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_FSL_ERRATUM_A008585)
33 extern struct static_key_false arch_timer_read_ool_enabled;
34 #define needs_fsl_a008585_workaround() \
35 	static_branch_unlikely(&arch_timer_read_ool_enabled)
36 #else
37 #define needs_fsl_a008585_workaround()  false
38 #endif
39 
40 u32 __fsl_a008585_read_cntp_tval_el0(void);
41 u32 __fsl_a008585_read_cntv_tval_el0(void);
42 u64 __fsl_a008585_read_cntvct_el0(void);
43 
44 /*
45  * The number of retries is an arbitrary value well beyond the highest number
46  * of iterations the loop has been observed to take.
47  */
48 #define __fsl_a008585_read_reg(reg) ({			\
49 	u64 _old, _new;					\
50 	int _retries = 200;				\
51 							\
52 	do {						\
53 		_old = read_sysreg(reg);		\
54 		_new = read_sysreg(reg);		\
55 		_retries--;				\
56 	} while (unlikely(_old != _new) && _retries);	\
57 							\
58 	WARN_ON_ONCE(!_retries);			\
59 	_new;						\
60 })
61 
62 #define arch_timer_reg_read_stable(reg) 		\
63 ({							\
64 	u64 _val;					\
65 	if (needs_fsl_a008585_workaround())		\
66 		_val = __fsl_a008585_read_##reg();	\
67 	else						\
68 		_val = read_sysreg(reg);		\
69 	_val;						\
70 })
71 
72 /*
73  * These register accessors are marked inline so the compiler can
74  * nicely work out which register we want, and chuck away the rest of
75  * the code.
76  */
77 static __always_inline
78 void arch_timer_reg_write_cp15(int access, enum arch_timer_reg reg, u32 val)
79 {
80 	if (access == ARCH_TIMER_PHYS_ACCESS) {
81 		switch (reg) {
82 		case ARCH_TIMER_REG_CTRL:
83 			write_sysreg(val, cntp_ctl_el0);
84 			break;
85 		case ARCH_TIMER_REG_TVAL:
86 			write_sysreg(val, cntp_tval_el0);
87 			break;
88 		}
89 	} else if (access == ARCH_TIMER_VIRT_ACCESS) {
90 		switch (reg) {
91 		case ARCH_TIMER_REG_CTRL:
92 			write_sysreg(val, cntv_ctl_el0);
93 			break;
94 		case ARCH_TIMER_REG_TVAL:
95 			write_sysreg(val, cntv_tval_el0);
96 			break;
97 		}
98 	}
99 
100 	isb();
101 }
102 
103 static __always_inline
104 u32 arch_timer_reg_read_cp15(int access, enum arch_timer_reg reg)
105 {
106 	if (access == ARCH_TIMER_PHYS_ACCESS) {
107 		switch (reg) {
108 		case ARCH_TIMER_REG_CTRL:
109 			return read_sysreg(cntp_ctl_el0);
110 		case ARCH_TIMER_REG_TVAL:
111 			return arch_timer_reg_read_stable(cntp_tval_el0);
112 		}
113 	} else if (access == ARCH_TIMER_VIRT_ACCESS) {
114 		switch (reg) {
115 		case ARCH_TIMER_REG_CTRL:
116 			return read_sysreg(cntv_ctl_el0);
117 		case ARCH_TIMER_REG_TVAL:
118 			return arch_timer_reg_read_stable(cntv_tval_el0);
119 		}
120 	}
121 
122 	BUG();
123 }
124 
125 static inline u32 arch_timer_get_cntfrq(void)
126 {
127 	return read_sysreg(cntfrq_el0);
128 }
129 
130 static inline u32 arch_timer_get_cntkctl(void)
131 {
132 	return read_sysreg(cntkctl_el1);
133 }
134 
135 static inline void arch_timer_set_cntkctl(u32 cntkctl)
136 {
137 	write_sysreg(cntkctl, cntkctl_el1);
138 }
139 
140 static inline u64 arch_counter_get_cntpct(void)
141 {
142 	/*
143 	 * AArch64 kernel and user space mandate the use of CNTVCT.
144 	 */
145 	BUG();
146 	return 0;
147 }
148 
149 static inline u64 arch_counter_get_cntvct(void)
150 {
151 	isb();
152 	return arch_timer_reg_read_stable(cntvct_el0);
153 }
154 
155 static inline int arch_timer_arch_init(void)
156 {
157 	return 0;
158 }
159 
160 #endif
161