target/linux/coldfire/patches/010-Add-SRAM-char-device-driver-support-for-MCF5445x.patch

   1 From f54ba59d355f59e4c01b5b9c7dbc2d27b47302d2 Mon Sep 17 00:00:00 2001
   2 From: Alison Wang <b18965@freescale.com>
   3 Date: Thu, 4 Aug 2011 09:59:41 +0800
   4 Subject: [PATCH 10/52] Add SRAM char device driver support for MCF5445x
   5
   6 Created "/dev/sram" device file and implemented the sram mmap() operation to
   7 provide interface for userspace access.
   8
   9 Signed-off-by: Alison Wang <b18965@freescale.com>
  10 ---
  11  drivers/char/Kconfig  |   11 ++++
  12  drivers/char/Makefile |    2 +
  13  drivers/char/sram.c   |  151 +++++++++++++++++++++++++++++++++++++++++++++++++
  14  3 files changed, 164 insertions(+), 0 deletions(-)
  15  create mode 100644 drivers/char/sram.c
  16
  17 --- a/drivers/char/Kconfig
  18 +++ b/drivers/char/Kconfig
  19 @@ -97,6 +97,17 @@ config DEVKMEM
  20           kind of kernel debugging operations.
  21           When in doubt, say "N".
  22
  23 +config DEVSRAM
  24 +       tristate "/dev/sram virtual device support"
  25 +       depends on M5445X
  26 +       default m
  27 +       help
  28 +         Say Y here if you want to suppot the SRAM char device. When in
  29 +         doubt, say "N".
  30 +
  31 +         It implements mmap system call to provide interface for
  32 +         user space access.
  33 +
  34  config BFIN_JTAG_COMM
  35         tristate "Blackfin JTAG Communication"
  36         depends on BLACKFIN
  37 --- a/drivers/char/Makefile
  38 +++ b/drivers/char/Makefile
  39 @@ -87,3 +87,5 @@ obj-$(CONFIG_RAMOOPS)         += ramoops.o
  40
  41  obj-$(CONFIG_JS_RTC)           += js-rtc.o
  42  js-rtc-y = rtc.o
  43 +
  44 +obj-$(CONFIG_DEVSRAM)          += sram.o
  45 --- /dev/null
  46 +++ b/drivers/char/sram.c
  47 @@ -0,0 +1,151 @@
  48 +/*
  49 + * linux/drivers/char/sram.c
  50 + *
  51 + * Copyright (C) 2009-2011 Freescale Semiconductor, Inc. All Rights Reserved.
  52 + * Author: Lanttor.Guo@freescale.com
  53 + *
  54 + * SRAM char device driver, implements mmap() system call to provide
  55 + * interface for user space access.
  56 + *
  57 + * This program is free software; you can redistribute it and/or modify
  58 + * it under the terms of the GNU General Public License as published by
  59 + * the Free Software Foundation; either version 2 of the License, or
  60 + * (at your option) any later version.
  61 + */
  62 +
  63 +#include <linux/module.h>
  64 +#include <linux/moduleparam.h>
  65 +#include <linux/init.h>
  66 +#include <linux/kernel.h>
  67 +#include <linux/slab.h>
  68 +#include <linux/fs.h>
  69 +#include <linux/errno.h>
  70 +#include <linux/types.h>
  71 +#include <linux/mm.h>
  72 +#include <linux/kdev_t.h>
  73 +#include <asm/page.h>
  74 +#include <linux/cdev.h>
  75 +#include <linux/device.h>
  76 +
  77 +MODULE_LICENSE("GPL");
  78 +
  79 +static struct class *sram_class;
  80 +static int sram_major;
  81 +static int sram_minor;
  82 +static struct cdev sram_cdev;
  83 +
  84 +/*
  85 + * Set up the cdev structure for sram.
