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// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
/*
* NX Hardware Random Number Generator
*
* Copyright 2013-2019 IBM Corp.
*/
#include <skiboot.h>
#include <xscom.h>
#include <io.h>
#include <cpu.h>
#include <nx.h>
#include <chip.h>
#include <phys-map.h>
#include <xscom-p9-regs.h>
/*
* On P9 the DARN instruction is used to access the HW RNG. There is still
* an NX RNG BAR, but it is used to configure which NX a core will source
* random numbers from rather than being a MMIO window.
*/
static void nx_init_p9_rng(uint32_t chip_id)
{
uint64_t bar, tmp;
if (chip_quirk(QUIRK_NO_RNG))
return;
phys_map_get(chip_id, NX_RNG, 0, &bar, NULL);
xscom_write(chip_id, P9X_NX_MMIO_BAR, bar | P9X_NX_MMIO_BAR_EN);
/* Read config register for pace info */
xscom_read(chip_id, P9X_NX_RNG_CFG, &tmp);
prlog(PR_INFO, "NX RNG[%x] pace:%lli\n", chip_id, 0xffff & (tmp >> 2));
}
void nx_create_rng_node(struct dt_node *node)
{
u64 bar, cfg;
u64 xbar, xcfg;
u32 pb_base;
u32 gcid;
u64 rng_addr, rng_len, len, addr_mask;
struct dt_node *rng;
int rc;
gcid = dt_get_chip_id(node);
pb_base = dt_get_address(node, 0, NULL);
if (dt_node_is_compatible(node, "ibm,power8-nx")) {
xbar = pb_base + NX_P8_RNG_BAR;
xcfg = pb_base + NX_P8_RNG_CFG;
addr_mask = NX_P8_RNG_BAR_ADDR;
} else if (dt_node_is_compatible(node, "ibm,power9-nx")) {
nx_init_p9_rng(gcid);
return;
} else {
prerror("NX%d: Unknown NX type!\n", gcid);
return;
}
rc = xscom_read(gcid, xbar, &bar); /* Get RNG BAR */
if (rc) {
prerror("NX%d: ERROR: XSCOM RNG BAR read failure %d\n",
gcid, rc);
return;
}
rc = xscom_read(gcid, xcfg, &cfg); /* Get RNG CFG */
if (rc) {
prerror("NX%d: ERROR: XSCOM RNG config read failure %d\n",
gcid, rc);
return;
}
/*
* We mask in-place rather than using GETFIELD for the base address
* as we happen to *know* that it's properly aligned in the register.
*
* FIXME? Always assusme BAR gets a valid address from FSP
*/
rng_addr = bar & addr_mask;
len = GETFIELD(NX_RNG_BAR_SIZE, bar);
if (len > 4) {
prerror("NX%d: Corrupted bar size %lld\n", gcid, len);
return;
}
rng_len = (u64[]){ 0x1000, /* 4K */
0x10000, /* 64K */
0x400000000UL, /* 16G*/
0x100000, /* 1M */
0x1000000 /* 16M */} [len];
prlog(PR_INFO, "NX%d: RNG BAR set to 0x%016llx..0x%016llx\n",
gcid, rng_addr, rng_addr + rng_len - 1);
/* RNG must be enabled before MMIO is enabled */
rc = xscom_write(gcid, xcfg, cfg | NX_RNG_CFG_ENABLE);
if (rc) {
prerror("NX%d: ERROR: XSCOM RNG config enable failure %d\n",
gcid, rc);
return;
}
/* The BAR needs to be enabled too */
rc = xscom_write(gcid, xbar, bar | NX_RNG_BAR_ENABLE);
if (rc) {
prerror("NX%d: ERROR: XSCOM RNG config enable failure %d\n",
gcid, rc);
return;
}
rng = dt_new_addr(dt_root, "hwrng", rng_addr);
if (!rng)
return;
dt_add_property_strings(rng, "compatible", "ibm,power-rng");
dt_add_property_u64s(rng, "reg", rng_addr, rng_len);
dt_add_property_cells(rng, "ibm,chip-id", gcid);
}
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