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-rw-r--r--arch/powerpc/platforms/powernv/opal-xscom.c128
1 files changed, 128 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 000000000000..4d99a8fd55ac
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/opal-xscom.c
@@ -0,0 +1,128 @@
+/*
+ * PowerNV LPC bus handling.
+ *
+ * Copyright 2013 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/bug.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+
+#include <asm/machdep.h>
+#include <asm/firmware.h>
+#include <asm/opal.h>
+#include <asm/scom.h>
+
+/*
+ * We could probably fit that inside the scom_map_t
+ * which is a void* after all but it's really too ugly
+ * so let's kmalloc it for now
+ */
+struct opal_scom_map {
+ uint32_t chip;
+ uint64_t addr;
+};
+
+static scom_map_t opal_scom_map(struct device_node *dev, u64 reg, u64 count)
+{
+ struct opal_scom_map *m;
+ const __be32 *gcid;
+
+ if (!of_get_property(dev, "scom-controller", NULL)) {
+ pr_err("%s: device %s is not a SCOM controller\n",
+ __func__, dev->full_name);
+ return SCOM_MAP_INVALID;
+ }
+ gcid = of_get_property(dev, "ibm,chip-id", NULL);
+ if (!gcid) {
+ pr_err("%s: device %s has no ibm,chip-id\n",
+ __func__, dev->full_name);
+ return SCOM_MAP_INVALID;
+ }
+ m = kmalloc(sizeof(struct opal_scom_map), GFP_KERNEL);
+ if (!m)
+ return NULL;
+ m->chip = be32_to_cpup(gcid);
+ m->addr = reg;
+
+ return (scom_map_t)m;
+}
+
+static void opal_scom_unmap(scom_map_t map)
+{
+ kfree(map);
+}
+
+static int opal_xscom_err_xlate(int64_t rc)
+{
+ switch(rc) {
+ case 0:
+ return 0;
+ /* Add more translations if necessary */
+ default:
+ return -EIO;
+ }
+}
+
+static u64 opal_scom_unmangle(u64 reg)
+{
+ /*
+ * XSCOM indirect addresses have the top bit set. Additionally
+ * the reset of the top 3 nibbles is 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 bit being in bit
+ * 4 (IBM notation) instead of bit 0 in this API, we do the
+ * conversion here. To leave room for further xscom address
+ * expansion, we only clear out the top byte
+ *
+ */
+ if (reg & (1ull << 59))
+ reg = (reg & ~(0xffull << 56)) | (1ull << 63);
+ return reg;
+}
+
+static int opal_scom_read(scom_map_t map, u64 reg, u64 *value)
+{
+ struct opal_scom_map *m = map;
+ int64_t rc;
+
+ reg = opal_scom_unmangle(reg);
+ rc = opal_xscom_read(m->chip, m->addr + reg, (uint64_t *)__pa(value));
+ return opal_xscom_err_xlate(rc);
+}
+
+static int opal_scom_write(scom_map_t map, u64 reg, u64 value)
+{
+ struct opal_scom_map *m = map;
+ int64_t rc;
+
+ reg = opal_scom_unmangle(reg);
+ rc = opal_xscom_write(m->chip, m->addr + reg, value);
+ return opal_xscom_err_xlate(rc);
+}
+
+static const struct scom_controller opal_scom_controller = {
+ .map = opal_scom_map,
+ .unmap = opal_scom_unmap,
+ .read = opal_scom_read,
+ .write = opal_scom_write
+};
+
+static int opal_xscom_init(void)
+{
+ if (firmware_has_feature(FW_FEATURE_OPALv3))
+ scom_init(&opal_scom_controller);
+ return 0;
+}
+arch_initcall(opal_xscom_init);