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    Subject[PATCH 4/4] add example files to the kernel sample directory
    Date
    From: Stefani Seibold <stefani@seibold.net>

    This patch add four examples to the kernel sample directory.

    It shows how to handle:
    - a byte stream fifo
    - a integer type fifo
    - a dynamic record sized fifo
    - the fifo DMA functions

    Signed-off-by: Stefani Seibold <stefani@seibold.net>
    ---
    samples/Kconfig | 10 ++
    samples/Makefile | 2 +-
    samples/kfifo/Makefile | 1 +
    samples/kfifo/bytestream-example.c | 163 +++++++++++++++++++++++++++++++++++
    samples/kfifo/dma-example.c | 115 +++++++++++++++++++++++++
    samples/kfifo/inttype-example.c | 157 +++++++++++++++++++++++++++++++++
    samples/kfifo/record-example.c | 167 ++++++++++++++++++++++++++++++++++++
    7 files changed, 614 insertions(+), 1 deletions(-)
    create mode 100644 samples/kfifo/Makefile
    create mode 100644 samples/kfifo/bytestream-example.c
    create mode 100644 samples/kfifo/dma-example.c
    create mode 100644 samples/kfifo/inttype-example.c
    create mode 100644 samples/kfifo/record-example.c

    diff --git a/samples/Kconfig b/samples/Kconfig
    index 8924f72..954a1d5 100644
    --- a/samples/Kconfig
    +++ b/samples/Kconfig
    @@ -44,4 +44,14 @@ config SAMPLE_HW_BREAKPOINT
    help
    This builds kernel hardware breakpoint example modules.

    +config SAMPLE_KFIFO
    + tristate "Build kfifo examples -- loadable modules only"
    + depends on m
    + help
    + This config option will allow you to build a number of
    + different kfifo sample modules showing how to use the
    + generic kfifo API.
    +
    + If in doubt, say "N" here.
    +
    endif # SAMPLES
    diff --git a/samples/Makefile b/samples/Makefile
    index 0f15e6d..76b3c34 100644
    --- a/samples/Makefile
    +++ b/samples/Makefile
    @@ -1,4 +1,4 @@
    # Makefile for Linux samples code

    obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ tracepoints/ trace_events/ \
    - hw_breakpoint/
    + hw_breakpoint/ kfifo/
    diff --git a/samples/kfifo/Makefile b/samples/kfifo/Makefile
    new file mode 100644
    index 0000000..bcc9484
    --- /dev/null
    +++ b/samples/kfifo/Makefile
    @@ -0,0 +1 @@
    +obj-$(CONFIG_SAMPLE_KFIFO) += bytestream-example.o dma-example.o inttype-example.o record-example.o
    diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c
    new file mode 100644
    index 0000000..642eef3
    --- /dev/null
    +++ b/samples/kfifo/bytestream-example.c
    @@ -0,0 +1,163 @@
    +/*
    + * Sample kfifo byte stream implementation
    + *
    + * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
    + *
    + * Released under the GPL version 2 only.
    + *
    + */
    +
    +#include <linux/init.h>
    +#include <linux/module.h>
    +#include <linux/proc_fs.h>
    +#include <linux/mutex.h>
    +#include <linux/kfifo.h>
    +
    +/*
    + * This module shows how to create a byte stream fifo.
    + */
    +
    +/* fifo size in elements (bytes) */
    +#define FIFO_SIZE 32
    +
    +/* name of the proc entry */
    +#define PROC_FIFO "bytestream-fifo"
    +
    +/* lock for procfs read access */
    +static DEFINE_MUTEX(read_lock);
    +
    +/* lock for procfs write access */
    +static DEFINE_MUTEX(write_lock);
    +
    +/*
    + * define DYNAMIC in this example for a dynamically allocated fifo.
    + *
    + * Otherwise the fifo storage will be a part of the fifo structure.
