From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id EC5132C008E for ; Mon, 4 Nov 2013 13:20:47 +1100 (EST) Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.13.8) with ESMTP id rA42Kd86020434 for ; Sun, 3 Nov 2013 20:20:41 -0600 Message-ID: <1383531635.4776.40.camel@pasglop> Subject: [PATCH] powerpc/scom: Improve debugfs interface From: Benjamin Herrenschmidt To: linuxppc-dev Date: Mon, 04 Nov 2013 13:20:35 +1100 Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , The current debugfs interface to scom is essentially unused and racy. It uses two different files "address" and "data" to perform accesses which is at best impractical for anything but manual use by a developer. This replaces it with an "access" file which represent the entire scom address space which can be lseek/read/writen too. This file only supports accesses that are 8 bytes aligned and multiple of 8 bytes in size. The offset is logically the SCOM address multiplied by 8. Since nothing in userspace exploits that file at the moment, the ABI change is a no-brainer. Signed-off-by: Benjamin Herrenschmidt --- This replaces the previously posted "powerpc/scom: Replace debugfs interface with cleaner sysfs" After discussion with Greg KH, we decided that debugfs was the right place to put that facility. arch/powerpc/sysdev/scom.c | 136 +++++++++++++++++++++++++++------------------ 1 file changed, 81 insertions(+), 55 deletions(-) diff --git a/arch/powerpc/sysdev/scom.c b/arch/powerpc/sysdev/scom.c index 3963d99..6f5a8d1 100644 --- a/arch/powerpc/sysdev/scom.c +++ b/arch/powerpc/sysdev/scom.c @@ -25,6 +25,7 @@ #include #include #include +#include const struct scom_controller *scom_controller; EXPORT_SYMBOL_GPL(scom_controller); @@ -98,61 +99,89 @@ EXPORT_SYMBOL_GPL(scom_map_device); #ifdef CONFIG_SCOM_DEBUGFS struct scom_debug_entry { struct device_node *dn; - unsigned long addr; - scom_map_t map; - spinlock_t lock; - char name[8]; - struct debugfs_blob_wrapper blob; + struct debugfs_blob_wrapper path; + char name[16]; }; -static int scom_addr_set(void *data, u64 val) -{ - struct scom_debug_entry *ent = data; - - ent->addr = 0; - scom_unmap(ent->map); - - ent->map = scom_map(ent->dn, val, 1); - if (scom_map_ok(ent->map)) - ent->addr = val; - else - return -EFAULT; - - return 0; -} - -static int scom_addr_get(void *data, u64 *val) +static ssize_t scom_debug_read(struct file *filp, char __user *ubuf, + size_t count, loff_t *ppos) { - struct scom_debug_entry *ent = data; - *val = ent->addr; - return 0; + struct scom_debug_entry *ent = filp->private_data; + u64 __user *ubuf64 = (u64 __user *)ubuf; + loff_t off = *ppos; + ssize_t done = 0; + u64 reg, reg_cnt, val; + scom_map_t map; + int rc; + + if (off < 0 || (off & 7) || (count & 7)) + return -EINVAL; + reg = off >> 3; + reg_cnt = count >> 3; + + map = scom_map(ent->dn, reg, reg_cnt); + if (!scom_map_ok(map)) + return -ENXIO; + + for (reg = 0; reg < reg_cnt; reg++) { + rc = scom_read(map, reg, &val); + if (!rc) + rc = put_user(val, ubuf64); + if (rc) { + if (!done) + done = rc; + break; + } + ubuf64++; + *ppos += 8; + done += 8; + } + scom_unmap(map); + return done; } -DEFINE_SIMPLE_ATTRIBUTE(scom_addr_fops, scom_addr_get, scom_addr_set, - "0x%llx\n"); -static int scom_val_set(void *data, u64 val) +static ssize_t scom_debug_write(struct file* filp, const char __user *ubuf, + size_t count, loff_t *ppos) { - struct scom_debug_entry *ent = data; - - if (!scom_map_ok(ent->map)) - return -EFAULT; - - scom_write(ent->map, 0, val); - - return 0; + struct scom_debug_entry *ent = filp->private_data; + u64 __user *ubuf64 = (u64 __user *)ubuf; + loff_t off = *ppos; + ssize_t done = 0; + u64 reg, reg_cnt, val; + scom_map_t map; + int rc; + + if (off < 0 || (off & 7) || (count & 7)) + return -EINVAL; + reg = off >> 3; + reg_cnt = count >> 3; + + map = scom_map(ent->dn, reg, reg_cnt); + if (!scom_map_ok(map)) + return -ENXIO; + + for (reg = 0; reg < reg_cnt; reg++) { + rc = get_user(val, ubuf64); + if (!rc) + rc = scom_write(map, reg, val); + if (rc) { + if (!done) + done = rc; + break; + } + ubuf64++; + done += 8; + } + scom_unmap(map); + return done; } -static int scom_val_get(void *data, u64 *val) -{ - struct scom_debug_entry *ent = data; - - if (!scom_map_ok(ent->map)) - return -EFAULT; - - return scom_read(ent->map, 0, val); -} -DEFINE_SIMPLE_ATTRIBUTE(scom_val_fops, scom_val_get, scom_val_set, - "0x%llx\n"); +static const struct file_operations scom_debug_fops = { + .read = scom_debug_read, + .write = scom_debug_write, + .open = simple_open, + .llseek = default_llseek, +}; static int scom_debug_init_one(struct dentry *root, struct device_node *dn, int i) @@ -165,11 +194,9 @@ static int scom_debug_init_one(struct dentry *root, struct device_node *dn, return -ENOMEM; ent->dn = of_node_get(dn); - ent->map = SCOM_MAP_INVALID; - spin_lock_init(&ent->lock); - snprintf(ent->name, 8, "scom%d", i); - ent->blob.data = (void*) dn->full_name; - ent->blob.size = strlen(dn->full_name); + snprintf(ent->name, 16, "%08x", i); + ent->path.data = (void*) dn->full_name; + ent->path.size = strlen(dn->full_name); dir = debugfs_create_dir(ent->name, root); if (!dir) { @@ -178,9 +205,8 @@ static int scom_debug_init_one(struct dentry *root, struct device_node *dn, return -1; } - debugfs_create_file("addr", 0600, dir, ent, &scom_addr_fops); - debugfs_create_file("value", 0600, dir, ent, &scom_val_fops); - debugfs_create_blob("devspec", 0400, dir, &ent->blob); + debugfs_create_blob("devspec", 0400, dir, &ent->path); + debugfs_create_file("access", 0600, dir, ent, &scom_debug_fops); return 0; }