1 /* SPDX-License-Identifier: GPL-2.0 */
4  * Definitions for the clocksource provided by the Hyper-V
5  * hypervisor to guest VMs, as described in the Hyper-V Top
18 #include <asm/hyperv-tlfs.h>
29 extern int hv_stimer_cleanup(unsigned int cpu);
30 extern void hv_stimer_legacy_init(unsigned int cpu, int sint);
31 extern void hv_stimer_legacy_cleanup(unsigned int cpu);
49 	 * The protocol for reading Hyper-V TSC page is specified in Hypervisor  in hv_read_tsc_page_tsc()
50 	 * Top-Level Functional Specification ver. 3.0 and above. To get the  in hv_read_tsc_page_tsc()
52 	 * - READ ReferenceTscSequence  in hv_read_tsc_page_tsc()
55 	 *   versions (up to 4.0b) contain a mistake and wrongly claim '-1'  in hv_read_tsc_page_tsc()
57 	 * - ReferenceTime =  in hv_read_tsc_page_tsc()
59 	 * - READ ReferenceTscSequence again. In case its value has changed  in hv_read_tsc_page_tsc()
65 		sequence = READ_ONCE(tsc_pg->tsc_sequence);  in hv_read_tsc_page_tsc()
69 		 * Make sure we read sequence before we read other values from  in hv_read_tsc_page_tsc()
74 		scale = READ_ONCE(tsc_pg->tsc_scale);  in hv_read_tsc_page_tsc()
75 		offset = READ_ONCE(tsc_pg->tsc_offset);  in hv_read_tsc_page_tsc()
79 		 * Make sure we read sequence after we read all other values  in hv_read_tsc_page_tsc()
84 	} while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);  in hv_read_tsc_page_tsc()
107 static inline int hv_stimer_cleanup(unsigned int cpu) { return 0; }  in hv_stimer_cleanup()  argument
108 static inline void hv_stimer_legacy_init(unsigned int cpu, int sint) {}  in hv_stimer_legacy_init()  argument
109 static inline void hv_stimer_legacy_cleanup(unsigned int cpu) {}  in hv_stimer_legacy_cleanup()  argument