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290 lines
7.0 KiB
290 lines
7.0 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Virtio I2C Bus Driver |
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* |
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* The Virtio I2C Specification: |
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* https://raw.githubusercontent.com/oasis-tcs/virtio-spec/master/virtio-i2c.tex |
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* |
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* Copyright (c) 2021 Intel Corporation. All rights reserved. |
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*/ |
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#include <linux/acpi.h> |
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#include <linux/completion.h> |
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#include <linux/err.h> |
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#include <linux/i2c.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/virtio.h> |
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#include <linux/virtio_ids.h> |
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#include <linux/virtio_config.h> |
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#include <linux/virtio_i2c.h> |
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/** |
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* struct virtio_i2c - virtio I2C data |
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* @vdev: virtio device for this controller |
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* @completion: completion of virtio I2C message |
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* @adap: I2C adapter for this controller |
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* @vq: the virtio virtqueue for communication |
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*/ |
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struct virtio_i2c { |
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struct virtio_device *vdev; |
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struct completion completion; |
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struct i2c_adapter adap; |
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struct virtqueue *vq; |
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}; |
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/** |
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* struct virtio_i2c_req - the virtio I2C request structure |
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* @out_hdr: the OUT header of the virtio I2C message |
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* @buf: the buffer into which data is read, or from which it's written |
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* @in_hdr: the IN header of the virtio I2C message |
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*/ |
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struct virtio_i2c_req { |
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struct virtio_i2c_out_hdr out_hdr ____cacheline_aligned; |
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uint8_t *buf ____cacheline_aligned; |
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struct virtio_i2c_in_hdr in_hdr ____cacheline_aligned; |
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}; |
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static void virtio_i2c_msg_done(struct virtqueue *vq) |
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{ |
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struct virtio_i2c *vi = vq->vdev->priv; |
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complete(&vi->completion); |
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} |
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static int virtio_i2c_prepare_reqs(struct virtqueue *vq, |
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struct virtio_i2c_req *reqs, |
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struct i2c_msg *msgs, int num) |
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{ |
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struct scatterlist *sgs[3], out_hdr, msg_buf, in_hdr; |
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int i; |
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for (i = 0; i < num; i++) { |
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int outcnt = 0, incnt = 0; |
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/* |
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* We don't support 0 length messages and so filter out |
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* 0 length transfers by using i2c_adapter_quirks. |
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*/ |
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if (!msgs[i].len) |
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break; |
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/* |
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* Only 7-bit mode supported for this moment. For the address |
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* format, Please check the Virtio I2C Specification. |
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*/ |
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reqs[i].out_hdr.addr = cpu_to_le16(msgs[i].addr << 1); |
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if (i != num - 1) |
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reqs[i].out_hdr.flags = cpu_to_le32(VIRTIO_I2C_FLAGS_FAIL_NEXT); |
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sg_init_one(&out_hdr, &reqs[i].out_hdr, sizeof(reqs[i].out_hdr)); |
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sgs[outcnt++] = &out_hdr; |
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reqs[i].buf = i2c_get_dma_safe_msg_buf(&msgs[i], 1); |
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if (!reqs[i].buf) |
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break; |
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sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len); |
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if (msgs[i].flags & I2C_M_RD) |
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sgs[outcnt + incnt++] = &msg_buf; |
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else |
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sgs[outcnt++] = &msg_buf; |
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sg_init_one(&in_hdr, &reqs[i].in_hdr, sizeof(reqs[i].in_hdr)); |
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sgs[outcnt + incnt++] = &in_hdr; |
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if (virtqueue_add_sgs(vq, sgs, outcnt, incnt, &reqs[i], GFP_KERNEL)) { |
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i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], false); |
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break; |
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} |
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} |
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return i; |
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} |
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static int virtio_i2c_complete_reqs(struct virtqueue *vq, |
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struct virtio_i2c_req *reqs, |
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struct i2c_msg *msgs, int num, |
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bool timedout) |
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{ |
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struct virtio_i2c_req *req; |
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bool failed = timedout; |
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unsigned int len; |
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int i, j = 0; |
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for (i = 0; i < num; i++) { |
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/* Detach the ith request from the vq */ |
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req = virtqueue_get_buf(vq, &len); |
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/* |
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* Condition req == &reqs[i] should always meet since we have |
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* total num requests in the vq. reqs[i] can never be NULL here. |
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*/ |
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if (!failed && (WARN_ON(req != &reqs[i]) || |
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req->in_hdr.status != VIRTIO_I2C_MSG_OK)) |
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failed = true; |
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i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], !failed); |
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if (!failed) |
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j++; |
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} |
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return timedout ? -ETIMEDOUT : j; |
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} |
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static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, |
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int num) |
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{ |
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struct virtio_i2c *vi = i2c_get_adapdata(adap); |
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struct virtqueue *vq = vi->vq; |
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struct virtio_i2c_req *reqs; |
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unsigned long time_left; |