    + */
    +#if 0
    +#define DYNAMIC
    +#endif
    +
    +#ifdef DYNAMIC
    +static struct kfifo test;
    +#else
    +static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
    +#endif
    +
    +static int __init testfunc(void)
    +{
    + unsigned char buf[6];
    + unsigned char i;
    + unsigned int ret;
    +
    + printk(KERN_INFO "byte stream fifo test start\n");
    +
    + /* put string into the fifo */
    + kfifo_in(&test, "hello", 5);
    +
    + /* put values into the fifo */
    + for (i = 0; i != 10; i++)
    + kfifo_put(&test, &i);
    +
    + /* show the number of used elements */
    + printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
    +
    + /* get max of 5 bytes from the fifo */
    + i = kfifo_out(&test, buf, 5);
    + printk(KERN_INFO "buf: %.*s\n", i, buf);
    +
    + /* get max of 2 elements from the fifo */
    + ret = kfifo_out(&test, buf, 2);
    + printk(KERN_INFO "ret: %d\n", ret);
    + /* and put it back to the end of the fifo */
    + ret = kfifo_in(&test, buf, ret);
    + printk(KERN_INFO "ret: %d\n", ret);
    +
    + /* put values into the fifo until is full */
    + for (i = 20; kfifo_put(&test, &i); i++)
    + ;
    +
    + printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
    +
    + /* print out all values in the fifo */
    + while (kfifo_get(&test, &i))
    + printk("%d ", i);
    + printk("\n");
    +
    + return 0;
    +}
    +
    +static ssize_t fifo_write(struct file *file, const char __user *buf,
    + size_t count, loff_t *ppos)
    +{
    + int ret;
    + unsigned int copied;
    +
    + if (mutex_lock_interruptible(&write_lock))
    + return -ERESTARTSYS;
    +
    + ret = kfifo_from_user(&test, buf, count, &copied);
    +
    + mutex_unlock(&write_lock);
    +
    + return ret ? ret : copied;
    +}
    +
    +static ssize_t fifo_read(struct file *file, char __user *buf,
    + size_t count, loff_t *ppos)
    +{
    + int ret;
    + unsigned int copied;
    +
    + if (mutex_lock_interruptible(&read_lock))
    + return -ERESTARTSYS;
    +
    + ret = kfifo_to_user(&test, buf, count, &copied);
    +
    + mutex_unlock(&read_lock);
    +
    + return ret ? ret : copied;
    +}
    +
    +static const struct file_operations fifo_fops = {
    + .owner = THIS_MODULE,
    + .read = fifo_read,
    + .write = fifo_write,
    +};
    +
    +static int __init example_init(void)
    +{
    +#ifdef DYNAMIC
    + int ret;
    +
    + ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
    + if (ret) {
    + printk(KERN_ERR "error kfifo_alloc\n");
    + return ret;
    + }
    +#else
    + INIT_KFIFO(test);
    +#endif
    + testfunc();
    +
    + if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
    +#ifdef DYNAMIC
    + kfifo_free(&test);
    +#endif
    + return -ENOMEM;
    + }
    + return 0;
    +}
    +
    +static void __exit example_exit(void)
    +{
    + remove_proc_entry(PROC_FIFO, NULL);
    +#ifdef DYNAMIC
    + kfifo_free(&test);
    +#endif
    +}
    +
    +module_init(example_init);
    +module_exit(example_exit);
    +MODULE_LICENSE("GPL");
    +MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
    diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
    new file mode 100644
    index 0000000..4ef4749
    --- /dev/null
    +++ b/samples/kfifo/dma-example.c
    @@ -0,0 +1,115 @@
    +/*
    + * Sample fifo dma implementation
    + *
    + * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
    + *
    + * Released under the GPL version 2 only.
    + *
    + */
    +
    +#include <linux/init.h>
    +#include <linux/module.h>
    +#include <linux/kfifo.h>
    +
    +/*
    + * This module shows how to handle fifo dma operations.
