1 /*
2  * arch/arm64/include/asm/arch_timer.h
3  *
4  * Copyright (C) 2012 ARM Ltd.
5  * Author: Marc Zyngier <marc.zyngier@arm.com>
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  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
18  */
19 #ifndef __ASM_ARCH_TIMER_H
20 #define __ASM_ARCH_TIMER_H
21 
22 #include <asm/barrier.h>
23 #include <asm/sysreg.h>
24 
25 #include <linux/bug.h>
26 #include <linux/init.h>
27 #include <linux/jump_label.h>
28 #include <linux/types.h>
29 
30 #include <clocksource/arm_arch_timer.h>
31 
32 #if IS_ENABLED(CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND)
33 extern struct static_key_false arch_timer_read_ool_enabled;
34 #define needs_unstable_timer_counter_workaround() \
35 	static_branch_unlikely(&arch_timer_read_ool_enabled)
36 #else
37 #define needs_unstable_timer_counter_workaround()  false
38 #endif
39 
40 
41 struct arch_timer_erratum_workaround {
42 	const char *id;		/* Indicate the Erratum ID */
43 	u32 (*read_cntp_tval_el0)(void);
44 	u32 (*read_cntv_tval_el0)(void);
45 	u64 (*read_cntvct_el0)(void);
46 };
47 
48 extern const struct arch_timer_erratum_workaround *timer_unstable_counter_workaround;
49 
50 #define arch_timer_reg_read_stable(reg) 		\
51 ({							\
52 	u64 _val;					\
53 	if (needs_unstable_timer_counter_workaround())		\
54 		_val = timer_unstable_counter_workaround->read_##reg();\
55 	else						\
56 		_val = read_sysreg(reg);		\
57 	_val;						\
58 })
59 
60 /*
61  * These register accessors are marked inline so the compiler can
62  * nicely work out which register we want, and chuck away the rest of
63  * the code.
64  */
65 static __always_inline
66 void arch_timer_reg_write_cp15(int access, enum arch_timer_reg reg, u32 val)
67 {
68 	if (access == ARCH_TIMER_PHYS_ACCESS) {
69 		switch (reg) {
70 		case ARCH_TIMER_REG_CTRL:
71 			write_sysreg(val, cntp_ctl_el0);
72 			break;
73 		case ARCH_TIMER_REG_TVAL:
74 			write_sysreg(val, cntp_tval_el0);
75 			break;
76 		}
77 	} else if (access == ARCH_TIMER_VIRT_ACCESS) {
78 		switch (reg) {
79 		case ARCH_TIMER_REG_CTRL:
80 			write_sysreg(val, cntv_ctl_el0);
81 			break;
82 		case ARCH_TIMER_REG_TVAL:
83 			write_sysreg(val, cntv_tval_el0);
84 			break;
85 		}
86 	}
87 
88 	isb();
89 }
90 
91 static __always_inline
92 u32 arch_timer_reg_read_cp15(int access, enum arch_timer_reg reg)
93 {
94 	if (access == ARCH_TIMER_PHYS_ACCESS) {
95 		switch (reg) {
96 		case ARCH_TIMER_REG_CTRL:
97 			return read_sysreg(cntp_ctl_el0);
98 		case ARCH_TIMER_REG_TVAL:
99 			return arch_timer_reg_read_stable(cntp_tval_el0);
100 		}
101 	} else if (access == ARCH_TIMER_VIRT_ACCESS) {
102 		switch (reg) {
103 		case ARCH_TIMER_REG_CTRL:
104 			return read_sysreg(cntv_ctl_el0);
105 		case ARCH_TIMER_REG_TVAL:
106 			return arch_timer_reg_read_stable(cntv_tval_el0);
107 		}
108 	}
109 
110 	BUG();
111 }
112 
113 static inline u32 arch_timer_get_cntfrq(void)
114 {
115 	return read_sysreg(cntfrq_el0);
116 }
117 
118 static inline u32 arch_timer_get_cntkctl(void)
119 {
120 	return read_sysreg(cntkctl_el1);
121 }
122 
123 static inline void arch_timer_set_cntkctl(u32 cntkctl)
124 {
125 	write_sysreg(cntkctl, cntkctl_el1);
126 }
127 
128 static inline u64 arch_counter_get_cntpct(void)
129 {
130 	/*
131 	 * AArch64 kernel and user space mandate the use of CNTVCT.
132 	 */
133 	BUG();
134 	return 0;
135 }
136 
137 static inline u64 arch_counter_get_cntvct(void)
138 {
139 	isb();
140 	return arch_timer_reg_read_stable(cntvct_el0);
141 }
142 
143 static inline int arch_timer_arch_init(void)
144 {
145 	return 0;
146 }
147 
148 #endif
149