pwm: max7360: Add MAX7360 PWM support

Add driver for Maxim Integrated MAX7360 PWM controller, supporting up to
8 independent PWM outputs.

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
Co-developed-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Uwe Kleine-König <ukleinek@kernel.org>
Link: https://lore.kernel.org/r/20250824-mdb-max7360-support-v14-4-435cfda2b1ea@bootlin.com
Signed-off-by: Lee Jones <lee@kernel.org>

drivers/pwm/Kconfig

@@ -432,6 +432,16 @@ config PWM_LPSS_PLATFORM
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-lpss-platform.
 
+config PWM_MAX7360
+	tristate "MAX7360 PWMs"
+	depends on MFD_MAX7360
+	help
+	  PWM driver for Maxim Integrated MAX7360 multifunction device, with
+	  support for up to 8 PWM outputs.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-max7360.
+
 config PWM_MC33XS2410
 	tristate "MC33XS2410 PWM support"
 	depends on OF

drivers/pwm/Makefile

@@ -38,6 +38,7 @@ obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
 obj-$(CONFIG_PWM_LPSS)		+= pwm-lpss.o
 obj-$(CONFIG_PWM_LPSS_PCI)	+= pwm-lpss-pci.o
 obj-$(CONFIG_PWM_LPSS_PLATFORM)	+= pwm-lpss-platform.o
+obj-$(CONFIG_PWM_MAX7360)	+= pwm-max7360.o
 obj-$(CONFIG_PWM_MC33XS2410)	+= pwm-mc33xs2410.o
 obj-$(CONFIG_PWM_MEDIATEK)	+= pwm-mediatek.o
 obj-$(CONFIG_PWM_MESON)		+= pwm-meson.o