    + */
    +
    +/* fifo size in elements (bytes) */
    +#define FIFO_SIZE 32
    +
    +static struct kfifo fifo;
    +
    +static int __init example_init(void)
    +{
    + int i;
    + unsigned int ret;
    + struct scatterlist sg[10];
    +
    + printk(KERN_INFO "DMA fifo test start\n");
    +
    + if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
    + printk(KERN_ERR "error kfifo_alloc\n");
    + return 1;
    + }
    +
    + printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
    +
    + kfifo_in(&fifo, "test", 4);
    +
    + for (i = 0; i != 9; i++)
    + kfifo_put(&fifo, &i);
    +
    + /* kick away first byte */
    + ret = kfifo_get(&fifo, &i);
    +
    + printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
    +
    + ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
    + printk(KERN_INFO "DMA sgl entries: %d\n", ret);
    +
    + /* if 0 was returned, fifo is full and no sgl was created */
    + if (ret) {
    + printk(KERN_INFO "scatterlist for receive:\n");
    + for (i = 0; i < ARRAY_SIZE(sg); i++) {
    + printk(KERN_INFO
    + "sg[%d] -> "
    + "page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
    + i, sg[i].page_link, sg[i].offset, sg[i].length);
    +
    + if (sg_is_last(&sg[i]))
    + break;
    + }
    +
    + /* but here your code to setup and exectute the dma operation */
    + /* ... */
    +
    + /* example: zero bytes received */
    + ret = 0;
    +
    + /* finish the dma operation and update the received data */
    + kfifo_dma_in_finish(&fifo, ret);
    + }
    +
    + ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
    + printk(KERN_INFO "DMA sgl entries: %d\n", ret);
    +
    + /* if 0 was returned, no data was available and no sgl was created */
    + if (ret) {
    + printk(KERN_INFO "scatterlist for transmit:\n");
    + for (i = 0; i < ARRAY_SIZE(sg); i++) {
    + printk(KERN_INFO
    + "sg[%d] -> "
    + "page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
    + i, sg[i].page_link, sg[i].offset, sg[i].length);
    +
    + if (sg_is_last(&sg[i]))
    + break;
    + }
    +
    + /* but here your code to setup and exectute the dma operation */
    + /* ... */
    +
    + /* example: 5 bytes transmitted */
    + ret = 5;
    +
    + /* finish the dma operation and update the transmitted data */
    + kfifo_dma_out_finish(&fifo, ret);
    + }
    +
    + printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
    +
    + return 0;
    +}
    +
    +static void __exit example_exit(void)
    +{
    +#ifdef DYNAMIC
    + kfifo_free(&test);
    +#endif
    +}
    +
    +module_init(example_init);
    +module_exit(example_exit);
    +MODULE_LICENSE("GPL");
    +MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
    diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c
    new file mode 100644
    index 0000000..d6c5b7d
    --- /dev/null
    +++ b/samples/kfifo/inttype-example.c
    @@ -0,0 +1,157 @@
    +/*
    + * Sample kfifo int type implementation
    + *
    + * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
    + *
    + * Released under the GPL version 2 only.
    + *
    + */
    +
    +#include <linux/init.h>
    +#include <linux/module.h>
    +#include <linux/proc_fs.h>
    +#include <linux/mutex.h>
    +#include <linux/kfifo.h>
    +
    +/*
    + * This module shows how to create a int type fifo.
    + */
    +
    +/* fifo size in elements (ints) */
    +#define FIFO_SIZE 32
    +
    +/* name of the proc entry */
    +#define PROC_FIFO "int-fifo"
    +
    +/* lock for procfs read access */
    +static DEFINE_MUTEX(read_lock);
    +
    +/* lock for procfs write access */
    +static DEFINE_MUTEX(write_lock);
    +
    +/*
    + * define DYNAMIC in this example for a dynamically allocated fifo.
    + *
    + * Otherwise the fifo storage will be a part of the fifo structure.
