Linux Device Drivers Development

Per-device data

In the probe function, it is a common task to track private (per-device) data to be used during the module lifetime. This has been discussed in Chapter 7, I2C Client Drivers.

The following are the prototypes of functions you use for setting/getting per-device data:

/* set the data */ 
void spi_set_drvdata(struct *spi_device, void *data); 
 
/* Get the data back */ 
 void *spi_get_drvdata(const struct *spi_device); 

Here is an example:

struct mc33880 { struct mutex lock; u8 bar; struct foo chip; struct spi_device *spi; }; static int mc33880_probe(struct spi_device *spi) { struct mc33880 *mc; [...] /* Device set up */ mc = devm_kzalloc(&spi->dev, sizeof(struct mc33880), GFP_KERNEL); if (!mc) return -ENOMEM; mutex_init(&mc->lock); ...