Basic device operations in spi driver

Question

I need to write an spi driver for omap4 from scratch. I am referring http://lxr.free-electrons.com/source/drivers/spi/spi-omap2-mcspi.c driver code. But, I am unable to understand how basic device operations are handled in this driver code. For example a char driver has the structure

struct file_operations scull_fops = {
.owner = THIS_MODULE,
.llseek = scull_llseek,
.read = scull_read,
.write = scull_write,
.ioctl = scull_ioctl,
.open = scull_open,
.release = scull_release,
};

containing the pointers to the basic functions like open, read, write etc...

I don't find these functions in http://lxr.free-electrons.com/source/drivers/spi/spi-omap2-mcspi.c

Somebody please help me identify how the device open, read & write are provided in the spi-omap2-mcspi.c code.

There are two types of SPI drivers: master drivers and slave (or target) protocol drivers. drivers/spi is a directory for master drivers, i.e. for the SPI master controllers. Are you writing a driver for the master or a slave device? — sawdust
Have you read the Linux/Documentation/spi/spi-summary document? — sawdust

krase krase · Accepted Answer · 2014-03-28T08:22:38

If you look at the bottom of the file you linked in your post, you will see the handling for the basic platform driver operations.

static const struct dev_pm_ops omap2_mcspi_pm_ops = {
        .resume = omap2_mcspi_resume,
        .runtime_resume = omap_mcspi_runtime_resume,
};

static struct platform_driver omap2_mcspi_driver = {
       .driver = {
                .name =         "omap2_mcspi",
                .owner =        THIS_MODULE,
                .pm =           &omap2_mcspi_pm_ops,
                .of_match_table = omap_mcspi_of_match,
       },
       .probe =        omap2_mcspi_probe,
       .remove =       omap2_mcspi_remove,
};

In the probe operation there you can see the setup of the spi specific operations for this driver:

     /* the spi->mode bits understood by this driver: */
     master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
     master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
     master->setup = omap2_mcspi_setup;
     master->auto_runtime_pm = true;
     master->transfer_one_message = omap2_mcspi_transfer_one_message;
     master->cleanup = omap2_mcspi_cleanup;
     master->dev.of_node = node;

Basic device operations in spi driver

1 Answers