[PATCH v2 4/6] hwmon: sparx5: add LAN969x PWM support

[Robert Marko]

The LAN969x fan controller provides an 8-bit PWM output with a
programmable frequency and polarity.

Expose pwm1 and pwm1_freq on the fan hwmon device. Parse the fan child
node's standard PWM specifier and use its period and polarity flags to
configure the hardware.

Signed-off-by: Robert Marko <robert.marko@xxxxxxxxxx>
---
Changes in v2:
- Drop the private mutex; hwmon serializes sysfs accesses.
- Preserve firmware PWM polarity when no fan child is present.
- Convert the DT period directly to a divider and reject invalid values
  before changing fan registers.

 Documentation/hwmon/sparx5-temp.rst |   9 ++
 drivers/hwmon/Kconfig               |   2 +-
 drivers/hwmon/sparx5-temp.c         | 198 ++++++++++++++++++++++++++--
 3 files changed, 196 insertions(+), 13 deletions(-)

diff --git a/Documentation/hwmon/sparx5-temp.rst b/Documentation/hwmon/sparx5-temp.rst
index a053d12fbdbbb..edb12f890172c 100644
--- a/Documentation/hwmon/sparx5-temp.rst
+++ b/Documentation/hwmon/sparx5-temp.rst
@@ -35,8 +35,17 @@ The following attributes are supported.
 ======================= ========================================================
 temp1_input		Die temperature (in millidegree Celsius.)
 fan1_input              Fan speed in RPM (LAN969x only).
+pwm1                    PWM duty cycle, from 0 to 255 (LAN969x only).
+pwm1_freq               PWM frequency in Hz (LAN969x only).
 ======================= ========================================================
 
 The tachometer counts pulses over one-second intervals, independently of the
 PWM output. The fan child's pulses-per-revolution property specifies how many
 pulses represent one revolution; it defaults to two.
+
+On LAN969x, the fan child's pwms property selects the initial PWM period and
+polarity. The output is dedicated to this fan and is not available to external
+PWM consumers. The pwm1 value describes the logical duty cycle independently
+of the output polarity. Frequency requests are rounded to the nearest
+hardware divider value; requests outside the divider range are rejected.
+pwm1_freq reports the resulting frequency.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index deb9eb82b8501..b77112518ebe6 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -673,7 +673,7 @@ config SENSORS_SPARX5
 	depends on ARCH_SPARX5 || ARCH_LAN969X || COMPILE_TEST
 	help
 	  If you say yes here you get support for temperature monitoring on
-	  Microchip Sparx5 and LAN969x SoCs, as well as fan monitoring on
+	  Microchip Sparx5 and LAN969x SoCs, as well as the fan controller on
 	  LAN969x SoCs.
 
 	  This driver can also be built as a module. If so, the module
diff --git a/drivers/hwmon/sparx5-temp.c b/drivers/hwmon/sparx5-temp.c
index 1f197004780cc..bdf08931f5b93 100644
--- a/drivers/hwmon/sparx5-temp.c
+++ b/drivers/hwmon/sparx5-temp.c
@@ -15,6 +15,8 @@
 #include <linux/platform_device.h>
 #include <linux/property.h>
 
+#include <dt-bindings/pwm/pwm.h>
+
 #define TEMP_CTRL		0
 #define TEMP_CFG		4
 #define  TEMP_CFG_CYCLES	GENMASK(24, 15)
@@ -24,14 +26,18 @@
 #define  TEMP_STAT_TEMP		GENMASK(11, 0)
 
 #define FAN_CFG			0
+#define  FAN_CFG_DUTY_CYCLE	GENMASK(23, 16)
+#define  FAN_CFG_INV_POL	BIT(3)
 #define  FAN_CFG_GATE_ENA	BIT(2)
 #define  FAN_CFG_STAT_MODE	BIT(0)
 #define FAN_PWM_FREQ		4
 #define  FAN_PWM_FREQ_CYCLES	GENMASK(27, 16)
+#define  FAN_PWM_FREQ_DIV	GENMASK(15, 0)
 #define FAN_CNT			8
 #define  FAN_CNT_DATA		GENMASK(15, 0)
 
 #define FAN_TACH_INTERVAL_HZ	100000
+#define FAN_PWM_FREQ_SCALE	256
 
 struct s5_match_data {
 	bool is_fan;
@@ -43,6 +49,8 @@ struct s5_hwmon {
 	struct clk *clk;
 	unsigned long clk_rate;
 	u32 pulses_per_revolution;
+	u32 pwm_period;
+	bool pwm_inverted;
 };
 
 static void s5_temp_enable(struct s5_hwmon *hwmon)
@@ -72,6 +80,11 @@ static void s5_fan_enable(struct s5_hwmon *hwmon)
 	/* Count all tachometer pulses over one-second intervals. */
 	val = readl(hwmon->fan + FAN_CFG);
 	val &= ~(FAN_CFG_STAT_MODE | FAN_CFG_GATE_ENA);
+	if (hwmon->pwm_period) {
+		val &= ~FAN_CFG_INV_POL;
+		if (hwmon->pwm_inverted)
+			val |= FAN_CFG_INV_POL;
+	}
 	writel(val, hwmon->fan + FAN_CFG);
 }
 
