diff options
Diffstat (limited to 'arch/powerpc/platforms/powernv/opal-xscom.c')
| -rw-r--r-- | arch/powerpc/platforms/powernv/opal-xscom.c | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/opal-xscom.c b/arch/powerpc/platforms/powernv/opal-xscom.c new file mode 100644 index 000000000..d5814c504 --- /dev/null +++ b/arch/powerpc/platforms/powernv/opal-xscom.c @@ -0,0 +1,210 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * PowerNV SCOM bus debugfs interface + * + * Copyright 2010 Benjamin Herrenschmidt, IBM Corp + * <benh@kernel.crashing.org> + * and David Gibson, IBM Corporation. + * Copyright 2013 IBM Corp. + */ + +#include <linux/kernel.h> +#include <linux/of.h> +#include <linux/bug.h> +#include <linux/gfp.h> +#include <linux/slab.h> +#include <linux/uaccess.h> + +#include <asm/machdep.h> +#include <asm/firmware.h> +#include <asm/opal.h> +#include <asm/debugfs.h> +#include <asm/prom.h> + +static u64 opal_scom_unmangle(u64 addr) +{ + u64 tmp; + + /* + * XSCOM addresses use the top nibble to set indirect mode and + * its form. Bits 4-11 are always 0. + * + * Because the debugfs interface uses signed offsets and shifts + * the address left by 3, we basically cannot use the top 4 bits + * of the 64-bit address, and thus cannot use the indirect bit. + * + * To deal with that, we support the indirect bits being in + * bits 4-7 (IBM notation) instead of bit 0-3 in this API, we + * do the conversion here. + * + * For in-kernel use, we don't need to do this mangling. In + * kernel won't have bits 4-7 set. + * + * So: + * debugfs will always set 0-3 = 0 and clear 4-7 + * kernel will always clear 0-3 = 0 and set 4-7 + */ + tmp = addr; + tmp &= 0x0f00000000000000; + addr &= 0xf0ffffffffffffff; + addr |= tmp << 4; + + return addr; +} + +static int opal_scom_read(uint32_t chip, uint64_t addr, u64 reg, u64 *value) +{ + int64_t rc; + __be64 v; + + reg = opal_scom_unmangle(addr + reg); + rc = opal_xscom_read(chip, reg, (__be64 *)__pa(&v)); + if (rc) { + *value = 0xfffffffffffffffful; + return -EIO; + } + *value = be64_to_cpu(v); + return 0; +} + +static int opal_scom_write(uint32_t chip, uint64_t addr, u64 reg, u64 value) +{ + int64_t rc; + + reg = opal_scom_unmangle(addr + reg); + rc = opal_xscom_write(chip, reg, value); + if (rc) + return -EIO; + return 0; +} + +struct scom_debug_entry { + u32 chip; + struct debugfs_blob_wrapper path; + char name[16]; +}; + +static ssize_t scom_debug_read(struct file *filp, char __user *ubuf, + size_t count, loff_t *ppos) +{ + 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_base, reg_cnt, val; + int rc; + + if (off < 0 || (off & 7) || (count & 7)) + return -EINVAL; + reg_base = off >> 3; + reg_cnt = count >> 3; + + for (reg = 0; reg < reg_cnt; reg++) { + rc = opal_scom_read(ent->chip, reg_base, reg, &val); + if (!rc) + rc = put_user(val, ubuf64); + if (rc) { + if (!done) + done = rc; + break; + } + ubuf64++; + *ppos += 8; + done += 8; + } + return done; +} + +static ssize_t scom_debug_write(struct file *filp, const char __user *ubuf, + size_t count, loff_t *ppos) +{ + 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_base, reg_cnt, val; + int rc; + + if (off < 0 || (off & 7) || (count & 7)) + return -EINVAL; + reg_base = off >> 3; + reg_cnt = count >> 3; + + for (reg = 0; reg < reg_cnt; reg++) { + rc = get_user(val, ubuf64); + if (!rc) + rc = opal_scom_write(ent->chip, reg_base, reg, val); + if (rc) { + if (!done) + done = rc; + break; + } + ubuf64++; + done += 8; + } + return done; +} + +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 chip) +{ + struct scom_debug_entry *ent; + struct dentry *dir; + + ent = kzalloc(sizeof(*ent), GFP_KERNEL); + if (!ent) + return -ENOMEM; + + ent->chip = chip; + snprintf(ent->name, 16, "%08x", chip); + ent->path.data = (void *)kasprintf(GFP_KERNEL, "%pOF", dn); + if (!ent->path.data) { + kfree(ent); + return -ENOMEM; + } + + ent->path.size = strlen((char *)ent->path.data); + + dir = debugfs_create_dir(ent->name, root); + if (!dir) { + kfree(ent->path.data); + kfree(ent); + return -1; + } + + debugfs_create_blob("devspec", 0400, dir, &ent->path); + debugfs_create_file("access", 0600, dir, ent, &scom_debug_fops); + + return 0; +} + +static int scom_debug_init(void) +{ + struct device_node *dn; + struct dentry *root; + int chip, rc; + + if (!firmware_has_feature(FW_FEATURE_OPAL)) + return 0; + + root = debugfs_create_dir("scom", powerpc_debugfs_root); + if (!root) + return -1; + + rc = 0; + for_each_node_with_property(dn, "scom-controller") { + chip = of_get_ibm_chip_id(dn); + WARN_ON(chip == -1); + rc |= scom_debug_init_one(root, dn, chip); + } + + return rc; +} +device_initcall(scom_debug_init); |