    + */
    +#if 0
    +#define DYNAMIC
    +#endif
    +
    +#ifdef DYNAMIC
    +static DECLARE_KFIFO_PTR(test, int);
    +#else
    +static DEFINE_KFIFO(test, int, FIFO_SIZE);
    +#endif
    +
    +static int __init testfunc(void)
    +{
    + int buf[6];
    + int i;
    + unsigned int ret;
    +
    + printk(KERN_INFO "int fifo test start\n");
    +
    + /* put values into the fifo */
    + for (i = 0; i != 10; i++)
    + kfifo_put(&test, &i);
    +
    + /* show the number of used elements */
    + printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
    +
    + /* get max of 2 elements from the fifo */
    + ret = kfifo_out(&test, buf, 2);
    + printk(KERN_INFO "ret: %d\n", ret);
    + /* and put it back to the end of the fifo */
    + ret = kfifo_in(&test, buf, ret);
    + printk(KERN_INFO "ret: %d\n", ret);
    +
    + for (i = 20; i != 30; i++)
    + kfifo_put(&test, &i);
    +
    + printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
    +
    + /* show the first value without removing from the fifo */
    + if (kfifo_peek(&test, &i))
    + printk(KERN_INFO "%d\n", i);
    +
    + /* print out all values in the fifo */
    + while (kfifo_get(&test, &i))
    + printk("%d ", i);
    + printk("\n");
    +
    + return 0;
    +}
    +
    +static ssize_t fifo_write(struct file *file, const char __user *buf,
    + size_t count, loff_t *ppos)
    +{
    + int ret;
    + unsigned int copied;
    +
    + if (mutex_lock_interruptible(&write_lock))
    + return -ERESTARTSYS;
    +
    + ret = kfifo_from_user(&test, buf, count, &copied);
    +
    + mutex_unlock(&write_lock);
    +
    + return ret ? ret : copied;
    +}
    +
    +static ssize_t fifo_read(struct file *file, char __user *buf,
    + size_t count, loff_t *ppos)
    +{
    + int ret;
    + unsigned int copied;
    +
    + if (mutex_lock_interruptible(&read_lock))
    + return -ERESTARTSYS;
    +
    + ret = kfifo_to_user(&test, buf, count, &copied);
    +
    + mutex_unlock(&read_lock);
    +
    + return ret ? ret : copied;
    +}
    +
    +static const struct file_operations fifo_fops = {
    + .owner = THIS_MODULE,
    + .read = fifo_read,
    + .write = fifo_write,
    +};
    +
    +static int __init example_init(void)
    +{
    +#ifdef DYNAMIC
    + int ret;
    +
    + ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
    + if (ret) {
    + printk(KERN_ERR "error kfifo_alloc\n");
    + return ret;
    + }
    +#endif
    + testfunc();
    +
    + if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
    +#ifdef DYNAMIC
    + kfifo_free(&test);
    +#endif
    + return -ENOMEM;
    + }
    + return 0;
    +}
    +
    +static void __exit example_exit(void)
    +{
    + remove_proc_entry(PROC_FIFO, NULL);
    +#ifdef DYNAMIC
    + kfifo_free(&test);
    +#endif
    +}
    +
    +module_init(example_init);
    +module_exit(example_exit);
    +MODULE_LICENSE("GPL");
    +MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
    diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c
    new file mode 100644
    index 0000000..32c6e0b
    --- /dev/null
    +++ b/samples/kfifo/record-example.c
    @@ -0,0 +1,167 @@
    +/*
    + * Sample dynamic sized record fifo implementation
    + *
    + * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
    + *
    + * Released under the GPL version 2 only.
    + *
    + */
    +
    +#include <linux/init.h>
    +#include <linux/module.h>
    +#include <linux/proc_fs.h>
    +#include <linux/mutex.h>
    +#include <linux/kfifo.h>
    +
    +/*
    + * This module shows how to create a variable sized record fifo.
    + */
    +
    +/* fifo size in elements (bytes) */
    +#define FIFO_SIZE 128
    +
    +/* name of the proc entry */
    +#define PROC_FIFO "record-fifo"
    +
    +/* lock for procfs read access */
    +static DEFINE_MUTEX(read_lock);
    +
    +/* lock for procfs write access */
    +static DEFINE_MUTEX(write_lock);
    +
    +/*
    + * define DYNAMIC in this example for a dynamically allocated fifo.