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int count; |
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reqs = kcalloc(num, sizeof(*reqs), GFP_KERNEL); |
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if (!reqs) |
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return -ENOMEM; |
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count = virtio_i2c_prepare_reqs(vq, reqs, msgs, num); |
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if (!count) |
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goto err_free; |
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/* |
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* For the case where count < num, i.e. we weren't able to queue all the |
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* msgs, ideally we should abort right away and return early, but some |
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* of the messages are already sent to the remote I2C controller and the |
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* virtqueue will be left in undefined state in that case. We kick the |
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* remote here to clear the virtqueue, so we can try another set of |
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* messages later on. |
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*/ |
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reinit_completion(&vi->completion); |
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virtqueue_kick(vq); |
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time_left = wait_for_completion_timeout(&vi->completion, adap->timeout); |
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if (!time_left) |
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dev_err(&adap->dev, "virtio i2c backend timeout.\n"); |
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count = virtio_i2c_complete_reqs(vq, reqs, msgs, count, !time_left); |
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err_free: |
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kfree(reqs); |
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return count; |
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} |
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static void virtio_i2c_del_vqs(struct virtio_device *vdev) |
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{ |
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vdev->config->reset(vdev); |
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vdev->config->del_vqs(vdev); |
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} |
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static int virtio_i2c_setup_vqs(struct virtio_i2c *vi) |
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{ |
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struct virtio_device *vdev = vi->vdev; |
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vi->vq = virtio_find_single_vq(vdev, virtio_i2c_msg_done, "msg"); |
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return PTR_ERR_OR_ZERO(vi->vq); |
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} |
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static u32 virtio_i2c_func(struct i2c_adapter *adap) |
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{ |
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return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK); |
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} |
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static struct i2c_algorithm virtio_algorithm = { |
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.master_xfer = virtio_i2c_xfer, |
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.functionality = virtio_i2c_func, |
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}; |
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static const struct i2c_adapter_quirks virtio_i2c_quirks = { |
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.flags = I2C_AQ_NO_ZERO_LEN, |
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}; |
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static int virtio_i2c_probe(struct virtio_device *vdev) |
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{ |
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struct virtio_i2c *vi; |
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int ret; |
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vi = devm_kzalloc(&vdev->dev, sizeof(*vi), GFP_KERNEL); |
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if (!vi) |
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return -ENOMEM; |
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vdev->priv = vi; |
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vi->vdev = vdev; |
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init_completion(&vi->completion); |
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ret = virtio_i2c_setup_vqs(vi); |
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if (ret) |
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return ret; |
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vi->adap.owner = THIS_MODULE; |
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snprintf(vi->adap.name, sizeof(vi->adap.name), |
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"i2c_virtio at virtio bus %d", vdev->index); |
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vi->adap.algo = &virtio_algorithm; |
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vi->adap.quirks = &virtio_i2c_quirks; |
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vi->adap.dev.parent = &vdev->dev; |
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vi->adap.dev.of_node = vdev->dev.of_node; |
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i2c_set_adapdata(&vi->adap, vi); |
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/* |
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* Setup ACPI node for controlled devices which will be probed through |
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* ACPI. |
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*/ |
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ACPI_COMPANION_SET(&vi->adap.dev, ACPI_COMPANION(vdev->dev.parent)); |
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ret = i2c_add_adapter(&vi->adap); |
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if (ret) |
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virtio_i2c_del_vqs(vdev); |
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return ret; |
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} |
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static void virtio_i2c_remove(struct virtio_device *vdev) |
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{ |
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struct virtio_i2c *vi = vdev->priv; |
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i2c_del_adapter(&vi->adap); |
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virtio_i2c_del_vqs(vdev); |
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} |
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static struct virtio_device_id id_table[] = { |
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{ VIRTIO_ID_I2C_ADAPTER, VIRTIO_DEV_ANY_ID }, |
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{} |
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}; |
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MODULE_DEVICE_TABLE(virtio, id_table); |
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#ifdef CONFIG_PM_SLEEP |
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static int virtio_i2c_freeze(struct virtio_device *vdev) |
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{ |
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virtio_i2c_del_vqs(vdev); |
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return 0; |
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} |
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static int virtio_i2c_restore(struct virtio_device *vdev) |
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{ |
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return virtio_i2c_setup_vqs(vdev->priv); |
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} |
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#endif |
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static struct virtio_driver virtio_i2c_driver = { |
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.id_table = id_table, |
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.probe = virtio_i2c_probe, |
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.remove = virtio_i2c_remove, |
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.driver = { |
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.name = "i2c_virtio", |
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}, |
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#ifdef CONFIG_PM_SLEEP |
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.freeze = virtio_i2c_freeze, |
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.restore = virtio_i2c_restore, |
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#endif |
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}; |
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module_virtio_driver(virtio_i2c_driver); |
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MODULE_AUTHOR("Jie Deng <[email protected]>"); |
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MODULE_AUTHOR("Conghui Chen <[email protected]>"); |
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MODULE_DESCRIPTION("Virtio i2c bus driver"); |
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MODULE_LICENSE("GPL");
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