Linux Device Drivers 3 examples

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+/*
+ * scull.h -- definitions for the char module
+ *
+ * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet
+ * Copyright (C) 2001 O'Reilly & Associates
+ *
+ * The source code in this file can be freely used, adapted,
+ * and redistributed in source or binary form, so long as an
+ * acknowledgment appears in derived source files.  The citation
+ * should list that the code comes from the book "Linux Device
+ * Drivers" by Alessandro Rubini and Jonathan Corbet, published
+ * by O'Reilly & Associates.   No warranty is attached;
+ * we cannot take responsibility for errors or fitness for use.
+ *
+ * $Id: scull.h,v 1.15 2004/11/04 17:51:18 rubini Exp $
+ */
+
+#ifndef _SCULL_H_
+#define _SCULL_H_
+
+#include <linux/ioctl.h> /* needed for the _IOW etc stuff used later */
+
+/*
+ * Macros to help debugging
+ */
+
+#undef PDEBUG             /* undef it, just in case */
+#ifdef SCULL_DEBUG
+#  ifdef __KERNEL__
+     /* This one if debugging is on, and kernel space */
+#    define PDEBUG(fmt, args...) printk( KERN_DEBUG "scull: " fmt, ## args)
+#  else
+     /* This one for user space */
+#    define PDEBUG(fmt, args...) fprintf(stderr, fmt, ## args)
+#  endif
+#else
+#  define PDEBUG(fmt, args...) /* not debugging: nothing */
+#endif
+
+#undef PDEBUGG
+#define PDEBUGG(fmt, args...) /* nothing: it's a placeholder */
+
+#ifndef SCULL_MAJOR
+#define SCULL_MAJOR 0   /* dynamic major by default */
+#endif
+
+#ifndef SCULL_NR_DEVS
+#define SCULL_NR_DEVS 4    /* scull0 through scull3 */
+#endif
+
+#ifndef SCULL_P_NR_DEVS
+#define SCULL_P_NR_DEVS 4  /* scullpipe0 through scullpipe3 */
+#endif
+
+/*
+ * The bare device is a variable-length region of memory.
+ * Use a linked list of indirect blocks.
+ *
+ * "scull_dev->data" points to an array of pointers, each
+ * pointer refers to a memory area of SCULL_QUANTUM bytes.
+ *
+ * The array (quantum-set) is SCULL_QSET long.
+ */
+#ifndef SCULL_QUANTUM
+#define SCULL_QUANTUM 4000
+#endif
+
+#ifndef SCULL_QSET
+#define SCULL_QSET    1000
+#endif
+
+/*
+ * The pipe device is a simple circular buffer. Here its default size
+ */
+#ifndef SCULL_P_BUFFER
+#define SCULL_P_BUFFER 4000
+#endif
+
+/*
+ * Representation of scull quantum sets.
+ */
+struct scull_qset {
+	void **data;
+	struct scull_qset *next;
+};
+
+struct scull_dev {
+	struct scull_qset *data;  /* Pointer to first quantum set */
+	int quantum;              /* the current quantum size */
+	int qset;                 /* the current array size */
+	unsigned long size;       /* amount of data stored here */
+	unsigned int access_key;  /* used by sculluid and scullpriv */
+	struct semaphore sem;     /* mutual exclusion semaphore     */
+	struct cdev cdev;	  /* Char device structure		*/
+};
+
+/*
+ * Split minors in two parts
+ */
+#define TYPE(minor)	(((minor) >> 4) & 0xf)	/* high nibble */
+#define NUM(minor)	((minor) & 0xf)		/* low  nibble */
+
+
+/*
+ * The different configurable parameters
+ */
+extern int scull_major;     /* main.c */
+extern int scull_nr_devs;
+extern int scull_quantum;
+extern int scull_qset;
+
+extern int scull_p_buffer;	/* pipe.c */
+
+
+/*
+ * Prototypes for shared functions
+ */
+
+int     scull_p_init(dev_t dev);
+void    scull_p_cleanup(void);
+int     scull_access_init(dev_t dev);
+void    scull_access_cleanup(void);
+
+int     scull_trim(struct scull_dev *dev);
+
+ssize_t scull_read(struct file *filp, char __user *buf, size_t count,
+                   loff_t *f_pos);
+ssize_t scull_write(struct file *filp, const char __user *buf, size_t count,
+                    loff_t *f_pos);
+loff_t  scull_llseek(struct file *filp, loff_t off, int whence);
+int     scull_ioctl(struct inode *inode, struct file *filp,
+                    unsigned int cmd, unsigned long arg);
+
+
+/*
+ * Ioctl definitions
+ */
+
+/* Use 'k' as magic number */
+#define SCULL_IOC_MAGIC  'k'
+/* Please use a different 8-bit number in your code */
+
+#define SCULL_IOCRESET    _IO(SCULL_IOC_MAGIC, 0)
+
+/*
+ * S means "Set" through a ptr,
+ * T means "Tell" directly with the argument value
+ * G means "Get": reply by setting through a pointer
+ * Q means "Query": response is on the return value
+ * X means "eXchange": switch G and S atomically
+ * H means "sHift": switch T and Q atomically
+ */
+#define SCULL_IOCSQUANTUM _IOW(SCULL_IOC_MAGIC,  1, int)
+#define SCULL_IOCSQSET    _IOW(SCULL_IOC_MAGIC,  2, int)
+#define SCULL_IOCTQUANTUM _IO(SCULL_IOC_MAGIC,   3)
+#define SCULL_IOCTQSET    _IO(SCULL_IOC_MAGIC,   4)
+#define SCULL_IOCGQUANTUM _IOR(SCULL_IOC_MAGIC,  5, int)
+#define SCULL_IOCGQSET    _IOR(SCULL_IOC_MAGIC,  6, int)
+#define SCULL_IOCQQUANTUM _IO(SCULL_IOC_MAGIC,   7)
+#define SCULL_IOCQQSET    _IO(SCULL_IOC_MAGIC,   8)
+#define SCULL_IOCXQUANTUM _IOWR(SCULL_IOC_MAGIC, 9, int)
+#define SCULL_IOCXQSET    _IOWR(SCULL_IOC_MAGIC,10, int)
+#define SCULL_IOCHQUANTUM _IO(SCULL_IOC_MAGIC,  11)
+#define SCULL_IOCHQSET    _IO(SCULL_IOC_MAGIC,  12)
+
+/*
+ * The other entities only have "Tell" and "Query", because they're
+ * not printed in the book, and there's no need to have all six.
+ * (The previous stuff was only there to show different ways to do it.
+ */
+#define SCULL_P_IOCTSIZE _IO(SCULL_IOC_MAGIC,   13)
+#define SCULL_P_IOCQSIZE _IO(SCULL_IOC_MAGIC,   14)
+/* ... more to come */
+
+#define SCULL_IOC_MAXNR 14
+
+#endif /* _SCULL_H_ */