Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753663AbbDGTYM (ORCPT ); Tue, 7 Apr 2015 15:24:12 -0400 Received: from mail-wi0-f171.google.com ([209.85.212.171]:38515 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753472AbbDGTYH (ORCPT ); Tue, 7 Apr 2015 15:24:07 -0400 From: Pantelis Antoniou To: Rob Herring Cc: Grant Likely , Andrew Morton , Matt Porter , Koen Kooi , Guenter Roeck , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Pantelis Antoniou , Pantelis Antoniou Subject: [PATCH v2 3/4] of: overlay: Add sysfs attributes Date: Tue, 7 Apr 2015 22:23:51 +0300 Message-Id: <1428434632-13789-4-git-send-email-pantelis.antoniou@konsulko.com> X-Mailer: git-send-email 1.7.12 In-Reply-To: <1428434632-13789-1-git-send-email-pantelis.antoniou@konsulko.com> References: <1428434632-13789-1-git-send-email-pantelis.antoniou@konsulko.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5997 Lines: 237 Implement a number of sysfs attributes for overlays. * A throw once master enable switch to protect against any further overlay applications if the administrator desires so. * A per overlay targets sysfs attribute listing the targets of the installed overlay. * A per overlay can_remove sysfs attribute that reports whether the overlay can be removed or not due to another overlapping overlay. Signed-off-by: Pantelis Antoniou --- drivers/of/overlay.c | 167 ++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 166 insertions(+), 1 deletion(-) diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c index f17f5ef..c54d097 100644 --- a/drivers/of/overlay.c +++ b/drivers/of/overlay.c @@ -21,6 +21,7 @@ #include #include #include +#include #include "of_private.h" @@ -55,8 +56,12 @@ struct of_overlay { struct kobject kobj; }; +/* master enable switch; once set to 0 can't be re-enabled */ +static atomic_t ov_enable = ATOMIC_INIT(1); + static int of_overlay_apply_one(struct of_overlay *ov, struct device_node *target, const struct device_node *overlay); +static int overlay_removal_is_ok(struct of_overlay *ov); static int of_overlay_apply_single_property(struct of_overlay *ov, struct device_node *target, struct property *prop) @@ -345,6 +350,144 @@ static struct kobj_type of_overlay_ktype = { static struct kset *ov_kset; +static ssize_t enable_read(struct file *filp, struct kobject *kobj, + struct bin_attribute *bin_attr, char *buf, + loff_t offset, size_t count) +{ + char tbuf[3]; + + if (offset < 0) + return -EINVAL; + + if (offset >= sizeof(tbuf)) + return 0; + + if (count > sizeof(tbuf) - offset) + count = sizeof(tbuf) - offset; + + /* fill in temp */ + tbuf[0] = '0' + atomic_read(&ov_enable); + tbuf[1] = '\n'; + tbuf[2] = '\0'; + + /* copy to buffer */ + memcpy(buf, tbuf + offset, count); + + return count; +} + +static ssize_t enable_write(struct file *filp, struct kobject *kobj, + struct bin_attribute *bin_attr, char *buf, + loff_t off, size_t count) +{ + unsigned int new_enable; + + if (off != 0 || (buf[0] != '0' && buf[0] != '1')) + return -EINVAL; + + new_enable = (unsigned int)(buf[0] - '0'); + if (new_enable > 1) + return -EINVAL; + + /* NOP for same value */ + if (new_enable == atomic_read(&ov_enable)) + return count; + + /* if we've disabled it, no going back */ + if (atomic_read(&ov_enable) == 0) + return -EPERM; + + atomic_set(&ov_enable, new_enable); + return count; +} + +/* just a single char + '\n' + '\0' */ +static BIN_ATTR_RW(enable, 3); + +static ssize_t targets_read(struct file *filp, struct kobject *kobj, + struct bin_attribute *bin_attr, char *buf, + loff_t offset, size_t count) +{ + struct of_overlay *ov = kobj_to_overlay(kobj); + struct of_overlay_info *ovinfo; + char *tmpbuf, *s, *e; + const char *name; + ssize_t ret; + int i, len; + + /* allocate work buffer; we know that PAGE_SIZE is enough */ + tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (tmpbuf == NULL) + return -ENOMEM; + + s = tmpbuf; + e = tmpbuf + PAGE_SIZE; + + mutex_lock(&of_mutex); + + /* targets */ + for (i = 0; i < ov->count; i++) { + ovinfo = &ov->ovinfo_tab[i]; + + name = of_node_full_name(ovinfo->target); + len = strlen(name); + if (s + len + 1 >= e) + return -ENOMEM; + memcpy(s, name, len); + s += len; + *s++ = '\n'; + } + if (s + 1 >= e) + return -ENOMEM; + *s++ = '\0'; + + /* the buffer is zero terminated */ + len = s - tmpbuf; + + mutex_unlock(&of_mutex); + + /* perform the read */ + ret = memory_read_from_buffer(buf, count, &offset, tmpbuf, len); + + /* free the temporary buffer */ + kfree(tmpbuf); + + return ret; +} + +/* targets property */ +static BIN_ATTR_RO(targets, PAGE_SIZE); + +static ssize_t can_remove_read(struct file *filp, struct kobject *kobj, + struct bin_attribute *bin_attr, char *buf, + loff_t offset, size_t count) +{ + struct of_overlay *ov = kobj_to_overlay(kobj); + char tbuf[3]; + + if (offset < 0) + return -EINVAL; + + if (offset >= sizeof(tbuf)) + return 0; + + if (count > sizeof(tbuf) - offset) + count = sizeof(tbuf) - offset; + + /* fill in temp */ + tbuf[0] = '0' + overlay_removal_is_ok(ov); + tbuf[1] = '\n'; + tbuf[2] = '\0'; + + /* copy to buffer */ + memcpy(buf, tbuf + offset, count); + + return count; +} + +/* can_remove property */ +static BIN_ATTR_RO(can_remove, 3); + /** * of_overlay_create() - Create and apply an overlay * @tree: Device node containing all the overlays @@ -360,6 +503,10 @@ int of_overlay_create(struct device_node *tree) struct of_overlay *ov; int err, id; + /* administratively disabled */ + if (!atomic_read(&ov_enable)) + return -EPERM; + /* allocate the overlay structure */ ov = kzalloc(sizeof(*ov), GFP_KERNEL); if (ov == NULL) @@ -416,6 +563,22 @@ int of_overlay_create(struct device_node *tree) goto err_cancel_overlay; } + /* create targets file */ + err = sysfs_create_bin_file(&ov->kobj, &bin_attr_targets); + if (err != 0) { + pr_err("%s: sysfs_create_bin_file() failed for tree@%s\n", + __func__, tree->full_name); + goto err_cancel_overlay; + } + + /* create can_remove file */ + err = sysfs_create_bin_file(&ov->kobj, &bin_attr_can_remove); + if (err != 0) { + pr_err("%s: sysfs_create_bin_file() failed for tree@%s\n", + __func__, tree->full_name); + goto err_cancel_overlay; + } + /* add to the tail of the overlay list */ list_add_tail(&ov->node, &ov_list); @@ -596,5 +759,7 @@ int of_overlay_init(void) if (!ov_kset) return -ENOMEM; - return 0; + rc = sysfs_create_bin_file(&ov_kset->kobj, &bin_attr_enable); + WARN(rc, "%s: error adding enable attribute\n", __func__); + return rc; } -- 1.7.12 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/