1 files changed, 140 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..22d5e1110
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/opal-xscom.c
@@ -0,0 +1,140 @@
+/*
+ * 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 %pOF is not a SCOM controller\n",
+			__func__, dev);
+		return SCOM_MAP_INVALID;
+	}
+	gcid = of_get_property(dev, "ibm,chip-id", NULL);
+	if (!gcid) {
+		pr_err("%s: device %pOF has no ibm,chip-id\n",
+			__func__, dev);
+		return SCOM_MAP_INVALID;
+	}
+	m = kmalloc(sizeof(*m), 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 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(scom_map_t map, u64 reg, u64 *value)
+{
+	struct opal_scom_map *m = map;
+	int64_t rc;
+	__be64 v;
+
+	reg = opal_scom_unmangle(m->addr + reg);
+	rc = opal_xscom_read(m->chip, reg, (__be64 *)__pa(&v));
+	*value = be64_to_cpu(v);
+	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(m->addr + reg);
+	rc = opal_xscom_write(m->chip, 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_OPAL))
+		scom_init(&opal_scom_controller);
+	return 0;
+}
+machine_arch_initcall(powernv, opal_xscom_init);