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From 96a8a4776cb142f5d2bb7f6379df9af40e727c0b Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Tue, 11 Jul 2023 10:17:29 +0100
Subject: [PATCH] hwmon: (pwm-fan) Add fan speed register support
Some platforms include a fan-speed register that reports RPM directly
as an alternative to counting interrupts from the fan tachometer input.
Add support for reading a register at a given offset (rpm-offset) within
a block declared in another node (rpm-regmap). This indirection allows
the usual address mapping to be performed, and for address sharing with
another driver.
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
drivers/hwmon/pwm-fan.c | 59 ++++++++++++++++++++++++++++++++++++-----
1 file changed, 52 insertions(+), 7 deletions(-)
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -12,6 +12,7 @@
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
+#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/regulator/consumer.h>
@@ -51,6 +52,9 @@ struct pwm_fan_ctx {
ktime_t sample_start;
struct timer_list rpm_timer;
+ void __iomem *rpm_regbase;
+ unsigned int rpm_offset;
+
unsigned int pwm_value;
unsigned int pwm_fan_state;
unsigned int pwm_fan_max_state;
@@ -61,6 +65,10 @@ struct pwm_fan_ctx {
struct hwmon_channel_info fan_channel;
};
+static const u32 rpm_reg_channel_config[] = {
+ HWMON_F_INPUT, 0
+};
+
/* This handler assumes self resetting edge triggered interrupt. */
static irqreturn_t pulse_handler(int irq, void *dev_id)
{
@@ -335,7 +343,10 @@ static int pwm_fan_read(struct device *d
}
return -EOPNOTSUPP;
case hwmon_fan:
- *val = ctx->tachs[channel].rpm;
+ if (ctx->rpm_regbase)
+ *val = (long)readl(ctx->rpm_regbase + ctx->rpm_offset);
+ else
+ *val = ctx->tachs[channel].rpm;
return 0;
default:
@@ -470,6 +481,7 @@ static void pwm_fan_cleanup(void *__ctx)
/* Switch off everything */
ctx->enable_mode = pwm_disable_reg_disable;
pwm_fan_power_off(ctx);
+ iounmap(ctx->rpm_regbase);
}
static int pwm_fan_probe(struct platform_device *pdev)
@@ -534,10 +546,23 @@ static int pwm_fan_probe(struct platform
return ret;
ctx->tach_count = platform_irq_count(pdev);
+ if (ctx->tach_count == 0) {
+ struct device_node *rpm_node;
+
+ rpm_node = of_parse_phandle(dev->of_node, "rpm-regmap", 0);
+ if (rpm_node)
+ ctx->rpm_regbase = of_iomap(rpm_node, 0);
+ }
+
if (ctx->tach_count < 0)
return dev_err_probe(dev, ctx->tach_count,
"Could not get number of fan tachometer inputs\n");
- dev_dbg(dev, "%d fan tachometer inputs\n", ctx->tach_count);
+ if (IS_ERR(ctx->rpm_regbase))
+ return dev_err_probe(dev, PTR_ERR(ctx->rpm_regbase),
+ "Could not get rpm reg\n");
+
+ dev_dbg(dev, "%d fan tachometer inputs, %d rpm regmap\n", ctx->tach_count,
+ !!ctx->rpm_regbase);
if (ctx->tach_count) {
channel_count++; /* We also have a FAN channel. */
@@ -554,12 +579,24 @@ static int pwm_fan_probe(struct platform
if (!fan_channel_config)
return -ENOMEM;
ctx->fan_channel.config = fan_channel_config;
+ } else if (ctx->rpm_regbase) {
+ channel_count++; /* We also have a FAN channel. */
+ ctx->fan_channel.type = hwmon_fan;
+ ctx->fan_channel.config = rpm_reg_channel_config;
+
+ if (of_property_read_u32(pdev->dev.of_node, "rpm-offset", &ctx->rpm_offset)) {
+ dev_err(&pdev->dev, "unable to read 'rpm-offset'");
+ ret = -EINVAL;
+ goto error;
+ }
}
channels = devm_kcalloc(dev, channel_count + 1,
sizeof(struct hwmon_channel_info *), GFP_KERNEL);
- if (!channels)
- return -ENOMEM;
+ if (!channels) {
+ ret = -ENOMEM;
+ goto error;
+ }
channels[0] = HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_ENABLE);
@@ -602,6 +639,8 @@ static int pwm_fan_probe(struct platform
mod_timer(&ctx->rpm_timer, jiffies + HZ);
channels[1] = &ctx->fan_channel;
+ } else if (ctx->rpm_regbase) {
+ channels[1] = &ctx->fan_channel;
}
ctx->info.ops = &pwm_fan_hwmon_ops;
@@ -611,12 +650,13 @@ static int pwm_fan_probe(struct platform
ctx, &ctx->info, NULL);
if (IS_ERR(hwmon)) {
dev_err(dev, "Failed to register hwmon device\n");
- return PTR_ERR(hwmon);
+ ret = PTR_ERR(hwmon);
+ goto error;
}
ret = pwm_fan_of_get_cooling_data(dev, ctx);
if (ret)
- return ret;
+ goto error;
ctx->pwm_fan_state = ctx->pwm_fan_max_state;
if (IS_ENABLED(CONFIG_THERMAL)) {
@@ -627,12 +667,17 @@ static int pwm_fan_probe(struct platform
dev_err(dev,
"Failed to register pwm-fan as cooling device: %d\n",
ret);
- return ret;
+ goto error;
}
ctx->cdev = cdev;
}
return 0;
+
+error:
+ if (ctx->rpm_regbase)
+ iounmap(ctx->rpm_regbase);
+ return ret;
}
static void pwm_fan_shutdown(struct platform_device *pdev)
|