) {

		if (i2c_req->end.result ==

			i2c_req->head.total_length - i2c_req->head.length)

			err = 0;

		else

			err = -EINVAL;

	} else {

		if (i2c_req->end.result == i2c_req->head.length)

			err = 0;

		else

			err = -EINVAL;

	}

req_exit:

	return err;

}



/* prepare the transfer req */

static struct virtio_i2c_req *virti2c_transfer_prepare(struct i2c_msg *msg_1,

						struct i2c_msg *msg_2)

{

	char *ptr  = NULL;

	int merge  = 0;

	struct virtio_i2c_req *i2c_req;



	if (msg_1 == NULL)

		return NULL;



	if (msg_2)

		merge = 1;



	i2c_req = kzalloc(sizeof(struct virtio_i2c_req), GFP_KERNEL);

	if (i2c_req == NULL)

		return NULL;



	if (merge)

		ptr = kzalloc((msg_1->len + msg_2->len), GFP_KERNEL);

	else

		ptr = msg_1->buf;

	if (ptr == NULL)

		goto err_mem;



	/* prepare the head */

	i2c_req->head.type = merge ?

		I2C_VIRTIO_RDWR : ((msg_1->flags & I2C_M_RD) ?

					I2C_VIRTIO_RD : I2C_VIRTIO_WR);

	i2c_req->head.addr = msg_1->addr;

	i2c_req->head.length = msg_1->len;

	if (merge)

		i2c_req->head.total_length = msg_1->len + msg_2->len;



	/* prepare the buf */

	if (merge)

		memcpy(ptr, msg_1->buf, msg_1->len);

	i2c_req->buf = ptr;



	return i2c_req;

err_mem:

	kfree(i2c_req);

	i2c_req = NULL;

	return NULL;

}



static void virti2c_transfer_end(struct virtio_i2c_req *req,

						struct i2c_msg *msg)

{

	if (req->head.type == I2C_VIRTIO_RDWR) {

		memcpy(msg->buf, req->buf + req->head.length, msg->len);

		kfree(req->buf);

		req->buf = NULL;

	}



	kfree(req);

	req = NULL;

}



static int virtio_i2c_master_xfer(struct i2c_adapter *adap,

				struct i2c_msg *msgs, int num)

{

	int i, ret;

	struct virtio_i2c_req *i2c_req;

	struct virtio_i2c *vi2c = i2c_get_adapdata(adap);



	if (num < 1) {

		dev_err(&vi2c->vdev->dev,

		"error on number of msgs(%d) received\n", num);

		return -EINVAL;

	}



	if (IS_ERR_OR_NULL(msgs)) {

		dev_err(&vi2c->vdev->dev, " error no msgs Accessing invalid pointer location\n");

		return PTR_ERR(msgs);

	}



	for (i = 0; i < num; i++) {



		if (msgs[i].flags & I2C_M_RD) {

			/* read the data from slave to master*/

			i2c_req = virti2c_transfer_prepare(&msgs[i], NULL);



		} else if ((i + 1 < num) && (msgs[i + 1].flags & I2C_M_RD) &&

				(msgs[i].addr == msgs[i + 1].addr)) {

			/* write then read from same address*/

			i2c_req = virti2c_transfer_prepare(&msgs[i],

								&msgs[i+1]);

			i += 1;



		} else {

			/* write the data to slave */

			i2c_req = virti2c_transfer_prepare(&msgs[i], NULL);

		}



		if (i2c_req == NULL) {

			ret = -ENOMEM;

			goto err;

		}

		ret = virti2c_transfer(vi2c, i2c_req);

		virti2c_transfer_end(i2c_req, &msgs[i]);

		if (ret)

			goto err;

	}

	return num;

err:

	return ret;

}



static u32 virtio_i2c_functionality(struct i2c_adapter *adapter)

{

	return  I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;

}



static struct i2c_algorithm virtio_i2c_algorithm = {

	.master_xfer = virtio_i2c_master_xfer,

	.functionality = virtio_i2c_functionality,

};