  86 + */
  87 +static void sram_setup_cdev(struct cdev *dev, int minor,
  88 +               const struct file_operations *fops)
  89 +{
  90 +       int err, devno = MKDEV(sram_major, minor);
  91 +
  92 +       cdev_init(dev, fops);
  93 +       dev->owner = THIS_MODULE;
  94 +       dev->ops = fops;
  95 +       err = cdev_add(dev, devno, 1);
  96 +       /* Fail gracefully if need be */
  97 +       if (err)
  98 +               printk(KERN_NOTICE "Error %d adding sram%d", err, minor);
  99 +}
 100 +
 101 +static int sram_open(struct inode *inode, struct file *filp)
 102 +{
 103 +       filp->f_mapping->backing_dev_info = &directly_mappable_cdev_bdi;
 104 +       return 0;
 105 +}
 106 +
 107 +static int sram_release(struct inode *inode, struct file *filp)
 108 +{
 109 +       return 0;
 110 +}
 111 +
 112 +void sram_vma_open(struct vm_area_struct *vma)
 113 +{
 114 +       printk(KERN_DEBUG "Sram VMA open, virt %lx, phys %lx\n",
 115 +                          vma->vm_start,
 116 +                          CONFIG_SRAM_BASE + (vma->vm_pgoff << PAGE_SHIFT));
 117 +}
 118 +
 119 +void sram_vma_close(struct vm_area_struct *vma)
 120 +{
 121 +       printk(KERN_DEBUG "Sram VMA close.\n");
 122 +}
 123 +
 124 +
 125 +static struct vm_operations_struct sram_remap_vm_ops = {
 126 +       .open =  sram_vma_open,
 127 +       .close = sram_vma_close,
 128 +};
 129 +
 130 +static int sram_remap_mmap(struct file *filp, struct vm_area_struct *vma)
 131 +{
 132 +       size_t size = vma->vm_end - vma->vm_start;
 133 +
 134 +       if (PAGE_ALIGN(size) > CONFIG_SRAM_SIZE) {
 135 +               printk(KERN_ERR "required length exceed the size "
 136 +                      "of physical sram (%x)\n", CONFIG_SRAM_SIZE);
 137 +               return -EAGAIN;
 138 +       }
 139 +
 140 +       if ((CONFIG_SRAM_BASE + (vma->vm_pgoff << PAGE_SHIFT) + size)
 141 +           > (CONFIG_SRAM_BASE + CONFIG_SRAM_SIZE)) {
 142 +               printk(KERN_ERR "required sram range exceed the size "
 143 +                      "of phisical sram\n");
 144 +               return -EAGAIN;
 145 +       }
 146 +
 147 +       if (remap_pfn_range(vma, vma->vm_start,
 148 +                           (CONFIG_SRAM_BASE >> PAGE_SHIFT) + vma->vm_pgoff,
 149 +                           size,
 150 +                           vma->vm_page_prot)) {
 151 +               printk(KERN_ERR "remap_pfn_range faile at %s()\n", __func__);
 152 +               return -EAGAIN;
 153 +       }
 154 +
 155 +       vma->vm_ops = &sram_remap_vm_ops;
 156 +       return 0;
 157 +}
 158 +
 159 +static const struct file_operations sram_ops = {
 160 +       .owner   = THIS_MODULE,
 161 +       .open    = sram_open,
 162 +       .release = sram_release,
 163 +       .mmap    = sram_remap_mmap,
 164 +};
 165 +
 166 +static int __init sram_chrdev_init(void)
 167 +{
 168 +       int minor_devs = 1;
 169 +       int result;
 170 +       dev_t dev = 0;
 171 +       sram_minor = 0;
 172 +
 173 +       result = alloc_chrdev_region(&dev, sram_minor, minor_devs, "sram");
 174 +       sram_major = MAJOR(dev);
 175 +       if (result < 0) {
 176 +               printk(KERN_WARNING "sram: can't get major %d\n", sram_major);
 177 +               return result;
 178 +       }
 179 +
 180 +       sram_setup_cdev(&sram_cdev, 0, &sram_ops);
 181 +
 182 +       sram_class = class_create(THIS_MODULE, "sram");
 183 +       device_create(sram_class, NULL, MKDEV(sram_major, sram_minor),
 184 +                     NULL, "sram");
 185 +
 186 +       return 0;
 187 +}
 188 +
 189 +static void sram_chrdev_cleanup(void)
 190 +{
 191 +       cdev_del(&sram_cdev);
 192 +       device_destroy(sram_class, MKDEV(sram_major, sram_minor));
 193 +       class_destroy(sram_class);
 194 +       unregister_chrdev_region(MKDEV(sram_major, 0), 1);
 195 +}
 196 +
 197 +module_init(sram_chrdev_init);
 198 +module_exit(sram_chrdev_cleanup);