drivers/pwm/pwm-max7360.c

@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2025 Bootlin
+ *
+ * Author: Kamel BOUHARA <kamel.bouhara@bootlin.com>
+ * Author: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
+ *
+ * PWM functionality of the MAX7360 multi-function device.
+ * https://www.analog.com/media/en/technical-documentation/data-sheets/MAX7360.pdf
+ *
+ * Limitations:
+ * - Only supports normal polarity.
+ * - The period is fixed to 2 ms.
+ * - Only the duty cycle can be changed, new values are applied at the beginning
+ *   of the next cycle.
+ * - When disabled, the output is put in Hi-Z immediately.
+ */
+#include <linux/bits.h>
+#include <linux/dev_printk.h>
+#include <linux/err.h>
+#include <linux/math64.h>
+#include <linux/mfd/max7360.h>
+#include <linux/minmax.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/regmap.h>
+#include <linux/time.h>
+#include <linux/types.h>
+
+#define MAX7360_NUM_PWMS			8
+#define MAX7360_PWM_MAX				255
+#define MAX7360_PWM_STEPS			256
+#define MAX7360_PWM_PERIOD_NS			(2 * NSEC_PER_MSEC)
+
+struct max7360_pwm_waveform {
+	u8 duty_steps;
+	bool enabled;
+};
+
+static int max7360_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct regmap *regmap = pwmchip_get_drvdata(chip);
+
+	/*
+	 * Make sure we use the individual PWM configuration register and not
+	 * the global one.
+	 * We never need to use the global one, so there is no need to revert
+	 * that in the .free() callback.
+	 */
+	return regmap_write_bits(regmap, MAX7360_REG_PWMCFG(pwm->hwpwm),
+				 MAX7360_PORT_CFG_COMMON_PWM, 0);
+}
+
+static int max7360_pwm_round_waveform_tohw(struct pwm_chip *chip,
+					   struct pwm_device *pwm,
+					   const struct pwm_waveform *wf,
+					   void *_wfhw)
+{
+	struct max7360_pwm_waveform *wfhw = _wfhw;
+	u64 duty_steps;
+
+	/*
+	 * Ignore user provided values for period_length_ns and duty_offset_ns:
+	 * we only support fixed period of MAX7360_PWM_PERIOD_NS and offset of 0.
+	 * Values from 0 to 254 as duty_steps will provide duty cycles of 0/256
+	 * to 254/256, while value 255 will provide a duty cycle of 100%.
+	 */
+	if (wf->duty_length_ns >= MAX7360_PWM_PERIOD_NS) {
+		duty_steps = MAX7360_PWM_MAX;
+	} else {
+		duty_steps = (u32)wf->duty_length_ns * MAX7360_PWM_STEPS / MAX7360_PWM_PERIOD_NS;
+		if (duty_steps == MAX7360_PWM_MAX)
+			duty_steps = MAX7360_PWM_MAX - 1;
+	}
+
+	wfhw->duty_steps = min(MAX7360_PWM_MAX, duty_steps);
+	wfhw->enabled = !!wf->period_length_ns;
+
+	if (wf->period_length_ns && wf->period_length_ns < MAX7360_PWM_PERIOD_NS)
+		return 1;
+	else
+		return 0;
+}
+
+static int max7360_pwm_round_waveform_fromhw(struct pwm_chip *chip, struct pwm_device *pwm,
+					     const void *_wfhw, struct pwm_waveform *wf)
+{
+	const struct max7360_pwm_waveform *wfhw = _wfhw;
+
+	wf->period_length_ns = wfhw->enabled ? MAX7360_PWM_PERIOD_NS : 0;
+	wf->duty_offset_ns = 0;
+
+	if (wfhw->enabled) {
+		if (wfhw->duty_steps == MAX7360_PWM_MAX)
+			wf->duty_length_ns = MAX7360_PWM_PERIOD_NS;
+		else
+			wf->duty_length_ns = DIV_ROUND_UP(wfhw->duty_steps * MAX7360_PWM_PERIOD_NS,
+							  MAX7360_PWM_STEPS);
+	} else {
+		wf->duty_length_ns = 0;
+	}
+
+	return 0;
+}
+
+static int max7360_pwm_write_waveform(struct pwm_chip *chip,
+				      struct pwm_device *pwm,
+				      const void *_wfhw)
+{
+	struct regmap *regmap = pwmchip_get_drvdata(chip);
+	const struct max7360_pwm_waveform *wfhw = _wfhw;
+	unsigned int val;
+	int ret;
+
+	if (wfhw->enabled) {
+		ret = regmap_write(regmap, MAX7360_REG_PWM(pwm->hwpwm), wfhw->duty_steps);
+		if (ret)
+			return ret;
+	}
+
+	val = wfhw->enabled ? BIT(pwm->hwpwm) : 0;
+	return regmap_write_bits(regmap, MAX7360_REG_GPIOCTRL, BIT(pwm->hwpwm), val);
+}
+
+static int max7360_pwm_read_waveform(struct pwm_chip *chip,
+				     struct pwm_device *pwm,
+				     void *_wfhw)
+{
+	struct regmap *regmap = pwmchip_get_drvdata(chip);
+	struct max7360_pwm_waveform *wfhw = _wfhw;
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(regmap, MAX7360_REG_GPIOCTRL, &val);
+	if (ret)
+		return ret;
+
+	if (val & BIT(pwm->hwpwm)) {
+		wfhw->enabled = true;
+		ret = regmap_read(regmap, MAX7360_REG_PWM(pwm->hwpwm), &val);
+		if (ret)
+			return ret;
+
+		wfhw->duty_steps = val;
+	} else {
+		wfhw->enabled = false;
+		wfhw->duty_steps = 0;
+	}
+
+	return 0;
+}
+
+static const struct pwm_ops max7360_pwm_ops = {
+	.request = max7360_pwm_request,
+	.round_waveform_tohw = max7360_pwm_round_waveform_tohw,
+	.round_waveform_fromhw = max7360_pwm_round_waveform_fromhw,
+	.read_waveform = max7360_pwm_read_waveform,
+	.write_waveform = max7360_pwm_write_waveform,
+};
+
+static int max7360_pwm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct pwm_chip *chip;
+	struct regmap *regmap;
+	int ret;
+
+	regmap = dev_get_regmap(dev->parent, NULL);
+	if (!regmap)
+		return dev_err_probe(dev, -ENODEV, "Could not get parent regmap\n");
+
+	/*
+	 * This MFD sub-device does not have any associated device tree node:
+	 * properties are stored in the device node of the parent (MFD) device
+	 * and this same node is used in phandles of client devices.
+	 * Reuse this device tree node here, as otherwise the PWM subsystem
+	 * would be confused by this topology.
+	 */
+	device_set_of_node_from_dev(dev, dev->parent);
+
+	chip = devm_pwmchip_alloc(dev, MAX7360_NUM_PWMS, 0);
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+	chip->ops = &max7360_pwm_ops;
+
+	pwmchip_set_drvdata(chip, regmap);
+
+	ret = devm_pwmchip_add(dev, chip);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to add PWM chip\n");
+
+	return 0;
+}
+
+static struct platform_driver max7360_pwm_driver = {
+	.driver = {
+		.name = "max7360-pwm",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.probe = max7360_pwm_probe,
+};
+module_platform_driver(max7360_pwm_driver);
+
+MODULE_DESCRIPTION("MAX7360 PWM driver");
+MODULE_AUTHOR("Kamel BOUHARA <kamel.bouhara@bootlin.com>");
+MODULE_AUTHOR("Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>");
+MODULE_LICENSE("GPL");