Link b/w client driver, device, controller driver & core driver

This blog explains the interconnection b/w client driver, controller driver & core driver.

Example: SPI-NOR FW, m25p80 client driver, SPI Xlnx controller driver

1) Client driver structure representation:-

struct m25p {
 struct spi_device *spi;
 struct spi_nor  spi_nor;
 u8   command[MAX_CMD_SIZE];
};

static int m25p_probe(struct spi_device *spi) {

struct flash_platform_data *data;
 struct m25p *flash;
 struct spi_nor *nor;

data = dev_get_platdata(&spi->dev); 

          flash_platform_data = spi_device->dev->platform_data;

/* Allocate memeory for m25p80 driver*/

flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL); 

/* SPI layer device & NOR FW layer device will be same  */ 

nor->dev = &spi->dev; 

spi_nor_set_flash_node(nor, spi->dev.of_node);

              nor->mtd->dev.of_node = device_node 

    /* Read whatever is there in "label" & assign it to mtd->name; */
              "label", &mtd->name 

/* This way spi-nor FW can access client device */

nor->priv = m25p80;

/* Device core layer driver data points to client driver structure */ 

spi_set_drvdata(spi, flash);

       spi_device->dev->driver_data = m25p80;

/* Connect the client driver with spi layer.

   Assign the spi_device to client driver spi_device pointer */ 

flash->spi = spi;

          m25p80->spi_device = spi_device (got as a param from **********) 

} 

struct spi_device *spi_new_device(struct spi_controller *ctlr,
      struct spi_board_info *chip)

struct spi_device *proxy; 

proxy = spi_alloc_device(ctlr);  

proxy->dev.platform_data = (void *) chip->platform_data; 

static int zynqmp_prepare_transfer_hardware(struct spi_master *master)
{
 struct zynqmp_qspi *xqspi = spi_master_get_devdata(master);

static int zynqmp_qspi_probe(struct platform_device *pdev)
{

 struct spi_master *master;
 struct zynqmp_qspi *xqspi;

xqspi = spi_master_get_devdata(master); 

        xqspi = ctlr->dev->driver_data; 

 master->dev.of_node = pdev->dev.of_node;

 
platform_set_drvdata(pdev, master);  

         pdev->dev->driver_data = master; 

     xqspi->dev = dev;