1 /*
2  * Copyright (c) 2015 Pengutronix, Sascha Hauer <kernel@pengutronix.de>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  * GNU General Public License for more details.
12  */
13 
14 #include <linux/export.h>
15 #include <linux/jiffies.h>
16 #include <linux/regmap.h>
17 #include <linux/soc/mediatek/infracfg.h>
18 #include <asm/processor.h>
19 
20 #define INFRA_TOPAXI_PROTECTEN		0x0220
21 #define INFRA_TOPAXI_PROTECTSTA1	0x0228
22 
23 /**
24  * mtk_infracfg_set_bus_protection - enable bus protection
25  * @regmap: The infracfg regmap
26  * @mask: The mask containing the protection bits to be enabled.
27  *
28  * This function enables the bus protection bits for disabled power
29  * domains so that the system does not hang when some unit accesses the
30  * bus while in power down.
31  */
32 int mtk_infracfg_set_bus_protection(struct regmap *infracfg, u32 mask)
33 {
34 	unsigned long expired;
35 	u32 val;
36 	int ret;
37 
38 	regmap_update_bits(infracfg, INFRA_TOPAXI_PROTECTEN, mask, mask);
39 
40 	expired = jiffies + HZ;
41 
42 	while (1) {
43 		ret = regmap_read(infracfg, INFRA_TOPAXI_PROTECTSTA1, &val);
44 		if (ret)
45 			return ret;
46 
47 		if ((val & mask) == mask)
48 			break;
49 
50 		cpu_relax();
51 		if (time_after(jiffies, expired))
52 			return -EIO;
53 	}
54 
55 	return 0;
56 }
57 
58 /**
59  * mtk_infracfg_clear_bus_protection - disable bus protection
60  * @regmap: The infracfg regmap
61  * @mask: The mask containing the protection bits to be disabled.
62  *
63  * This function disables the bus protection bits previously enabled with
64  * mtk_infracfg_set_bus_protection.
65  */
66 int mtk_infracfg_clear_bus_protection(struct regmap *infracfg, u32 mask)
67 {
68 	unsigned long expired;
69 	int ret;
70 
71 	regmap_update_bits(infracfg, INFRA_TOPAXI_PROTECTEN, mask, 0);
72 
73 	expired = jiffies + HZ;
74 
75 	while (1) {
76 		u32 val;
77 
78 		ret = regmap_read(infracfg, INFRA_TOPAXI_PROTECTSTA1, &val);
79 		if (ret)
80 			return ret;
81 
82 		if (!(val & mask))
83 			break;
84 
85 		cpu_relax();
86 		if (time_after(jiffies, expired))
87 			return -EIO;
88 	}
89 
90 	return 0;
91 }
92