@@ -111,6 +124,32 @@ static int s5_read_fan(struct s5_hwmon *hwmon, long *val)
 	return 0;
 }
 
+static int s5_read_pwm(struct s5_hwmon *hwmon, long *val)
+{
+	u32 data;
+
+	data = readl_relaxed(hwmon->fan + FAN_CFG);
+	*val = FIELD_GET(FAN_CFG_DUTY_CYCLE, data);
+
+	return 0;
+}
+
+static int s5_read_pwm_freq(struct s5_hwmon *hwmon, long *val)
+{
+	unsigned long rate;
+	u32 divider;
+
+	divider = readl_relaxed(hwmon->fan + FAN_PWM_FREQ);
+	divider = FIELD_GET(FAN_PWM_FREQ_DIV, divider);
+	if (!divider)
+		return -ENODATA;
+
+	rate = DIV_ROUND_CLOSEST(hwmon->clk_rate, FAN_PWM_FREQ_SCALE);
+	*val = DIV_ROUND_CLOSEST(rate, divider);
+
+	return 0;
+}
+
 static int s5_read(struct device *dev, enum hwmon_sensor_types type,
 		   u32 attr, int channel, long *val)
 {
@@ -125,6 +164,18 @@ static int s5_read(struct device *dev, enum hwmon_sensor_types type,
 		if (attr == hwmon_fan_input && hwmon->fan)
 			return s5_read_fan(hwmon, val);
 		break;
+	case hwmon_pwm:
+		if (!hwmon->fan)
+			break;
+		switch (attr) {
+		case hwmon_pwm_input:
+			return s5_read_pwm(hwmon, val);
+		case hwmon_pwm_freq:
+			return s5_read_pwm_freq(hwmon, val);
+		default:
+			break;
+		}
+		break;
 	default:
 		break;
 	}
@@ -132,6 +183,85 @@ static int s5_read(struct device *dev, enum hwmon_sensor_types type,
 	return -EOPNOTSUPP;
 }
 
+static int s5_write_pwm(struct s5_hwmon *hwmon, long val)
+{
+	u32 data;
+
+	if (val < 0 || val > 255)
+		return -EINVAL;
+
+	data = readl_relaxed(hwmon->fan + FAN_CFG);
+	data &= ~FAN_CFG_DUTY_CYCLE;
+	data |= FIELD_PREP(FAN_CFG_DUTY_CYCLE, val);
+	writel_relaxed(data, hwmon->fan + FAN_CFG);
+
+	return 0;
+}
+
+static void s5_write_pwm_divider(struct s5_hwmon *hwmon, u32 divider)
+{
+	u32 data;
+
+	data = readl_relaxed(hwmon->fan + FAN_PWM_FREQ);
+	data &= ~FAN_PWM_FREQ_DIV;
+	data |= FIELD_PREP(FAN_PWM_FREQ_DIV, divider);
+	writel_relaxed(data, hwmon->fan + FAN_PWM_FREQ);
+}
+
+static int s5_write_pwm_period(struct s5_hwmon *hwmon)
+{
+	unsigned long rate;
+	u64 divider;
+
+	rate = DIV_ROUND_CLOSEST(hwmon->clk_rate, FAN_PWM_FREQ_SCALE);
+	divider = DIV_ROUND_CLOSEST_ULL((u64)rate * hwmon->pwm_period,
+					NSEC_PER_SEC);
+	if (!divider || divider > FIELD_MAX(FAN_PWM_FREQ_DIV))
+		return -ERANGE;
+
+	s5_write_pwm_divider(hwmon, divider);
+
+	return 0;
+}
+
+static int s5_write_pwm_freq(struct s5_hwmon *hwmon, long val)
+{
+	unsigned long rate, divider;
+
+	if (val <= 0)
+		return -EINVAL;
+
+	rate = DIV_ROUND_CLOSEST(hwmon->clk_rate, FAN_PWM_FREQ_SCALE);
+	if (val < DIV_ROUND_CLOSEST(rate, FIELD_MAX(FAN_PWM_FREQ_DIV)) ||
+	    val > rate)
+		return -ERANGE;
+
+	divider = DIV_ROUND_CLOSEST(rate, val);
+	divider = min_t(unsigned long, divider, FIELD_MAX(FAN_PWM_FREQ_DIV));
+
+	s5_write_pwm_divider(hwmon, divider);
+
+	return 0;
+}
+
+static int s5_write(struct device *dev, enum hwmon_sensor_types type,
+		    u32 attr, int channel, long val)
+{
+	struct s5_hwmon *hwmon = dev_get_drvdata(dev);
+
+	if (type != hwmon_pwm || !hwmon->fan)
+		return -EOPNOTSUPP;
+
+	switch (attr) {
+	case hwmon_pwm_input:
+		return s5_write_pwm(hwmon, val);
+	case hwmon_pwm_freq:
+		return s5_write_pwm_freq(hwmon, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
 static umode_t s5_is_visible(const void *_data, enum hwmon_sensor_types type,
 			     u32 attr, int channel)
 {
@@ -144,6 +274,12 @@ static umode_t s5_is_visible(const void *_data, enum hwmon_sensor_types type,
 		if (hwmon->fan && attr == hwmon_fan_input)
 			return 0444;
 		return 0;
+	case hwmon_pwm:
+		if (!hwmon->fan)
+			return 0;
+		if (attr == hwmon_pwm_input || attr == hwmon_pwm_freq)
+			return 0644;
+		return 0;
 	default:
 		return 0;
 	}
@@ -157,12 +293,14 @@ static const struct hwmon_channel_info * const s5_temp_info[] = {
 
