drivers/ptp/ptp_vmw.c

   1 // SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
   2 /*
   3  * Copyright (C) 2020 VMware, Inc., Palo Alto, CA., USA
   4  *
   5  * PTP clock driver for VMware precision clock virtual device.
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/acpi.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/ptp_clock_kernel.h>
  14 #include <asm/hypervisor.h>
  15 #include <asm/vmware.h>
  16
  17 #define VMWARE_MAGIC 0x564D5868
  18 #define VMWARE_CMD_PCLK(nr) ((nr << 16) | 97)
  19 #define VMWARE_CMD_PCLK_GETTIME VMWARE_CMD_PCLK(0)
  20
  21 static struct acpi_device *ptp_vmw_acpi_device;
  22 static struct ptp_clock *ptp_vmw_clock;
  23
  24
  25 static int ptp_vmw_pclk_read(u64 *ns)
  26 {
  27         u32 ret, nsec_hi, nsec_lo, unused1, unused2, unused3;
  28
  29         asm volatile (VMWARE_HYPERCALL :
  30                 "=a"(ret), "=b"(nsec_hi), "=c"(nsec_lo), "=d"(unused1),
  31                 "=S"(unused2), "=D"(unused3) :
  32                 "a"(VMWARE_MAGIC), "b"(0),
  33                 "c"(VMWARE_CMD_PCLK_GETTIME), "d"(0) :
  34                 "memory");
  35
  36         if (ret == 0)
  37                 *ns = ((u64)nsec_hi << 32) | nsec_lo;
  38         return ret;
  39 }
  40
  41 /*
  42  * PTP clock ops.
  43  */
  44
  45 static int ptp_vmw_adjtime(struct ptp_clock_info *info, s64 delta)
  46 {
  47         return -EOPNOTSUPP;
  48 }
  49
  50 static int ptp_vmw_adjfine(struct ptp_clock_info *info, long delta)
  51 {
  52         return -EOPNOTSUPP;
  53 }
  54
  55 static int ptp_vmw_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
  56 {
  57         u64 ns;
  58
  59         if (ptp_vmw_pclk_read(&ns) != 0)
  60                 return -EIO;
  61         *ts = ns_to_timespec64(ns);
  62         return 0;
  63 }
  64
  65 static int ptp_vmw_settime(struct ptp_clock_info *info,
  66                           const struct timespec64 *ts)
  67 {
  68         return -EOPNOTSUPP;
  69 }
  70
  71 static int ptp_vmw_enable(struct ptp_clock_info *info,
  72                          struct ptp_clock_request *request, int on)
  73 {
  74         return -EOPNOTSUPP;
  75 }
  76
  77 static struct ptp_clock_info ptp_vmw_clock_info = {
  78         .owner          = THIS_MODULE,
  79         .name           = "ptp_vmw",
  80         .max_adj        = 0,
  81         .adjtime        = ptp_vmw_adjtime,
  82         .adjfine        = ptp_vmw_adjfine,
  83         .gettime64      = ptp_vmw_gettime,
  84         .settime64      = ptp_vmw_settime,
  85         .enable         = ptp_vmw_enable,
  86 };
  87
  88 /*
  89  * ACPI driver ops for VMware "precision clock" virtual device.
  90  */
  91
  92 static int ptp_vmw_acpi_add(struct acpi_device *device)
  93 {
  94         ptp_vmw_clock = ptp_clock_register(&ptp_vmw_clock_info, NULL);
  95         if (IS_ERR(ptp_vmw_clock)) {
  96                 pr_err("failed to register ptp clock\n");
  97                 return PTR_ERR(ptp_vmw_clock);
  98         }
  99
 100         ptp_vmw_acpi_device = device;
 101         return 0;
 102 }
 103
 104 static void ptp_vmw_acpi_remove(struct acpi_device *device)
 105 {
 106         ptp_clock_unregister(ptp_vmw_clock);
 107 }
 108
 109 static const struct acpi_device_id ptp_vmw_acpi_device_ids[] = {
 110         { "VMW0005", 0 },
 111         { "", 0 },
 112 };
 113
 114 MODULE_DEVICE_TABLE(acpi, ptp_vmw_acpi_device_ids);
 115
 116 static struct acpi_driver ptp_vmw_acpi_driver = {
 117         .name = "ptp_vmw",
 118         .ids = ptp_vmw_acpi_device_ids,
 119         .ops = {
 120                 .add = ptp_vmw_acpi_add,
 121                 .remove = ptp_vmw_acpi_remove
 122         },
 123         .owner  = THIS_MODULE
 124 };
 125
 126 static int __init ptp_vmw_init(void)
 127 {
 128         if (x86_hyper_type != X86_HYPER_VMWARE)
 129                 return -1;
 130         return acpi_bus_register_driver(&ptp_vmw_acpi_driver);
 131 }
 132
 133 static void __exit ptp_vmw_exit(void)
 134 {
 135         acpi_bus_unregister_driver(&ptp_vmw_acpi_driver);
 136 }
 137
 138 module_init(ptp_vmw_init);
 139 module_exit(ptp_vmw_exit);
 140
 141 MODULE_DESCRIPTION("VMware virtual PTP clock driver");
 142 MODULE_AUTHOR("VMware, Inc.");
 143 MODULE_LICENSE("Dual BSD/GPL");