1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2017 Linaro Ltd.
4 *
5 * Author: Linus Walleij <linus.walleij@linaro.org>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2, as
9 * published by the Free Software Foundation.
10 *
11 */
12#include <linux/init.h>
13#include <linux/kernel.h>
14#include <linux/mfd/syscon.h>
15#include <linux/regmap.h>
16#include <linux/of.h>
17
18#define GLOBAL_WORD_ID 0x00
19#define GEMINI_GLOBAL_ARB1_CTRL 0x2c
20#define GEMINI_ARB1_BURST_MASK GENMASK(21, 16)
21#define GEMINI_ARB1_BURST_SHIFT 16
22/* These all define the priority on the BUS2 backplane */
23#define GEMINI_ARB1_PRIO_MASK GENMASK(9, 0)
24#define GEMINI_ARB1_DMAC_HIGH_PRIO BIT(0)
25#define GEMINI_ARB1_IDE_HIGH_PRIO BIT(1)
26#define GEMINI_ARB1_RAID_HIGH_PRIO BIT(2)
27#define GEMINI_ARB1_SECURITY_HIGH_PRIO BIT(3)
28#define GEMINI_ARB1_GMAC0_HIGH_PRIO BIT(4)
29#define GEMINI_ARB1_GMAC1_HIGH_PRIO BIT(5)
30#define GEMINI_ARB1_USB0_HIGH_PRIO BIT(6)
31#define GEMINI_ARB1_USB1_HIGH_PRIO BIT(7)
32#define GEMINI_ARB1_PCI_HIGH_PRIO BIT(8)
33#define GEMINI_ARB1_TVE_HIGH_PRIO BIT(9)
34
35#define GEMINI_DEFAULT_BURST_SIZE 0x20
36#define GEMINI_DEFAULT_PRIO (GEMINI_ARB1_GMAC0_HIGH_PRIO | \
37 GEMINI_ARB1_GMAC1_HIGH_PRIO)
38
39static int __init gemini_soc_init(void)
40{
41 struct regmap *map;
42 u32 rev;
43 u32 val;
44 int ret;
45
46 /* Multiplatform guard, only proceed on Gemini */
47 if (!of_machine_is_compatible(compat: "cortina,gemini"))
48 return 0;
49
50 map = syscon_regmap_lookup_by_compatible(s: "cortina,gemini-syscon");
51 if (IS_ERR(ptr: map))
52 return PTR_ERR(ptr: map);
53 ret = regmap_read(map, GLOBAL_WORD_ID, val: &rev);
54 if (ret)
55 return ret;
56
57 val = (GEMINI_DEFAULT_BURST_SIZE << GEMINI_ARB1_BURST_SHIFT) |
58 GEMINI_DEFAULT_PRIO;
59
60 /* Set up system arbitration */
61 regmap_update_bits(map,
62 GEMINI_GLOBAL_ARB1_CTRL,
63 GEMINI_ARB1_BURST_MASK | GEMINI_ARB1_PRIO_MASK,
64 val);
65
66 pr_info("Gemini SoC %04x revision %02x, set arbitration %08x\n",
67 rev >> 8, rev & 0xff, val);
68
69 return 0;
70}
71subsys_initcall(gemini_soc_init);
72

source code of linux/drivers/soc/gemini/soc-gemini.c