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Message-ID: <a5edf505-9b77-461e-ae8d-510e6ed3f950@portwell.com.tw>
Date: Thu, 4 Sep 2025 17:29:23 +0800
From: Yen-Chi Huang <jesse.huang@...twell.com.tw>
To: hansg@...nel.org, ilpo.jarvinen@...ux.intel.com, jdelvare@...e.com,
linux@...ck-us.net
Cc: platform-driver-x86@...r.kernel.org, linux-hwmon@...r.kernel.org,
linux-kernel@...r.kernel.org, jay.chen@...onical.com,
jesse.huang@...twell.com.tw
Subject: [PATCH v4] platform/x86: portwell-ec: Add hwmon support for voltage
and temperature
Integrates voltage and temperature monitoring into the driver via the hwmon
subsystem, enabling standardized reporting via tools like lm-sensors.
Signed-off-by: Yen-Chi Huang <jesse.huang@...twell.com.tw>
---
This version removes board-specific details such as labels and voltage
scaling factors. The driver now follows a generic approach, delegating
customization to userspace (e.g. via sensors.conf in lm-sensors), which
is the standard and more flexible practice.
v3->v4:
- Remove .driver_data and related per-board hwmon data structures.
- Remove unused pwec_hwmon_is_visible() and pwec_hwmon_init().
- Clarify driver header comments.
V2->V3:
- Replace hardcoded `1000` with `MILLIDEGREE_PER_DEGREE` and double check
- Fix comma placement and spacing coding style issues
- Simplify pwec_hwmon_is_visible() with ternary operator
V1->V2:
- Removed `msb_reg` from `struct pwec_hwmon_data`
- Updated `pwec_read16_stable()` to assume MSB follows LSB
- Moved `hwmon_channel_info` to per-board data and assigned it to `.info` at runtime
- Replaced the `pwec_board_data[]` array with a standalone struct
- Replaced literal `1000` with `MILLIDEGREE_PER_DEGREE`
- Removed unused include and sorted header includes
Previous versions (for reference):
v3 patch: https://lore.kernel.org/platform-driver-x86/d6429164-46dc-4c0d-8d6f-4650e0b92f22@portwell.com.tw/
---
drivers/platform/x86/portwell-ec.c | 84 ++++++++++++++++++++++++++++--
1 file changed, 79 insertions(+), 5 deletions(-)
diff --git a/drivers/platform/x86/portwell-ec.c b/drivers/platform/x86/portwell-ec.c
index 322f296e9315..0e748bfe4a23 100644
--- a/drivers/platform/x86/portwell-ec.c
+++ b/drivers/platform/x86/portwell-ec.c
@@ -5,15 +5,13 @@
* Tested on:
* - Portwell NANO-6064
*
- * This driver provides support for GPIO and Watchdog Timer
- * functionalities of the Portwell boards with ITE embedded controller (EC).
+ * This driver supports Portwell boards with an ITE embedded controller (EC).
* The EC is accessed through I/O ports and provides:
+ * - Temperature and voltage readings (hwmon)
* - 8 GPIO pins for control and monitoring
* - Hardware watchdog with 1-15300 second timeout range
*
- * It integrates with the Linux GPIO and Watchdog subsystems, allowing
- * userspace interaction with EC GPIO pins and watchdog control,
- * ensuring system stability and configurability.
+ * It integrates with the Linux hwmon, GPIO and Watchdog subsystems.
*
* (C) Copyright 2025 Portwell, Inc.
