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

1From f54ba59d355f59e4c01b5b9c7dbc2d27b47302d2 Mon Sep 17 00:00:00 2001
2From: Alison Wang <b18965@freescale.com>
3Date: Thu, 4 Aug 2011 09:59:41 +0800
4Subject: [PATCH 10/52] Add SRAM char device driver support for MCF5445x
5
6Created "/dev/sram" device file and implemented the sram mmap() operation to
7provide interface for userspace access.
8
9Signed-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);
199

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