/* virtqueue incoming data interrupt IRQ */

static void virti2c_vq_isr(struct virtqueue *vq)

{

	struct virtio_i2c *vi2c = vq->vdev->priv;



	wake_up(&vi2c->inq);

}



static int virti2c_init_vqs(struct virtio_i2c *vi2c)

{

	struct virtqueue *vqs[1];

	vq_callback_t *cbs[] = { virti2c_vq_isr };

	static const char * const names[] = { "virti2c_vq_isr" };

	int err;



	err = virtio_find_vqs(vi2c->vdev, 1, vqs, cbs, names, NULL);

	if (err)

		return err;

	vi2c->vq = vqs[0];



	return 0;

}



static void virti2c_del_vqs(struct virtio_i2c *vi2c)

{

	vi2c->vdev->config->del_vqs(vi2c->vdev);

}



static int virti2c_init_hw(struct virtio_device *vdev,

				struct virtio_i2c *vi2c)

{

	int err;



	i2c_set_adapdata(&vi2c->adapter, vi2c);

	vi2c->adapter.algo = &virtio_i2c_algorithm;



	vi2c->adapter.owner = THIS_MODULE;

	vi2c->adapter.dev.parent = &vdev->dev;

	vi2c->adapter.dev.of_node = vdev->dev.parent->of_node;



	/* read virtio i2c config info */

	vi2c->adapter.nr = virtio_cread32(vdev, I2C_ADAPTER_NR);

	snprintf(vi2c->adapter.name, sizeof(vi2c->adapter.name),

				"virtio_i2c_%d", vi2c->adapter.nr);



	err = i2c_add_numbered_adapter(&vi2c->adapter);

	if (err)

		return err;

	return 0;

}



static int virti2c_probe(struct virtio_device *vdev)

{

	struct virtio_i2c *vi2c;

	int err = 0;



	if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1))

		return -ENODEV;



	vi2c = kzalloc(sizeof(*vi2c), GFP_KERNEL);

	if (!vi2c)

		return -ENOMEM;



	vi2c->vdev = vdev;

	vdev->priv = vi2c;

	init_waitqueue_head(&vi2c->inq);



	err = virti2c_init_vqs(vi2c);

	if (err)

		goto err_init_vq;



	err = virti2c_init_hw(vdev, vi2c);

	if (err)

		goto err_init_hw;



	virtio_device_ready(vdev);



	virtqueue_enable_cb(vi2c->vq);

	return 0;



err_init_hw:

	virti2c_del_vqs(vi2c);

err_init_vq:

	kfree(vi2c);

	return err;

}

static void virti2c_remove(struct virtio_device *vdev)

{

	struct virtio_i2c *vi2c = vdev->priv;



	i2c_del_adapter(&vi2c->adapter);

	vdev->config->reset(vdev);

	virti2c_del_vqs(vi2c);

	kfree(vi2c);

}



static unsigned int features[] = {

	/* none */

};

static struct virtio_device_id id_table[] = {

	{ VIRTIO_ID_I2C, VIRTIO_DEV_ANY_ID },

	{ 0 },

};



static struct virtio_driver virtio_i2c_driver = {

	.driver.name		= KBUILD_MODNAME,

	.driver.owner		= THIS_MODULE,

	.feature_table		= features,

	.feature_table_size	= ARRAY_SIZE(features),

	.id_table		= id_table,

	.probe			= virti2c_probe,

	.remove			= virti2c_remove,

};



module_virtio_driver(virtio_i2c_driver);

MODULE_DEVICE_TABLE(virtio, id_table);



MODULE_DESCRIPTION("Virtio i2c frontend driver");

MODULE_LICENSE("GPL v2");

include/uapi/linux/virtio_ids.h

+2 −0
Original line number Diff line number Diff line
@@ -44,4 +44,6 @@ 
#define VIRTIO_ID_VSOCK        19 /* virtio vsock transport */

#define VIRTIO_ID_CRYPTO       20 /* virtio crypto */



#define VIRTIO_ID_I2C		32 /* virtio i2c */



#endif /* _LINUX_VIRTIO_IDS_H */