    + *
    + * Otherwise the fifo storage will be a part of the fifo structure.
    + */
    +#if 0
    +#define DYNAMIC
    +#endif
    +
    +/*
    + * struct kfifo_rec_ptr_1 and STRUCT_KFIFO_REC_1 can handle records of a
    + * length between 0 and 255 bytes.
    + *
    + * struct kfifo_rec_ptr_2 and STRUCT_KFIFO_REC_2 can handle records of a
    + * length between 0 and 65535 bytes.
    + */
    +
    +#ifdef DYNAMIC
    +struct kfifo_rec_ptr_1 test;
    +
    +#else
    +typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
    +
    +static mytest test;
    +#endif
    +
    +static int __init testfunc(void)
    +{
    + char buf[100];
    + unsigned int i;
    + unsigned int ret;
    + struct { unsigned char buf[6]; } hello = { "hello" };
    +
    + printk(KERN_INFO "record fifo test start\n");
    +
    + kfifo_in(&test, &hello, sizeof(hello));
    +
    + /* show the size of the next record in the fifo */
    + printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test));
    +
    + /* put in variable length data */
    + for (i = 0; i < 10; i++) {
    + memset(buf, 'a' + i, i + 1);
    + kfifo_in(&test, buf, i + 1);
    + }
    +
    + printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
    +
    + /* show the first record without removing from the fifo */
    + ret = kfifo_out_peek(&test, buf, sizeof(buf));
    + if (ret)
    + printk(KERN_INFO "%.*s\n", ret, buf);
    +
    + /* print out all records in the fifo */
    + while (!kfifo_is_empty(&test)) {
    + ret = kfifo_out(&test, buf, sizeof(buf));
    + printk(KERN_INFO "%.*s\n", ret, buf);
    + }
    +
    + return 0;
    +}
    +
    +static ssize_t fifo_write(struct file *file, const char __user *buf,
    + size_t count, loff_t *ppos)
    +{
    + int ret;
    + unsigned int copied;
    +
    + if (mutex_lock_interruptible(&write_lock))
    + return -ERESTARTSYS;
    +
    + ret = kfifo_from_user(&test, buf, count, &copied);
    +
    + mutex_unlock(&write_lock);
    +
    + return ret ? ret : copied;
    +}
    +
    +static ssize_t fifo_read(struct file *file, char __user *buf,
    + size_t count, loff_t *ppos)
    +{
    + int ret;
    + unsigned int copied;
    +
    + if (mutex_lock_interruptible(&read_lock))
    + return -ERESTARTSYS;
    +
    + ret = kfifo_to_user(&test, buf, count, &copied);
    +
    + mutex_unlock(&read_lock);
    +
    + return ret ? ret : copied;
    +}
    +
    +static const struct file_operations fifo_fops = {
    + .owner = THIS_MODULE,
    + .read = fifo_read,
    + .write = fifo_write,
    +};
    +
    +static int __init example_init(void)
    +{
    +#ifdef DYNAMIC
    + int ret;
    +
    + ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
    + if (ret) {
    + printk(KERN_ERR "error kfifo_alloc\n");
    + return ret;
    + }
    +#else
    + INIT_KFIFO(test);
    +#endif
    + testfunc();
    +
    + if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
    +#ifdef DYNAMIC
    + kfifo_free(&test);
    +#endif
    + return -ENOMEM;
    + }
    + return 0;
    +}
    +
    +static void __exit example_exit(void)
    +{
    + remove_proc_entry(PROC_FIFO, NULL);
    +#ifdef DYNAMIC
    + kfifo_free(&test);
    +#endif
    +}
    +
    +module_init(example_init);
    +module_exit(example_exit);
    +MODULE_LICENSE("GPL");
    +MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
    --
    1.7.0.4


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