Use sysfs new_id file to enable spidev at runtime. new_id file accepts bus number and chip select in 'B.C' format.
With reference to the last ML discussion here[1] regarding the solution for spidev with device trees. This patch adds support to load spidevB.C via sysfs new_id file as suggested by Greg. [1] http://thread.gmane.org/gmane.linux.kernel.spi.devel/20331/focus=20369 Suggested-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> Signed-off-by: Bhuvanchandra DV <bhuvanchandra...@toradex.com> Signed-off-by: Stefan Agner <stefan.ag...@toradex.com> --- Documentation/ABI/testing/sysfs-bus-spi-spidev | 8 +++ drivers/spi/spidev.c | 75 +++++++++++++++++++++++--- 2 files changed, 77 insertions(+), 6 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-bus-spi-spidev diff --git a/Documentation/ABI/testing/sysfs-bus-spi-spidev b/Documentation/ABI/testing/sysfs-bus-spi-spidev new file mode 100644 index 0000000..3f6e092 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-spi-spidev @@ -0,0 +1,8 @@ +What: /sys/bus/spi/drivers/spidev/new_id +Date: March 2016 +Description: + This allows to load spidev at runtime. new_id file accepts bus + number and chip select in 'B.C' format. + e.g. + To load spidev1.1 at runtime: + $ echo 1.1 > /sys/bus/spi/drivers/spidev/new_id diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c index e3c19f3..99e9842 100644 --- a/drivers/spi/spidev.c +++ b/drivers/spi/spidev.c @@ -667,6 +667,57 @@ static int spidev_release(struct inode *inode, struct file *filp) return 0; } +/** + * new_id_store - add a new spidevB.C instance + * @driver: target device driver + * @buf: buffer for scanning bus number and chip select + * @count: input size + * + * Adds a new dynamic spidev instance based on the requested bus number + * and chip select. + */ +static ssize_t new_id_store(struct device_driver *drv, const char *buf, + size_t count) +{ + int ret; + u32 bus, cs; + struct spi_device *spi; + struct spi_master *master; + + ret = sscanf(buf, "%u.%u", &bus, &cs); + + if (ret < 2) + return -EINVAL; + + master = spi_busnum_to_master(bus); + if (!master) + return -ENODEV; + + if (cs >= master->num_chipselect) + return -ENODEV; + + spi = spi_alloc_device(master); + if (!spi) { + dev_err(&master->dev, "Couldn't allocate spidev device\n"); + return -ENOMEM;; + } + + spi->chip_select = cs; + master->bus_num = bus; + + strlcpy(spi->modalias, "spidev", sizeof(spi->modalias)); + + ret = spi_add_device(spi); + if (ret) { + dev_err(&master->dev, "Couldn't add spidev device\n"); + spi_dev_put(spi); + return ret; + } + + return count; +} +static DRIVER_ATTR_WO(new_id); + static const struct file_operations spidev_fops = { .owner = THIS_MODULE, /* REVISIT switch to aio primitives, so that userspace @@ -817,21 +868,33 @@ static int __init spidev_init(void) spidev_class = class_create(THIS_MODULE, "spidev"); if (IS_ERR(spidev_class)) { - unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); - return PTR_ERR(spidev_class); + status = PTR_ERR(spidev_class); + goto err_unregister_chrdev; } status = spi_register_driver(&spidev_spi_driver); - if (status < 0) { - class_destroy(spidev_class); - unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); - } + if (status < 0) + goto err_destroy_class; + + status = driver_create_file(&spidev_spi_driver.driver, &driver_attr_new_id); + if (status < 0) + goto err_unregister_driver; + + return status; + +err_unregister_driver: + spi_unregister_driver(&spidev_spi_driver); +err_destroy_class: + class_destroy(spidev_class); +err_unregister_chrdev: + unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); return status; } module_init(spidev_init); static void __exit spidev_exit(void) { + driver_remove_file(&spidev_spi_driver.driver, &driver_attr_new_id); spi_unregister_driver(&spidev_spi_driver); class_destroy(spidev_class); unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name); -- 2.7.3
