Update driver xdpe152c4.c

[<Shirley.Lin@infineon.com>]

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Dear Linux Kernel administrators, Good Day.

We have urgent requirement to update driver link, https://github.com/torvalds/linux/blob/master/drivers/hwmon/pmbus/xdpe152c4.c<https://github.com/torvalds/linux/blob/master/drivers/hwmon/pmbus/xdpe152c4.c#L72>

Please help to review the attached Linux Kernel patch for xdpe152xx driver.

PEC Retry Functionality added for both read_word_data() & read_byte_data() cases of PMBUS.

Updated by : Yadav Ashish (PSS PCS RD FW HD) Ashish.Yadav@infineon.com<mailto:Ashish.Yadav@infineon.com>

Kindly leave your comment or give us approval for upstream.

Thanks a lot.
Best Regards,
Shirley Lin

Infineon Technologies Taiwan Co. Ltd.
Field Application Engineer
IFTW PSS SMD GC TM DCO
Office: +886 2 2652 6866
Mobile: +886 9 7822 9671
Shirley.Lin@infineon.com<mailto:Shirley.Lin@infineon.com>

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Neihu District, Taipei 114063
Taiwan

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From 16fd1cd36bc890604355ddee0a5753559292f932 Mon Sep 17 00:00:00 2001
From: Ashish Yadav <ashish.yadav@infineon.com>
Date: Sat, 29 Mar 2025 12:25:39 +0530
Subject: [PATCH] XDPE152xx PMBUS Driver: PEC RETRY

xdpe152xx driver retry to read data in case of PEC Error or Nack on PMBUS.

Signed-off-by: Ashish Yadav <ashish.yadav@infineon.com>
---
 drivers/hwmon/pmbus/xdpe152c4.c | 63 ++++++++++++++++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/pmbus/xdpe152c4.c b/drivers/hwmon/pmbus/xdpe152c4.c
index 235e6b41a..a61ba4a56 100644
--- a/drivers/hwmon/pmbus/xdpe152c4.c
+++ b/drivers/hwmon/pmbus/xdpe152c4.c
@@ -10,12 +10,73 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/delay.h>
 #include "pmbus.h"
 
-#define XDPE152_PAGE_NUM 2
+#define XDPE152_PAGE_NUM	2
+#define XDPE152_RETRY_BUS_READ	4
+
+static int xdpe152_read_word_data(struct i2c_client *client, int page,
+					int phase, int reg)
+{
+	int ret = 0;
+	int retry = 0;
+
+	/* Virtual PMBUS Command not supported */
+	if (reg >= PMBUS_VIRT_BASE) {
+		ret = -ENXIO;
+		return ret;
+	}
+
+	do {
+		ret = pmbus_read_word_data(client, page, phase, reg);
+		if (ret == -EBADMSG || ret == -ENXIO) {
+			/* PEC Error or NACK: try again */
+			retry++;
+			/* Sleep for an approximate time */
+			usleep_range(25, 50);
+			continue;
+		} else {
+			break;
+		}
+
+	} while (retry < XDPE152_RETRY_BUS_READ);
+
+	if (ret < 0)
+		pr_warn("PMBUS READ ERROR:%d\n", ret);
+
+	return ret;
+}
+
+static int xdpe152_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+	int ret = 0;
+	int retry = 0;
+
+	do {
+		ret = pmbus_read_byte_data(client, page, reg);
+		if (ret == -EBADMSG || ret == -ENXIO) {
+			/* PEC Error or NACK: try again */
+			retry++;
+			/* Sleep for an approximate time */
+			usleep_range(25, 50);
+			continue;
+		} else {
+			break;
+		}
+
+	} while (retry < XDPE152_RETRY_BUS_READ);
+
+	if (ret < 0)
+		pr_warn("PMBUS READ ERROR:%d\n", ret);
+
+	return ret;
+}
 
 static struct pmbus_driver_info xdpe152_info = {
 	.pages = XDPE152_PAGE_NUM,
+	.read_word_data = xdpe152_read_word_data,
+	.read_byte_data = xdpe152_read_byte_data,
 	.format[PSC_VOLTAGE_IN] = linear,
 	.format[PSC_VOLTAGE_OUT] = linear,
 	.format[PSC_TEMPERATURE] = linear,
-- 
2.39.5


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