From: Peng Fan <[email protected]> spi-virtio registers a SPI controller, but we still need to register a SPI device to initiate the SPI virtio transfer.
To Xen hypervisor, there might be no 'passthrough' node for DomU, so add a sysfs interface to allow creating/deleting a SPI device. Usage: echo "spidev" > /sys/class/spi_master/spi0/new_device echo "spi0.0" > /sys/class/spi_master/spi0/delete_device Signed-off-by: Peng Fan <[email protected]> --- drivers/spi/spi-virtio.c | 171 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 171 insertions(+) diff --git a/drivers/spi/spi-virtio.c b/drivers/spi/spi-virtio.c index 2acb929b2c6907d6b073829c153d1e1d3bb729b5..9014d52da76b0f2e2c3f049605968fbbb790905e 100644 --- a/drivers/spi/spi-virtio.c +++ b/drivers/spi/spi-virtio.c @@ -5,12 +5,15 @@ * Copyright (C) 2025 Qualcomm Innovation Center, Inc. All rights reserved. */ +#include <linux/cleanup.h> #include <linux/completion.h> #include <linux/interrupt.h> #include <linux/io.h> +#include <linux/kstrtox.h> #include <linux/module.h> #include <linux/spi/spi.h> #include <linux/stddef.h> +#include <linux/string.h> #include <linux/virtio.h> #include <linux/virtio_ring.h> #include <linux/virtio_spi.h> @@ -330,6 +333,170 @@ static void virtio_spi_del_vq(void *data) vdev->config->del_vqs(vdev); } +static ssize_t new_device_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct spi_controller *ctlr = container_of(dev, struct spi_controller, dev); + char *cs_str = NULL, *max_hz_str = NULL, *mode_str = NULL; + u32 mode = SPI_MODE_0, max_hz = 500000, cs = 0; /* MODE_0, 500KHz */ + char *tok, *save; + struct spi_board_info bi = { }; + struct spi_device *spi; + char *modalias = NULL; + int err; + + char *kbuf __free(kfree) = kstrdup(buf, GFP_KERNEL); + if (!kbuf) + return -ENOMEM; + + /* + * Parse: "<modalias> <cs> [max_hz] [mode]" + * Example: "spidev 0 5000000 0" + */ + tok = strim(strsep(&kbuf, "\n")); + if (!tok || !*tok) + return -EINVAL; + + save = tok; + + /* Extract all tokens first */ + modalias = strsep(&save, " \t"); + if (save && *save) + cs_str = strsep(&save, " \t"); + if (save && *save) + max_hz_str = strsep(&save, " \t"); + if (save && *save) + mode_str = strsep(&save, " \t"); + + /* Validate required parameters */ + if (!modalias || !*modalias) { + dev_err(dev, "Missing modalias\n"); + return -EINVAL; + } + + if (cs_str && *cs_str) { + /* Parse chip_select (optional) */ + err = kstrtou32(cs_str, 0, &cs); + if (err) { + dev_err(dev, "Invalid chip_select: %s\n", cs_str); + return -EINVAL; + } + + if (cs >= ctlr->num_chipselect) { + dev_err(dev, "chip_select %u out of range (max %u)\n", + cs, ctlr->num_chipselect - 1); + return -EINVAL; + } + } + + /* Parse max_speed_hz (optional) */ + if (max_hz_str && *max_hz_str) { + err = kstrtou32(max_hz_str, 0, &max_hz); + if (err) { + dev_err(dev, "Invalid max_speed_hz: %s\n", max_hz_str); + return -EINVAL; + } + + if (max_hz == 0 || max_hz > ctlr->max_speed_hz) { + dev_err(dev, "max_speed_hz %u out of range (1-%u)\n", + max_hz, ctlr->max_speed_hz); + return -EINVAL; + } + } + + /* Parse mode (optional) */ + if (mode_str && *mode_str) { + err = kstrtouint(mode_str, 0, &mode); + if (err) { + dev_err(dev, "Invalid mode: %s\n", mode_str); + return -EINVAL; + } + } + + /* Check for extra unexpected parameters */ + if (save && *save) + dev_warn(dev, "Ignoring extra parameters: %s\n", save); + + /* Populate board info */ + strscpy(bi.modalias, modalias, sizeof(bi.modalias)); + bi.chip_select = cs; + bi.max_speed_hz = max_hz; + bi.mode = mode; + + /* Serialize against controller add/remove paths */ + mutex_lock(&ctlr->bus_lock_mutex); + spi = spi_new_device(ctlr, &bi); + mutex_unlock(&ctlr->bus_lock_mutex); + + if (!spi) { + dev_err(dev, "Failed to create SPI device %s (cs=%u, mode=0x%x)\n", + modalias, cs, mode); + return -ENODEV; + } + + dev_info(dev, "Created SPI device %s: cs=%u, max_hz=%u, mode=0x%x\n", + modalias, cs, max_hz, mode); + + /* + * generic "spidev" may NOT auto-bind. force-bind from userspace via: + * echo spidev > /sys/bus/spi/devices/spiB.C/driver_override + * echo spiB.C > /sys/bus/spi/drivers/spidev/bind + */ + + return count; +} + +static ssize_t delete_device_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct spi_controller *ctlr = container_of(dev, struct spi_controller, dev); + struct spi_device *spi; + struct device *child; + char *device_name; + + char *kbuf __free(kfree) = kstrdup(buf, GFP_KERNEL); + if (!kbuf) + return -ENOMEM; + + device_name = strim(kbuf); + if (!device_name || !*device_name) { + dev_err(dev, "Empty device name\n"); + return -EINVAL; + } + + guard(mutex)(&ctlr->bus_lock_mutex); + + /* Find and remove device with matching name */ + child = device_find_child_by_name(&ctlr->dev, device_name); + if (!child) { + dev_err(dev, "SPI device '%s' not found\n", device_name); + return -ENODEV; + } + + spi = to_spi_device(child); + dev_info(dev, "Removing SPI device %s (cs=%u, modalias=%s)\n", + dev_name(&spi->dev), spi_get_chipselect(spi, 0), + spi->modalias); + + spi_unregister_device(spi); + + return count; +} + +static DEVICE_ATTR_WO(new_device); +static DEVICE_ATTR_WO(delete_device); + +static struct attribute *virtio_spi_attrs[] = { + &dev_attr_new_device.attr, + &dev_attr_delete_device.attr, + NULL, +}; + +static const struct attribute_group virtio_spi_attr_group = { + .attrs = virtio_spi_attrs, +}; + static int virtio_spi_probe(struct virtio_device *vdev) { struct virtio_spi_priv *priv; @@ -366,6 +533,10 @@ static int virtio_spi_probe(struct virtio_device *vdev) if (ret) return dev_err_probe(&vdev->dev, ret, "Cannot register controller\n"); + ret = devm_device_add_group(&ctrl->dev, &virtio_spi_attr_group); + if (ret) + return dev_err_probe(&ctrl->dev, ret, "Cannot add virtio_spi_attr_group\n"); + return 0; } --- base-commit: bc04acf4aeca588496124a6cf54bfce3db327039 change-id: 20251205-v-spi-55a2a0ae8cc9 Best regards, -- Peng Fan <[email protected]>
