--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Virtio I2C Bus Driver
+ *
+ * The Virtio I2C Specification:
+ * https://raw.githubusercontent.com/oasis-tcs/virtio-spec/master/virtio-i2c.tex
+ *
+ * Copyright (c) 2021 Intel Corporation. All rights reserved.
+ */
+
+#include <linux/acpi.h>
+#include <linux/completion.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/virtio.h>
+#include <linux/virtio_ids.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_i2c.h>
+
+/**
+ * struct virtio_i2c - virtio I2C data
+ * @vdev: virtio device for this controller
+ * @completion: completion of virtio I2C message
+ * @adap: I2C adapter for this controller
+ * @vq: the virtio virtqueue for communication
+ */
+struct virtio_i2c {
+ struct virtio_device *vdev;
+ struct completion completion;
+ struct i2c_adapter adap;
+ struct virtqueue *vq;
+};
+
+/**
+ * struct virtio_i2c_req - the virtio I2C request structure
+ * @out_hdr: the OUT header of the virtio I2C message
+ * @buf: the buffer into which data is read, or from which it's written
+ * @in_hdr: the IN header of the virtio I2C message
+ */
+struct virtio_i2c_req {
+ struct virtio_i2c_out_hdr out_hdr ____cacheline_aligned;
+ uint8_t *buf ____cacheline_aligned;
+ struct virtio_i2c_in_hdr in_hdr ____cacheline_aligned;
+};
+
+static void virtio_i2c_msg_done(struct virtqueue *vq)
+{
+ struct virtio_i2c *vi = vq->vdev->priv;
+
+ complete(&vi->completion);
+}
+
+static int virtio_i2c_prepare_reqs(struct virtqueue *vq,
+ struct virtio_i2c_req *reqs,
+ struct i2c_msg *msgs, int num)
+{
+ struct scatterlist *sgs[3], out_hdr, msg_buf, in_hdr;
+ int i;
+
+ for (i = 0; i < num; i++) {
+ int outcnt = 0, incnt = 0;
+
+ /*
+ * We don't support 0 length messages and so filter out
+ * 0 length transfers by using i2c_adapter_quirks.
+ */
+ if (!msgs[i].len)
+ break;
+
+ /*
+ * Only 7-bit mode supported for this moment. For the address
+ * format, Please check the Virtio I2C Specification.
+ */
+ reqs[i].out_hdr.addr = cpu_to_le16(msgs[i].addr << 1);
+
+ if (i != num - 1)
+ reqs[i].out_hdr.flags = cpu_to_le32(VIRTIO_I2C_FLAGS_FAIL_NEXT);
+
+ sg_init_one(&out_hdr, &reqs[i].out_hdr, sizeof(reqs[i].out_hdr));
+ sgs[outcnt++] = &out_hdr;
+
+ reqs[i].buf = i2c_get_dma_safe_msg_buf(&msgs[i], 1);
+ if (!reqs[i].buf)
+ break;
+
+ sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len);
+
+ if (msgs[i].flags & I2C_M_RD)
+ sgs[outcnt + incnt++] = &msg_buf;
+ else
+ sgs[outcnt++] = &msg_buf;
+
+ sg_init_one(&in_hdr, &reqs[i].in_hdr, sizeof(reqs[i].in_hdr));
+ sgs[outcnt + incnt++] = &in_hdr;
+
+ if (virtqueue_add_sgs(vq, sgs, outcnt, incnt, &reqs[i], GFP_KERNEL)) {
+ i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], false);
+ break;
+ }
+ }
+
+ return i;
+}
+
+static int virtio_i2c_complete_reqs(struct virtqueue *vq,
+ struct virtio_i2c_req *reqs,
+ struct i2c_msg *msgs, int num,
+ bool timedout)
+{
+ struct virtio_i2c_req *req;
+ bool failed = timedout;
+ unsigned int len;
+ int i, j = 0;
+
+ for (i = 0; i < num; i++) {
+ /* Detach the ith request from the vq */
+ req = virtqueue_get_buf(vq, &len);
+
+ /*
+ * Condition req == &reqs[i] should always meet since we have
+ * total num requests in the vq. reqs[i] can never be NULL here.
+ */
+ if (!failed && (WARN_ON(req != &reqs[i]) ||
+ req->in_hdr.status != VIRTIO_I2C_MSG_OK))
+ failed = true;
+
+ i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], !failed);
+
+ if (!failed)
+ j++;
+ }
+
+ return timedout ? -ETIMEDOUT : j;
+}
+
+static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+ int num)
+{
+ struct virtio_i2c *vi = i2c_get_adapdata(adap);
+ struct virtqueue *vq = vi->vq;
+ struct virtio_i2c_req *reqs;
+ unsigned long time_left;
+ int count;
+
+ reqs = kcalloc(num, sizeof(*reqs), GFP_KERNEL);
+ if (!reqs)
+ return -ENOMEM;
+
+ count = virtio_i2c_prepare_reqs(vq, reqs, msgs, num);
+ if (!count)
+ goto err_free;
+
+ /*
+ * For the case where count < num, i.e. we weren't able to queue all the
+ * msgs, ideally we should abort right away and return early, but some
+ * of the messages are already sent to the remote I2C controller and the
+ * virtqueue will be left in undefined state in that case. We kick the
+ * remote here to clear the virtqueue, so we can try another set of
+ * messages later on.
