Linux Device Drivers 3 examples

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diff --git a/scullp/scullp.h b/scullp/scullp.h
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+/* -*- C -*-
+ * scullp.h -- definitions for the scullp 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.
+ */
+
+#include <linux/ioctl.h>
+#include <linux/cdev.h>
+
+/*
+ * Macros to help debugging
+ */
+
+#undef PDEBUG             /* undef it, just in case */
+#ifdef SCULLP_DEBUG
+#  ifdef __KERNEL__
+     /* This one if debugging is on, and kernel space */
+#    define PDEBUG(fmt, args...) printk( KERN_DEBUG "scullp: " 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 */
+
+#define SCULLP_MAJOR 0   /* dynamic major by default */
+
+#define SCULLP_DEVS 4    /* scullp0 through scullp3 */
+
+/*
+ * The bare device is a variable-length region of memory.
+ * Use a linked list of indirect blocks.
+ *
+ * "scullp_dev->data" points to an array of pointers, each
+ * pointer refers to a memory page.
+ *
+ * The array (quantum-set) is SCULLP_QSET long.
+ */
+#define SCULLP_ORDER    0 /* one page at a time */
+#define SCULLP_QSET     500
+
+struct scullp_dev {
+	void **data;
+	struct scullp_dev *next;  /* next listitem */
+	int vmas;                 /* active mappings */
+	int order;                /* the current allocation order */
+	int qset;                 /* the current array size */
+	size_t size;              /* 32-bit will suffice */
+	struct semaphore sem;     /* Mutual exclusion */
+	struct cdev cdev;
+};
+
+extern struct scullp_dev *scullp_devices;
+
+extern struct file_operations scullp_fops;
+
+/*
+ * The different configurable parameters
+ */
+extern int scullp_major;     /* main.c */
+extern int scullp_devs;
+extern int scullp_order;
+extern int scullp_qset;
+
+/*
+ * Prototypes for shared functions
+ */
+int scullp_trim(struct scullp_dev *dev);
+struct scullp_dev *scullp_follow(struct scullp_dev *dev, int n);
+
+
+#ifdef SCULLP_DEBUG
+#  define SCULLP_USE_PROC
+#endif
+
+/*
+ * Ioctl definitions
+ */
+
+/* Use 'K' as magic number */
+#define SCULLP_IOC_MAGIC  'K'
+
+#define SCULLP_IOCRESET    _IO(SCULLP_IOC_MAGIC, 0)
+
+/*
+ * S means "Set" through a ptr,
+ * T means "Tell" directly
+ * G means "Get" (to a pointed var)
+ * Q means "Query", response is on the return value
+ * X means "eXchange": G and S atomically
+ * H means "sHift": T and Q atomically
+ */
+#define SCULLP_IOCSORDER   _IOW(SCULLP_IOC_MAGIC,  1, int)
+#define SCULLP_IOCTORDER   _IO(SCULLP_IOC_MAGIC,   2)
+#define SCULLP_IOCGORDER   _IOR(SCULLP_IOC_MAGIC,  3, int)
+#define SCULLP_IOCQORDER   _IO(SCULLP_IOC_MAGIC,   4)
+#define SCULLP_IOCXORDER   _IOWR(SCULLP_IOC_MAGIC, 5, int)
+#define SCULLP_IOCHORDER   _IO(SCULLP_IOC_MAGIC,   6)
+#define SCULLP_IOCSQSET    _IOW(SCULLP_IOC_MAGIC,  7, int)
+#define SCULLP_IOCTQSET    _IO(SCULLP_IOC_MAGIC,   8)
+#define SCULLP_IOCGQSET    _IOR(SCULLP_IOC_MAGIC,  9, int)
+#define SCULLP_IOCQQSET    _IO(SCULLP_IOC_MAGIC,  10)
+#define SCULLP_IOCXQSET    _IOWR(SCULLP_IOC_MAGIC,11, int)
+#define SCULLP_IOCHQSET    _IO(SCULLP_IOC_MAGIC,  12)
+
+#define SCULLP_IOC_MAXNR 12
+
+
+