 static const struct hwmon_channel_info * const s5_fan_info[] = {
 	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
+	HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_FREQ),
 	NULL
 };
 
 static const struct hwmon_ops s5_hwmon_ops = {
 	.is_visible = s5_is_visible,
 	.read = s5_read,
+	.write = s5_write,
 };
 
 static const struct hwmon_chip_info s5_temp_chip_info = {
@@ -175,6 +313,42 @@ static const struct hwmon_chip_info s5_fan_chip_info = {
 	.info = s5_fan_info,
 };
 
+static int s5_get_fan_data(struct device *dev, struct device_node *fan_np,
+			   struct s5_hwmon *hwmon)
+{
+	struct of_phandle_args args;
+	int ret;
+
+	ret = of_parse_phandle_with_args(fan_np, "pwms", "#pwm-cells", 0,
+					 &args);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to parse fan PWM\n");
+
+	if (args.np != dev->of_node || args.args_count != 2 || !args.args[0] ||
+	    args.args[1] & ~PWM_POLARITY_INVERTED) {
+		of_node_put(args.np);
+		return dev_err_probe(dev, -EINVAL, "invalid fan PWM specifier\n");
+	}
+
+	hwmon->pwm_period = args.args[0];
+	hwmon->pwm_inverted = args.args[1] & PWM_POLARITY_INVERTED;
+	of_node_put(args.np);
+
+	if (of_property_present(fan_np, "pulses-per-revolution")) {
+		ret = of_property_read_u32(fan_np, "pulses-per-revolution",
+					   &hwmon->pulses_per_revolution);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "invalid pulses-per-revolution\n");
+	}
+	if (!hwmon->pulses_per_revolution ||
+	    hwmon->pulses_per_revolution > 4)
+		return dev_err_probe(dev, -EINVAL,
+				     "invalid pulses-per-revolution\n");
+
+	return 0;
+}
+
 static int s5_temp_probe(struct platform_device *pdev)
 {
 	const struct s5_match_data *match_data;
@@ -201,18 +375,11 @@ static int s5_temp_probe(struct platform_device *pdev)
 		hwmon->fan = base;
 		hwmon->pulses_per_revolution = 2;
 		fan_np = of_get_available_child_by_name(dev->of_node, "fan");
-		if (fan_np &&
-		    of_property_present(fan_np, "pulses-per-revolution")) {
-			ret = of_property_read_u32(fan_np, "pulses-per-revolution",
-						   &hwmon->pulses_per_revolution);
+		if (fan_np) {
+			ret = s5_get_fan_data(dev, fan_np, hwmon);
 			if (ret)
-				return dev_err_probe(dev, ret,
-						     "invalid pulses-per-revolution\n");
+				return ret;
 		}
-		if (!hwmon->pulses_per_revolution ||
-		    hwmon->pulses_per_revolution > 4)
-			return dev_err_probe(dev, -EINVAL,
-					     "invalid pulses-per-revolution\n");
 	} else {
 		hwmon->base = base;
 	}
@@ -222,10 +389,17 @@ static int s5_temp_probe(struct platform_device *pdev)
 		return PTR_ERR(hwmon->clk);
 	hwmon->clk_rate = clk_get_rate(hwmon->clk);
 
-	if (is_fan)
+	if (is_fan) {
+		if (hwmon->pwm_period) {
+			ret = s5_write_pwm_period(hwmon);
+			if (ret)
+				return dev_err_probe(dev, ret,
+						     "invalid fan PWM period\n");
+		}
 		s5_fan_enable(hwmon);
-	else
+	} else {
 		s5_temp_enable(hwmon);
+	}
 
 	hwmon_dev = devm_hwmon_device_register_with_info(dev,
 					is_fan ? "lan969x_fan" : "s5_temp", hwmon,
-- 
2.56.0