+ */
+
+ reinit_completion(&vi->completion);
+ virtqueue_kick(vq);
+
+ time_left = wait_for_completion_timeout(&vi->completion, adap->timeout);
+ if (!time_left)
+ dev_err(&adap->dev, "virtio i2c backend timeout.\n");
+
+ count = virtio_i2c_complete_reqs(vq, reqs, msgs, count, !time_left);
+
+err_free:
+ kfree(reqs);
+ return count;
+}
+
+static void virtio_i2c_del_vqs(struct virtio_device *vdev)
+{
+ vdev->config->reset(vdev);
+ vdev->config->del_vqs(vdev);
+}
+
+static int virtio_i2c_setup_vqs(struct virtio_i2c *vi)
+{
+ struct virtio_device *vdev = vi->vdev;
+
+ vi->vq = virtio_find_single_vq(vdev, virtio_i2c_msg_done, "msg");
+ return PTR_ERR_OR_ZERO(vi->vq);
+}
+
+static u32 virtio_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+}
+
+static struct i2c_algorithm virtio_algorithm = {
+ .master_xfer = virtio_i2c_xfer,
+ .functionality = virtio_i2c_func,
+};
+
+static const struct i2c_adapter_quirks virtio_i2c_quirks = {
+ .flags = I2C_AQ_NO_ZERO_LEN,
+};
+
+static int virtio_i2c_probe(struct virtio_device *vdev)
+{
+ struct virtio_i2c *vi;
+ int ret;
+
+ vi = devm_kzalloc(&vdev->dev, sizeof(*vi), GFP_KERNEL);
+ if (!vi)
+ return -ENOMEM;
+
+ vdev->priv = vi;
+ vi->vdev = vdev;
+
+ init_completion(&vi->completion);
+
+ ret = virtio_i2c_setup_vqs(vi);
+ if (ret)
+ return ret;
+
+ vi->adap.owner = THIS_MODULE;
+ snprintf(vi->adap.name, sizeof(vi->adap.name),
+ "i2c_virtio at virtio bus %d", vdev->index);
+ vi->adap.algo = &virtio_algorithm;
+ vi->adap.quirks = &virtio_i2c_quirks;
+ vi->adap.dev.parent = &vdev->dev;
+ vi->adap.dev.of_node = vdev->dev.of_node;
+ i2c_set_adapdata(&vi->adap, vi);
+
+ /*
+ * Setup ACPI node for controlled devices which will be probed through
+ * ACPI.
+ */
+ ACPI_COMPANION_SET(&vi->adap.dev, ACPI_COMPANION(vdev->dev.parent));
+
+ ret = i2c_add_adapter(&vi->adap);
+ if (ret)
+ virtio_i2c_del_vqs(vdev);
+
+ return ret;
+}
+
+static void virtio_i2c_remove(struct virtio_device *vdev)
+{
+ struct virtio_i2c *vi = vdev->priv;
+
+ i2c_del_adapter(&vi->adap);
+ virtio_i2c_del_vqs(vdev);
+}
+
+static struct virtio_device_id id_table[] = {
+ { VIRTIO_ID_I2C_ADAPTER, VIRTIO_DEV_ANY_ID },
+ {}
+};
+MODULE_DEVICE_TABLE(virtio, id_table);
+
+#ifdef CONFIG_PM_SLEEP
+static int virtio_i2c_freeze(struct virtio_device *vdev)
+{
+ virtio_i2c_del_vqs(vdev);
+ return 0;
+}
+
+static int virtio_i2c_restore(struct virtio_device *vdev)
+{
+ return virtio_i2c_setup_vqs(vdev->priv);
+}
+#endif
+
+static struct virtio_driver virtio_i2c_driver = {
+ .id_table = id_table,
+ .probe = virtio_i2c_probe,
+ .remove = virtio_i2c_remove,
+ .driver = {
+ .name = "i2c_virtio",
+ },
+#ifdef CONFIG_PM_SLEEP
+ .freeze = virtio_i2c_freeze,
+ .restore = virtio_i2c_restore,
+#endif
+};
+module_virtio_driver(virtio_i2c_driver);
+
+MODULE_AUTHOR("Jie Deng <jie.deng@intel.com>");
+MODULE_AUTHOR("Conghui Chen <conghui.chen@intel.com>");
+MODULE_DESCRIPTION("Virtio i2c bus driver");
+MODULE_LICENSE("GPL");
projects / linux-2.6-microblaze.git / commitdiff