[PATCH v14 04/10] pwm: max7360: Add MAX7360 PWM support

Mathieu Dubois-Briand
2025-08-24T11:58:07Z

From: Kamel Bouhara <kamel.bouhara@bootlin.com>

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>
---
drivers/pwm/Kconfig | 10 +++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-max7360.c | 209 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 220 insertions(+)

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index f00ce973dddf..f2b1ce47de7f 100644
--- a/drivers/pwm/Kconfig
+++ b/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
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index ff4f47e5fb7a..dfa8b4966ee1 100644
--- a/drivers/pwm/Makefile
+++ b/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
diff --git a/drivers/pwm/pwm-max7360.c b/drivers/pwm/pwm-max7360.c
new file mode 100644
index 000000000000..ebf93a7aee5b
--- /dev/null
+++ b/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");

--
2.39.5