diff options
Diffstat (limited to 'arch/powerpc/platforms/powernv/opal-xscom.c')
| -rw-r--r-- | arch/powerpc/platforms/powernv/opal-xscom.c | 133 |
1 files changed, 133 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 00000000000..4cd2ea6c0db --- /dev/null +++ b/arch/powerpc/platforms/powernv/opal-xscom.c @@ -0,0 +1,133 @@ +/* + * 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 addr) +{ + /* + * XSCOM indirect addresses have the top bit set. Additionally + * the rest 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 + * + * For in-kernel use, we also support the real indirect bit, so + * we test for any of the top 5 bits + * + */ + if (addr & (0x1full << 59)) + addr = (addr & ~(0xffull << 56)) | (1ull << 63); + 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_OPALv3)) + scom_init(&opal_scom_controller); + return 0; +} +arch_initcall(opal_xscom_init); |