* Author: Yen-Chi Huang (jesse.huang@...twell.com.tw)
@@ -25,6 +23,7 @@
#include <linux/bitfield.h>
#include <linux/dmi.h>
#include <linux/gpio/driver.h>
+#include <linux/hwmon.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
@@ -32,6 +31,7 @@
#include <linux/platform_device.h>
#include <linux/sizes.h>
#include <linux/string.h>
+#include <linux/units.h>
#include <linux/watchdog.h>
#define PORTWELL_EC_IOSPACE 0xe300
@@ -52,6 +52,9 @@
#define PORTWELL_EC_FW_VENDOR_LENGTH 3
#define PORTWELL_EC_FW_VENDOR_NAME "PWG"
+#define PORTWELL_EC_ADC_VREF 3000
+#define PORTWELL_EC_ADC_MAX 1023
+
static bool force;
module_param(force, bool, 0444);
MODULE_PARM_DESC(force, "Force loading EC driver without checking DMI boardname");
@@ -79,6 +82,20 @@ static u8 pwec_read(u8 address)
return inb(PORTWELL_EC_IOSPACE + address);
}
+/* Ensure consistent 16-bit read across potential MSB rollover. */
+static u16 pwec_read16_stable(u8 lsb_reg)
+{
+ u8 lsb, msb, old_msb;
+
+ do {
+ old_msb = pwec_read(lsb_reg + 1);
+ lsb = pwec_read(lsb_reg);
+ msb = pwec_read(lsb_reg + 1);
+ } while (msb != old_msb);
+
+ return (msb << 8) | lsb;
+}
+
/* GPIO functions */
static int pwec_gpio_get(struct gpio_chip *chip, unsigned int offset)
@@ -204,6 +221,54 @@ static struct watchdog_device ec_wdt_dev = {
.max_timeout = PORTWELL_WDT_EC_MAX_COUNT_SECOND,
};
+/* HWMON functions */
+
+static const u8 pwec_hwmon_temp_regs[] = { 0x0, 0x2, 0x4 };
+static const u8 pwec_hwmon_in_regs[] = { 0x20, 0x22, 0x24, 0x30, 0x32 };
+
+static int pwec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, long *val)
+{
+ u8 tmp8;
+ u16 tmp16;
+
+ switch (type) {
+ case hwmon_temp:
+ tmp8 = pwec_read(pwec_hwmon_temp_regs[channel]);
+ *val = tmp8 * MILLIDEGREE_PER_DEGREE;
+ return 0;
+ case hwmon_in:
+ tmp16 = pwec_read16_stable(pwec_hwmon_in_regs[channel]);
+ *val = (tmp16 * PORTWELL_EC_ADC_VREF) / PORTWELL_EC_ADC_MAX;
+ return 0;
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+
+static const struct hwmon_channel_info *pwec_hwmon_info[] = {
+ HWMON_CHANNEL_INFO(temp,
+ HWMON_T_INPUT,
+ HWMON_T_INPUT,
+ HWMON_T_INPUT),
+ HWMON_CHANNEL_INFO(in,
+ HWMON_I_INPUT,
+ HWMON_I_INPUT,
+ HWMON_I_INPUT,
+ HWMON_I_INPUT,
+ HWMON_I_INPUT),
+ NULL
+};
+
+static const struct hwmon_ops pwec_hwmon_ops = {
+ .read = pwec_hwmon_read,
+};
+
+static struct hwmon_chip_info pwec_hwmon_chip_info = {
+ .ops = &pwec_hwmon_ops,
+ .info = pwec_hwmon_info,
+};
+
static int pwec_firmware_vendor_check(void)
{
u8 buf[PORTWELL_EC_FW_VENDOR_LENGTH + 1];
@@ -218,6 +283,7 @@ static int pwec_firmware_vendor_check(void)
static int pwec_probe(struct platform_device *pdev)
{
+ struct device *hwmon_dev;
int ret;
if (!devm_request_region(&pdev->dev, PORTWELL_EC_IOSPACE,
@@ -236,6 +302,14 @@ static int pwec_probe(struct platform_device *pdev)
return ret;
}
+ if (IS_REACHABLE(CONFIG_HWMON)) {
+ hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
+ "portwell-ec", NULL, &pwec_hwmon_chip_info, NULL);
+ ret = PTR_ERR_OR_ZERO(hwmon_dev);
+ if (ret)
+ return ret;
+ }
+
ec_wdt_dev.parent = &pdev->dev;
ret = devm_watchdog_register_device(&pdev->dev, &ec_wdt_dev);
if (ret < 0) {
--
2.34.1
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