[PATCH v2 1/2] ptp/ptp_vmw: Implement PTP clock adjustments ops

[Ajay Kaher <ajay.kaher@broadcom.com>]

Implement PTP clock ops that set time and frequency of the underlying
clock. On supported versions of VMware precision clock virtual device,
new commands can adjust its time and frequency, allowing time transfer
from a virtual machine to the underlying hypervisor.

In case of error, vmware_hypercall doesn't return Linux defined errno,
converting it to -EIO.

Cc: Shubham Gupta <shubham-sg.gupta@broadcom.com>
Cc: Nick Shi <nick.shi@broadcom.com>
Tested-by: Karen Wang <karen.wang@broadcom.com>
Tested-by: Hari Krishna Ginka <hari-krishna.ginka@broadcom.com>
Signed-off-by: Ajay Kaher <ajay.kaher@broadcom.com>
---
 drivers/ptp/ptp_vmw.c | 39 +++++++++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/drivers/ptp/ptp_vmw.c b/drivers/ptp/ptp_vmw.c
index 20ab05c4d..7d117eee4 100644
--- a/drivers/ptp/ptp_vmw.c
+++ b/drivers/ptp/ptp_vmw.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
 /*
- * Copyright (C) 2020 VMware, Inc., Palo Alto, CA., USA
+ * Copyright (C) 2020-2023 VMware, Inc., Palo Alto, CA., USA
+ * Copyright (C) 2024-2025 Broadcom Ltd.
  *
  * PTP clock driver for VMware precision clock virtual device.
  */
@@ -16,20 +17,36 @@
 
 #define VMWARE_CMD_PCLK(nr) ((nr << 16) | 97)
 #define VMWARE_CMD_PCLK_GETTIME VMWARE_CMD_PCLK(0)
+#define VMWARE_CMD_PCLK_SETTIME VMWARE_CMD_PCLK(1)
+#define VMWARE_CMD_PCLK_ADJTIME VMWARE_CMD_PCLK(2)
+#define VMWARE_CMD_PCLK_ADJFREQ VMWARE_CMD_PCLK(3)
 
 static struct acpi_device *ptp_vmw_acpi_device;
 static struct ptp_clock *ptp_vmw_clock;
 
+/*
+ * Helpers for reading and writing to precision clock device.
+ */
 
-static int ptp_vmw_pclk_read(u64 *ns)
+static int ptp_vmw_pclk_read(int cmd, u64 *ns)
 {
 	u32 ret, nsec_hi, nsec_lo;
 
-	ret = vmware_hypercall3(VMWARE_CMD_PCLK_GETTIME, 0,
-				&nsec_hi, &nsec_lo);
+	ret = vmware_hypercall3(cmd, 0, &nsec_hi, &nsec_lo);
 	if (ret == 0)
 		*ns = ((u64)nsec_hi << 32) | nsec_lo;
-	return ret;
+
+	return ret != 0 ? -EIO : 0;
+}
+
+static int ptp_vmw_pclk_write(int cmd, u64 in)
+{
+	u32 ret, unused;
+
+	ret = vmware_hypercall5(cmd, 0, 0, in >> 32, in & 0xffffffff,
+				&unused);
+
+	return ret != 0 ? -EIO : 0;
 }
 
 /*
@@ -38,19 +55,19 @@ static int ptp_vmw_pclk_read(u64 *ns)
 
 static int ptp_vmw_adjtime(struct ptp_clock_info *info, s64 delta)
 {
-	return -EOPNOTSUPP;
+	return ptp_vmw_pclk_write(VMWARE_CMD_PCLK_ADJTIME, (u64)delta);
 }
 
 static int ptp_vmw_adjfine(struct ptp_clock_info *info, long delta)
 {
-	return -EOPNOTSUPP;
+	return ptp_vmw_pclk_write(VMWARE_CMD_PCLK_ADJFREQ, (u64)delta);
 }
 
 static int ptp_vmw_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
 {
 	u64 ns;
 
-	if (ptp_vmw_pclk_read(&ns) != 0)
+	if (ptp_vmw_pclk_read(VMWARE_CMD_PCLK_GETTIME, &ns) != 0)
 		return -EIO;
 	*ts = ns_to_timespec64(ns);
 	return 0;
@@ -59,7 +76,9 @@ static int ptp_vmw_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
 static int ptp_vmw_settime(struct ptp_clock_info *info,
 			  const struct timespec64 *ts)
 {
-	return -EOPNOTSUPP;
+	u64 ns = timespec64_to_ns(ts);
+
+	return ptp_vmw_pclk_write(VMWARE_CMD_PCLK_SETTIME, ns);
 }
 
 static int ptp_vmw_enable(struct ptp_clock_info *info,
@@ -71,7 +90,7 @@ static int ptp_vmw_enable(struct ptp_clock_info *info,
 static struct ptp_clock_info ptp_vmw_clock_info = {
 	.owner		= THIS_MODULE,
 	.name		= "ptp_vmw",
-	.max_adj	= 0,
+	.max_adj	= 999999999,
 	.adjtime	= ptp_vmw_adjtime,
 	.adjfine	= ptp_vmw_adjfine,
 	.gettime64	= ptp_vmw_gettime,
-- 
2.40.4