srm_env.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * srm_env.c - Access to SRM environment
  4 *             variables through linux' procfs
  5 *
  6 * (C) 2001,2002,2006 by Jan-Benedict Glaw <jbglaw@lug-owl.de>
  7 *
  8 * This driver is a modified version of Erik Mouw's example proc
  9 * interface, so: thank you, Erik! He can be reached via email at
 10 * <J.A.K.Mouw@its.tudelft.nl>. It is based on an idea
 11 * provided by DEC^WCompaq^WIntel's "Jumpstart" CD. They
 12 * included a patch like this as well. Thanks for idea!
 13 */
 14
 15#include <linux/kernel.h>
 16#include <linux/gfp.h>
 17#include <linux/module.h>
 18#include <linux/init.h>
 19#include <linux/proc_fs.h>
 20#include <linux/seq_file.h>
 21#include <asm/console.h>
 22#include <linux/uaccess.h>
 23#include <asm/machvec.h>
 24
 25#define BASE_DIR	"srm_environment"	/* Subdir in /proc/		*/
 26#define NAMED_DIR	"named_variables"	/* Subdir for known variables	*/
 27#define NUMBERED_DIR	"numbered_variables"	/* Subdir for all variables	*/
 28#define VERSION		"0.0.6"			/* Module version		*/
 29#define NAME		"srm_env"		/* Module name			*/
 30
 31MODULE_AUTHOR("Jan-Benedict Glaw <jbglaw@lug-owl.de>");
 32MODULE_DESCRIPTION("Accessing Alpha SRM environment through procfs interface");
 33MODULE_LICENSE("GPL");
 34
 35typedef struct _srm_env {
 36	char			*name;
 37	unsigned long		id;
 38} srm_env_t;
 39
 40static struct proc_dir_entry	*base_dir;
 41static struct proc_dir_entry	*named_dir;
 42static struct proc_dir_entry	*numbered_dir;
 43
 44static srm_env_t	srm_named_entries[] = {
 45	{ "auto_action",	ENV_AUTO_ACTION		},
 46	{ "boot_dev",		ENV_BOOT_DEV		},
 47	{ "bootdef_dev",	ENV_BOOTDEF_DEV		},
 48	{ "booted_dev",		ENV_BOOTED_DEV		},
 49	{ "boot_file",		ENV_BOOT_FILE		},
 50	{ "booted_file",	ENV_BOOTED_FILE		},
 51	{ "boot_osflags",	ENV_BOOT_OSFLAGS	},
 52	{ "booted_osflags",	ENV_BOOTED_OSFLAGS	},
 53	{ "boot_reset",		ENV_BOOT_RESET		},
 54	{ "dump_dev",		ENV_DUMP_DEV		},
 55	{ "enable_audit",	ENV_ENABLE_AUDIT	},
 56	{ "license",		ENV_LICENSE		},
 57	{ "char_set",		ENV_CHAR_SET		},
 58	{ "language",		ENV_LANGUAGE		},
 59	{ "tty_dev",		ENV_TTY_DEV		},
 60	{ NULL,			0			},
 61};
 62
 63static int srm_env_proc_show(struct seq_file *m, void *v)
 64{
 65	unsigned long	ret;
 66	unsigned long	id = (unsigned long)m->private;
 67	char		*page;
 68
 69	page = (char *)__get_free_page(GFP_USER);
 70	if (!page)
 71		return -ENOMEM;
 72
 73	ret = callback_getenv(id, page, PAGE_SIZE);
 74
 75	if ((ret >> 61) == 0) {
 76		seq_write(m, page, ret);
 77		ret = 0;
 78	} else
 79		ret = -EFAULT;
 80	free_page((unsigned long)page);
 81	return ret;
 82}
 83
 84static int srm_env_proc_open(struct inode *inode, struct file *file)
 85{
 86	return single_open(file, srm_env_proc_show, pde_data(inode));
 87}
 88
 89static ssize_t srm_env_proc_write(struct file *file, const char __user *buffer,
 90				  size_t count, loff_t *pos)
 91{
 92	int res;
 93	unsigned long	id = (unsigned long)pde_data(file_inode(file));
 94	char		*buf = (char *) __get_free_page(GFP_USER);
 95	unsigned long	ret1, ret2;
 96
 97	if (!buf)
 98		return -ENOMEM;
 99
100	res = -EINVAL;
101	if (count >= PAGE_SIZE)
102		goto out;
103
104	res = -EFAULT;
105	if (copy_from_user(buf, buffer, count))
106		goto out;
107	buf[count] = '\0';
108
109	ret1 = callback_setenv(id, buf, count);
110	if ((ret1 >> 61) == 0) {
111		do
112			ret2 = callback_save_env();
113		while((ret2 >> 61) == 1);
114		res = (int) ret1;
115	}
116
117 out:
118	free_page((unsigned long)buf);
119	return res;
120}
121
122static const struct proc_ops srm_env_proc_ops = {
123	.proc_open	= srm_env_proc_open,
124	.proc_read	= seq_read,
125	.proc_lseek	= seq_lseek,
126	.proc_release	= single_release,
127	.proc_write	= srm_env_proc_write,
128};
129
130static int __init
131srm_env_init(void)
132{
133	srm_env_t	*entry;
134	unsigned long	var_num;
135
136	/*
137	 * Check system
138	 */
139	if (!alpha_using_srm) {
140		printk(KERN_INFO "%s: This Alpha system doesn't "
141				"know about SRM (or you've booted "
142				"SRM->MILO->Linux, which gets "
143				"misdetected)...\n", __func__);
144		return -ENODEV;
145	}
146
147	/*
148	 * Create base directory
149	 */
150	base_dir = proc_mkdir(BASE_DIR, NULL);
151	if (!base_dir) {
152		printk(KERN_ERR "Couldn't create base dir /proc/%s\n",
153				BASE_DIR);
154		return -ENOMEM;
155	}
156
157	/*
158	 * Create per-name subdirectory
159	 */
160	named_dir = proc_mkdir(NAMED_DIR, base_dir);
161	if (!named_dir) {
162		printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
163				BASE_DIR, NAMED_DIR);
164		goto cleanup;
165	}
166
167	/*
168	 * Create per-number subdirectory
169	 */
170	numbered_dir = proc_mkdir(NUMBERED_DIR, base_dir);
171	if (!numbered_dir) {
172		printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
173				BASE_DIR, NUMBERED_DIR);
174		goto cleanup;
175
176	}
177
178	/*
179	 * Create all named nodes
180	 */
181	entry = srm_named_entries;
182	while (entry->name && entry->id) {
183		if (!proc_create_data(entry->name, 0644, named_dir,
184			     &srm_env_proc_ops, (void *)entry->id))
185			goto cleanup;
186		entry++;
187	}
188
189	/*
190	 * Create all numbered nodes
191	 */
192	for (var_num = 0; var_num <= 255; var_num++) {
193		char name[4];
194		sprintf(name, "%ld", var_num);
195		if (!proc_create_data(name, 0644, numbered_dir,
196			     &srm_env_proc_ops, (void *)var_num))
197			goto cleanup;
198	}
199
200	printk(KERN_INFO "%s: version %s loaded successfully\n", NAME,
201			VERSION);
202
203	return 0;
204
205cleanup:
206	remove_proc_subtree(BASE_DIR, NULL);
207	return -ENOMEM;
208}
209
210static void __exit
211srm_env_exit(void)
212{
213	remove_proc_subtree(BASE_DIR, NULL);
214	printk(KERN_INFO "%s: unloaded successfully\n", NAME);
215}
216
217module_init(srm_env_init);
218module_exit(srm_env_exit);