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-rw-r--r--arch/powerpc/platforms/powernv/opal-xscom.c210
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..f67235d1b
--- /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 <linux/debugfs.h>
+
+#include <asm/machdep.h>
+#include <asm/firmware.h>
+#include <asm/opal.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", arch_debugfs_dir);
+ 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);