Re: [PATCH v2 3/3] virtio-spi: Add virtio SPI driver.

From: Haixu Cui
Date: Mon Mar 18 2024 - 05:40:07 EST


Hello,

As Mark recommended, I reserve the virtio_spi_probe function only and list my comments.

On 3/4/2024 11:43 PM, Harald Mommer wrote:
+static int virtio_spi_probe(struct virtio_device *vdev)
+{
+ struct device_node *np = vdev->dev.parent->of_node;
+ struct virtio_spi_priv *priv;
+ struct spi_controller *ctrl;
+ int err;
+ u32 bus_num;
+ u16 csi;
+
+ 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;
+ dev_set_drvdata(&vdev->dev, ctrl);

ctrl->dev.of_node is not set, so the child node cannot be parsed. I would say, it's necessary to support the virtio spi device node in the format:

virtio-spi@4b013000 {
compatible = "virtio,mmio";
reg = <0x4b013000 0x1000>;
interrupts = <0 497 4>;

spi {
compatible = "virtio,device2d";
#address-cells = <1>;
#size-cells = <0>;

spidev {
compatible = "xxx";
reg = <0>;
spi-max-frequency = <100000>;
};
};
};
+
+ init_completion(&priv->spi_req.completion);
+
+ err = of_property_read_u32(np, "spi,bus-num", &bus_num);
+ if (!err && bus_num <= S16_MAX)
+ ctrl->bus_num = (s16)bus_num;
+
+ virtio_spi_read_config(vdev);
+
+ ctrl->transfer_one = virtio_spi_transfer_one;
+
+ err = virtio_spi_find_vqs(priv);
+ if (err) {
+ dev_err(&vdev->dev, "Cannot setup virtqueues\n");
+ return err;
+ }
+
+ err = spi_register_controller(ctrl);
+ if (err) {
+ dev_err(&vdev->dev, "Cannot register controller\n");
+ goto err_return;
+ }
+
+ board_info.max_speed_hz = priv->max_freq_hz;
+ /* spi_new_device() currently does not use bus_num but better set it */
+ board_info.bus_num = (u16)ctrl->bus_num;
+
+ /* Add chip selects to controller */

Creating the spi devices here statically, will introduce conflicts if the same spi devices also in the device-tree.

+ for (csi = 0; csi < ctrl->num_chipselect; csi++) {
+ dev_dbg(&vdev->dev, "Setting up CS=%u\n", csi);
+ board_info.chip_select = csi;
+
+ if (!(priv->mode_func_supported & VIRTIO_SPI_CS_HIGH))
+ board_info.mode = SPI_MODE_0;
+ else
+ board_info.mode = SPI_MODE_0 | SPI_CS_HIGH;
+
+ if (!spi_new_device(ctrl, &board_info)) {
+ dev_err(&vdev->dev, "Cannot setup device %u\n", csi);
+ spi_unregister_controller(ctrl);
+ err = -ENODEV;
+ goto err_return;
+ }
+ }
+
+ return 0;
+
+err_return:
+ vdev->config->del_vqs(vdev);
+ return err;
+}
+